Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

NASA Astrophysics Data System (ADS)

Mou, Guobin; Wang, Tinggui; Yang, Chenwei

2017-07-01

The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

Inverse Compton X-ray signature of AGN feedback

NASA Astrophysics Data System (ADS)

Bourne, Martin A.; Nayakshin, Sergei

2013-12-01

Bright AGN frequently show ultrafast outflows (UFOs) with outflow velocities vout ˜ 0.1c. These outflows may be the source of AGN feedback on their host galaxies sought by galaxy formation modellers. The exact effect of the outflows on the ambient galaxy gas strongly depends on whether the shocked UFOs cool rapidly or not. This in turn depends on whether the shocked electrons share the same temperature as ions (one-temperature regime, 1T) or decouple (2T), as has been recently suggested. Here we calculate the inverse Compton spectrum emitted by such shocks, finding a broad feature potentially detectable either in mid-to-high energy X-rays (1T case) or only in the soft X-rays (2T). We argue that current observations of AGN do not seem to show evidence for the 1T component. The limits on the 2T emission are far weaker, and in fact it is possible that the observed soft X-ray excess of AGN is partially or fully due to the 2T shock emission. This suggests that UFOs are in the energy-driven regime outside the central few pc, and must pump considerable amounts of not only momentum but also energy into the ambient gas. We encourage X-ray observers to look for the inverse Compton components calculated here in order to constrain AGN feedback models further.

Momentum-driven Winds from Radiatively Efficient Black Hole Accretion and Their Impact on Galaxies

NASA Astrophysics Data System (ADS)

Brennan, Ryan; Choi, Ena; Somerville, Rachel S.; Hirschmann, Michaela; Naab, Thorsten; Ostriker, Jeremiah P.

2018-06-01

We explore the effect of momentum-driven winds representing radiation-pressure-driven outflows from accretion onto supermassive black holes in a set of numerical hydrodynamical simulations. We explore two matched sets of cosmological zoom-in runs of 24 halos with masses ∼1012.0–1013.4 M ⊙ run with two different feedback models. Our “NoAGN” model includes stellar feedback via UV heating, stellar winds and supernovae, photoelectric heating, and cosmic X-ray background heating from a metagalactic background. Our fiducial “MrAGN” model is identical except that it also includes a model for black hole seeding and accretion, as well as heating and momentum injection associated with the radiation from black hole accretion. Our MrAGN model launches galactic outflows, which result in both “ejective” feedback—the outflows themselves that drive gas out of galaxies—and “preventative” feedback, which suppresses the inflow of new and recycling gas. As much as 80% of outflowing galactic gas can be expelled, and accretion can be suppressed by as much as a factor of 30 in the MrAGN runs when compared with the NoAGN runs. The histories of NoAGN galaxies are recycling dominated, with ∼70% of material that leaves the galaxy eventually returning, and the majority of outflowing gas reaccretes on 1 Gyr timescales without AGN feedback. Outflowing gas in the MrAGN runs has a higher characteristic velocity (500–1000 km s‑1 versus 100–300 km s‑1 for outflowing NoAGN gas) and travels as far as a few megaparsecs. Only ∼10% of ejected material is reaccreted in the MrAGN galaxies.

New Insights into the Spectral Variability and Physical Conditions of the X-Ray Absorbers in NGC 4151

NASA Astrophysics Data System (ADS)

Couto, J. D.; Kraemer, S. B.; Turner, T. J.; Crenshaw, D. M.

2016-12-01

We investigate the relationship between the long-term X-ray spectral variability in the Seyfert 1.5 galaxy NGC 4151 and its intrinsic absorption, by comparing the 2014 simultaneous ultraviolet/X-ray observations taken with Hubble STIS Echelle and Chandra HETGS with archival observations from Chandra, XMM-Newton, and Suzaku. The observations are divided into “high” and “low” states, with the low states showing strong and unabsorbed extended emission at energies below 2 keV. Our X-ray model consists of a broken powerlaw, neutral reflection, and the two dominant absorption components identified by Kraemer et al. (2005, hereafter KRA2005) X-High and D+Ea, which are present in all epochs. The model fittings suggest that the absorbers are very stable, with the principal changes in the intrinsic absorption resulting from variations in the ionization state of the gas as the ionizing continuum varies. However, the low states show evidence of larger column densities in one or both of the absorbers. Among plausible explanations for the column increase, we discuss the possibility of an expanding/contracting X-ray corona. As suggested by KRA2005, there seem to be contributions from magnetohydrodynamic (MHD) winds to the mass outflow. Along with the ultra-fast outflow absorber identified by Tombesi et al. (2010), X-High is consistent with being magnetically driven. On the other hand, it is unlikely that D+Ea is part of the MHD flow, and it is possible that it is radiatively accelerated. These results suggest that at a sufficiently large radial distance there is a break point between MHD-dominated and radiatively driven outflows.

Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mou, Guobin; Wang, Tinggui; Yang, Chenwei, E-mail: gbmou@ustc.edu.cn

The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but ismore » close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.« less

Effect of nuclear stars gravity on quasar radiation feedback on the parsec-scale

NASA Astrophysics Data System (ADS)

Yang, Xiao-Hong; Bu, De-Fu

2018-05-01

It is often suggested that a super massive black hole is embedded in a nuclear bulge of size of a few 102 parsec . The nuclear stars gravity is not negligible near ˜10parsec. In order to study the effect of nuclear stars gravity on quasar radiation feedback on the parsec scale, we have simulated the parsec scale flows irradiated by a quasar by taking into account the gravitational potential of both the black hole and the nuclear star cluster. We find that the effect of nuclear stars gravity on the parsec-scale flows is related to the fraction of X-ray photons in quasar radiation. For the models in which the fraction of X-ray photons is not small (e.g. the X-ray photons contribute to 20% of the quasar radiation), the nuclear stars gravity is very helpful to collimate the outflows driven by UV photons, significantly weakens the outflow power at the outer boundary and significantly enhances the net accretion rate onto the black hole. For the models in which X-ray photons are significantly decreased (e.g. the X-ray photons contribute to 5% of the quasar radiation), the nuclear stars gravity can just slightly change properties of outflow and slightly enhance the net accretion rate onto the black hole.

Thermal Disk Winds in X-Ray Binaries: Realistic Heating and Cooling Rates Give Rise to Slow, but Massive, Outflows

NASA Astrophysics Data System (ADS)

Higginbottom, N.; Proga, D.; Knigge, C.; Long, K. S.

2017-02-01

A number of X-ray binaries exhibit clear evidence for the presence of disk winds in the high/soft state. A promising driving mechanism for these outflows is mass loss driven by the thermal expansion of X-ray heated material in the outer disk atmosphere. Higginbottom & Proga recently demonstrated that the properties of thermally driven winds depend critically on the shape of the thermal equilibrium curve, since this determines the thermal stability of the irradiated material. For a given spectral energy distribution, the thermal equilibrium curve depends on an exact balance between the various heating and cooling mechanisms at work. Most previous work on thermally driven disk winds relied on an analytical approximation to these rates. Here, we use the photoionization code cloudy to generate realistic heating and cooling rates which we then use in a 2.5D hydrodynamic model computed in ZEUS to simulate thermal winds in a typical black hole X-ray binary. We find that these heating and cooling rates produce a significantly more complex thermal equilibrium curve, with dramatically different stability properties. The resulting flow, calculated in the optically thin limit, is qualitatively different from flows calculated using approximate analytical rates. Specifically, our thermal disk wind is much denser and slower, with a mass-loss rate that is a factor of two higher and characteristic velocities that are a factor of three lower. The low velocity of the flow—{v}\\max ≃ 200 km s-1—may be difficult to reconcile with observations. However, the high mass-loss rate—15 × the accretion rate—is promising, since it has the potential to destabilize the disk. Thermally driven disk winds may therefore provide a mechanism for state changes.

Fast Ionized X-ray Absorbers in AGNs

NASA Astrophysics Data System (ADS)

Fukumura, K.; Tombesi, F.; Kazanas, D.; Shrader, C.; Behar, E.; Contopoulos, I.

2015-07-01

We present a study of X-ray ionization of MHD accretion-disk wind models in an effort to explain the highly-ionized ultra-fast outflows (UFOs) identified as X-ray absorbers recently detected in various sub-classes of Seyfert AGNs. Our primary focus is to show that magnetically-driven outflows are physically plausible candidates to account for the AGN X-ray spectroscopic observations. We calculate its X-ray ionization and the ensuing X-ray absorption line spectra in comparison with an XXM-Newton/EPIC spectrum of the narrow-line Seyfert AGN, PG 1211+143. We find, through identifying the detected features with Fe Kα transitions, that the absorber has a characteristic ionization parameter of log(xi[erg cm/s]) = 5-6 and a hydrogen-equivalent column density on the order of 1e23 cm-2, outflowing at a sub-relativistic velocity of v/c = 0.1-0.2. The best-fit model favors its radial location at R = 200 Rs (Rs is the Schwarzschild radius), with a disk inner truncation radius at Rt = 30Rs. The overall K-shell feature in data is suggested to be dominated by Fe XXV with very little contribution from Fe XXVI and weakly-ionized iron, which is in a good agreement with a series of earlier analysis of the UFOs in various AGNs including PG 1211+143.

Strong disk winds traced throughout outbursts in black-hole X-ray binaries

NASA Astrophysics Data System (ADS)

Tetarenko, B. E.; Lasota, J.-P.; Heinke, C. O.; Dubus, G.; Sivakoff, G. R.

2018-02-01

Recurring outbursts associated with matter flowing onto compact stellar remnants (such as black holes, neutron stars and white dwarfs) in close binary systems provide a way of constraining the poorly understood accretion process. The light curves of these outbursts are shaped by the efficiency of angular-momentum (and thus mass) transport in the accretion disks, which has traditionally been encoded in a viscosity parameter, α. Numerical simulations of the magneto-rotational instability that is believed to be the physical mechanism behind this transport yield values of α of roughly 0.1–0.2, consistent with values determined from observations of accreting white dwarfs. Equivalent viscosity parameters have hitherto not been estimated for disks around neutron stars or black holes. Here we report the results of an analysis of archival X-ray light curves of 21 outbursts in black-hole X-ray binaries. By applying a Bayesian approach to a model of accretion, we determine corresponding values of α of around 0.2–1.0. These high values may be interpreted as an indication either of a very high intrinsic rate of angular-momentum transport in the disk, which could be sustained by the magneto-rotational instability only if a large-scale magnetic field threads the disk, or that mass is being lost from the disk through substantial outflows, which strongly shape the outburst in the black-hole X-ray binary. The lack of correlation between our estimates of α and the accretion state of the binaries implies that such outflows can remove a substantial fraction of the disk mass in all accretion states and therefore suggests that the outflows correspond to magnetically driven disk winds rather than thermally driven ones, which require specific radiative conditions.

Strong disk winds traced throughout outbursts in black-hole X-ray binaries.

PubMed

Tetarenko, B E; Lasota, J-P; Heinke, C O; Dubus, G; Sivakoff, G R

2018-02-01

Recurring outbursts associated with matter flowing onto compact stellar remnants (such as black holes, neutron stars and white dwarfs) in close binary systems provide a way of constraining the poorly understood accretion process. The light curves of these outbursts are shaped by the efficiency of angular-momentum (and thus mass) transport in the accretion disks, which has traditionally been encoded in a viscosity parameter, α. Numerical simulations of the magneto-rotational instability that is believed to be the physical mechanism behind this transport yield values of α of roughly 0.1-0.2, consistent with values determined from observations of accreting white dwarfs. Equivalent viscosity parameters have hitherto not been estimated for disks around neutron stars or black holes. Here we report the results of an analysis of archival X-ray light curves of 21 outbursts in black-hole X-ray binaries. By applying a Bayesian approach to a model of accretion, we determine corresponding values of α of around 0.2-1.0. These high values may be interpreted as an indication either of a very high intrinsic rate of angular-momentum transport in the disk, which could be sustained by the magneto-rotational instability only if a large-scale magnetic field threads the disk, or that mass is being lost from the disk through substantial outflows, which strongly shape the outburst in the black-hole X-ray binary. The lack of correlation between our estimates of α and the accretion state of the binaries implies that such outflows can remove a substantial fraction of the disk mass in all accretion states and therefore suggests that the outflows correspond to magnetically driven disk winds rather than thermally driven ones, which require specific radiative conditions.

New Insights into AGN Mass Outflows: Detailed Study of the Spectral Properties of NGC 4151

NASA Astrophysics Data System (ADS)

Denes Couto, Jullianna

2017-08-01

Active Galactic Nuclei (AGNs) exist in a few percent of all massive galaxies. It is believed that AGNs are powered by accretion of matter onto a supermassive black hole (SMBH), generating in the process huge amounts of radiation that span the entire electromagnetic spectrum. In turn, this also triggers the so-called AGN Feedback phenomenon, by inducing the formation of accretion disk winds (or outflows) that accelerate highly ionized gas outwards and affect the intergalactic medium of the host galaxy, reducing star formation rates and preventing bulge growth. It has been suggested that a dominant component of mass outflows is observable in the X-rays, and there are a limited number of detailed studies of single objects for which the relation between outflows and power of the central engine can be determined directly. The Seyfert 1.5 galaxy NGC 4151 is a great study candidate, given its proximity (14.077 Mpc, z = 0.0033), X-ray brightness and orientation. Over the past decades, it has been the target of many single and multiwavelength observations, and its heavily absorbed X-ray spectrum and complex absorption features have been extensively stud- ied and characterized. I have investigated the relationship between the long term X-ray spectral variability in and its intrinsic absorption, by comparing our 2014 simultaneous ultraviolet/X-Ray observations taken with Hubble Space Telescope Imaging Spectrometer (STIS) Echelle and Chandra High Energy Transmission Grating Spectrometer (HETGS) with archival observations from Chandra, XMM-Newton and Suzaku. The observations were divided into "high" and "low" flux states, with the low states showing strong and unabsorbed extended emission at energies below 2 keV. The X-ray model consists of a broken powerlaw, neutral reflection and two dominant absorption components, a high and a low ionization component, which are present in all epochs. The model fittings suggest that the absorbers are very stable, with the principal changes in the intrinsic absorption resulting from a response to the variable strength of the ionizing continuum. However, the low states show evidence of larger column densities in one or both of the absorbers. Among plausible explanations for the column increase, I discuss the possibility of an expanding/contracting X-ray corona. The higher ionization component is consistent with being part of a magnetohydrodynamic (MHD) wind, while the lower is possibly radiatively driven, which suggests that at a sufficiently large radial distance there could be a break point between MHD-dominated and radiatively driven outflows. The final model of the absorbed continuum was used as input to the analysis of the soft X-ray emission, which arises in an extended medium of several hundred parsecs. There is evidence of at least four components of gas, with different ionization states and different kinematic profiles. I calculated global covering factors, total masses, mass outflow rates and kinetic luminosity estimates for each component. The models results indicate that it is unlikely that the X-ray wind could contribute significantly to a large scale feedback on NGC 4151. However, this might not be the case for more powerful and energetic sources.

Properties of Neutrino-driven Ejecta from the Remnant of a Binary Neutron Star Merger: Pure Radiation Hydrodynamics Case

NASA Astrophysics Data System (ADS)

Fujibayashi, Sho; Sekiguchi, Yuichiro; Kiuchi, Kenta; Shibata, Masaru

2017-09-01

We performed general relativistic, long-term, axisymmetric neutrino radiation hydrodynamics simulations for the remnant formed after a binary neutron star merger, which consists of a massive neutron star and a torus surrounding it. As an initial condition, we employ the result derived in a three-dimensional, numerical relativity simulation for the binary neutron star merger. We investigate the properties of neutrino-driven ejecta. Due to the pair-annihilation heating, the dynamics of the neutrino-driven ejecta are significantly modified. The kinetic energy of the ejecta is about two times larger than that in the absence of pair-annihilation heating. This suggests that the pair-annihilation heating plays an important role in the evolution of merger remnants. The relativistic outflow, which is required for driving gamma-ray bursts, is not observed because the specific heating rate around the rotational axis is not sufficiently high, due to the baryon loading caused by the neutrino-driven ejecta from the massive neutron star. We discuss the condition for launching the relativistic outflow and the nucleosynthesis in the ejecta.

A New Look at Speeding Outflows

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-02-01

The compact centers of active galaxies known as active galactic nuclei, or AGN are known for the dynamic behavior they exhibit as the supermassive black holes at their centers accrete matter. New observations of outflows from a nearby AGN provide a more detailed look at what happens in these extreme environments.Outflows from GiantsThe powerful radio jets of Cygnus A, which extend far beyond the galaxy. [NRAO/AUI]AGN consist of a supermassive black hole of millions to tens of billions of solar masses surrounded by an accretion disk of in-falling matter. But not all the material falling toward the black hole accretes! Some of it is flung from the AGN via various types of outflows.The most well-known of these outflows are powerful radio jets collimated and incredibly fast-moving streams of particles that blast their way out of the host galaxy and into space. Only around 10% of AGN are observed to host such jets, however and theres another outflow thats more ubiquitous.Fast-Moving AbsorbersPerhaps 30% of AGN both those with and without observed radio jets host wider-angle, highly ionized gaseous outflows known as ultra-fast outflows (UFOs). Ultraviolet and X-ray radiation emitted from the AGN is absorbed by the UFO, revealing the outflows presence: absorption lines appear in the ultraviolet and X-ray spectra of the AGN, blue-shifted due to the high speeds of the absorbing gas in the outflow.Quasar PG 1211+143, indicated by the crosshairs at the center of the image, in the color context of its surroundings. [SDSS/S. Karge]But what is the nature of UFOs? Are they disk winds? Or are they somehow related to the radio jets? And what impact do they have on the AGNs host galaxy?X-ray and Ultraviolet CooperationNew observations are now providing fresh information about one particular UFO. A team of scientists led by Ashkbiz Danehkar (Harvard-Smithsonian Center for Astrophysics) recently used the Chandra and Hubble space telescopes to make the first simultaneous observations of the same outflow a UFO in quasar PG 1211+143 in both X-rays and in ultraviolet.Danehkar and collaborators found absorption lines in both sets of data revealing an outflow moving at 17,000 km/s (for reference, thats 5.6% of the speed of light, and more than 1,500 times faster than Elon Musks roadster will be traveling at its maximum speed in the orbit it was launched onto yesterday by the Falcon Heavy). Having the information both from the X-ray and the ultraviolet data provides the opportunity to better asses the UFOs physical characteristics.The X-ray spectrum for PG 1211+143 was obtained by Chandra HETGS (top); the ultraviolet spectrum was obtained by HST-COS G130M (bottom). [Adapted from Danehkar et al. 2018]A Link Between Black Holes and Galaxies?The authors use models of the data to demonstrate the plausibility of a scenario in which a shock driven by the radio jet gives rise to the fast bulk outflows detected in the X-ray and ultraviolet spectra.They also estimate the impact that the outflows might have on the AGNs host galaxy, demonstrating that the energy injected into the galaxy could be somewhere between 0.02% and 0.6% of the AGNs total luminosity. At the higher end of this range, this could have an evolutionary impact on the host galaxy, suggesting a possible link between the black holes behavior and how its host galaxy evolves.In order to draw definitive conclusions, we will need higher-resolution observations that can determine the total size and extent of these outflows. For that, we may need to wait for 2023, when a proposed X-ray spectrometer that might fit the bill, Arcus, may be launched.CitationAshkbiz Danehkar et al 2018 ApJ 853 165. doi:10.3847/1538-4357/aaa427

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujibayashi, Sho; Sekiguchi, Yuichiro; Kiuchi, Kenta

We performed general relativistic, long-term, axisymmetric neutrino radiation hydrodynamics simulations for the remnant formed after a binary neutron star merger, which consists of a massive neutron star and a torus surrounding it. As an initial condition, we employ the result derived in a three-dimensional, numerical relativity simulation for the binary neutron star merger. We investigate the properties of neutrino-driven ejecta. Due to the pair-annihilation heating, the dynamics of the neutrino-driven ejecta are significantly modified. The kinetic energy of the ejecta is about two times larger than that in the absence of pair-annihilation heating. This suggests that the pair-annihilation heating playsmore » an important role in the evolution of merger remnants. The relativistic outflow, which is required for driving gamma-ray bursts, is not observed because the specific heating rate around the rotational axis is not sufficiently high, due to the baryon loading caused by the neutrino-driven ejecta from the massive neutron star. We discuss the condition for launching the relativistic outflow and the nucleosynthesis in the ejecta.« less

Superwind Outflow in Seyfert Galaxies? : Optical Observations of an Edge-On Sample

NASA Astrophysics Data System (ADS)

Colbert, E.; Gallimore, J.; Baum, S.; O'Dea, C.; Lehnert, M.

1994-12-01

Large-scale galactic winds (superwinds) are commonly found flowing out of the nuclear region of ultraluminous infrared and powerful starburst galaxies. Stellar winds and supernovae from the nuclear starburst are thought to provide the energy to drive these superwinds. The outflowing gas escapes along the rotation axis, sweeping up and shock-heating clouds in the halo, which produces optical line emission, X-rays and radio synchrotron emission. These features can most easily be studied in edge-on systems, so that the wind emission is not confused by that from the disk. Diffuse radio emission has been found (Baum et al. 1993, ApJ, 419, 553) to extend out to kpc-scales in a number of edge-on Seyfert galaxies. We have therefore launched a systematic search for superwind outflows in Seyferts. We present here narrow-band optical images and optical spectra for a sample of edge-on Seyferts. These data have been used to estimate the frequency of occurence of superwinds. Approximately half of the sample objects show evidence for extended emission-line regions which are preferentially oriented perpendicular to the galaxy disk. It is possible that these emission-line regions may be energized by a superwind outflow from a circumnuclear starburst, although there may also be a contribution from the AGN itself. A goal of this work is to find a diagnostic that can be used to distinguish between large-scale outflows that are driven by starbursts and those that are driven by an AGN. The presence of starburst-driven superwinds in Seyferts, if established, would have important implications for the connection between starburst galaxies and AGN.

X-Ray Modeling of the Intrinsic Absorption in NGC 4151

NASA Astrophysics Data System (ADS)

Denes Couto, Jullianna; Kraemer, Steven; Turner, T. Jane; Crenshaw, D. Michael

2017-01-01

We have investigated the relationship between the long term X-ray spectral variability in the Seyfert 1.5 galaxy NGC 4151 and its intrinsic absorption, by comparing our 2014 simultaneous ultraviolet/X-Ray observations taken with Hubble STIS Echelle and Chandra HETGS with archival observations from Chandra, XMM-Newton and Suzaku. The observations were divided into "high" and "low" states, with the low states showing strong and unabsorbed extended emission at energies below 2 keV. Our X-ray model consists of a broken powerlaw, neutral reflection and the two dominant absorption components identified by Kraemer et al (2005), X-High and D+Ea, which are present in all epochs. The model fittings suggest that the absorbers are very stable, with the principal changes in the intrinsic absorption resulting from variations in the ionization state of the gas in response to the variable strength of the ionizing continuum. However, the low states show evidence of larger column densities in one or both of the absorbers. Among plausible explanations for the column increase, we discuss the possibility of an expanding/contracting X-ray corona. X-High is consistent with being part of a magnetohydrodynamic (MHD) wind, while D+Ea is possibly radiatively driven, which suggests that at a sufficiently large radial distance there could be a break point between MHD-dominated and radiatively driven outflows. Preliminary results on the analysis of the AGN mass outflow rates and kinematics of the ionized gas in the extended emission region of NGC 4151 will also be presented.

High-redshift Extremely Red Quasars in X-Rays

NASA Astrophysics Data System (ADS)

Goulding, Andy D.; Zakamska, Nadia L.; Alexandroff, Rachael M.; Assef, Roberto J.; Banerji, Manda; Hamann, Fred; Wylezalek, Dominika; Brandt, William N.; Greene, Jenny E.; Lansbury, George B.; Pâris, Isabelle; Richards, Gordon; Stern, Daniel; Strauss, Michael A.

2018-03-01

Quasars may have played a key role in limiting the stellar mass of massive galaxies. Identifying those quasars in the process of removing star formation fuel from their hosts is an exciting ongoing challenge in extragalactic astronomy. In this paper, we present X-ray observations of 11 extremely red quasars (ERQs) with L bol ∼ 1047 erg s‑1 at z = 1.5–3.2 with evidence for high-velocity (v ≥slant 1000 km s‑1) [O III] λ5007 outflows. X-rays allow us to directly probe circumnuclear obscuration and to measure the instantaneous accretion luminosity. We detect 10 out of 11 ERQs available in targeted and archival data. Using a combination of X-ray spectral fitting and hardness ratios, we find that all of the ERQs show signs of absorption in the X-rays with inferred column densities of N H ≈ 1023 cm‑2, including four Compton-thick candidates (N H ≥slant 1024 cm‑2). We stack the X-ray emission of the seven weakly detected sources, measuring an average column density of N H ∼ 8 × 1023 cm‑2. The absorption-corrected (intrinsic) 2–10 keV X-ray luminosity of the stack is 2.7 × 1045 erg s‑1, consistent with X-ray luminosities of type 1 quasars of the same infrared luminosity. Thus, we find that ERQs are a highly obscured, borderline Compton-thick population, and based on optical and infrared data we suggest that these objects are partially hidden by their own equatorial outflows. However, unlike some quasars with known outflows, ERQs do not appear to be intrinsically underluminous in X-rays for their bolometric luminosity. Our observations indicate that low X-rays are not necessary to enable some types of radiatively driven winds.

Radiation hydrodynamic simulations of line-driven disk winds for ultra-fast outflows

NASA Astrophysics Data System (ADS)

Nomura, Mariko; Ohsuga, Ken; Takahashi, Hiroyuki R.; Wada, Keiichi; Yoshida, Tessei

2016-02-01

Using two-dimensional radiation hydrodynamic simulations, we investigate the origin of the ultra-fast outflows (UFOs) that are often observed in luminous active galactic nuclei (AGNs). We found that the radiation force due to the spectral lines generates strong winds (line-driven disk winds) that are launched from the inner region of accretion disks (˜30 Schwarzschild radii). A wide range of black hole masses (MBH) and Eddington ratios (ε) was investigated to study the conditions causing the line-driven winds. For MBH = 106-109 M⊙ and ε = 0.1-0.7, funnel-shaped disk winds appear, in which dense matter is accelerated outward with an opening angle of 70°-80° and with 10% of the speed of light. If we observe the wind along its direction, the velocity, the column density, and the ionization state are consistent with those of the observed UFOs. As long as obscuration by the torus does not affect the observation of X-ray bands, the UFOs could be statistically observed in about 13%-28% of the luminous AGNs, which is not inconsistent with the observed ratio (˜40%). We also found that the results are insensitive to the X-ray luminosity and the density of the disk surface. Thus, we can conclude that UFOs could exist in any luminous AGNs, such as narrow-line Seyfert 1s and quasars with ε > 0.1, with which fast line-driven winds are associated.

Radiation-hydrodynamic simulations of thermally-driven disc winds in X-ray binaries: A direct comparison to GRO J1655-40

NASA Astrophysics Data System (ADS)

Higginbottom, Nick; Knigge, Christian; Long, Knox S.; Matthews, James H.; Sim, Stuart A.; Hewitt, Henrietta A.

2018-06-01

Essentially all low-mass X-ray binaries (LMXBs) in the soft state appear to drive powerful equatorial disc winds. A simple mechanism for driving such outflows involves X-ray heating of the top of the disc atmosphere to the Compton temperature. Beyond the Compton radius, the thermal speed exceeds the escape velocity, and mass loss is inevitable. Here, we present the first coupled radiation-hydrodynamic simulation of such thermally-driven disc winds. The main advance over previous modelling efforts is that the frequency-dependent attenuation of the irradiating SED is taken into account. We can therefore relax the approximation that the wind is optically thin throughout which is unlikely to hold in the crucial acceleration zone of the flow. The main remaining limitations of our simulations are connected to our treatment of optically thick regions. Adopting parameters representative of the wind-driving LMXB GRO J1655-40, our radiation-hydrodynamic model yields a mass-loss rate that is ≃ 5 × lower than that suggested by pure hydrodynamic, optically thin models. This outflow rate still represents more than twice the accretion rate and agrees well with the mass-loss rate inferred from Chandra/HETG observations of GRO J1655-40 at a time when the system had a similar luminosity to that adopted in our simulations. The Fe XXV and Fe XXVI Lyman {α } absorption line profiles observed in this state are slightly stronger than those predicted by our simulations but the qualitative agreement between observed and simulated outflow properties means that thermal driving is a viable mechanism for powering the disc winds seen in soft-state LMXBs.

A Mechanism for Bulk Energization in the Impulsive Phase of Solar Flares: MHD Turbulent Cascade

NASA Technical Reports Server (NTRS)

LaRosa, T. N.; Moore, R. L.

1993-01-01

We propose that the large production rate (approximately 10(exp 36)/s) of energetic electrons (greater than or approximately equal to 25 keV) required to account for the impulsive-phase hard X-ray burst in large flares is achieved through MHD turbulent cascade of the bulk kinetic energy of the outflows from many separate reconnection events. Focusing on large two- ribbon eruptive flares as representative of most large flares, we envision the reconnection events to be the driven reconnection of oppositely directed elementary flux tubes pressing into the flare-length current-sheet interface that forms in the wake of the eruption of the sheared core of the preflare bipolar field configuration. We point out that, because the outflows from these driven reconnection events have speeds of order the Alfven speed and because the magnetic field reduces the shear viscosity of the plasma, it is reasonable that the outflows are unstable and turbulent, so that the kinetic energy of an outflow is rapidly dissipated through turbulent cascade. If the largest eddies in the turbulence have diameters of order the expected widths of the outflows (10(exp 7)-10(exp 8)cm), then the cascade dissipation of each of these eddies could produce approximately 10(exp 26) erg burst of energized electrons (approximately 3 x (10(exp 33) 25 keV electrons) in approximately 0.3 s, which agrees well with hard X-ray and radio sub-bursts commonly observed during the impulsive phase. Of order 10(exp 2) simultaneous reconnection events with turbulent outflow would produce the observed rate of impulsive-phase plasma energization in the most powerful flares (approximately 10(exp 36) 25 keV electrons/ s); this number of reconnection sites can easily fit within the estimated 3 x 10(exp 9) cm span of the overall current-sheet dissipation region formed in these large flares. We therefore conclude that MHD turbulent cascade is a promising mechanism for the plasma energization observed in the impulsive phase of solar flares.

Neutrino-heated winds from rotating protomagnetars

NASA Astrophysics Data System (ADS)

Vlasov, Andrey D.; Metzger, Brian D.; Thompson, Todd A.

2014-11-01

We calculate the steady-state properties of neutrino-driven winds from strongly magnetized, rotating protoneutron stars (PNSs; `protomagnetars') under the assumption that the outflow geometry is set by the force-free magnetic field of an aligned dipole. Our goal is to assess protomagnetars as sites of r-process nucleosynthesis and gamma-ray burst engines using a more realistic outflow geometry than assumed in previous works. One-dimensional solutions calculated along flux tubes corresponding to different polar field lines are stitched together to determine the global properties of the flow at a given neutrino luminosity and rotation period. Protomagnetars with rotation periods of P ˜ 2-5 ms are shown to produce outflows more favourable for the production of third-peak r-process nuclei due to their much shorter expansion times through the seed nucleus formation region, yet only moderately lower entropies, as compared to normal spherical PNS winds. Protomagnetars with moderately rapid birth periods P ˜ 3-5 ms may thus represent a promising galactic r-process site which is compatible with a variety of other observations, including the recent discovery of possible magnetar-powered supernovae in metal-poor galaxies. We also confirm previous results that the outflows from protomagnetars with P ˜ 1-2 ms can achieve maximum Lorentz factors Γmax ˜ 100-1000 in the range necessary to power gamma-ray bursts (GRBs). The implications of GRB jets with a heavy nuclei-dominated composition as sources of ultrahigh energy cosmic rays are also addressed.

Spatially resolved rest-UV spectroscopy of a prototypical quasar driven superwind at low-z

NASA Astrophysics Data System (ADS)

Johnson, Sean

2017-08-01

Powerful galaxy-wide winds launched by quasars are thought to be a common evolutionary phase of massive galaxies, but observations of this phenomena are scarce. We have conducted a multi-wavelength observational campaign for J1356+1026, a poster-child obscured quasar driving a superwind at z=0.123. J1356+1026 is driving a nuclear molecular outflow and an extended ionized outflow observed as an [OIII] emitting bubble at 10 kpc that is spatially coincident with soft X-ray emission. Quasar-driven winds carry material at a wide range of densities and temperatures making it difficult to measure their energetics and the dominant phases are unknown. Here we propose spatially resolved rest-UV spectroscopy by acquiring circum-nuclear absorption spectra of J1356+1026 and emission spectra of its off-nucleus bubble using COS+G140L. The circum-nuclear spectrum will provide measurements of the outflow velocity through blueshifted absorption while the off-nuclear spectrum of the bubble will measure the ionization state and mechanisms of the outflow through powerful UV diagnostic lines. Together, these spectra will enable a more complete mass, energy and momentum accounting of a spatially resolved quasar driven superwind for the first time. Furthermore, detection of shocked gas through OVI emission will enable us to infer properties of the enigmatic volume-filling, low density component of the wind. To our knowledge, this will be the first spatially resolved rest UV spectroscopy of a quasar wind and the proposed observations will serve as a pilot to guide future HST proposals.

THE NATURE AND FREQUENCY OF OUTFLOWS FROM STARS IN THE CENTRAL ORION NEBULA CLUSTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

O’Dell, C. R.; Ferland, G. J.; Henney, W. J.

Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig–Haro objects known within the inner Orion Nebula. We find that the best-known Herbig–Haro shocks originate from relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks aremore » the result of a single stellar source having jets oriented in multiple directions at similar times. This explains the feature that shocks aligned in opposite directions in the plane of the sky are usually blueshifted because the redshifted outflows pass into the optically thick photon-dominated region behind the nebula. There are two regions from which optical outflows originate for which there are no candidate sources in the SIMBAD database.« less

Two separate outflows in the dual supermassive black hole system NGC 6240

NASA Astrophysics Data System (ADS)

Müller-Sánchez, F.; Nevin, R.; Comerford, J. M.; Davies, R. I.; Privon, G. C.; Treister, E.

2018-04-01

Theoretical models and numerical simulations have established a framework of galaxy evolution in which galaxies merge and create dual supermassive black holes (with separations of one to ten kiloparsecs), which eventually sink into the centre of the merger remnant, emit gravitational waves and coalesce. The merger also triggers star formation and supermassive black hole growth, and gas outflows regulate the stellar content1-3. Although this theoretical picture is supported by recent observations of starburst-driven and supermassive black hole-driven outflows4-6, it remains unclear how these outflows interact with the interstellar medium. Furthermore, the relative contributions of star formation and black hole activity to galactic feedback remain unknown7-9. Here we report observations of dual outflows in the central region of the prototypical merger NGC 6240. We find a black-hole-driven outflow of [O iii] to the northeast and a starburst-driven outflow of Hα to the northwest. The orientations and positions of the outflows allow us to isolate them spatially and study their properties independently. We estimate mass outflow rates of 10 and 75 solar masses per year for the Hα bubble and the [O iii] cone, respectively. Their combined mass outflow is comparable to the star formation rate10, suggesting that negative feedback on star formation is occurring.

Two separate outflows in the dual supermassive black hole system NGC 6240.

PubMed

Müller-Sánchez, F; Nevin, R; Comerford, J M; Davies, R I; Privon, G C; Treister, E

2018-04-01

Theoretical models and numerical simulations have established a framework of galaxy evolution in which galaxies merge and create dual supermassive black holes (with separations of one to ten kiloparsecs), which eventually sink into the centre of the merger remnant, emit gravitational waves and coalesce. The merger also triggers star formation and supermassive black hole growth, and gas outflows regulate the stellar content 1-3 . Although this theoretical picture is supported by recent observations of starburst-driven and supermassive black hole-driven outflows 4-6 , it remains unclear how these outflows interact with the interstellar medium. Furthermore, the relative contributions of star formation and black hole activity to galactic feedback remain unknown 7-9 . Here we report observations of dual outflows in the central region of the prototypical merger NGC 6240. We find a black-hole-driven outflow of [O III] to the northeast and a starburst-driven outflow of Hα to the northwest. The orientations and positions of the outflows allow us to isolate them spatially and study their properties independently. We estimate mass outflow rates of 10 and 75 solar masses per year for the Hα bubble and the [O III] cone, respectively. Their combined mass outflow is comparable to the star formation rate 10 , suggesting that negative feedback on star formation is occurring.

Compact objects at the heart of outflows in large and small systems

NASA Astrophysics Data System (ADS)

Sell, Paul Harrison

2013-12-01

This thesis focuses on studying and assessing high-energy feedback generated by both stellar mass and supermassive compact objects. From these two perspectives, I help bridge the gap in understanding how jets and winds can transform their much larger environments in thousands to millions of years, astronomically short timescales. I have acquired X-ray and optical data that aim to elucidate the role these objects play in powering parsec-scale shockwaves in the ISM and in driving kiloparsec-scale outflows in galaxies. I present Chandra X-ray imaging, Hubble Space Telescope imaging, and WIYN Hydra multi-object optical spectroscopic observations. The data reveal the morphologies of the systems and constrain on a range of interesting parameters: power, outflow velocity, density, accretion efficiency, and timescale. My analysis provides perspective on the importance of black holes, both large and small, and neutron stars for driving outflows into the interstellar and intergalactic medium. On kiloparsec scales, I explore the nature of what appear to be merging or recently merging post-starburst galaxies with very high-velocity winds. This work is part of a multiwavelength effort to characterize the niche these galaxies fill in the larger scheme of galaxy evolution. My focus is on the accretion activity of the coalescing supermassive black holes in their cores. This work leads us to compare the relative importance of a massive starburst to the supermassive black holes in the cores of the galaxies. On parsec scales, I present case studies of two prominent microquasars, Galactic X-ray binaries with jets, Circinus X-1 and Cygnus X-1. In the case of Circinus X-1, I present very deep follow-up observations of parsec-scale shock plumes driven by a powerful, bipolar jet. In the case of Cygnus X-1, I present follow-up observations to probe a recently discovered outflow near the binary. I calculate robust, physically motivated limits on the total power needed to drive the outflows in both of these systems.

Fast ionized X-ray absorbers in AGNs

NASA Astrophysics Data System (ADS)

Fukumura, K.; Tombesi, F.; Kazanas, D.; Shrader, C.; Behar, E.; Contopoulos, I.

2016-05-01

We investigate the physics of the X-ray ionized absorbers often identified as warm absorbers (WAs) and ultra-fast outflows (UFOs) in Seyfert AGNs from spectroscopic studies in the context of magnetically-driven accretion-disk wind scenario. Launched and accelerated by the action of a global magnetic field anchored to an underlying accretion disk around a black hole, outflowing plasma is irradiated and ionized by an AGN radiation field characterized by its spectral energy density (SED). By numerically solving the Grad-Shafranov equation in the magnetohydrodynamic (MHD) framework, the physical property of the magnetized disk-wind is determined by a wind parameter set, which is then incorporated into radiative transfer calculations with xstar photoionization code under heating-cooling equilibrium state to compute the absorber's properties such as column density N_H, line-of-sight (LoS) velocity v, ionization parameter ξ, among others. Assuming that the wind density scales as n ∝ r-1, we calculate theoretical absorption measure distribution (AMD) for various ions seen in AGNs as well as line spectra especially for the Fe Kα absorption feature by focusing on a bright quasar PG 1211+143 as a case study and show the model's plausibility. In this note we demonstrate that the proposed MHD-driven disk-wind scenario is not only consistent with the observed X-ray data, but also help better constrain the underlying nature of the AGN environment in a close proximity to a central engine.

Wind influence on a coastal buoyant outflow

NASA Astrophysics Data System (ADS)

Whitney, Michael M.; Garvine, Richard W.

2005-03-01

This paper investigates the interplay between river discharge and winds in forcing coastal buoyant outflows. During light winds a plume influenced by the Earth's rotation will flow down shelf (in the direction of Kelvin wave propagation) as a slender buoyancy-driven coastal current. Downwelling favorable winds augment this down-shelf flow, narrow the plume, and mix the water column. Upwelling favorable winds drive currents that counter the buoyancy-driven flow, spread plume waters offshore, and rapidly mix buoyant waters. Two criteria are developed to assess the wind influence on a buoyant outflow. The wind strength index (Ws) determines whether a plume's along-shelf flow is in a wind-driven or buoyancy-driven state. Ws is the ratio of the wind-driven and buoyancy-driven along-shelf velocities. Wind influence on across-shelf plume structure is rated with a timescale (ttilt) for the isopycnal tilting caused by wind-driven Ekman circulation. These criteria are used to characterize wind influence on the Delaware Coastal Current and can be applied to other coastal buoyant outflows. The Delaware buoyant outflow is simulated for springtime high-river discharge conditions. Simulation results and Ws values reveal that the coastal current is buoyancy-driven most of the time (∣Ws∣ < 1 on average). Wind events, however, overwhelm the buoyancy-driven flow (∣Ws∣ > 1) several times during the high-discharge period. Strong upwelling events reverse the buoyant outflow; they constitute an important mechanism for transporting fresh water up shelf. Across-shelf plume structure is more sensitive to wind influence than the along-shelf flow. Values of ttilt indicate that moderate or strong winds persisting throughout a day can modify plume width significantly. Plume widening during upwelling events is accompanied by mixing that can erase the buoyant outflow.

CHEERS Results from NGC 3393. II. Investigating the Extended Narrow-line Region Using Deep Chandra Observations and Hubble Space Telescope Narrow-line Imaging

NASA Astrophysics Data System (ADS)

Maksym, W. Peter; Fabbiano, Giuseppina; Elvis, Martin; Karovska, Margarita; Paggi, Alessandro; Raymond, John; Wang, Junfeng; Storchi-Bergmann, Thaisa

2017-07-01

The CHandra Extended Emission Line Region Survey (CHEERS) is an X-ray study of nearby active galactic nuclei (AGNs) designed to take full advantage of Chandra's unique angular resolution by spatially resolving feedback signatures and effects. In the second paper of a series on CHEERS target NGC 3393, we examine deep high-resolution Chandra images and compare them with Hubble Space Telescope narrow-line images of [O III], [S II], and Hα, as well as previously unpublished mid-ultraviolet (MUV) images. The X-rays provide unprecedented evidence that the S-shaped arms that envelope the nuclear radio outflows extend only ≲0.″2 (≲50 pc) across. The high-resolution multiwavelength data suggest that the extended narrow-line region is a complex multiphase structure in the circumnuclear interstellar medium (ISM). Its ionization structure is highly stratified with respect to outflow-driven bubbles in the bicone and varies dramatically on scales of ˜10 pc. Multiple findings show likely contributions from shocks to the feedback in regions where radio outflows from the AGN most directly influence the ISM. These findings include Hα evidence for gas compression and extended MUV emission and are in agreement with existing STIS kinematics. Extended filamentary structure in the X-rays and optical suggests the presence of an undetected plasma component, whose existence could be tested with deeper radio observations.

ACTIVE GALACTIC NUCLEUS OBSCURATION FROM WINDS: FROM DUSTY INFRARED-DRIVEN TO WARM AND X-RAY PHOTOIONIZED

PubMed Central

Dorodnitsyn, A.; Kallman, T.

2016-01-01

We present calculations of AGN winds at ~parsec scales, along with the associated obscuration. We take into account the pressure of infrared radiation on dust grains and the interaction of X-rays from a central black hole with hot and cold plasma. Infrared radiation (IR) is incorporated in radiation-hydrodynamic simulations adopting the flux-limited diffusion approximation. We find that in the range of X-ray luminosities L=0.05 – 0.6Ledd, the Compton-thick part of the flow (aka torus) has an opening angle of approximately 72° – 75° regardless of the luminosity. At L ≳ 0.1 the outflowing dusty wind provides the obscuration with IR pressure playing a major role. The global flow consists of two phases: the cold flow at inclinations θ ≳ 70° and a hot, ionized wind of lower density at lower inclinations. The dynamical pressure of the hot wind is important in shaping the denser IR supported flow. At luminosities ≤0.1Ledd episodes of outflow are followed by extended periods when the wind switches to slow accretion. PMID:27642184

Fast Ionized X-Ray Absorbers in AGNs

NASA Technical Reports Server (NTRS)

Fukumura, K.; Tombesi, F.; Kazanas, D.; Shrader, C.; Behar, E.; Contopoulos, I.

2016-01-01

We investigate the physics of the X-ray ionized absorbers often identified as warm absorbers (WAs) and ultra-fast outflows (UFOs) in Seyfert AGNs from spectroscopic studies in the context of magnetically-driven accretion-disk wind scenario. Launched and accelerated by the action of a global magnetic field anchored to an underlying accretion disk around a black hole, outflowing plasma is irradiated and ionized by an AGN radiation field characterized by its spectral energy density (SED). By numerically solving the Grad-Shafranov equation in the magnetohydrodynamic (MHD) framework, the physical property of the magnetized disk-wind is determined by a wind parameter set, which is then incorporated into radiative transfer calculations with xstar photoionization code under heating-cooling equilibrium state to compute the absorber's properties such as column density N(sub H), line-of-sight (LoS) velocity v, ionization parameter xi, among others. Assuming that the wind density scales as n varies as r(exp. -1), we calculate theoretical absorption measure distribution (AMD) for various ions seen in AGNs as well as line spectra especially for the Fe K alpha absorption feature by focusing on a bright quasar PG 1211+143 as a case study and show the model's plausibility. In this note we demonstrate that the proposed MHD-driven disk-wind scenario is not only consistent with the observed X-ray data, but also help better constrain the underlying nature of the AGN environment in a close proximity to a central engine.

Three-Dimensional General-Relativistic Magnetohydrodynamic Simulations of Remnant Accretion Disks from Neutron Star Mergers: Outflows and r -Process Nucleosynthesis

NASA Astrophysics Data System (ADS)

Siegel, Daniel M.; Metzger, Brian D.

2017-12-01

The merger of binary neutron stars, or of a neutron star and a stellar-mass black hole, can result in the formation of a massive rotating torus around a spinning black hole. In addition to providing collimating media for γ -ray burst jets, unbound outflows from these disks are an important source of mass ejection and rapid neutron capture (r -process) nucleosynthesis. We present the first three-dimensional general-relativistic magnetohydrodynamic (GRMHD) simulations of neutrino-cooled accretion disks in neutron star mergers, including a realistic equation of state valid at low densities and temperatures, self-consistent evolution of the electron fraction, and neutrino cooling through an approximate leakage scheme. After initial magnetic field amplification by magnetic winding, we witness the vigorous onset of turbulence driven by the magnetorotational instability (MRI). The disk quickly reaches a balance between heating from MRI-driven turbulence and neutrino cooling, which regulates the midplane electron fraction to a low equilibrium value Ye≈0.1 . Over the 380-ms duration of the simulation, we find that a fraction ≈20 % of the initial torus mass is unbound in powerful outflows with asymptotic velocities v ≈0.1 c and electron fractions Ye≈0.1 - 0.25 . Postprocessing the outflows through a nuclear reaction network shows the production of a robust second- and third-peak r process. Though broadly consistent with the results of previous axisymmetric hydrodynamical simulations, extrapolation of our results to late times suggests that the total ejecta mass from GRMHD disks is significantly higher. Our results provide strong evidence that postmerger disk outflows are an important site for the r process.

Three-Dimensional General-Relativistic Magnetohydrodynamic Simulations of Remnant Accretion Disks from Neutron Star Mergers: Outflows and r-Process Nucleosynthesis.

PubMed

Siegel, Daniel M; Metzger, Brian D

2017-12-08

The merger of binary neutron stars, or of a neutron star and a stellar-mass black hole, can result in the formation of a massive rotating torus around a spinning black hole. In addition to providing collimating media for γ-ray burst jets, unbound outflows from these disks are an important source of mass ejection and rapid neutron capture (r-process) nucleosynthesis. We present the first three-dimensional general-relativistic magnetohydrodynamic (GRMHD) simulations of neutrino-cooled accretion disks in neutron star mergers, including a realistic equation of state valid at low densities and temperatures, self-consistent evolution of the electron fraction, and neutrino cooling through an approximate leakage scheme. After initial magnetic field amplification by magnetic winding, we witness the vigorous onset of turbulence driven by the magnetorotational instability (MRI). The disk quickly reaches a balance between heating from MRI-driven turbulence and neutrino cooling, which regulates the midplane electron fraction to a low equilibrium value Y_{e}≈0.1. Over the 380-ms duration of the simulation, we find that a fraction ≈20% of the initial torus mass is unbound in powerful outflows with asymptotic velocities v≈0.1c and electron fractions Y_{e}≈0.1-0.25. Postprocessing the outflows through a nuclear reaction network shows the production of a robust second- and third-peak r process. Though broadly consistent with the results of previous axisymmetric hydrodynamical simulations, extrapolation of our results to late times suggests that the total ejecta mass from GRMHD disks is significantly higher. Our results provide strong evidence that postmerger disk outflows are an important site for the r process.

Line-driven disc wind model for ultrafast outflows in active galactic nuclei - scaling with luminosity

NASA Astrophysics Data System (ADS)

Nomura, M.; Ohsuga, K.

2017-03-01

In order to reveal the origin of the ultrafast outflows (UFOs) that are frequently observed in active galactic nuclei (AGNs), we perform two-dimensional radiation hydrodynamics simulations of the line-driven disc winds, which are accelerated by the radiation force due to the spectral lines. The line-driven winds are successfully launched for the range of MBH = 106-9 M⊙ and ε = 0.1-0.5, and the resulting mass outflow rate (dot{M_w}), momentum flux (dot{p_w}), and kinetic luminosity (dot{E_w}) are in the region containing 90 per cent of the posterior probability distribution in the dot{M}_w-Lbol plane, dot{p}_w-Lbol plane, and dot{E}_w-Lbol plane shown in Gofford et al., where MBH is the black hole mass, ε is the Eddington ratio, and Lbol is the bolometric luminosity. The best-fitting relations in Gofford et al., d log dot{M_w}/d log {L_bol}˜ 0.9, d log dot{p_w}/d log {L_bol}˜ 1.2, and d log dot{E_w}/d log {L_bol}˜ 1.5, are roughly consistent with our results, d log dot{M_w}/d log {L_bol}˜ 9/8, d log dot{p_w}/d log {L_bol}˜ 10/8, and d log dot{E_w}/d log {L_bol}˜ 11/8. In addition, our model predicts that no UFO features are detected for the AGNs with ε ≲ 0.01, since the winds do not appear. Also, only AGNs with MBH ≲ 108 M⊙ exhibit the UFOs when ε ∼ 0.025. These predictions nicely agree with the X-ray observations. These results support that the line-driven disc wind is the origin of the UFOs.

Quantifying the AGN-driven outflows in ULIRGs (QUADROS) II: evidence for compact outflow regions from HST [OIII] imaging observations

NASA Astrophysics Data System (ADS)

Tadhunter, C.; Zaurín, J. Rodríguez; Rose, M.; Spence, R. A. W.; Batcheldor, D.; Berg, M. A.; Ramos Almeida, C.; Spoon, H. W. W.; Sparks, W.; Chiaberge, M.

2018-05-01

The true importance of the warm, AGN-driven outflows for the evolution of galaxies remains uncertain. Measurements of the radial extents of the outflows are key for quantifying their masses and kinetic powers, and also establishing whether the AGN outflows are galaxy-wide. Therefore, as part of a larger project to investigate the significance of warm, AGN-driven outflows in the most rapidly evolving galaxies in the local universe, here we present deep Hubble Space Telescope (HST) narrow-band [OIII]λ5007 observations of a complete sample of 8 nearby ULIRGs with optical AGN nuclei. Combined with the complementary information provided by our ground-based spectroscopy, the HST images show that the warm gas outflows are relatively compact for most of the objects in the sample: in three objects the outflow regions are barely resolved at the resolution of HST (0.065 < R[OIII] < 0.12 kpc); in a further four cases the outflows are spatially resolved but with flux weighted mean radii in the range 0.65 < R[OIII] < 1.2 kpc; and in only one object (Mrk273) is there clear evidence for a more extended outflow, with a maximum extent of R[OIII] ˜ 5 kpc. Overall, our observations show little evidence for the galaxy-wide outflows predicted by some models of AGN feedback.

Fast Outflow of Molecular Gas in the Seyfert Galaxy IC 5063

NASA Astrophysics Data System (ADS)

Morganti, Raffaella; Oosterloo, T.; Oonk, R.; Tadhunter, C.

2017-11-01

AGN-driven gas outflows may play an important role in the evolution of galaxies, as they impact on the growth on the central supermassive black hole as well on the star formation of the host galaxy. Much of the detailed physics of these gas outflows, and their actual impact on the host galaxy, is still not well understood. We present a detailed analysis, using ALMA observations, of the radio-jet driven outflow of molecular gas in the nearby radio-loud Seyfert galaxy IC 5063 which allows to derive important physical parameters of the gas and the outflow which, in turn, provide crucial input to numerical models. In recent years, a surprising result in the field of AGN-driven outflows has been that the cold phases of the gas (atomic and molecular) in some galaxies are the massive components of these outflows, despite the huge amounts of energy involved in driving these outflows. However, why most of the outflowing gas should be molecular/atomic, and in general, what are the physical conditions of the gas in the outflows and what really drives them, are still open questions. We present the results obtained from ALMA observations of multiple CO transitions and other molecules of what appears to be a textbook case of a jet-driven multi- phase outflow in the central regions of the Seyfert galaxy IC 5063. The data on multiple transitions allow us to derive the physical conditions in the different regions of the outflowing molecular gas. The signature of the impact of the radio jet is clearly seen in the spatial distribution of the excitation temperature and pressure of the outflowing gas, with the highest excitation and pressure found for the gas with the highest outflow velocities. We obtain a detailed three- dimensional picture of the outflow, and its kinematics, and find that outflowing molecular gas is present across the entire region co-spatial with the radio plasma, providing unambiguous evidence that the radio jets/cocoon are responsible for the outflow. The detailed information about the physical condition of the gas in a fast outflow will serve as template for the signatures of the impact of a radio plasma jet on a gas-rich ISM and its associated star formation, and guide the studies of outflows in other galaxies, including higher redshift objects.

Quenching star formation with quasar outflows launched by trapped IR radiation

NASA Astrophysics Data System (ADS)

Costa, Tiago; Rosdahl, Joakim; Sijacki, Debora; Haehnelt, Martin G.

2018-06-01

We present cosmological radiation-hydrodynamic simulations, performed with the code RAMSES-RT, of radiatively-driven outflows in a massive quasar host halo at z = 6. Our simulations include both single- and multi-scattered radiation pressure on dust from a quasar and are compared against simulations performed with thermal feedback. For radiation pressure-driving, we show that there is a critical quasar luminosity above which a galactic outflow is launched, set by the equilibrium of gravitational and radiation forces. While this critical luminosity is unrealistically high in the single-scattering limit for plausible black hole masses, it is in line with a ≈ 3 × 10^9 M_⊙ black hole accreting at its Eddington limit, if infrared (IR) multi-scattering radiation pressure is included. The outflows are fast (v ≳ 1000 km s^{-1}) and strongly mass-loaded with peak mass outflow rates ≈ 10^3 - 10^4 M_⊙ yr^{-1}, but short-lived (< 10 Myr). Outflowing material is multi-phase, though predominantly composed of cool gas, forming via a thermal instability in the shocked swept-up component. Radiation pressure- and thermally-driven outflows both affect their host galaxies significantly, but in different, complementary ways. Thermally-driven outflows couple more efficiently to diffuse halo gas, generating more powerful, hotter and more volume-filling outflows. IR radiation, through its ability to penetrate dense gas via diffusion, is more efficient at ejecting gas from the bulge. The combination of gas ejection through outflows with internal pressurisation by trapped IR radiation leads to a complete shut down of star formation in the bulge. We hence argue that radiation pressure-driven feedback may be an important ingredient in regulating star formation in compact starbursts, especially during the quasar's `obscured' phase.

Galactic outflows, star formation histories, and time-scales in starburst dwarf galaxies from STARBIRDS

NASA Astrophysics Data System (ADS)

McQuinn, Kristen B. W.; Skillman, Evan D.; Heilman, Taryn N.; Mitchell, Noah P.; Kelley, Tyler

2018-07-01

Winds are predicted to be ubiquitous in low-mass, actively star-forming galaxies. Observationally, winds have been detected in relatively few local dwarf galaxies, with even fewer constraints placed on their time-scales. Here, we compare galactic outflows traced by diffuse, soft X-ray emission from Chandra Space Telescope archival observations to the star formation histories derived from Hubble Space Telescope imaging of the resolved stellar populations in six starburst dwarfs. We constrain the longevity of a wind to have an upper limit of 25 Myr based on galaxies whose starburst activity has already declined, although a larger sample is needed to confirm this result. We find an average 16 per cent efficiency for converting the mechanical energy of stellar feedback to thermal, soft X-ray emission on the 25 Myr time-scale, somewhat higher than simulations predict. The outflows have likely been sustained for time-scales comparable to the duration of the starbursts (i.e. 100s Myr), after taking into account the time for the development and cessation of the wind. The wind time-scales imply that material is driven to larger distances in the circumgalactic medium than estimated by assuming short, 5-10 Myr starburst durations, and that less material is recycled back to the host galaxy on short time-scales. In the detected outflows, the expelled hot gas shows various morphologies that are not consistent with a simple biconical outflow structure. The sample and analysis are part of a larger program, the STARBurst IRregular Dwarf Survey (STARBIRDS), aimed at understanding the life cycle and impact of starburst activity in low-mass systems.

CHEERS Results from NGC 3393. II. Investigating the Extended Narrow-line Region Using Deep Chandra Observations and Hubble Space Telescope Narrow-line Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maksym, W. Peter; Fabbiano, Giuseppina; Elvis, Martin

The CHandra Extended Emission Line Region Survey (CHEERS) is an X-ray study of nearby active galactic nuclei (AGNs) designed to take full advantage of Chandra 's unique angular resolution by spatially resolving feedback signatures and effects. In the second paper of a series on CHEERS target NGC 3393, we examine deep high-resolution Chandra images and compare them with Hubble Space Telescope narrow-line images of [O iii], [S ii], and H α , as well as previously unpublished mid-ultraviolet (MUV) images. The X-rays provide unprecedented evidence that the S-shaped arms that envelope the nuclear radio outflows extend only ≲0.″2 (≲50 pc)more » across. The high-resolution multiwavelength data suggest that the extended narrow-line region is a complex multiphase structure in the circumnuclear interstellar medium (ISM). Its ionization structure is highly stratified with respect to outflow-driven bubbles in the bicone and varies dramatically on scales of ∼10 pc. Multiple findings show likely contributions from shocks to the feedback in regions where radio outflows from the AGN most directly influence the ISM. These findings include H α evidence for gas compression and extended MUV emission and are in agreement with existing STIS kinematics. Extended filamentary structure in the X-rays and optical suggests the presence of an undetected plasma component, whose existence could be tested with deeper radio observations.« less

Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Chi-Ho; Krolik, Julian H.

2017-07-01

Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply towardmore » the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.« less

UNRAVELLING THE COMPLEX STRUCTURE OF AGN-DRIVEN OUTFLOWS. II. PHOTOIONIZATION AND ENERGETICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karouzos, Marios; Woo, Jong-Hak; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr

2016-12-20

Outflows have been shown to be prevalent in galaxies hosting luminous active galactic nuclei (AGNs); they present a physically plausible way to couple the AGN energy output with the interstellar medium of their hosts. Despite their prevalence, accurate characterization of these outflows has been challenging. In the second of a series of papers, we use Gemini Multi-Object Spectrograph integral field unit (IFU) data of six local ( z  < 0.1) and moderate-luminosity Type 2 AGNs to study the ionization properties and energetics of AGN-driven outflows. We find strong evidence connecting the extreme kinematics of the ionized gas to the AGN photoionization.more » The kinematic component related to the AGN-driven outflow is clearly separated from other kinematic components, such as virial motions or rotation, on the velocity and velocity dispersion diagram. Our spatially resolved kinematic analysis reveals that 30 to 90% of the total mass and kinetic energy of the outflow is contained within the central kpc of the galaxy. The spatially integrated mass and kinetic energy of the gas entrained in the outflow correlate well with the AGN bolometric luminosity and results in energy conversion efficiencies between 0.01% and 1%. Intriguingly, we detect ubiquitous signs of ongoing circumnuclear star formation. Their small size, the centrally contained mass and energy, and the universally detected circumnuclear star formation cast doubts on the potency of these AGN-driven outflows as agents of galaxy-scale negative feedback.« less

Active galactic nucleus outflows in galaxy discs

NASA Astrophysics Data System (ADS)

Hartwig, Tilman; Volonteri, Marta; Dashyan, Gohar

2018-05-01

Galactic outflows, driven by active galactic nuclei (AGNs), play a crucial role in galaxy formation and in the self-regulated growth of supermassive black holes (BHs). AGN feedback couples to and affects gas, rather than stars, and in many, if not most, gas-rich galaxies cold gas is rotationally supported and settles in a disc. We present a 2D analytical model for AGN-driven outflows in a gaseous disc and demonstrate the main improvements, compared to existing 1D solutions. We find significant differences for the outflow dynamics and wind efficiency. The outflow is energy-driven due to inefficient cooling up to a certain AGN luminosity (˜1043 erg s-1 in our fiducial model), above which the outflow remains momentum-driven in the disc up to galactic scales. We reproduce results of 3D simulations that gas is preferentially ejected perpendicular to the disc and find that the fraction of ejected interstellar medium is lower than in 1D models. The recovery time of gas in the disc, defined as the free-fall time from the radius to which the AGN pushes the ISM at most, is remarkably short, of the order 1 Myr. This indicates that AGN-driven winds cannot suppress BH growth for long. Without the inclusion of supernova feedback, we find a scaling of the BH mass with the halo velocity dispersion of MBH ∝ σ4.8.

AGN Obscuration from Winds: From Dusty Infrared-Driven to Warm and X-Ray Photoionized

NASA Technical Reports Server (NTRS)

Dorodnitsyn, A.; Kallman, T.

2012-01-01

We present calculations of AGN winds at approximate parsec scales, along with the associated obscuration. We take into account the pressure of infrared radiation on dust grains and the interaction of X-rays from a central black hole with hot and cold plasma. Infrared radiation (IR) is incorporated in radiation-hydrodynamic simulations adopting the flux-limited diffusion approximation. We find that in the range of X-ray luminosities L=0.05 - 0.6L(sub Edd) the Compton-thick part of the flow (aka torus) has an opening angle of approximately 72? -75? regardless of the luminosity. At L 0.1 the outflowing dusty wind provides the obscuration with IR pressure playing a major role. The global flow consists of two phases: the cold flow at inclinations (theta) greater than or approximately 70? and a hot, ionized wind of lower density at lower inclinations. The dynamical pressure of the hot wind is important in shaping the denser IR supported flow. At luminosities less than or equal to 0.1L(sub Edd) episodes of outflow are followed by extended periods when the wind switches to slow accretion.

Disk-driven hydromagnetic winds as a key ingredient of active galactic nuclei unification schemes

NASA Technical Reports Server (NTRS)

Konigl, Arieh; Kartje, John F.

1994-01-01

Centrifugally driven winds from the surfaces of magnetized accretion disks have been recognized as an attractive mechanism of removing the angular momentum of the accreted matter and of producing the bipolar outflows and jets that are often associated with compact astronomical objects. As previously suggested in the context of young stellar objects, such winds have unique observational manifestations stemming from their highly stratified density and velocity structure and from their exposure to the strong continuum radiation field of the compact object. We have applied this scenario to active galactic nuclei (AGNs) and investigated the properties of hydromagnetic outflows that originate within approximately 10(M(sub 8)) pc of the central 10(exp 8)(M(sub 8)) solar mass black hole. On the basis of our results, we propose that hydromagnetic disk-driven winds may underlie the classification of broad-line and narrow-line AGNs (e.g., the Seyfert 1/Seyfert 2 dichotomy) as well as the apparent dearth of luminous Seyfert 2 galaxies. More generally, we demonstrate that such winds could strongly influence the spectral characteristics of Seyfert galaxies, QSOs, and BL Lac objects (BLOs). In our picture, the torus is identified with the outer regions of the wind where dust uplifted from the disk surfaces by gas-grain collisions is embedded in the outflow. Using an efficient radiative transfer code, we show that the infrared emission of Seyfert galaxies and QSOs can be attributed to the reprocessing of the UV/soft X-ray AGN continuum by the dust in the wind and the disk. We demonstrate that the radiation pressure force flattens the dust distribution in objects with comparatively high (but possibly sub-Eddington) bolometric luminosities, and we propose this as one likely reason for the apparent paucity of narrow-line objects among certain high-luminosity AGNs. Using the XSTAR photoionization code, we show that the inner regions of the wind could naturally account for the warm (greater than or approximately equal to 10(exp 5) K) and hot (greater than or approximately equal to 10(exp 6) K) gas components that have been inferred to exist on scales less than or approximately equal to 10(exp 2) pc in several Seyfert galaxies. We suggest that the partially ionized gas in the inner regions of the wind, rather than the dusty, neutral outflow that originates further out in the disk, could account for the bulk of the X-ray absorption in Seyferts observed at relatively small angles to their symmetry axes. Finally, we discuss the application of this model to the interpretation of the approximately 0.6 keV X-ray absorption feature reported in several BLOs.

Buoyant AGN Bubbles in the Quasi-isothermal Potential of NGC 1399

NASA Astrophysics Data System (ADS)

Su, Yuanyuan; Nulsen, Paul E. J.; Kraft, Ralph P.; Forman, William R.; Jones, Christine; Irwin, Jimmy A.; Randall, Scott W.; Churazov, Eugene

2017-10-01

The Fornax Cluster is a low-mass cool-core galaxy cluster. We present a deep Chandra study of NGC 1399, the central dominant elliptical galaxy of Fornax. The cluster center harbors two symmetric X-ray cavities coincident with a pair of radio lobes fed by two collimated jets along a north-south axis. A temperature map reveals that the active galactic nucleus (AGN) outburst has created a channel filled with cooler gas out to a radius of 10 kpc. The cavities are surrounded by cool bright rims and filaments that may have been lifted from smaller radii by the buoyant bubbles. X-ray imaging suggests a potential ghost bubble of ≳5 kpc diameter to the northwest. We find that the amount of gas lifted by AGN bubbles is comparable to that which would otherwise cool, demonstrating that AGN-driven outflow is effective in offsetting cooling in low-mass clusters. The cluster cooling timescale is > 30 times longer than the dynamical timescale, which is consistent with the lack of cold molecular gas at the cluster center. The X-ray hydrostatic mass is consistent within 10%, with the total mass derived from the optical data. The observed entropy profile rises linearly, following a steeper slope than that observed at the centers of massive clusters; gas shed by stars in NGC 1399 may be incorporated in the hot phase. However, it is far-fetched for supernova-driven outflow to produce and maintain the thermal distribution in NGC 1399, and it is in tension with the metal content in the hot gas.

Broad Absorption Line Quasars with Polar Outflows

NASA Astrophysics Data System (ADS)

Wang, Junxian

2005-10-01

It is widely accepted that the broad absorption line (BAL) outflow exists in most (if not all) quasars with a small covering factor. Various evidences show that equatorial outflows are responsible for the BALs in most BAL QSOs. By searching for radio variable quasars in SDSS, we built the first sample of 6 BAL QSOs with polar BAL outflows. It is very likely that polar outflows are associated with relativistic jets, and their origins should be different from the equatorial outflows in the majority of BAL QSOs. We propose an XMM snapshot survey to a) check whether strong X-ray absorption, one of the most prominent characteristics of most BAL QSOs, also exist in the polar outflows b) check whether face-on BAL QSOs are otherwise X-ray normal c) provide a baseline for future extensive X-ray studies.

Superwind Outflows in Seyfert Galaxies? : Large-Scale Radio Maps of an Edge-On Sample

NASA Astrophysics Data System (ADS)

Colbert, E.; Gallimore, J.; Baum, S.; O'Dea, C.

1995-03-01

Large-scale galactic winds (superwinds) are commonly found flowing out of the nuclear region of ultraluminous infrared and powerful starburst galaxies. Stellar winds and supernovae from the nuclear starburst provide the energy to drive these superwinds. The outflowing gas escapes along the rotation axis, sweeping up and shock-heating clouds in the halo, which produces optical line emission, radio synchrotron emission, and X-rays. These features can most easily be studied in edge-on systems, so that the wind emission is not confused by that from the disk. We have begun a systematic search for superwind outflows in Seyfert galaxies. In an earlier optical emission-line survey, we found extended minor axis emission and/or double-peaked emission line profiles in >~30% of the sample objects. We present here large-scale (6cm VLA C-config) radio maps of 11 edge-on Seyfert galaxies, selected (without bias) from a distance-limited sample of 23 edge-on Seyferts. These data have been used to estimate the frequency of occurrence of superwinds. Preliminary results indicate that four (36%) of the 11 objects observed and six (26%) of the 23 objects in the distance-limited sample have extended radio emission oriented perpendicular to the galaxy disk. This emission may be produced by a galactic wind blowing out of the disk. Two (NGC 2992 and NGC 5506) of the nine objects for which we have both radio and optical data show good evidence for a galactic wind in both datasets. We suggest that galactic winds occur in >~30% of all Seyferts. A goal of this work is to find a diagnostic that can be used to distinguish between large-scale outflows that are driven by starbursts and those that are driven by an AGN. The presence of starburst-driven superwinds in Seyferts, if established, would have important implications for the connection between starburst galaxies and AGN.

A Missing-link in the Supernova-GRB Connection: The Case of SN 2012ap

NASA Astrophysics Data System (ADS)

Chakraborti, Sayan; Soderberg, Alicia; Chomiuk, Laura; Kamble, Atish; Yadav, Naveen; Ray, Alak; Hurley, Kevin; Margutti, Raffaella; Milisavljevic, Dan; Bietenholz, Michael; Brunthaler, Andreas; Pignata, Giuliano; Pian, Elena; Mazzali, Paolo; Fransson, Claes; Bartel, Norbert; Hamuy, Mario; Levesque, Emily; MacFadyen, Andrew; Dittmann, Jason; Krauss, Miriam; Briggs, M. S.; Connaughton, V.; Yamaoka, K.; Takahashi, T.; Ohno, M.; Fukazawa, Y.; Tashiro, M.; Terada, Y.; Murakami, T.; Goldsten, J.; Barthelmy, S.; Gehrels, N.; Cummings, J.; Krimm, H.; Palmer, D.; Golenetskii, S.; Aptekar, R.; Frederiks, D.; Svinkin, D.; Cline, T.; Mitrofanov, I. G.; Golovin, D.; Litvak, M. L.; Sanin, A. B.; Boynton, W.; Fellows, C.; Harshman, K.; Enos, H.; von Kienlin, A.; Rau, A.; Zhang, X.; Savchenko, V.

2015-06-01

Gamma-ray bursts (GRBs) are characterized by ultra-relativistic outflows, while supernovae are generally characterized by non-relativistic ejecta. GRB afterglows decelerate rapidly, usually within days, because their low-mass ejecta rapidly sweep up a comparatively larger mass of circumstellar material. However, supernovae with heavy ejecta can be in nearly free expansion for centuries. Supernovae were thought to have non-relativistic outflows except for a few relativistic ones accompanied by GRBs. This clear division was blurred by SN 2009bb, the first supernova with a relativistic outflow without an observed GRB. However, the ejecta from SN 2009bb was baryon loaded and in nearly free expansion for a year, unlike GRBs. We report the first supernova discovered without a GRB but with rapidly decelerating mildly relativistic ejecta, SN 2012ap. We discovered a bright and rapidly evolving radio counterpart driven by the circumstellar interaction of the relativistic ejecta. However, we did not find any coincident GRB with an isotropic fluence of more than one-sixth of the fluence from GRB 980425. This shows for the first time that central engines in SNe Ic, even without an observed GRB, can produce both relativistic and rapidly decelerating outflows like GRBs.

Dissecting the Butterfly: Dual Outflows in the Dual AGN NGC 6240

NASA Astrophysics Data System (ADS)

Mueller Sanchez, Francisco; Comerford, Julie; Nevin, Rebecca; Davies, Richard; Treister, Ezequiel; Privon, George

2018-01-01

Current theories of galaxy evolution invoke some kind of feedback (from the stars or the supermassive black hole) to explain the properties of galaxies. However, numerical simulations and observations have not been able to evaluate the real impact of feedback in galaxies. This is largely because most studies have focused on studying stellar feedback or AGN feedback alone, instead of considering the combined effect of both. In fact, this is an unexplored territory for observations due to the difficulty of separating the contribution from the two sources.In this contribution I present the discovery of a dual outflow of different species of gas in the prototypical merging galaxy NGC 6240 using HST imaging, long-slit and integral-eld spectroscopy: an AGN-driven outflow of highly-ionized gas to the northeast and a starburst-driven outflow of ionized hydrogen to the northwest. The AGN outflow extends up to 4 kpc along a position angle of 56 degrees, has a conical shape with an opening angle of 52 degrees and a maximum line-of-sight velocity of 350 km/s. The WFC3 images also reveal a bubble of Halpha emission in the northwest, which has no counterpart in [O III], consistent with a scenario in which the starburst is ionizing and driving outflowing winds which inflate the bubble at an expansion velocity of 380 km/s. Assuming a spherical geometry for the starburst-driven bubble and a conical geometry for the AGN-driven outflow, we estimate mass outflow rates of 26 Msun/yr and 62 Msun/yr, respectively. We conclude that the AGN contribution to the evolution of the merger remnant and the formation of outflowing winds is signicant in the central 5 kpc of NGC 6240.

Particle Acceleration in Relativistic Outflows

NASA Technical Reports Server (NTRS)

Bykov, Andrei; Gehrels, Neil; Krawczynski, Henric; Lemoine, Martin; Pelletier, Guy; Pohl, Martin

2012-01-01

In this review we confront the current theoretical understanding of particle acceleration at relativistic outflows with recent observational results on various source classes thought to involve such outflows, e.g. gamma-ray bursts, active galactic nuclei, and pulsar wind nebulae. We highlight the possible contributions of these sources to ultra-high-energy cosmic rays.

Variable X-Ray Absorption in the Mini-BAL QSO PG 1126-041

NASA Technical Reports Server (NTRS)

Giustini, M.; Cappi, M.; Chartas, G.; Dadina, M.; Eracleous, M.; Ponti, G.; Proga, D.; Tombesi, F.; Vignali, C.; Palumbo, G. G. C.

2011-01-01

Context. X-ray studies of AGN with powerful nuclear winds are important to constrain the physics of the inner accretion/ejection flow around SMBH, and to understand the impact of such winds on the AGN environment. Aims. Our main scientific goal is to constrain the properties of a variable outflowing absorber that is thought to be launched near the SMBH of the mini-BAL QSO PG 1126-041 using a multi-epoch observational campaign performed with XMM-Newton. Methods. We performed temporally resolved X-ray spectroscopy and simultaneous UV and X-ray photometry on the most complete set of observations and on the deepest X-ray exposure of a mini-BAL QSO to date. Results. We found complex X-ray spectral variability on time scales of both months and hours, best reproduced by means of variable massive ionized absorbers along the line of sight. As a consequence, the observed optical-to-X-ray spectral index is found to be variable with time. In the highest signal-to-noise observation we detected highly ionized X-ray absorbing material outflowing much faster (u(sub X) approx. 16 500 km/s) than the UV absorbing one (u(sub uv) approx. 5,000 km/s). This highly ionized absorber is found to be variable on very short (a few kiloseconds) time scales. Conclusions. Our findings are qualitatively consistent with line driven accretion disk winds scenarios. Our observations have opened the time-resolved X-ray spectral analysis field for mini-BAL QSOs; only with future deep studies will we be able to map the dynamics of the inner flow and understand the physics of AGN winds and their impact on the environment.

Does the X-ray outflow quasar PDS 456 have a UV outflow at 0.3c?

NASA Astrophysics Data System (ADS)

Hamann, Fred; Chartas, George; Reeves, James; Nardini, Emanuele

2018-05-01

The quasar PDS 456 (at redshift ˜0.184) has a prototype ultra-fast outflow (UFO) measured in X-rays. This outflow is highly ionized with relativistic speeds, large total column densities log NH(cm-2) > 23, and large kinetic energies that could be important for feedback to the host galaxy. A UV spectrum of PDS 456 obtained with the Hubble Space Telescope in 2000 contains one well-measured broad absorption line (BAL) at ˜1346 Å (observed) that might be Ly α at v ≈ 0.06c or N V λ1240 at v ≈ 0.08c. However, we use photoionization models and comparisons to other outflow quasars to show that these BAL identifications are problematic because other lines that should accompany them are not detected. We argue that the UV BAL is probably C IV at v ≈ 0.30c. This would be the fastest UV outflow ever reported, but its speed is similar to the X-ray outflow and its appearance overall is similar to relativistic UV BALs observed in other quasars. The C IV BAL identification is also supported indirectly by the tentative detection of another broad C IV line at v ≈ 0.19c. The high speeds suggest that the UV outflow originates with the X-ray UFO crudely 20-30 rg from the central black hole. We speculate that the C IV BAL might form in dense clumps embedded in the X-ray UFO, requiring density enhancements of only ≳0.4 dex compared to clumpy structures already inferred for the soft X-ray absorber in PDS 456. The C IV BAL might therefore be the first detection of low-ionization clumps proposed previously to boost the opacities in UFOs for radiative driving.

Active Galactic Nucleus Obscuration from Winds: From Dusty Infrared-Driven to Warm and X-Ray Photoionized

NASA Technical Reports Server (NTRS)

Dorodnitsyn, Anton V.; Kallman, Timothy R.

2012-01-01

We present calculations of active galactic nucleus winds at approx.parsec scales along with the associated obscuration. We take into account the pressure of infrared radiation on dust grains and the interaction of X-rays from a central black hole with hot and cold plasma. Infrared radiation (IR) is incorporated in radiation-hydrodynamic simulations adopting the flux-limited diffusion approximation. We find that in the range of X-ray luminosities L = 0.05-0.6 L(sub Edd), the Compton-thick part of the flow (aka torus) has an opening angle of approximately 72deg - 75deg regardless of the luminosity. At L > or approx. 0.1, the outflowing dusty wind provides the obscuration with IR pressure playing a major role. The global flow consists of two phases: the cold flow at inclinations (theta) > or approx.70deg and a hot, ionized wind of lower density at lower inclinations. The dynamical pressure of the hot wind is important in shaping the denser IR-supported flow. At luminosities < or = 0.1 L(sub Edd) episodes of outflow are followed by extended periods when the wind switches to slow accretion. Key words: acceleration of particles . galaxies: active . hydrodynamics . methods: numerical Online-only material: color figures

On the Role of Ionospheric Ions in Sawtooth Events

NASA Astrophysics Data System (ADS)

Lund, E. J.; Nowrouzi, N.; Kistler, L. M.; Cai, X.; Frey, H. U.

2016-12-01

Global multifluid simulations have suggested that ions of ionospheric origin play a key role in driving sawtooth events, particularly events driven by coronal mass ejections (CMEs), through a feedback mechanism.1,2 The energy input from the first substorm causes ion outflow, which is claimed to drive the next substorm. We show that in situ data from Cluster in the tail during sawtooth events do not support this hypothesis. We show two detailed event studies, one driven by a CME and one driven by a streaming interaction region (SIR), as well as a statistical survey of all sawtooth events for which Cluster tail data are available. While examples exist of nightside outflow reaching the mid-tail ( 19 RE) region during CME-driven events, the overwhelming majority of both CME-driven and SIR-driven sawtooth injections have ionospheric ions in this region originating from the cusp, where the outflow is predominantly directly driven by the solar wind. The 19 RE region is critical because that is the region where near-Earth neutral line reconnection occurs. We conclude that while ionospheric outflow may contribute to sawtooth events, the injections are not the result of a feedback between the tail and the ionosphere. 1O. J. Brambles et al. (2011), Science 332, 1183, doi:10.1126/science.1202869.2O. J. Brambles et al. (2013), JGR 118, 6026, doi:10.1002/jgra.50522.

A MISSING-LINK IN THE SUPERNOVA–GRB CONNECTION: THE CASE OF SN 2012ap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborti, Sayan; Soderberg, Alicia; Kamble, Atish

2015-06-01

Gamma-ray bursts (GRBs) are characterized by ultra-relativistic outflows, while supernovae are generally characterized by non-relativistic ejecta. GRB afterglows decelerate rapidly, usually within days, because their low-mass ejecta rapidly sweep up a comparatively larger mass of circumstellar material. However, supernovae with heavy ejecta can be in nearly free expansion for centuries. Supernovae were thought to have non-relativistic outflows except for a few relativistic ones accompanied by GRBs. This clear division was blurred by SN 2009bb, the first supernova with a relativistic outflow without an observed GRB. However, the ejecta from SN 2009bb was baryon loaded and in nearly free expansion formore » a year, unlike GRBs. We report the first supernova discovered without a GRB but with rapidly decelerating mildly relativistic ejecta, SN 2012ap. We discovered a bright and rapidly evolving radio counterpart driven by the circumstellar interaction of the relativistic ejecta. However, we did not find any coincident GRB with an isotropic fluence of more than one-sixth of the fluence from GRB 980425. This shows for the first time that central engines in SNe Ic, even without an observed GRB, can produce both relativistic and rapidly decelerating outflows like GRBs.« less

The multi-phase winds of Markarian 231: from the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow

NASA Astrophysics Data System (ADS)

Feruglio, C.; Fiore, F.; Carniani, S.; Piconcelli, E.; Zappacosta, L.; Bongiorno, A.; Cicone, C.; Maiolino, R.; Marconi, A.; Menci, N.; Puccetti, S.; Veilleux, S.

2015-11-01

Mrk 231 is a nearby ultra-luminous IR galaxy exhibiting a kpc-scale, multi-phase AGN-driven outflow. This galaxy represents the best target to investigate in detail the morphology and energetics of powerful outflows, as well as their still poorly-understood expansion mechanism and impact on the host galaxy. In this work, we present the best sensitivity and angular resolution maps of the molecular disk and outflow of Mrk 231, as traced by CO(2-1) and (3-2) observations obtained with the IRAM/PdBI. In addition, we analyze archival deep Chandra and NuSTAR X-ray observations. We use this unprecedented combination of multi-wavelength data sets to constrain the physical properties of both the molecular disk and outflow, the presence of a highly-ionized ultra-fast nuclear wind, and their connection. The molecular CO(2-1) outflow has a size of 1 kpc, and extends in all directions around the nucleus, being more prominent along the south-west to north-east direction, suggesting a wide-angle biconical geometry. The maximum projected velocity of the outflow is nearly constant out to 1 kpc, thus implying that the density of the outflowing material must decrease from the nucleus outwards as r-2. This suggests that either a large part of the gas leaves the flow during its expansion or that the bulk of the outflow has not yet reached out to 1 kpc, thus implying a limit on its age of 1 Myr. Mapping the mass and energy rates of the molecular outflow yields dot {M} OF = [500-1000] M⊙ yr-1 and Ėkin,OF = [7-10] × 1043 erg s-1. The total kinetic energy of the outflow is Ekin,OF is of the same order of the total energy of the molecular disk, Edisk. Remarkably, our analysis of the X-ray data reveals a nuclear ultra-fast outflow (UFO) with velocity -20 000 km s-1, dot {M}UFO = [0.3-2.1] M⊙ yr-1, and momentum load dot {P}UFO/ dot {P}rad = [0.2-1.6]. We find Ėkin,UFO Ėkin,OF as predicted for outflows undergoing an energy conserving expansion. This suggests that most of the UFO kinetic energy is transferred to mechanical energy of the kpc-scale outflow, strongly supporting that the energy released during accretion of matter onto super-massive black holes is the ultimate driver of giant massive outflows. The momentum flux dot {P}OF derived for the large scale outflows in Mrk 231 enables us to estimate a momentum boost dot {P}OF/ dot {P} UFO ≈ [30-60]. The ratios Ėkin,UFO/Lbol,AGN = [1-5] % and Ėkin,OF/Lbol,AGN = [1-3] % agree with the requirements of the most popular models of AGN feedback. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain), and with Chandra and NuSTAR observatories.

Unifying the Micro and Macro Properties of AGN Feeding and Feedback

NASA Astrophysics Data System (ADS)

Gaspari, Massimo; Sądowski, Aleksander

2017-03-01

We unify the feeding and feedback of supermassive black holes with the global properties of galaxies, groups, and clusters by linking for the first time the physical mechanical efficiency at the horizon and megaparsec scale. The macro hot halo is tightly constrained by the absence of overheating and overcooling as probed by X-ray data and hydrodynamic simulations ({\\varepsilon }{BH}≃ {10}-3 {T}{{x},7.4}). The micro flow is shaped by general-relativistic effects tracked by state-of-the-art GR-RMHD simulations ({\\varepsilon }\\bullet ≃ 0.03). The supermassive black hole properties are tied to the X-ray halo temperature {T}{{x}}, or related cosmic scaling relation (as {L}{{x}}). The model is minimally based on first principles, such as conservation of energy and mass recycling. The inflow occurs via chaotic cold accretion (CCA), the rain of cold clouds condensing out of the quenched cooling flow and then recurrently funneled via inelastic collisions. Within 100s gravitational radii, the accretion energy is transformed into ultrafast 104 km s-1 outflows (UFOs) ejecting most of the inflowing mass. At larger radii, the energy-driven outflow entrains progressively more mass: at roughly kiloparsec scale, the velocities of the hot/warm/cold outflows are a few 103, 1000, and 500 km s-1, with median mass rates ˜ 10, 100, and several 100 {M}⊙ yr-1, respectively. The unified CCA model is consistent with the observations of nuclear UFOs and ionized, neutral, and molecular macro outflows. We provide step-by-step implementation for subgrid simulations, (semi)analytic works, or observational interpretations that require self-regulated AGN feedback at coarse scales, avoiding the a-posteriori fine-tuning of efficiencies.

XMM-Newton Proposal 03060602

NASA Astrophysics Data System (ADS)

Strickland, David

2004-10-01

We propose to observe 3 edge-on Milky-Way-like normal spiral galaxies in order to constrain the presence, properties and physical origin of hot gas in their halos, a topic about which relatively little is currently known. These observations will complete our sample of 8 edge-on normal spirals for which we have a wide range of existing observational data, so that all galaxies will have deep XMM-Newton and/or Chandra observations. With this sample we can assess the relative contribution to the halo X-ray emission of normal spirals from SNII-driven galactic fountains, accretion of primordial gas, and SNIa-driven outflows. The observations will robustly detect NGC 891-like hot halos, broadly quantify their properties, and can be used to constrain the efficiency of mechanical energy feedback.

The Soft X-ray View of Ultra Fast Outflows

NASA Astrophysics Data System (ADS)

Reeves, J.; Braito, V.; Nardini, E.; Matzeu, G.; Lobban, A.; Costa, M.; Pounds, K.; Tombesi, F.; Behar, E.

2017-10-01

The recent large XMM-Newton programmes on the nearby quasars PDS 456 and PG 1211+143 have revealed prototype ultra fast outflows in the iron K band through highly blue shifted absorption lines. The wind velocities are in excess of 0.1c and are likely to make a significant contribution to the host galaxy feedback. Here we present evidence for the signature of the fast wind in the soft X-ray band from these luminous quasars, focusing on the spectroscopy with the RGS. In PDS 456, the RGS spectra reveal the presence of soft X-ray broad absorption line profiles, which suggests that PDS 456 is an X-ray equivalent to the BAL quasars, with outflow velocities reaching 0.2c. In PG 1211, the soft X-ray RGS spectra show a complex of several highly blue shifted absorption lines over a wide range of ionisation and reveal outflowing components with velocities between 0.06-0.17c. For both quasars, the soft X-ray absorption is highly variable, even on timescales of days and is most prominent when the quasar flux is low. Overall the results imply the presence of a soft X-ray component of the ultra fast outflows, which we attribute to a clumpy or inhomogeneous phase of the disk wind.

Pulsar-Wind Nebulae and Magnetar Outflows: Observations at Radio, X-Ray, and Gamma-Ray Wavelengths

NASA Astrophysics Data System (ADS)

Reynolds, Stephen P.; Pavlov, George G.; Kargaltsev, Oleg; Klingler, Noel; Renaud, Matthieu; Mereghetti, Sandro

2017-07-01

We review observations of several classes of neutron-star-powered outflows: pulsar-wind nebulae (PWNe) inside shell supernova remnants (SNRs), PWNe interacting directly with interstellar medium (ISM), and magnetar-powered outflows. We describe radio, X-ray, and gamma-ray observations of PWNe, focusing first on integrated spectral-energy distributions (SEDs) and global spectral properties. High-resolution X-ray imaging of PWNe shows a bewildering array of morphologies, with jets, trails, and other structures. Several of the 23 so far identified magnetars show evidence for continuous or sporadic emission of material, sometimes associated with giant flares, and a few "magnetar-wind nebula" have been recently identified.

Simulating Supernovae Driven Outflows in Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Rodriguez, Jaimee-Ian

2018-01-01

Galactic outflows, or winds, prove to be a necessary input for galactic simulations to produce results comparable to observation, for it solves issues caused by what previous literature dubbed the “angular momentum catastrophe.” While it is known that the nature of outflows depends on the nature of the Interstellar Medium (ISM), the mechanisms behind outflows are still not completely understood. We investigate the driving force behind galactic outflows and the factors that influence their behavior, hypothesizing that supernovae within the galaxy drive these winds. We study isolated, high-resolution, smooth particle hydrodynamic simulations, focusing specifically on dwarf galaxies due to their shallow potential wells, which allow for more significant outflows. We find that outflows follow star formation (and associated supernovae) suggesting the causal relationship between the two. Furthermore, simulations with higher diffusivity differ little in star formation rate, but show significantly lower outflow rates, suggesting that environmental factors that have little effect on regulating star formation can greatly influence outflows, and so efficient outflows can be driven by a constant rate of supernovae, depending on ISM behavior. We are currently analyzing disk morphology and ambient density in order to comprehend the effect of supernovae on the immediate interstellar gas. By attaining greater understanding of the origin of galactic outflows, we will be able to not only improve the accuracy of simulations, we will also be able to gain greater insight into galactic formation and evolution, as outflows and resultant inflows may be vital to the regulation of galaxies throughout their lifetimes.

Dynamical efficiency of collisionless magnetized shocks in relativistic jets

NASA Astrophysics Data System (ADS)

Aloy, Miguel A.; Mimica, Petar

2011-09-01

The so-called internal shock model aims to explain the light-curves and spectra produced by non-thermal processes originated in the flow of blazars and gamma-ray bursts. A long standing question is whether the tenuous collisionless shocks, driven inside a relativistic flow, are efficient enough to explain the amount of energy observed as compared with the expected kinetic power of the outflow. In this work we study the dynamic efficiency of conversion of kinetic-to-thermal/magnetic energy of internal shocks in relativistic magnetized outflows. We find that the collision between shells with a non-zero relative velocity can yield either two oppositely moving shocks (in the frame where the contact surface is at rest), or a reverse shock and a forward rarefaction. For moderately magnetized shocks (magnetization σ ~= 0.1), the dynamic efficiency in a single two-shell interaction can be as large as 40%. Hence, the dynamic efficiency of moderately magnetized shocks is larger than in the corresponding unmagnetized two-shell interaction. We find that the efficiency is only weakly dependent on the Lorentz factor of the shells and, thus internal shocks in the magnetized flow of blazars and gamma-ray bursts are approximately equally efficient.

CHANDRA AND SWIFT X-RAY OBSERVATIONS OF THE X-RAY PULSAR SMC X-2 DURING THE OUTBURST OF 2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, K. L.; Hu, C.-P; Lin, L. C. C.

2016-09-10

We report the Chandra /HRC-S and Swift /XRT observations for the 2015 outburst of the high-mass X-ray binary pulsar in the Small Magellanic Cloud, SMC X-2. While previous studies suggested that either an O star or a Be star in the field is the high-mass companion of SMC X-2, our Chandra /HRC-S image unambiguously confirms the O-type star as the true optical counterpart. Using the Swift /XRT observations, we extracted accurate orbital parameters of the pulsar binary through a time of arrivals analysis. In addition, there were two X-ray dips near the inferior conjunction, which are possibly caused by eclipsesmore » or an ionized high-density shadow wind near the companion’s surface. Finally, we propose that an outflow driven by the radiation pressure from day ∼10 played an important role in the X-ray/optical evolution of the outburst.« less

The collapse of a molecular cloud core to stellar densities using radiation non-ideal magnetohydrodynamics

NASA Astrophysics Data System (ADS)

Wurster, James; Bate, Matthew R.; Price, Daniel J.

2018-04-01

We present results from radiation non-ideal magnetohydrodynamics (MHD) calculations that follow the collapse of rotating, magnetized, molecular cloud cores to stellar densities. These are the first such calculations to include all three non-ideal effects: ambipolar diffusion, Ohmic resistivity, and the Hall effect. We employ an ionization model in which cosmic ray ionization dominates at low temperatures and thermal ionization takes over at high temperatures. We explore the effects of varying the cosmic ray ionization rate from ζcr = 10-10 to 10-16 s-1. Models with ionization rates ≳10-12 s-1 produce results that are indistinguishable from ideal MHD. Decreasing the cosmic ray ionization rate extends the lifetime of the first hydrostatic core up to a factor of 2, but the lifetimes are still substantially shorter than those obtained without magnetic fields. Outflows from the first hydrostatic core phase are launched in all models, but the outflows become broader and slower as the ionization rate is reduced. The outflow morphology following stellar core formation is complex and strongly dependent on the cosmic ray ionization rate. Calculations with high ionization rates quickly produce a fast (≈14 km s-1) bipolar outflow that is distinct from the first core outflow, but with the lowest ionization rate, a slower (≈3-4 km s-1) conical outflow develops gradually and seamlessly merges into the first core outflow.

The energetics of AGN radiation pressure-driven outflows

NASA Astrophysics Data System (ADS)

Ishibashi, W.; Fabian, A. C.; Maiolino, R.

2018-05-01

The increasing observational evidence of galactic outflows is considered as a sign of active galactic nucleus (AGN) feedback in action. However, the physical mechanism responsible for driving the observed outflows remains unclear, and whether it is due to momentum, energy, or radiation is still a matter of debate. The observed outflow energetics, in particular the large measured values of the momentum ratio (\\dot{p}/(L/c) ˜ 10) and energy ratio (\\dot{E}_k/L ˜ 0.05), seems to favour the energy-driving mechanism; and most observational works have focused their comparison with wind energy-driven models. Here, we show that AGN radiation pressure on dust can adequately reproduce the observed outflow energetics (mass outflow rate, momentum flux, and kinetic power), as well as the scalings with luminosity, provided that the effects of radiation trapping are properly taken into account. In particular, we predict a sublinear scaling for the mass outflow rate (\\dot{M} ∝ L^{1/2}) and a superlinear scaling for the kinetic power (\\dot{E}_k ∝ L^{3/2}), in agreement with the observational scaling relations reported in the most recent compilation of AGN outflow data. We conclude that AGN radiative feedback can account for the global outflow energetics, at least equally well as the wind energy-driving mechanism, and therefore both physical models should be considered in the interpretation of future AGN outflow observations.

Far-Ultraviolet Observations of Outflows from Infrared-Luminous Galaxies

NASA Astrophysics Data System (ADS)

Leitherer, Claus; Chandar, Rupali; Tremonti, Christy A.; Wofford, Aida

2013-03-01

We have obtained ultraviolet spectra between 1150 and 1450 Å of four ultraviolet-bright, infrared-luminous starburst galaxies. Our selected sight-lines towards the starburst nuclei probe the conditions in the starburst-driven outflows. We detect outflowing gas with velocities of up to ˜900 km s-1. It is likely that the outflows are a major source of metal enrichment of the galaxies' halos. The mass outflow rates of several tens of M⊙ yr-1 are similar to the star-formation rates. The outflows may quench star formation and ultimately regulate the starburst.

A search for outflows from X-ray bright points in coronal holes

NASA Technical Reports Server (NTRS)

Mullan, D. J.; Waldron, W. L.

1986-01-01

Properties of X-ray bright points using two of the instruments on Solar Maximum Mission were investigated. The mass outflows from magnetic regions were modeled using a two dimensional MHD code. It was concluded that mass can be detected from X-ray bright points provided that the magnetic topology is favorable.

Late-time X-rays to map the Zoo of Engine-driven Stellar Explosions

NASA Astrophysics Data System (ADS)

Margutti, Raffaella

2017-09-01

We propose a continuation of our effort to monitor nearby long GRBs (z <=0.3) with Chandra. Our synergistic multi-wavelength program (radio, optical, Swift and proposed Chandra) is designed to extract the true energy of these explosions and to reveal the activity of their central engines. This effort allows us to: (i) investigate whether sub-energetic GRBs share the same explosion mechanisms and central engines as ordinary GRBs; (ii) investigate what essential physical property enables only a small fraction of supernovae to harbor a relativistic outflow; (iii) understand if jet-driven explosions are common in all SNe. These objectives are only possible by expanding the current small sample of well-observed local GRBs and by drawing comparisons with cosmological GRBs and common SNe.

Ultrafast outflows disappear in high-radiation fields

NASA Astrophysics Data System (ADS)

Pinto, C.; Alston, W.; Parker, M. L.; Fabian, A. C.; Gallo, L. C.; Buisson, D. J. K.; Walton, D. J.; Kara, E.; Jiang, J.; Lohfink, A.; Reynolds, C. S.

2018-05-01

Ultrafast outflows (UFOs) are the most extreme winds launched by active galactic nuclei (AGN) due to their mildly relativistic speeds (˜0.1-0.3c) and are thought to significantly contribute to galactic evolution via AGN feedback. Their nature and launching mechanism are however not well understood. Recently, we have discovered the presence of a variable UFO in the narrow-line Seyfert 1 IRAS 13224-3809. The UFO varies in response to the brightness of the source. In this work we perform flux-resolved X-ray spectroscopy to study the variability of the UFO and found that the ionization parameter is correlated with the luminosity. In the brightest states the gas is almost completely ionized by the powerful radiation field and the UFO is hardly detected. This agrees with our recent results obtained with principal component analysis. We might have found the tip of the iceberg: the high ionization of the outflowing gas may explain why it is commonly difficult to detect UFOs in AGN and possibly suggest that we may underestimate their actual feedback. We have also found a tentative correlation between the outflow velocity and the luminosity, which is expected from theoretical predictions of radiation-pressure-driven winds. This trend is rather marginal due to the Fe XXV-XXVI degeneracy. Further work is needed to break such degeneracy through time-resolved spectroscopy.

Intermittent Reconnection Downflow Enhancements In A Simulated Flux Rope Eruption

NASA Astrophysics Data System (ADS)

Kliem, Bernhard; Linton, M. G.

2009-05-01

Supra-arcade downflows in X-ray and EUV flare emissions and post-eruption inflows in coronagraph data have been interpreted to be signatures of the downward reconnection outflow from a vertical (flare) current sheet. These downflows show an intermittent occurrence pattern, indicating that the reconnection is bursty in time or patchy in space, or both. We present MHD simulations of such reconnection in the realistic configuration of a vertical current sheet formed beneath and driven by an erupting flux rope. The reconnection is found to develop bursty outflows, both upward and downward, with the upward outflows generally showing the stronger variablity. While the reconnection starts early in the rise of the flux rope and its peak upward outflow velocity is closely correlated with the rope's rise velocity, the burstiness develops in a clear fashion only as the rope's height has increased from the initial position by about an order of magnitude, so that the current sheet has reached a sufficient vertical extent. The reconnection downflow shows a series of enhancements, each of them starting at a successively greater height from a newly developed magnetic X line. The plasma temporarily accelerated downward in such an enhancement soon turns into a gradual deceleration and then eventually comes to rest on top of previously accelerated plasma. These findings are consistent with the observations of intermittent downflows.

Magnetized Reverse Shock: Density-fluctuation-induced Field Distortion, Polarization Degree Reduction, and Application to GRBs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng Wei; Zhang Bing; Li Hui

The early optical afterglow emission of several gamma-ray bursts (GRBs) shows a high linear polarization degree (PD) of tens of percent, suggesting an ordered magnetic field in the emission region. The light curves are consistent with being of a reverse shock (RS) origin. However, the magnetization parameter, σ , of the outflow is unknown. If σ is too small, an ordered field in the RS may be quickly randomized due to turbulence driven by various perturbations so that the PD may not be as high as observed. Here we use the “Athena++” relativistic MHD code to simulate a relativistic jetmore » with an ordered magnetic field propagating into a clumpy ambient medium, with a focus on how density fluctuations may distort the ordered magnetic field and reduce PD in the RS emission for different σ values. For a given density fluctuation, we discover a clear power-law relationship between the relative PD reduction and the σ value of the outflow. Such a relation may be applied to estimate σ of the GRB outflows using the polarization data of early afterglows.« less

Magnetized Reverse Shock: Density-fluctuation-induced Field Distortion, Polarization Degree Reduction, and Application to GRBs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Wei; Zhang, Bing; Li, Hui

We report that the early optical afterglow emission of several gamma-ray bursts (GRBs) shows a high linear polarization degree (PD) of tens of percent, suggesting an ordered magnetic field in the emission region. The light curves are consistent with being of a reverse shock (RS) origin. However, the magnetization parameter, σ, of the outflow is unknown. If σ is too small, an ordered field in the RS may be quickly randomized due to turbulence driven by various perturbations so that the PD may not be as high as observed. Here we use the "Athena++" relativistic MHD code to simulate amore » relativistic jet with an ordered magnetic field propagating into a clumpy ambient medium, with a focus on how density fluctuations may distort the ordered magnetic field and reduce PD in the RS emission for different σ values. For a given density fluctuation, we discover a clear power-law relationship between the relative PD reduction and the σ value of the outflow. Finally, such a relation may be applied to estimate σ of the GRB outflows using the polarization data of early afterglows.« less

Magnetized Reverse Shock: Density-fluctuation-induced Field Distortion, Polarization Degree Reduction, and Application to GRBs

DOE PAGES

Deng, Wei; Zhang, Bing; Li, Hui; ...

2017-08-03

We report that the early optical afterglow emission of several gamma-ray bursts (GRBs) shows a high linear polarization degree (PD) of tens of percent, suggesting an ordered magnetic field in the emission region. The light curves are consistent with being of a reverse shock (RS) origin. However, the magnetization parameter, σ, of the outflow is unknown. If σ is too small, an ordered field in the RS may be quickly randomized due to turbulence driven by various perturbations so that the PD may not be as high as observed. Here we use the "Athena++" relativistic MHD code to simulate amore » relativistic jet with an ordered magnetic field propagating into a clumpy ambient medium, with a focus on how density fluctuations may distort the ordered magnetic field and reduce PD in the RS emission for different σ values. For a given density fluctuation, we discover a clear power-law relationship between the relative PD reduction and the σ value of the outflow. Finally, such a relation may be applied to estimate σ of the GRB outflows using the polarization data of early afterglows.« less

Compact Starburst Galaxies with Fast Outflows: Spatially Resolved Stellar Mass Profiles

NASA Astrophysics Data System (ADS)

Gottlieb, Sophia; Diamond-Stanic, Aleksandar; Lipscomb, Charles; Ohene, Senyo; Rines, Josh; Moustakas, John; Sell, Paul; Tremonti, Christy; Coil, Alison; Rudnick, Gregory; Hickox, Ryan C.; Geach, James; Kepley, Amanda

2018-01-01

Powerful galactic winds driven by stellar feedback and black hole accretion are thought to play an important role in regulating star formation in galaxies. In particular, strong stellar feedback from supernovae, stellar winds, radiation pressure, and cosmic rays is required by simulations of star-forming galaxies to prevent the vast majority of baryons from cooling and collapsing to form stars. However, it remains unclear whether these stellar processes play a significant role in expelling gas and shutting down star formation in massive progenitors of quiescent galaxies. What are the limits of stellar feedback? We present multi-band photometry with HST/WFC3 (F475W, F814W, F160W) for a dozen compact starburst galaxies at z~0.6 with half-light radii that suggest incredibly large central escape velocities. These massive galaxies are driving fast (>1000 km/s) outflows that have been previously attributed to stellar feedback associated with the compact (r~100 pc) starburst. But how compact is the stellar mass? In the context of the stellar feedback hypothesis, it is unclear whether these fast outflows are being driven at velocities comparable to the escape velocity of an incredibly dense stellar system (as predicted by some models of radiation-pressure winds) or at velocities that exceed the central escape velocity by large factor. Our spatially resolved measurements with HST show that the stellar mass is more extended than the light, and this requires that the physical mechanism responsible for driving the winds must be able to launch gas at velocities that are factors of 5-10 beyond the central escape velocity.

Modelling the thermal X-ray emission around the Galactic centre from colliding Wolf-Rayet winds

NASA Astrophysics Data System (ADS)

Russell, Christopher M. P.; Wang, Q. Daniel; Cuadra, Jorge

2017-11-01

We compute the thermal X-ray emission from hydrodynamic simulations of the 30 Wolf-Rayet (WR) stars orbiting within a parsec of Sgr A*, with the aim of interpreting the Chandra X-ray observations of this region. The model well reproduces the spectral shape of the observations, indicating that the shocked WR winds are the dominant source of this thermal emission. The model X-ray flux is tied to the strength of the Sgr A* outflow, which clears out hot gas from the vicinity of Sgr A*. A moderate outflow best fits the present-day observations, even though this supermassive black hole (SMBH) outflow ended ~100 yr ago.

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova

DOE PAGES

Evans, P. A.; Cenko, S. B.; Kennea, J. A.; ...

2017-10-16

With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. However, a complete picture of compact object mergers requires the detection of an electromagnetic (EM) counterpart. Here, we report ultraviolet (UV) and x-ray observations by Swift and the Nuclear Spectroscopic Telescope ARray (NuSTAR) of the EM counterpart of the binary neutron star merger GW 170817. The bright, rapidly fading ultraviolet emission indicates a high mass (≈ 0.03 solar masses) wind-driven outflow with moderate electron fraction (Ye ≈ 0.27). Combined with the x-ray limits, we favor an observer viewing angle of ≈30°more » away from the orbital rotation axis, which avoids both obscuration from the heaviest elements in the orbital plane and a direct view of any ultra-relativistic, highly collimated ejecta (a γ-ray burst afterglow).« less

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova.

PubMed

Evans, P A; Cenko, S B; Kennea, J A; Emery, S W K; Kuin, N P M; Korobkin, O; Wollaeger, R T; Fryer, C L; Madsen, K K; Harrison, F A; Xu, Y; Nakar, E; Hotokezaka, K; Lien, A; Campana, S; Oates, S R; Troja, E; Breeveld, A A; Marshall, F E; Barthelmy, S D; Beardmore, A P; Burrows, D N; Cusumano, G; D'Aì, A; D'Avanzo, P; D'Elia, V; de Pasquale, M; Even, W P; Fontes, C J; Forster, K; Garcia, J; Giommi, P; Grefenstette, B; Gronwall, C; Hartmann, D H; Heida, M; Hungerford, A L; Kasliwal, M M; Krimm, H A; Levan, A J; Malesani, D; Melandri, A; Miyasaka, H; Nousek, J A; O'Brien, P T; Osborne, J P; Pagani, C; Page, K L; Palmer, D M; Perri, M; Pike, S; Racusin, J L; Rosswog, S; Siegel, M H; Sakamoto, T; Sbarufatti, B; Tagliaferri, G; Tanvir, N R; Tohuvavohu, A

2017-12-22

With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. A complete picture of compact object mergers, however, requires the detection of an electromagnetic (EM) counterpart. We report ultraviolet (UV) and x-ray observations by Swift and the Nuclear Spectroscopic Telescope Array of the EM counterpart of the binary neutron star merger GW170817. The bright, rapidly fading UV emission indicates a high mass (≈0.03 solar masses) wind-driven outflow with moderate electron fraction ( Y e ≈ 0.27). Combined with the x-ray limits, we favor an observer viewing angle of ≈30° away from the orbital rotation axis, which avoids both obscuration from the heaviest elements in the orbital plane and a direct view of any ultrarelativistic, highly collimated ejecta (a γ-ray burst afterglow). Copyright © 2017, American Association for the Advancement of Science.

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, P. A.; Cenko, S. B.; Kennea, J. A.

With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. However, a complete picture of compact object mergers requires the detection of an electromagnetic (EM) counterpart. Here, we report ultraviolet (UV) and x-ray observations by Swift and the Nuclear Spectroscopic Telescope ARray (NuSTAR) of the EM counterpart of the binary neutron star merger GW 170817. The bright, rapidly fading ultraviolet emission indicates a high mass (≈ 0.03 solar masses) wind-driven outflow with moderate electron fraction (Ye ≈ 0.27). Combined with the x-ray limits, we favor an observer viewing angle of ≈30°more » away from the orbital rotation axis, which avoids both obscuration from the heaviest elements in the orbital plane and a direct view of any ultra-relativistic, highly collimated ejecta (a γ-ray burst afterglow).« less

THE MOLECULAR WIND IN THE NEAREST SEYFERT GALAXY CIRCINUS REVEALED BY ALMA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zschaechner, Laura K.; Walter, Fabian; Farina, Emanuele P.

2016-12-01

We present ALMA observations of the inner 1′ (1.2 kpc) of the Circinus galaxy, the nearest Seyfert. We target CO (1–0) in the region associated with a well-known multiphase outflow driven by the central active galactic nucleus (AGN). While the geometry of Circinus and its outflow make disentangling the latter difficult, we see indications of outflowing molecular gas at velocities consistent with the ionized outflow. We constrain the mass of the outflowing molecular gas to be 1.5 × 10{sup 5}−5.1 × 10{sup 6} M {sub ⊙}, yielding a molecular outflow rate of 0.35–12.3 M {sub ⊙} yr{sup −1}. The values within this range aremore » comparable to the star formation (SF) rate in Circinus, indicating that the outflow indeed regulates SF to some degree. The molecular outflow in Circinus is considerably lower in mass and energetics than previously studied AGN-driven outflows, especially given its high ratio of AGN luminosity to bolometric luminosity. The molecular outflow in Circinus is, however, consistent with some trends put forth by Cicone et al., including a linear relation between kinetic power and AGN luminosity, as well as its momentum rate versus bolometric luminosity (although the latter places Circinus among the starburst galaxies in that sample). We detect additional molecular species including CN and C{sup 17}O.« less

The Origin of the Extra-nuclear X-ray Emission in the Seyfert Galaxy NGC 2992

NASA Astrophysics Data System (ADS)

Colbert, E. J. M.; Strickland, D. K.; Veilleux, S.; Weaver, K. A.

2004-12-01

We present an analysis of a Chandra ACIS observation of the edge-on Seyfert galaxy NGC 2992. We find extended X-ray emission with Lx(total) in excess of 10**40 erg/s. The brightest nebula is positioned a few 100 pc from the X-ray core, and is spatially coincident with optical line and radio emission. This emission nebula may be energized by the AGN, as opposed to a nuclear starburst. The expected kpc-scale X-ray emission due to a starburst-driven wind is larger than a few 10**39 erg/s, and we present large-scale X-ray emission that may be associated with such an outflow. The extra-nuclear emission has a very soft spectrum. Chandra and XMM spectra of the total nuclear region show a very prominent ``soft excess'' below 2-3 keV. We shall discuss the spectral properties of this soft excess, and will compare with the results from the spatial analysis, and with AGN and starburst models for extranuclear X-ray nebulae.

The response of relativistic outflowing gas to the inner accretion disk of a black hole.

PubMed

Parker, Michael L; Pinto, Ciro; Fabian, Andrew C; Lohfink, Anne; Buisson, Douglas J K; Alston, William N; Kara, Erin; Cackett, Edward M; Chiang, Chia-Ying; Dauser, Thomas; De Marco, Barbara; Gallo, Luigi C; Garcia, Javier; Harrison, Fiona A; King, Ashley L; Middleton, Matthew J; Miller, Jon M; Miniutti, Giovanni; Reynolds, Christopher S; Uttley, Phil; Vasudevan, Ranjan; Walton, Dominic J; Wilkins, Daniel R; Zoghbi, Abderahmen

2017-03-01

The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these-the ultrafast outflows-are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224-3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very different scales: the X-ray emission from within a few gravitational radii of the black hole ionizing the disk wind hundreds of gravitational radii further away as the X-ray flux rises.

X-raying the most luminous quasars at cosmic noon

NASA Astrophysics Data System (ADS)

Piconcelli, E.; Martocchia, S.; Zappacosta, L.

2017-10-01

The WISE/SDSS hyper-luminous (log L_Bol > 47) quasar (WISSH) survey is performing a multi-band systematic exploration of the most luminous AGN shining at the golden epoch of AGN activity (i.e. z ˜ 2-4). This gives the opportunity of overcoming the luminosity bias in the exploration of the accretion phenomenon and the impact of AGN radiative output on the host. In this talk, I present the results of our study of the X-ray spectra of 40 WISSH quasars. I report on the correlations between the X-ray and Optical, UV and MIR properties, and the behavior of the X-ray bolometric correction at the brightest end of the luminosity function. I discuss the relative X-ray weakness of these very powerful quasars compared to less luminous AGN. This X-ray weakness can be a key ingredient for accelerating powerful ionized outflows (ubiquitously revealed in the UV/optical spectra of WISSH quasars) and, furthermore, radiation-driven winds can be effective in destroying the X-ray corona and quenching the X-ray emission. The potential offered by Athena in studying this extreme class of AGN is also discussed.

Naked-eye optical flash from gamma-ray burst 080319B: Tracing the decaying neutrons in the outflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan Yizhong; Zhang Bing; Wei Daming

For an unsteady baryonic gamma-ray burst (GRB) outflow, the fast and slow proton shells collide with each other and produce energetic soft gamma-ray emission. If the outflow has a significant neutron component, the ultrarelativistic neutrons initially expand freely until decaying at a larger radius. The late-time proton shells ejected from the GRB central engine, after powering the regular internal shocks, will sweep these {beta}-decay products and give rise to very bright UV/optical emission. The naked-eye optical flash from GRB 080319B, an energetic explosion in the distant Universe, can be well explained in this way.

NuSTAR View of the Black Hole Wind in the Galaxy Merger IRAS F11119+3257

NASA Astrophysics Data System (ADS)

Tombesi, F.; Veilleux, S.; Meléndez, M.; Lohfink, A.; Reeves, J. N.; Piconcelli, E.; Fiore, F.; Feruglio, C.

2017-12-01

Galactic winds driven by active galactic nuclei (AGNs) have been invoked to play a fundamental role in the co-evolution between supermassive black holes and their host galaxies. Finding observational evidence of such feedback mechanisms is of crucial importance and it requires a multi-wavelength approach in order to compare winds at different scales and phases. In Tombesi et al., we reported the detection of a powerful ultra-fast outflow (UFO) in the Suzaku X-ray spectrum of the ultra-luminous infrared galaxy IRAS F11119+3257. The comparison with a galaxy-scale OH molecular outflow observed with Herschel in the same source supported the energy-conserving scenario for AGN feedback. The main objective of this work is to perform an independent check of the Suzaku results using the higher sensitivity and wider X-ray continuum coverage of NuSTAR. We clearly detect a highly ionized Fe K UFO in the 100 ks NuSTAR spectrum with parameters N H = (3.2 ± 1.5) × 1024 cm-2, log ξ = {4.0}-0.3+1.2 erg s-1 cm, and {v}{out}={0.253}-0.118+0.061c. The launching radius is likely at a distance of r ≥ 16r s from the black hole. The mass outflow rate is in the range of {\\dot{M}}{out} ≃ 0.5-2 M ⊙ yr-1. The UFO momentum rate and power are {\\dot{P}}{out} ≃ 0.5-2 L AGN/c and {\\dot{E}}{out} ≃ 7%-27% L AGN, respectively. The UFO parameters are consistent between the 2013 Suzaku and the 2015 NuSTAR observations. Only the column density is found to be variable, possibly suggesting a clumpy wind. The comparison with the energetics of molecular outflows estimated in infrared and millimeter wavelengths support a connection between the nuclear and galaxy-scale winds in luminous AGNs.

A VERSATILE FAMILY OF GALACTIC WIND MODELS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bustard, Chad; Zweibel, Ellen G.; D’Onghia, Elena, E-mail: bustard@wisc.edu

2016-03-01

We present a versatile family of model galactic outflows including non-uniform mass and energy source distributions, a gravitational potential from an extended mass source, and radiative losses. The model easily produces steady-state wind solutions for a range of mass-loading factors, energy-loading factors, galaxy mass, and galaxy radius. We find that, with radiative losses included, highly mass-loaded winds must be driven at high central temperatures, whereas low mass-loaded winds can be driven at low temperatures just above the peak of the cooling curve, meaning radiative losses can drastically affect the wind solution even for low mass-loading factors. By including radiative losses,more » we are able to show that subsonic flows can be ignored as a possible mechanism for expelling mass and energy from a galaxy compared to the more efficient transonic solutions. Specifically, the transonic solutions with low mass loading and high energy loading are the most efficient. Our model also produces low-temperature, high-velocity winds that could explain the prevalence of low-temperature material in observed outflows. Finally, we show that our model, unlike the well-known Chevalier and Clegg model, can reproduce the observed linear relationship between wind X-ray luminosity and star formation rate (SFR) over a large range of SFR from 1–1000 M{sub ⊙} yr{sup −1} assuming the wind mass-loading factor is higher for low-mass, and hence, low-SFR galaxies. We also constrain the allowed mass-loading factors that can fit the observed X-ray luminosity versus SFR trend, further suggesting an inverse relationship between mass loading and SFR as explored in advanced numerical simulations.« less

DIFFUSIVE PARTICLE ACCELERATION IN SHOCKED, VISCOUS ACCRETION DISKS: GREEN'S FUNCTION ENERGY DISTRIBUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becker, Peter A.; Das, Santabrata; Le, Truong, E-mail: pbecker@gmu.edu, E-mail: sbdas@iitg.ernet.in, E-mail: truong.le@nhrec.org

2011-12-10

The acceleration of relativistic particles in a viscous accretion disk containing a standing shock is investigated as a possible explanation for the energetic outflows observed around radio-loud black holes. The energy/space distribution of the accelerated particles is computed by solving a transport equation that includes the effects of first-order Fermi acceleration, bulk advection, spatial diffusion, and particle escape. The velocity profile of the accreting gas is described using a model for shocked viscous disks recently developed by the authors, and the corresponding Green's function distribution for the accelerated particles in the disk and the outflow is obtained using a classicalmore » method based on eigenfunction analysis. The accretion-driven, diffusive shock acceleration scenario explored here is conceptually similar to the standard model for the acceleration of cosmic rays at supernova-driven shocks. However, in the disk application, the distribution of the accelerated particles is much harder than would be expected for a plane-parallel shock with the same compression ratio. Hence the disk environment plays a key role in enhancing the efficiency of the shock acceleration process. The presence of the shock helps to stabilize the disk by reducing the Bernoulli parameter, while channeling the excess binding energy into the escaping relativistic particles. In applications to M87 and Sgr A*, we find that the kinetic power in the jet is {approx}0.01 M-dot c{sup 2}, and the outflowing relativistic particles have a mean energy {approx}300 times larger than that of the thermal gas in the disk at the shock radius. Our results suggest that a standing shock may be an essential ingredient in accretion onto underfed black holes, helping to resolve the long-standing problem of the stability of advection-dominated accretion disks.« less

Ionised outflows in z ~ 2.4 quasar host galaxies

NASA Astrophysics Data System (ADS)

Carniani, S.; Marconi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Cano-Díaz, M.; Cicone, C.; Comastri, A.; Cresci, G.; Fiore, F.; Feruglio, C.; La Franca, F.; Mainieri, V.; Mannucci, F.; Nagao, T.; Netzer, H.; Piconcelli, E.; Risaliti, G.; Schneider, R.; Shemmer, O.

2015-08-01

Aims: Outflows driven by active galactic nuclei (AGN) are invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super-massive black holes and their host galaxies. We here aim to detect extended ionised outflows in luminous quasars, where we expect the highest activity both in star formation and in black-hole accretion. Currently, there are only a few studies based on spatially resolved observations of outflows at high redshift, z > 2. Methods: We analysed a sample of six luminous (L > 1047 erg/s) quasars at z ~ 2.4, observed in H-band using the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematic analysis of the [Oiii] emission line at λ = 5007 Å. Results: We detect fast, spatially extended outflows in five out of six targets. [Oiii]λ5007 has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km s-1 and line widths up to 1500 km s-1. Using the spectroastrometric method, we infer a size of the ionised outflows of up to ~2 kpc. The properties of the ionised outflows, mass outflow rate, momentum rate, and kinetic power, are correlated with the AGN luminosity. The increase in outflow rate with increasing AGN luminosity is consistent with the idea that a luminous AGN pushes away the surrounding gas through fast outflows that are driven by radiation pressure, which depends on the emitted luminosity. Conclusions: We derive mass outflow rates of about 6-700 M⊙ yr-1 for our sample, which are lower than those observed in molecular outflows. The physical properties of ionised outflows show dependences on AGN luminosity that are similar to those of molecular outflows, but indicate that the mass of ionised gas is lower than that of molecular outflows. Alternatively, this discrepancy between ionised and molecular outflows could be explained with different acceleration mechanisms. Based on Observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, P.ID: 086.B-0579(A).

Can Radio Emission From Luminous Obscured AGN Blow Kpc-scale Ionized Outflows?

NASA Astrophysics Data System (ADS)

Goulding, Andy

2017-09-01

We propose joint VLA radio and Chandra X-ray to observe 4 AGN selected from the SDSS-BOSS and the Hyper Suprime-Cam surveys that present spectacular extended outflowing [O III] regions, reaching up to 50kpc in diameter. Our proposed observations allow us to study the mechanical and kinematical output of the AGN through radio and X-ray observations, measure the fraction of the AGN bolometric luminosity that is transferred to the outflow, and to determine the morphology and spectral index (by producing high-res continuum maps) of the radio emission that may be co-spatial with the extended ionized AGN outflow. In turn, our study will determine what role the AGN plays in producing extended outflows, and hence, provide an in-depth understanding of the physical drivers of AGN feedback.

Measuring the Impact of AGN Outflows via Intensive UV and X-ray Monitoring Campaigns

NASA Astrophysics Data System (ADS)

Kriss, Gerard

2015-08-01

Observations of AGN outflows have progressed from the era of single-object surveys to intensive monitoring campaigns spanning weeks to months. The combination of multiple observations, improved temporal coverage, multi-wavelength monitoring in both the X-ray and UV bands, and the baseline of prior historical observations has enabled determinations of the locations, mass flux, and kinetic luminosities of the outflowing absorbing gas in several AGN, notably Mrk 509, NGC 5548, Mrk 335, and NGC 985. Another intensive campaign is planned for 2015-2016 on NGC 7469. In all cases, the mass flux and kinetic energy is dominated by the higher-ionization X-ray absorbing gas. But the higher-resolution UV observations give a kinematically resolved picture of the overall outflow. In most cases, the outflowing gas is located at parsec to kpc scales, with insufficient kinetic luminosity to have an evolutionary impact on the host galaxy. Typically, the kinetic luminosity is less than a percent of the Eddington luminosity. In some cases, transient, broad UV absorption troughs have appeared (e.g., Mrk 335 and NGC 5548), with variability timescales suggesting locations near the broad-line region of the AGN. Yet these higher-velocity outflows also have low-impact kinetic luminosities. In the best-studied case of NGC 5548, the strength of the broad UV absorption lines varies with the degree of soft X-ray obscuration first revealed by XMM-Newton spectra. The lower-ionization, narrow associated absorption lines in the UV spectrum of NGC 5548 that appeared concurrently with the soft X-ray obscuration vary in response to the changing UV flux on a daily basis. The intensive monitoring allows us to fit time-dependent photoionization models to the UV-absorbing gas, allowing precise determinations of the locations, mass flux, and kinetic luminosities of the absorbers.

X-Ray Evidence for the Accretion Disc-Outflow Connection in 3C 111

NASA Technical Reports Server (NTRS)

Tombesi, Frank; Sambruna, R. M.; Reeves, J. N.; Reynolds, C. S.; Braito, V.

2011-01-01

We present the spectral analysis of three Suzaku X-ray Imaging Spectrometer observations of 3C III requested to monitor the predicted variability of its ultrafast outflow on approximately 7 d time-scales. We detect an ionized iron emission line in the first observation and a blueshifted absorption line in the second, when the flux is approximately 30 per cent higher. The location of the material is constrained at less than 0.006 pc from the variability. Detailed modelling supports an identification with ionized reflection off the accretion disc at approximately 20-100rg from the black hole and a highly ionized and massive ultrafast outflow with velocity approximately 0.1c, respectively. The outflow is most probably accelerated by radiation pressure, but additional magnetic thrust cannot be excluded. The measured high outflow rate and mechanical energy support the claims that disc outflows may have a significant feedback role. This work provides the first direct evidence for an accretion disc-outflow connection in a radio-loud active galactic nucleus, possibly linked also to the jet activity.

HELICAL MAGNETIC FIELDS IN THE NGC 1333 IRAS 4A PROTOSTELLAR OUTFLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ching, Tao-Chung; Lai, Shih-Ping; Zhang, Qizhou

We present Submillimeter Array polarization observations of the CO J = 3–2 line toward NGC 1333 IRAS 4A. The CO Stokes I maps at an angular resolution of ∼1″ reveal two bipolar outflows from the binary sources of NGC 1333 IRAS 4A. The kinematic features of the CO emission can be modeled by wind-driven outflows at ∼20° inclined from the plane of the sky. Close to the protostars the CO polarization, at an angular resolution of ∼2.″3, has a position angle approximately parallel to the magnetic field direction inferred from the dust polarizations. The CO polarization direction appears to vary smoothly frommore » an hourglass field around the core to an arc-like morphology wrapping around the outflow, suggesting a helical structure of magnetic fields that inherits the poloidal fields at the launching point and consists of toroidal fields at a farther distance of outflow. The helical magnetic field is consistent with the theoretical expectations for launching and collimating outflows from a magnetized rotating disk. Considering that the CO polarized emission is mainly contributed from the low-velocity and low-resolution data, the helical magnetic field is likely a product of the wind–envelope interaction in the wind-driven outflows. The CO data reveal a PA of ∼30° deflection in the outflows. The variation in the CO polarization angle seems to correlate with the deflections. We speculate that the helical magnetic field contributes to ∼10° deflection of the outflows by means of Lorentz force.« less

MHD Wind Models in X-Ray Binaries and AGN

NASA Astrophysics Data System (ADS)

Behar, Ehud; Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris R.; Tombesi, Francesco; Contopoulos, Ioannis

2017-08-01

Self-similar magnetohydrodynamic (MHD) wind models that can explain both the kinematics and the ionization structure of outflows from accretion sources will be presented.The X-ray absorption-line properties of these outflows are diverse, their velocity ranging from 0.001c to 0.1c, and their ionization ranging from neutral to fully ionized.We will show how the velocity structure and density profile of the wind can be tightly constrained, by finding the scaling of the magnetic flux with the distance from the center that best matches observations, and with no other priors.It will be demonstrated that the same basic MHD wind structure that successfully accounts for the X-ray absorber properties of outflows from supermassive black holes, also reproduces the high-resolution X-ray spectrum of the accreting stellar-mass black hole GRO J1655-40 for a series of ions between ~1A and ~12A.These results support both the magnetic nature of these winds, as well as the universal nature of magnetic outflows across all black hole sizes.

A Study of PG Quasar-Driven Outflows with COS

NASA Astrophysics Data System (ADS)

Hamann, Frederick

2013-10-01

Quasar outflows are an important part of the quasar phenomenon, but many questions remain about their energetics, physical properties and the role they might play in providing feedback to host galaxy evolution. We searched our own COS far-UV observations from the QUEST survey and other large COS programs to find a sample of 6 bright PG quasars with broad {FWHM > 400 km/s} high velocity {v > 1000 km/s} absorption lines that clearly form in quasar-driven winds. These quasars can fill an important gap in our understanding between local Seyferts with low-speed winds and high-redshift quasars with extreme BAL outflows. They are also well-studied at other wavelengths, with some evidence for the quasars driving galaxy-scale blowouts and shutting down star formation. But almost nothing is known about the quasar outflows themselves. We propose a detailed study of these 6 outflow quasars using new COS FUV observations to 1} expand the existing wavelength coverage across critical lines that are diagnostic of the outflow physical conditions, kinetic energies, and metallicities, and 2} check for line variability as an indicator of the outflow structure and locations. This quasar sample includes unusual cases with many low-abundance {PV 1118,1128 and SIV 1063} and excited-state lines {SIV 1073*, CIII* 1175, CII* 1335} that will provide unprecedented constraints on the outflow properties, plus the first known OVI-only mini-BAL outflow {no lower ions detected} for which we will cover NeVIII 770,780 to probe the highest ionization gas. The high FUV sensitivity of COS is uniquely able to measure this wide range of outflow lines in low-redshift quasars with no Lya forest contamination.

A STUDY OF THE X-RAYED OUTFLOW OF APM 08279+5255 THROUGH PHOTOIONIZATION CODES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saez, Cristian; Chartas, George, E-mail: saez@astro.psu.edu, E-mail: chartasg@cofc.edu

2011-08-20

We present new results from our study of the X-rayed outflow of the z = 3.91 gravitationally lensed broad absorption line quasar APM 08279+5255. These results are based on spectral fits to all the long exposure observations of APM 08279+5255 using a new quasar-outflow model. This model is based on CLOUDY{sup 3} CLOUDY is a photoionization code designed to simulate conditions in interstellar matter under a broad range of conditions. We have used version 08.00 of the code last described by Ferland et al. (1998). The atomic database used by CLOUDY is described in Ferguson et al. (2001) and http://www.pa.uky.edu/{approx}verner/atom.html.more » simulations of a near-relativistic quasar outflow. The main conclusions from our multi-epoch spectral re-analysis of Chandra, XMM-Newton, and Suzaku observations of APM 08279+5255 are the following. (1) In every observation, we confirm the presence of two strong features, one at rest-frame energies between 1-4 keV and the other between 7-18 keV. (2) We confirm that the low-energy absorption (1-4 keV rest frame) arises from a low-ionization absorber with log(N{sub H}/cm{sup -2}) {approx} 23 and the high-energy absorption (7-18 keV rest frame) arises from highly ionized (3 {approx}< log {xi} {approx}< 4, where {xi} is the ionization parameter) iron in a near-relativistic outflowing wind. Assuming this interpretation, we find that the velocities on the outflow could get up to {approx}0.7c. (3) We confirm a correlation between the maximum outflow velocity and the photon index and find possible trends between the maximum outflow velocity and the X-ray luminosity, and between the total column density and the photon index. We performed calculations of the force multipliers of material illuminated by absorbed power laws and a Mathews-Ferland spectral energy distribution (SED). We found that variations of the X-ray and UV parts of the SEDs and the presence of a moderate absorbing shield will produce important changes in the strength of the radiative driving force. These results support the observed trend found between the outflow velocity and X-ray photon index in APM 08279+5255. If this result is confirmed it will imply that radiation pressure is an important mechanism in producing quasar outflows.« less

Swift observations of V404 Cyg during the 2015 outburst: X-ray outflows from super-Eddington accretion

NASA Astrophysics Data System (ADS)

Motta, S. E.; Kajava, J. J. E.; Sánchez-Fernández, C.; Beardmore, A. P.; Sanna, A.; Page, K. L.; Fender, R.; Altamirano, D.; Charles, P.; Giustini, M.; Knigge, C.; Kuulkers, E.; Oates, S.; Osborne, J. P.

2017-10-01

The black hole (BH) binary V404 Cyg entered the outburst phase in 2015 June after 26 yr of X-ray quiescence, and with its behaviour broke the outburst evolution pattern typical of most BH binaries. We observed the entire outburst with the Swift satellite and performed time-resolved spectroscopy of its most active phase, obtaining over a thousand spectra with exposures from tens to hundreds of seconds. All the spectra can be fitted with an absorbed power-law model, which most of the time required the presence of a partial covering. A blueshifted iron-Kα line appears in 10 per cent of the spectra together with the signature of high column densities, and about 20 per cent of the spectra seem to show signatures of reflection. None of the spectra showed the unambiguous presence of soft disc-blackbody emission, while the observed bolometric flux exceeded the Eddington value in 3 per cent of the spectra. Our results can be explained assuming that the inner part of the accretion flow is inflated into a slim disc that both hides the innermost (and brightest) regions of the flow, and produces a cold, clumpy, high-density outflow that introduces the high absorption and fast spectral variability observed. We argue that the BH in V404 Cyg might have been accreting erratically or even continuously at Eddington/super-Eddington rates - thus sustaining a surrounding slim disc - while being partly or completely obscured by the inflated disc and its outflow. Hence, the largest flares produced by the source might not be accretion-driven events, but instead the effects of the unveiling of the extremely bright source hidden within the system.

Identification of the High-energy Gamma-Ray Source 3FGL J1544.6-1125 as a Transitional Millisecond Pulsar Binary in an Accreting State

NASA Astrophysics Data System (ADS)

Bogdanov, Slavko; Halpern, Jules P.

2015-04-01

We present X-ray, ultraviolet, and optical observations of 1RXS J154439.4-112820, the most probable counterpart of the unassociated Fermi-LAT source 3FGL J1544.6-1125. The optical data reveal rapid variability, which is a feature of accreting systems. The X-rays exhibit large-amplitude variations in the form of fast switching (within ˜10 s) between two distinct flux levels that differ by a factor of ≈10. The detailed optical and X-ray behavior is virtually identical to that seen in the accretion-disk-dominated states of the transitional millisecond pulsar (MSP) binaries PSR J1023+0038 and XSS J12270-4859, which are also associated with γ-ray sources. Based on the available observational evidence, we conclude that 1RXS J154439.4-112820 and 3FGL J1544.6-1125 are the same object, with the X-rays arising from intermittent low-luminosity accretion onto an MSP and the γ-rays originating from an accretion-driven outflow. 1RXS J154439.4-112820 is only the fourth γ-ray-emitting low-mass X-ray binary system to be identified and is likely to sporadically undergo transformations to a non-accreting rotation-powered pulsar system.

The origin of X-ray protrusions in the VELA supernova remnant

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

We propose a possible explanation for the formation of X-ray protrusions in the Vela SNR, recently observed by the ROSAT X-ray telescope (Aschenbach, Egger & Trumper, 1995, Nature, 373, 587). We suggest that the highly asymmetric shape of the Vela SNR is the result of the interaction of the SN ejecta/shock with the pre-existing wind-driven shell blown-up in a medium with a density gradient (perpendicular to the Galactic plane). The interaction of the radiative (north-east) half of the remnant, approaching towards the Galactic plane, with dense obstacles (cloudlets or wind zones of stars) can produce X-ray "bullets" radially moving beyond the SNR boundary. These "bullets" originate due to the cooling and condensation of a gas swept-up by converging conical shocks arising behind the dense obstacles overtaken by the SN shock. The X-ray protrusions observed in the western part of the remnant might be explained by outflows of hot gas of the SNR's interior emanating through the gaps in the shell. The origin of the X-ray "jet" (Markwardt & Ogelman, 1995, Nature, 375, 40) in the central part of the Vela SNR is also discussed.

Constraining MHD Disk-Winds with X-ray Absorbers

NASA Astrophysics Data System (ADS)

Fukumura, Keigo; Tombesi, F.; Shrader, C. R.; Kazanas, D.; Contopoulos, J.; Behar, E.

2014-01-01

From the state-of-the-art spectroscopic observations of active galactic nuclei (AGNs) the robust features of absorption lines (e.g. most notably by H/He-like ions), called warm absorbers (WAs), have been often detected in soft X-rays (< 2 keV). While the identified WAs are often mildly blueshifted to yield line-of-sight velocities up to ~100-3,000 km/sec in typical X-ray-bright Seyfert 1 AGNs, a fraction of Seyfert galaxies such as PG 1211+143 exhibits even faster absorbers (v/ 0.1-0.2) called ultra-fast outflows (UFOs) whose physical condition is much more extreme compared with the WAs. Motivated by these recent X-ray data we show that the magnetically- driven accretion-disk wind model is a plausible scenario to explain the characteristic property of these X-ray absorbers. As a preliminary case study we demonstrate that the wind model parameters (e.g. viewing angle and wind density) can be constrained by data from PG 1211+143 at a statistically significant level with chi-squared spectral analysis. Our wind models can thus be implemented into the standard analysis package, XSPEC, as a table spectrum model for general analysis of X-ray absorbers.

Chandra imaging of the kpc extended outflow in 1H 0419-577

NASA Astrophysics Data System (ADS)

Di Gesu, L.; Costantini, E.; Piconcelli, E.; Kaastra, J. S.; Mehdipour, M.; Paltani, S.

2017-12-01

The Seyfert 1 galaxy 1H 0419-577 hosts a kpc extended outflow that is evident in the [O III] image and that is also detected as a warm absorber in the UV/X-ray spectrum. Here, we analyze a 30 ks Chandra-ACIS X-ray image, with the aim of resolving the diffuse extranuclear X-ray emission and of investigating its relationship with the galactic outflow. Thanks to its sub-arcsecond spatial resolution, Chandra resolves the circumnuclear X-ray emission, which extends up to a projected distance of at least 16 kpc from the center. The morphology of the diffuse X-ray emission is spherically symmetrical. We could not recover a morphological resemblance between the soft X-ray emission and the ionization bicone that is traced by the [O III] outflow. Our spectral analysis indicates that one of the possible explanations for the extended emission is thermal emission from a low-density (nH 10-3 cm-3) hot plasma (Te 0.22 keV). If this is the case, we may be witnessing the cooling of a shock-heated wind bubble. In this scenario, the [O III] emission line and the X-ray/UV absorption lines may trace cooler clumps that are entrained in the hot outflow. Alternatively, the extended emission could be to due to a blend of emission lines from a photoionized gas component having a hydrogen column density of NH 2.1 × 1022 cm-2 and an ionization parameter of log ξ 1.3. Because the source is viewed almost edge-on we argue that the photoionized gas nebula must be distributed mostly along the polar directions, outside our line of sight. In this geometry, the X-ray/UV warm absorber must trace a different gas component, physically disconnected from the emitting gas, and located closer to the equatorial plane.

Ionized and Neutral Outflows in the QUEST QSOs

NASA Astrophysics Data System (ADS)

Veilleux, Sylvain

2011-10-01

The role of galactic winds in gas-rich mergers is of crucial importance to understand galaxy and SMBH evolution. In recent months, our group has had three major scientific breakthroughs in this area: {1} The discovery with Herschel of massive molecular {OH-absorbing} outflows in several ULIRGs, including the nearest quasar, Mrk 231. {2} The independent discovery from mm-wave interferometric observations in the same object of a spatially resolved molecular {CO-emitting} wind with estimated mass outflow rate 3x larger than the star formation rate and spatially coincident with blueshifted neutral {Na ID-absorbing} gas in optical long-slit spectra. {3} The unambiguous determination from recent Gemini/IFU observations that the Na ID outflow in this object is wide-angle, thus driven by a QSO wind rather than a jet. This powerful outflow may be the long-sought "smoking gun" of quasar mechanical feedback purported to transform gas-rich mergers. However, our Herschel survey excludes all FIR-faint {UV-bright} "classic" QSOs by necessity. So here we propose a complementary FUV absorption-line survey of all FIR-bright -and- FIR-faint QSOs from the same parent sample. New {19 targets} and archival {11} spectra will be used to study, for the first time, the gaseous environments of QSOs as a function of host properties and age across the merger sequence ULIRG -> QSO. These data will allow us to distinguish between ionized & neutral quasar-driven outflows, starburst-driven winds, and tidal debris around the mergers. They will also be uniquely suited for a shallow but broad study of the warm & warm-hot intergalactic media, complementary to on-going surveys that are deeper but narrower.

Discovery of an Ultraviolet Counterpart to an Ultrafast X-Ray Outflow in the Quasar PG 1211+143

NASA Astrophysics Data System (ADS)

Kriss, Gerard A.; Lee, Julia C.; Danehkar, Ashkbiz; Nowak, Michael A.; Fang, Taotao; Hardcastle, Martin J.; Neilsen, Joseph; Young, Andrew

2018-02-01

We observed the quasar PG 1211+143 using the Cosmic Origins Spectrograph on the Hubble Space Telescope in 2015 April as part of a joint campaign with the Chandra X-ray Observatory and the Jansky Very Large Array. Our ultraviolet spectra cover the wavelength range 912–2100 Å. We find a broad absorption feature (∼ 1080 {km} {{{s}}}-1) at an observed wavelength of 1240 Å. Interpreting this as H I Lyα, in the rest frame of PG 1211+143 (z = 0.0809), this corresponds to an outflow velocity of ‑16,980 {km} {{{s}}}-1 (outflow redshift {z}{out}∼ -0.0551), matching the moderate ionization X-ray absorption system detected in our Chandra observation and reported previously by Pounds et al. With a minimum H I column density of {log} {N}{{H}{{I}}}> 14.5, and no absorption in other UV resonance lines, this Lyα absorber is consistent with arising in the same ultrafast outflow as the X-ray absorbing gas. The Lyα feature is weak or absent in archival ultraviolet spectra of PG 1211+143, strongly suggesting that this absorption is transient, and intrinsic to PG 1211+143. Such a simultaneous detection in two independent wavebands for the first time gives strong confirmation of the reality of an ultrafast outflow in an active galactic nucleus.

A Search for H I Lyα Counterparts to Ultrafast X-Ray Outflows

NASA Astrophysics Data System (ADS)

Kriss, Gerard A.; Lee, Julia C.; Danehkar, Ashkbiz

2018-06-01

Prompted by the H I Lyα absorption associated with the X-ray ultrafast outflow at ‑17,300 km s‑1 in the quasar PG 1211+143, we have searched archival UV spectra at the expected locations of H I Lyα absorption for a large sample of ultrafast outflows identified in XMM-Newton and Suzaku observations. Sixteen of the X-ray outflows have predicted H I Lyα wavelengths falling within the bandpass of spectra from either the Far Ultraviolet Spectroscopic Explorer or the Hubble Space Telescope, although none of the archival observations were simultaneous with the X-ray observations in which ultrafast X-ray outflows (UFOs) were detected. In our spectra broad features with FWHM of 1000 km s‑1 have 2σ upper limits on the H I column density of generally ≲2 × 1013 cm‑2. Using grids of photoionization models covering a broad range of spectral energy distributions (SEDs), we find that producing Fe XXVI Lyα X-ray absorption with equivalent widths >30 eV and associated H I Lyα absorption with {N}{{H}{{I}}}< 2× {10}13 {cm}}-2 requires total absorbing column densities {N}{{H}}> 5× {10}22 {cm}}-2 and ionization parameters log ξ ≳ 3.7. Nevertheless, a wide range of SEDs would predict observable H I Lyα absorption if ionization parameters are only slightly below peak ionization fractions for Fe XXV and Fe XXVI. The lack of Lyα features in the archival UV spectra indicates that the UFOs have very high ionization parameters, that they have very hard UV-ionizing spectra, or that they were not present at the time of the UV spectral observations owing to variability.

Quantifying the AGN-driven outflows in ULIRGs (QUADROS) III: Measurements of the radii and kinetic powers of 8 near-nuclear outflows

NASA Astrophysics Data System (ADS)

Spence, R. A. W.; Tadhunter, C. N.; Rose, M.; Rodríguez Zaurín, J.

2018-05-01

As part of the QUADROS project to quantify the impact of AGN-driven outflows in rapidly evolving galaxies in the local universe, we present observations of 8 nearby ULIRGs (0.04 < z < 0.2) taken with the ISIS spectrograph on the William Herschel Telescope (WHT), and also summarize the results of the project as a whole. Consistent with Rose et al. (2018), we find that the outflow regions are compact (0.08 < R_{[O III]} < 1.5 kpc), and the electron densities measured using the [S II], [O II] trans-auroral emission-line ratios are relatively high (2.5 < log ne (cm-3) < 4.5, median log ne (cm-3) ˜ 3.1). Many of the outflow regions are also significantly reddened (median E(B - V) ˜ 0.5). Assuming that the de-projected outflow velocities are represented by the 5^{th} percentile velocities (v05) of the broad, blueshifted components of [O III] λ5007, we calculate relatively modest mass outflow rates (0.1 < \\dot{M} < 20 M⊙ yr-1, median \\dot{M} ˜ 2 M⊙ yr-1), and find kinetic powers as a fraction of the AGN bolometric luminosity (\\dot{F} = \\dot{E}/L_bol) in the range 0.02 < \\dot{F} < 3 per cent, median \\dot{F} ˜ 0.3 per cent). The latter estimates are in line with the predictions of multi-stage outflow models, or single-stage models in which only a modest fraction of the initial kinetic power of the inner disk winds is transferred to the larger-scale outflows. Considering the QUADROS sample as a whole, we find no clear evidence for correlations between the properties of the outflows and the bolometric luminosities of the AGN, albeit based on a sample that covers a relatively small range in Lbol. Overall, our results suggest that there is a significant intrinsic scatter in outflow properties of ULIRGs for a given AGN luminosity.

Quasars Outflows As A Function of SED - An Empirical Approach

NASA Astrophysics Data System (ADS)

Richmond, Joseph M.; Ganguly, Rajib

2015-08-01

Feedback from quasars (jets, outflows, and luminosity) is now recognized as a vital phase in describing galaxy evolution, growth, and star formation efficiency. Regarding outflows, roughly 60% are observed to have outflowing gas appearing at large velocities and with a variety of velocity dispersions. The most extreme observed form of these outflows appears in the ultraviolet spectrum of 15-20% of objects. Understanding the physics of these outflows is important for both astrophysical and cosmological reasons. Establishing empirical relationships to test the theoretical models of how these outflows are driven (and hence, how they impact their surroundings) is currently plagued by having too few objects, where other parameters like the black hole mass or accretion rate, may add to the scatter. We aim to fix this by using a systematic study of a large sample of objects. As a follow up to a previous study, we have identified a sample of nearly 11000 z=1.7-2 quasars using archived data from the Sloan Digital Sky Survey (Data Release 7), of which roughly 4400 appear to show outflows according to the visual inspection. The specific redshift range is chosen to feature both the Mg II 2800 emission line as well as wavelengths extending to nearly 20,000 km/s blueward of the C IV 1549 emission line. Our goals for this study are: (1) To temper our visual inspection schemes with a more automated, computer-driven scheme; (2) To measure the properties of the outflows (velocity, velocity dispersion, equivalent width, ionization); (3) To supplement the SDSS spectra with photometric measurements from GALEX, 2MASS, and WISE to further characterize the spectral energy distributions (SEDs) and dust content; (4) To form spectral composites to investigate possible SED changes with outflow properties; and (5) To use published estimates of the quasar physical properties (black hole mass, accretion rate, etc.) to fully establish in an empirical way the complex dependencies between the properties of the outflow, and the physical properties of the system.

The origin of ultrafast outflows in AGN: Monte Carlo simulations of the wind in PDS 456

NASA Astrophysics Data System (ADS)

Hagino, Kouichi; Odaka, Hirokazu; Done, Chris; Gandhi, Poshak; Watanabe, Shin; Sako, Masao; Takahashi, Tadayuki

2015-01-01

Ultrafast outflows (UFOs) are seen in many AGN, giving a possible mode for AGN feedback on to the host galaxy. However, the mechanism(s) for the launch and acceleration of these outflows are currently unknown, with UV line driving apparently strongly disfavoured as the material along the line of sight is so highly ionized that it has no UV transitions. We revisit this issue using the Suzaku X-ray data from PDS 456, an AGN with the most powerful UFO seen in the local Universe. We explore conditions in the wind by developing a new 3D Monte Carlo code for radiation transport. The code only handles highly ionized ions, but the data show the ionization state of the wind is high enough that this is appropriate, and this restriction makes it fast enough to explore parameter space. We reproduce the results of earlier work, confirming that the mass-loss rate in the wind is around 30 per cent of the inferred inflow rate through the outer disc. We show for the first time that UV line driving is likely to be a major contribution to the wind acceleration. The mass-loss rate in the wind matches that predicted from a purely line driven system, and this UV absorption can take place out of the line of sight. Continuum driving should also play a role as the source is close to Eddington. This predicts that the most extreme outflows will be produced from the highest mass accretion rate flows on to high-mass black holes, as observed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Daeun; Woo, Jong-Hak; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr

Energetic ionized gas outflows driven by active galactic nuclei (AGNs) have been studied as a key phenomenon related to AGN feedback. To probe the kinematics of the gas in the narrow-line region, [O iii] λ 5007 has been utilized in a number of studies showing nonvirial kinematic properties due to AGN outflows. In this paper, we statistically investigate whether the H α emission line is influenced by AGN-driven outflows by measuring the kinematic properties based on the H α line profile and comparing them with those of [O iii]. Using the spatially integrated spectra of ∼37,000 Type 2 AGNs atmore » z < 0.3 selected from the Sloan Digital Sky Survey DR7, we find a nonlinear correlation between H α velocity dispersion and stellar velocity dispersion that reveals the presence of the nongravitational component, especially for AGNs with a wing component in H α . The large H α velocity dispersion and velocity shift of luminous AGNs are clear evidence of AGN outflow impacts on hydrogen gas, while relatively smaller kinematic properties compared to those of [O iii] imply that the observed outflow effect on the H α line is weaker than the case of [O iii].« less

Probing the Physical Properties and Origins of Ultra-fast Outflows in AGN

NASA Astrophysics Data System (ADS)

Kraemer, Steven B.; Tombesi, Francesco; Bottorff, Mark

2017-01-01

Approximately half of Type 1 AGN possess intrinsic absorption and high resolution UV and X-ray spectroscopy have revealed that the absorbing gas is radially outflowing, with velocities of 100s to 1000s km/sec. X-ray ("warm") absorbers, originally revealed by the presence of bound-free edges of O~VII and O~VIII, are more highly ionized than their UV counterparts, and photo-ionization modeling studies have determined that they have ionization parameters of logU ~ -1 to 1. Recently, muchmore highly ionized gas, with logU > 2, has been detected in XMM-Newton spectra, as evidenced by absorption lines from H- and He-like Fe. Some of these absorbers, ``Ultra Fast Outlows (UFOs)'', have radial velocities up to 0.2c. We have undertaken a detailed photo-ionization study of high-ionization Fe absorbers, both UFOs and non-UFOs, in a sample of AGN observed by XMM-Newton. We find that the UFOs are completely Compton-cooled, unlike the non-UFOS. Both types are too highly ionized to be radiatively accelerated, hence they are more likely driven via Magneto-Hydrodynamic processes. Their large column densities and velocity gradients are consistent with flows along magnetic streamlines emanating from accretion disks. Open questions include: the temporal stability of the UFOs, the apparent lack of non-UFOs in UFO sources, and their relationship to warm absorbers.

Cosmic Ray Production in Supernovae

NASA Astrophysics Data System (ADS)

Bykov, A. M.; Ellison, D. C.; Marcowith, A.; Osipov, S. M.

2018-02-01

We give a brief review of the origin and acceleration of cosmic rays (CRs), emphasizing the production of CRs at different stages of supernova evolution by the first-order Fermi shock acceleration mechanism. We suggest that supernovae with trans-relativistic outflows, despite being rather rare, may accelerate CRs to energies above 10^{18} eV over the first year of their evolution. Supernovae in young compact clusters of massive stars, and interaction powered superluminous supernovae, may accelerate CRs well above the PeV regime. We discuss the acceleration of the bulk of the galactic CRs in isolated supernova remnants and re-acceleration of escaped CRs by the multiple shocks present in superbubbles produced by associations of OB stars. The effects of magnetic field amplification by CR driven instabilities, as well as superdiffusive CR transport, are discussed for nonthermal radiation produced by nonlinear shocks of all speeds including trans-relativistic ones.

The Nature of the UV/X-ray Absorber In PG 2302+029

NASA Technical Reports Server (NTRS)

Sabra, Bassem M.; Hamann, Fred; Jannuzi, Buell T.; George, Ian M.; Shields, Joseph C.

2003-01-01

We present Chandra X-ray observations of the radio-quiet QSO PG 2302+029. This quasar has a rare system of ultra-high velocity (-56,000 km s(exp -1) UV absorption lines that form in an outflow from the active nucleus. The Chandra data indicate that soft X-ray absorption is also present. We perform a joint UV and X-ray analysis, using photoionization calculations, to determine the nature of the absorbing gas. The UV and X-ray datasets were not obtained simultaneously. Nonetheless, our analysis suggests that the X-ray absorption occurs at high velocities in the same general region as the UV absorber. There are not enough constraints to rule out multi-zone models. In fact, the distinct broad and narrow UV line profiles clearly indicate that multiple zones are present. Our preferred estimates of the ionization and total column density in the X-ray absorber (logU = 1.6, N(sub eta) = 10(exp 22.4) cm (exp -2) over predict the O VI lambda lambda1032,1038 absorption unless the X-ray absorber is also outflowing at approximately 56,000 km s(exp-l), but they over predict the Ne VIII lambda lambda 770,780 absorption at all velocities. If we assume that the X-ray absorbing gas is outflowing at the same velocity of the UV-absorbing wind and that the wind is radiatively accelerated, then the outflow must be launched at a radius of less than or equal to 10(exp 15) cm from the central continuum source. The smallness of this radius casts doubts on the assumption of radiative acceleration.

Radio jets clearing the way through galaxies: the view from Hi and molecular gas

NASA Astrophysics Data System (ADS)

Morganti, Raffaella

2015-03-01

Massive gas outflows are considered a key component in the process of galaxy formation and evolution. Because of this, they are the topic of many studies aimed at learning more about their occurrence, location and physical conditions as well as the mechanism(s) at their origin. This contribution presents recent results on two of the best examples of jet-driven outflows traced by cold and molecular gas. Thanks to high-spatial resolution observations, we have been able to locate the region where the outflow occurs. This appears to be coincident with bright radio features and regions where the interaction between radio plasma jet and ISM is known to occur, thus strongly supporting the idea of jet-driven outflows. We have also imaged the distribution of the outflowing gas. The results clearly show the effect that expanding radio jets and lobes have on the ISM. This appears to be in good agreement with what predicted from numerical simulations. Furthermore, the results show that cold gas is associated with these powerful phenomena and can be formed - likely via efficient cooling - even after a strong interaction and fast shocks. The discovery of similar fast outflows of cold gas in weak radio sources is further increasing the relevance that the effect of the radio plasma can have on the surrounding medium and on the host galaxy.

Theory of Bipolar Outflows from Accreting Hot Stars

NASA Astrophysics Data System (ADS)

Konigl, A.

1996-05-01

There is a growing number of observational indicators for the presence of bipolar outflows in massive, young stellar objects that are still accreting mass as part of their formation process. In particular, there is evidence that the outflows from these objects can attain higher velocities and kinetic luminosities than their lower-mass counterparts. Furthermore, the higher-mass objects appear to smoothly continue the correlation found in T Tauri stars between outflow and accretion signatures, and in several cases there are direct clues to the existence of a disk from optical and infrared spectroscopy. These results suggest that the disk--outflow connection found in low-mass pre--main-sequence stars extends to more massive objects, and that a similar physical mechanism may drive the outflows in both cases. In this presentation, I first critically examine the observational basis for this hypothesis, considering, among other things, the possibility that several low-luminosity outflows might occasionally masquerade as a single flow from a luminous object, and the effects that the radiation field of a hot star could have on the spectroscopic diagnostics of an accretion-driven outflow. I then go on to consider how the commonly invoked centrifugally driven wind models of bipolar outflows in low-mass stars would be affected by the various physical processes (such as photoionization, photoevaporation, radiation pressure, and stellar wind ram pressure) that operate in higher-mass stars. I conclude by mentioning some of the tantalizing questions that one could hope to address as this young field of research continues to develop (for example: is there a high-mass analog of the FU Orionis outburst phenomenon? Could one use observations of progressively more massive, and hence less convective, stars to elucidate the role of stellar magnetic fields in the accretion and outflow processes? Would it be possible to observationally identify massive stars that have reached the main sequence while they were still accreting? Does the evolution of protostellar disks differ in low-mass and high-mass objects?).

Line asymmetry in the Seyfert Galaxy NGC 3783

NASA Technical Reports Server (NTRS)

Ramirez, J. M.; Bautista, Manuel; Kallman, Timothy

2005-01-01

We have reanalyzed the 900 ks Chandra X-ray spectrum of NGC 3783, finding evidence on the asymmetry of the spectral absorption lines. The lines are fitted with a parametric expression that results from an analytical treatment of radiatively driven winds. The line asymmetry distribution derived from the spectrum is consistent with a non-spherical outflow with a finite optical depth. Within this scenario, our model explains the observed correlations between the line velocity shifts and the ionization parameter and between the line velocity shift and the line asymmetry. The present results may provide a framework for detailed testing of models for the dynamic and physical properties of warm absorber in Seyfert galaxies.

Accretion and Outflows in X-ray Binaries: What's Really Going on During X-ray Quiescence

NASA Astrophysics Data System (ADS)

MacDonald, Rachel K. D.; Bailyn, Charles D.; Buxton, Michelle

2015-01-01

X-ray binaries, consisting of a star and a stellar-mass black hole, are wonderful laboratories for studying accretion and outflows. They evolve on timescales quite accessible to us, unlike their supermassive cousins, and allow the possibility of gaining a deeper understanding of these two common astrophysical processes. Different wavelength regimes reveal different aspects of the systems: radio emission is largely generated by outflows and jets, X-ray emission by inner accretion flows, and optical/infrared (OIR) emission by the outer disk and companion star. The search for relationships between these different wavelengths is thus an area of active research, aiming to reveal deeper connections between accretion and outflows.Initial evidence for a strong, tight correlation between radio and X-ray emission has weakened as further observations and newly-discovered sources have been obtained. This has led to discussions of multiple tracks or clusters, or the possibility that no overall relation exists for the currently-known population of X-ray binaries. Our ability to distinguish among these options is hampered by a relative lack of observations at lower luminosities, and especially of truly X-ray quiescent (non-outbursting) systems. Although X-ray binaries spend the bulk of their existence in quiescence, few quiescent sources have been observed and multiple observations of individual sources are largely nonexistent. Here we discuss new observations of the lowest-luminosity quiescent X-ray binary, A0620-00, and the place this object occupies in investigations of the radio/X-ray plane. For the first time, we also incorporate simultaneous OIR data with the radio and X-ray data.In December 2013 we took simultaneous observations of A0620-00 in the X-ray (Chandra), the radio (EVLA), and the OIR (SMARTS 1.3m). These X-ray and radio data allowed us to investigate similarities among quiescent X-ray binaries, and changes over time for this individual object, in the radio/X-ray plane. In addition, our OIR observations allowed us to examine the radio and X-ray information in relation to the different OIR states of behavior (passive and active) known to exist during X-ray quiescence.

IDENTIFICATION OF THE HIGH-ENERGY GAMMA-RAY SOURCE 3FGL J1544.6–1125 AS A TRANSITIONAL MILLISECOND PULSAR BINARY IN AN ACCRETING STATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogdanov, Slavko; Halpern, Jules P.

We present X-ray, ultraviolet, and optical observations of 1RXS J154439.4–112820, the most probable counterpart of the unassociated Fermi-LAT source 3FGL J1544.6–1125. The optical data reveal rapid variability, which is a feature of accreting systems. The X-rays exhibit large-amplitude variations in the form of fast switching (within ∼10 s) between two distinct flux levels that differ by a factor of ≈10. The detailed optical and X-ray behavior is virtually identical to that seen in the accretion-disk-dominated states of the transitional millisecond pulsar (MSP) binaries PSR J1023+0038 and XSS J12270–4859, which are also associated with γ-ray sources. Based on the available observationalmore » evidence, we conclude that 1RXS J154439.4–112820 and 3FGL J1544.6–1125 are the same object, with the X-rays arising from intermittent low-luminosity accretion onto an MSP and the γ-rays originating from an accretion-driven outflow. 1RXS J154439.4–112820 is only the fourth γ-ray-emitting low-mass X-ray binary system to be identified and is likely to sporadically undergo transformations to a non-accreting rotation-powered pulsar system.« less

AGN outflows and feedback twenty years on

NASA Astrophysics Data System (ADS)

Harrison, C. M.; Costa, T.; Tadhunter, C. N.; Flütsch, A.; Kakkad, D.; Perna, M.; Vietri, G.

2018-03-01

It is twenty years since the seminal works by Magorrian and co-authors and by Silk and Rees, which, along with other related work, ignited an explosion of publications connecting active galactic nucleus (AGN)-driven outflows to galaxy evolution. With a surge in observations of AGN outflows, studies are attempting to test AGN feedback models directly using the outflow properties. With a focus on outflows traced by optical and CO emission lines, we discuss significant challenges that greatly complicate this task, from both an observational and theoretical perspective. We highlight the observational uncertainties involved and the assumptions required when deriving kinetic coupling efficiencies (that is, outflow kinetic power as a fraction of AGN luminosity) from typical observations. Based on recent models we demonstrate that extreme caution should be taken when comparing observationally derived kinetic coupling efficiencies to coupling efficiencies from fiducial feedback models.

Rapidly variable relatvistic absorption

NASA Astrophysics Data System (ADS)

Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.

2017-10-01

I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.

On the Fraction of Quasars with Outflows

NASA Astrophysics Data System (ADS)

Ganguly, Rajib; Brotherton, Michael S.

2008-01-01

Outflows from active galactic nuclei (AGNs) seem to be common and are thought to be important from a variety of perspectives: as an agent of chemical enhancement of the interstellar and intergalactic media, as an agent of angular momentum removal from the accreting central engine, and as an agent limiting star formation in starbursting systems by blowing out gas and dust from the host galaxy. To understand these processes, we must determine what fraction of AGNs feature outflows and understand what forms they take. We examine recent surveys of quasar absorption lines, reviewing the best means to determine if systems are intrinsic and result from outflowing material, and the limitations of approaches taken to date. The surveys reveal that, while the fraction of specific forms of outflows depends on AGN properties, the overall fraction displaying outflows is fairly constant, approximately 60%, over many orders of magnitude in luminosity. We emphasize some issues concerning classification of outflows driven by data type rather than necessarily the physical nature of outflows and illustrate how understanding outflows probably requires a more comprehensive approach than has usually been taken in the past.

Do Radio Jets Contribute to Driving Ionized Gas Outflows in Moderate Luminosity Type 2 AGN?

NASA Astrophysics Data System (ADS)

Fowler, Julia; Sajina, Anna; Lacy, Mark

2016-01-01

This poster examines the role of AGN-driven feedback in low to intermediate power radio galaxies. We begin with [OIII] measurements of ionized gas outflows in 29 moderate AGN-luminosity z~0.3-0.7 dust-obscured Type 2 AGN. We aim to examine the relative role of the AGN itself, of star-formation and of nascent radio jets in driving these outflows. The strength of the AGN and star formation are based on the [OIII] luminosities, and the far-IR luminosities respectively. For the radio jets, we present multi-frequency radio (X, S, and L-bands) JVLA imaging of our sample, which allows us both to constrain the overall radio power, but also look for signatures of young radio sources, including Giga-hertz Peaked Spectrum (GPS) sources, as well as small-scale jets. While radio jet-driven outflows are well known for powerful radio-loud galaxies, this study allows us to constrain the degree to which this mechanism is significant at more modest radio luminosities of L5GHz~10^22-25 W/Hz.

Investigation of Dual Active Nuclei, Outflows, Shock-heated Gas, and Young Star Clusters in Markarian 266

NASA Astrophysics Data System (ADS)

Mazzarella, J. M.; Iwasawa, K.; Vavilkin, T.; Armus, L.; Kim, D.-C.; Bothun, G.; Evans, A. S.; Spoon, H. W. W.; Haan, S.; Howell, J. H.; Lord, S.; Marshall, J. A.; Ishida, C. M.; Xu, C. K.; Petric, A.; Sanders, D. B.; Surace, J. A.; Appleton, P.; Chan, B. H. P.; Frayer, D. T.; Inami, H.; Khachikian, E. Ye.; Madore, B. F.; Privon, G. C.; Sturm, E.; U, Vivian; Veilleux, S.

2012-11-01

Results of observations with the Spitzer, Hubble, GALEX, Chandra, and XMM-Newton space telescopes are presented for the luminous infrared galaxy (LIRG) merger Markarian 266. The SW (Seyfert 2) and NE (LINER) nuclei reside in galaxies with Hubble types SBb (pec) and S0/a (pec), respectively. Both companions are more luminous than L* galaxies and they are inferred to each contain a ≈2.5 × 108 M ⊙ black hole. Although the nuclei have an observed hard X-ray flux ratio of fX (NE)/fX (SW) = 6.4, Mrk 266 SW is likely the primary source of a bright Fe Kα line detected from the system, consistent with the reflection-dominated X-ray spectrum of a heavily obscured active galactic nucleus (AGN). Optical knots embedded in an arc with aligned radio continuum radiation, combined with luminous H2 line emission, provide evidence for a radiative bow shock in an AGN-driven outflow surrounding the NE nucleus. A soft X-ray emission feature modeled as shock-heated plasma with T ~ 107 K is cospatial with radio continuum emission between the galaxies. Mid-infrared diagnostics provide mixed results, but overall suggest a composite system with roughly equal contributions of AGN and starburst radiation powering the bolometric luminosity. Approximately 120 star clusters have been detected, with most having estimated ages less than 50 Myr. Detection of 24 μm emission aligned with soft X-rays, radio continuum, and ionized gas emission extending ~34'' (20 kpc) north of the galaxies is interpreted as ~2 × 107 M ⊙ of dust entrained in an outflowing superwind. At optical wavelengths this Northern Loop region is resolved into a fragmented morphology indicative of Rayleigh-Taylor instabilities in an expanding shell of ionized gas. Mrk 266 demonstrates that the dust "blow-out" phase can begin in a LIRG well before the galaxies fully coalesce during a subsequent ultraluminous infrared galaxy (ULIRG) phase, and rapid gas consumption in luminous dual AGNs with kiloparsec-scale separations early in the merger process may explain the paucity of detected binary QSOs (with parsec-scale orbital separations) in spectroscopic surveys. An evolutionary sequence is proposed representing a progression from dual to binary AGNs, accompanied by an increase in observed Lx /L ir ratios by over two orders of magnitude.

Another piece of the puzzle: The fast H I outflow in Mrk 231

NASA Astrophysics Data System (ADS)

Morganti, Raffaella; Veilleux, Sylvain; Oosterloo, Tom; Teng, Stacy H.; Rupke, David

2016-09-01

We present the detection, performed with the Westerbork Synthesis Radio Telescope (WSRT) and the Karl Jansky Very Large Array (VLA), of a fast H I 21 cm outflow in the ultra-luminous infrared galaxy Mrk 231. The outflow is observed as shallow H I absorption blueshifted ~1300 km s-1 with respect to the systemic velocity and located against the inner kpc of the radio source. The outflowing gas has an estimated column density between 5 and 15 × 1018Tspin cm-2. We derive the Tspin to lie in the range 400-2000 K and the corresponding H I densities are nHI ~ 10-100 cm-3. Our results complement previous findings and confirm the multiphase nature of the outflow in Mrk 231. Although effects of the interaction between the radio plasma and the surrounding medium cannot be ruled out, the energetics and the lack of a clear kpc-scale jet suggest that the most likely origin of the H I outflow is a wide-angle nuclear wind, as earlier proposed to explain the neutral outflow traced by Na I and molecular gas in this source. Our results suggest that an H I component is present in fast outflows regardless of the acceleration mechanism (wind vs. jet driven) and that it must be connected with common properties of the pre-interaction gas involved. Considering the observed similarity of their column densities, the H I outflow likely represents the inner part of the broad wind identified on larger scales in atomic Na I. The mass outflow rate of the H I outflow (between 8 and 18 M⊙ yr-1) does not appear to be as large as that observed in molecular gas, partly owing to the smaller sizes of the outflowing region sampled by the H I absorption. These characteristics are commonly seen in other cases of outflows driven by the active galactic nucleus (AGN) suggesting that the H I may represent a short intermediate phase in the rapid cooling of the gas. The results further confirm H I as a good tracer for AGN-driven outflows not only in powerful radio sources. We also obtained deeper continuum images than previously available. They confirm the complex structure of the radio continuum originating both from the AGN and star formation. At the resolution obtained with the VLA (~1'') we do not see a kpc-scale jet. Instead, we detect a plateau of emission, likely due to star formation, surrounding the bright nuclear region. We also detect a poorly collimated bridge which may represent the channel feeding the southern lobe. The unprecedented depth of the low-resolution WSRT image reveals radio emission extending 50'' (43 kpc) to the south and 20'' (17 kpc) to the north. The continuum images and the average spectra (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A30

Jet outflow and open field line measurements on the C-2U advanced beam-driven field-reversed configuration plasma experiment.

PubMed

Sheftman, D; Gupta, D; Roche, T; Thompson, M C; Giammanco, F; Conti, F; Marsili, P; Moreno, C D

2016-11-01

Knowledge and control of the axial outflow of plasma particles and energy along open-magnetic-field lines are of crucial importance to the stability and longevity of the advanced beam-driven field-reversed configuration plasma. An overview of the diagnostic methods used to perform measurements on the open field line plasma on C-2U is presented, including passive Doppler impurity spectroscopy, microwave interferometry, and triple Langmuir probe measurements. Results of these measurements provide the jet ion temperature and axial velocity, electron density, and high frequency density fluctuations.

Jet outflow and open field line measurements on the C-2U advanced beam-driven field-reversed configuration plasma experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheftman, D., E-mail: dsheftman@trialphaenergy.com; Gupta, D.; Roche, T.

Knowledge and control of the axial outflow of plasma particles and energy along open-magnetic-field lines are of crucial importance to the stability and longevity of the advanced beam-driven field-reversed configuration plasma. An overview of the diagnostic methods used to perform measurements on the open field line plasma on C-2U is presented, including passive Doppler impurity spectroscopy, microwave interferometry, and triple Langmuir probe measurements. Results of these measurements provide the jet ion temperature and axial velocity, electron density, and high frequency density fluctuations.

Tracing Galactic Outflows to the Source: Spatially Resolved Feedback in M83 with COS

NASA Astrophysics Data System (ADS)

Aloisi, Alessandra

2016-10-01

Star-formation (SF) feedback plays a vital role in shaping galaxy properties, but there are many open questions about how this feedback is created, propagated, and felt by galaxies. SF-driven feedback can be observationally constrained with rest-frame UV absorption-line spectroscopy that accesses a range of powerful gas density and kinematic diagnostics. Studies at both high and low redshift show clear evidence for large-scale outflows in star-forming galaxies that scale with galaxy SF rate. However, by sampling one sightline or the galaxy as a whole, these studies are not tailored to reveal how the large-scale outflows develop from their ultimate sources at the scale of individual SF regions. We propose the first spatially-resolved COS G130M/G160M (1130-1800 A) study of the ISM in the nearby (4.6 Mpc) face-on spiral starburst M83 using individual young star clusters as background sources. This is the first down-the-barrel study where blueshifted absorptions can be identified directly with outflowing gas in a spatially resolved fashion. The kpc-scale flows sampled by the COS pointings will be anchored to the properties of the large-scale (10-100 kpc) flows thanks to the wealth of multi-wavelength observations of M83 from X-ray to radio. A comparison of COS data with mock spectra from constrained simulations of spiral galaxies with FIRE (Feedback In Realistic Environments; a code with unprecedented 1-100 pc spatial resolution and self-consistent treatments of stellar feedback) will provide an important validation of these simulations and will supply the community with a powerful and well-tested tool for galaxy formation predictions applicable to all redshifts.

On the X-Ray Low- and High-Velocity Outflows in Active Galactic Nuclei

NASA Technical Reports Server (NTRS)

Ramirez, J. M.; Tombesi, F.

2012-01-01

An exploration of the relationship between bolometric luminosity and outflow velocity for two classes of X-ray outflows in a large sample of active galactic nuclei has been performed. We find that line radiation pressure could be one physical mechanism that might accelerate the gas we observe in warm absorber, v approx. 100-1000 km/s, and on comparable but less stringent grounds the ultrafast outflows, v approx. 0.03-0.3c. If comparable with the escape velocity of the system, the first is naturally located at distances of the dusty torus, '" I pc, and the second at subparsec scales, approx.0.01 pc, in accordance with large set of observational evidence existing in the literature. The presentation of this relationship might give us key clues for our understanding of the different physical mechanisms acting in the centre of galaxies, the feedback process and its impact on the evolution of the host galaxy.

Outflows in X-ray binaries

NASA Astrophysics Data System (ADS)

Diaz Trigo, M.

2017-10-01

Accretion onto neutron stars and black holes powers the most luminous phenomena in the Universe. Associated to it is the existence of outflows, in the form of uncollimated winds or highly collimated relativistic jets. The origin of outflows and their feedback to the environment is one of the most debated topics in astrophysics today. In this talk I will review the current understanding of accretion disc winds in X-ray binaries, their launching mechanism and their relation to specific accretion states. I will also discuss the potential interplay between the appearance/disappearance of such winds and relativistic jets and the insight gained with ongoing multi-wavelength observational programmes focused on the variability of such phenomena.

Warm Absorber Diagnostics of AGN Dynamics

NASA Astrophysics Data System (ADS)

Kallman, Timothy

Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are key for validating and testing models. New in this work is treatment of magnetically driven models, self-consistent calculation of the physical properties of the accretion flow and winds and their spectra. This will allow us to test the range of plausible physical origins for warm absorbers.

Probing the connection between the accretion disk, outflows and the jet in 3C111

NASA Astrophysics Data System (ADS)

Tombesi, Francesco

2011-10-01

Recent XMM-Newton and Suzaku observations of 3C111 demonstrated the presence of ultra-fast outflows (UFOs) with v~0.1c and their relation with the accretion disk. Independent studies found that X-ray dips are followed by ejection of superluminal radio knots, therefore providing a proof of the disk-jet connection. We acquired evidence that UFOs are preferentially present between X-ray dips and new knots, possibly indicating also a link between disk outflows and the jet. The goal of this XMM-Newton proposal is to confirm this evidence. Given the strong correlation with X-rays, we will use an ongoing optical monitoring campaign to trigger a 90ks observation within two days of a dip to detect a UFO and we request a possible additional 60ks >15 days after to compare with the non-dipped state.

Magnetically driven jets and winds: Exact solutions

NASA Technical Reports Server (NTRS)

Contopoulos, J.; Lovelace, R. V. E.

1994-01-01

We present a general class of self-similar solutions of the full set of MHD equations that include matter flow, electromagnetic fields, pressure, and gravity. The solutions represent axisymmetric, time-independent, nonrelativistic, ideal, magnetohydrodynamic, collimated outflows (jet and winds) from magnetized accretion disks around compact objects. The magnetic field extracts angular momentum from the disk, accelerates the outflows perpedicular to the disk, and provides collimation at large distances. The terminal outflow velocities are of the order of or greater than the rotational velocity of the disk at the base of the flow. When a nonzero electric current flows along the jet, the outflow radius oscillates with axial distance, whereas when the total electric current is zero (with the return current flowing across the jet's cross section), the outflow radius increase to a maximum and then decreases. The method can also be applied to relativistic outflows.

Multi-Band Light Curves from Two-Dimensional Simulations of Gamma-Ray Burst Afterglows

NASA Astrophysics Data System (ADS)

MacFadyen, Andrew

2010-01-01

The dynamics of gamma-ray burst outflows is inherently multi-dimensional. 1.) We present high resolution two-dimensional relativistic hydrodynamics simulations of GRBs in the afterglow phase using adaptive mesh refinement (AMR). Using standard synchrotron radiation models, we compute multi-band light curves, from the radio to X-ray, directly from the 2D hydrodynamics simulation data. We will present on-axis light curves for both constant density and wind media. We will also present off-axis light curves relevant for searches for orphan afterglows. We find that jet breaks are smoothed due to both off-axis viewing and wind media effects. 2.) Non-thermal radiation mechanisms in GRB afterglows require substantial magnetic field strengths. In turbulence driven by shear instabilities in relativistic magnetized gas, we demonstrate that magnetic field is naturally amplified to half a percent of the total energy (epsilon B = 0.005). We will show high resolution three dimensional relativistic MHD simulations of this process as well as particle in cell (PIC) simulations of mildly relativistic collisionless shocks.

Discovery of radio emission from the symbiotic X-ray binary system GX 1+4

NASA Astrophysics Data System (ADS)

van den Eijnden, J.; Degenaar, N.; Russell, T. D.; Miller-Jones, J. C. A.; Wijnands, R.; Miller, J. M.; King, A. L.; Rupen, M. P.

2018-02-01

We report the discovery of radio emission from the accreting X-ray pulsar and symbiotic X-ray binary GX 1+4 with the Karl G. Jansky Very Large Array. This is the first radio detection of such a system, wherein a strongly magnetized neutron star accretes from the stellar wind of an M-type giant companion. We measure a 9 GHz radio flux density of 105.3 ± 7.3 μJy, but cannot place meaningful constraints on the spectral index due to a limited frequency range. We consider several emission mechanisms that could be responsible for the observed radio source. We conclude that the observed properties are consistent with shocks in the interaction of the accretion flow with the magnetosphere, a synchrotron-emitting jet, or a propeller-driven outflow. The stellar wind from the companion is unlikely to be the origin of the radio emission. If the detected radio emission originates from a jet, it would show that strong magnetic fields (≥1012 G) do not necessarily suppress jet formation.

ALMA and VLA observations of emission from the environment of Sgr A*

NASA Astrophysics Data System (ADS)

Yusef-Zadeh, F.; Schödel, R.; Wardle, M.; Bushouse, H.; Cotton, W.; Royster, M. J.; Kunneriath, D.; Roberts, D. A.; Gallego-Cano, E.

2017-10-01

We present 44 and 226 GHz observations of the Galactic Centre within 20 arcsec of Sgr A*. Millimetre continuum emission at 226 GHz is detected from eight stars that have previously been identified at near-IR and radio wavelengths. We also detect a 5.8 mJy source at 226 GHz coincident with the magnetar SGR J1745-29 located 2.39 arcsec SE of Sgr A* and identify a new 2.5 arcsec × 1.5 arcsec halo of mm emission centred on Sgr A*. The X-ray emission from this halo has been detected previously and is interpreted in terms of a radiatively inefficient accretion flow. The mm halo surrounds an EW linear feature that appears to arise from Sgr A* and coincides with the diffuse X-ray emission and a minimum in the near-IR extinction. We argue that the millimetre emission is produced by synchrotron emission from relativistic electrons in equipartition with an ˜1.5 mG magnetic field. The origin of this is unclear but its coexistence with hot gas supports scenarios in which the gas is produced by the interaction of winds either from the fast moving S-stars, the photoevaporation of low-mass YSO discs or by a jet-driven outflow from Sgr A*. The spatial anti-correlation of the X-ray, radio and mm emission from the halo and the low near-IR extinction provides a compelling evidence of an outflow sweeping up the interstellar material, creating a dust cavity within 2 arcsec of Sgr A*. Finally, the radio and mm counterparts to eight near-IR identified stars within ˜10 arcsec of Sgr A* provide accurate astrometry to determine the positional shift between the peak emission at 44 and 226 GHz.

A Massive X-ray Outflow From The Quasar PDS 456

NASA Technical Reports Server (NTRS)

Reeves, J. N.; O'Brien, P. T.; Ward, M. J.

2003-01-01

We report on XMM-Newton spectroscopic observations of the luminous, radio-quiet quasar PDS 456. The hard X-ray spectrum of PDS 456 shows a deep absorption trough (constituting 50% of the continuum) at energies above 7 keV in the quasar rest frame, which can be attributed to a series of blue-shifted K-shell absorption edges due to highly ionized iron. The higher resolution soft X-ray grating RGS spectrum exhibits a broad absorption line feature near 1 keV, which can be modeled by a blend of L-shell transitions from highly ionized iron (Fe XVII - XXIV). An extreme outflow velocity of approx. 50000 km/s is required to model the K and L shell iron absorption present in the XMM-Newton data. Overall, a large column density (N(sub H) = 5 x 10(exp 23)/sq cm) of highly ionized gas (log xi = 2.5) is required in PDS 456. A large mass outflow rate of approx. 10 solar mass/year (assuming a conservative outflow covering factor of 0.1 steradian) is derived, which is of the same order as the overall mass accretion rate in PDS 456. This represents a substantial fraction (approx. 10%) of the quasar energy budget, whilst the large column and outflow velocity place PDS 456 towards the extreme end of the broad absorption line quasar population.

Evidence for Pulsation-Driven Mass Loss from δ Cephei

NASA Astrophysics Data System (ADS)

Marengo, M.; Evans, N. R.; Matthews, L. D.; Bono, G.; Barmby, P.; Welch, D. L.; Romaniello, M.; Su, K. Y. L.; Fazio, G. G.; Huelsman, D.

We found the first direct evidence that the Cepheid class namesake, δ Cephei, is currently losing mass. These observations are based on data obtained with the Spitzer Space Telescope in the infrared, and with the Very Large Array in the radio. We found that δ Cephei is associated with a vast circumstellar structure, reminiscent of a bow shock. This structure is created as the wind from the star interacts with the local interstellar medium. We measure an outflow velocity of ≈ 35. 5 km s- 1 and a mass loss rate of ≈ 10- 7-10- 6 M ⊙ year- 1. The very low dust content of the outflow suggests that the wind is possibly pulsation-driven, rather than dust-driven as common for other classes of evolved stars.

NEUTRON-STAR MERGER EJECTA AS OBSTACLES TO NEUTRINO-POWERED JETS OF GAMMA-RAY BURSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Just, O.; Janka, H.-T.; Schwarz, N.

2016-01-10

We present the first special relativistic, axisymmetric hydrodynamic simulations of black hole-torus systems (approximating general relativistic gravity) as remnants of binary-neutron star (NS–NS) and neutron star–black hole (NS–BH) mergers, in which the viscously driven evolution of the accretion torus is followed with self-consistent energy-dependent neutrino transport and the interaction with the cloud of dynamical ejecta expelled during the NS–NS merging is taken into account. The modeled torus masses, BH masses and spins, and the ejecta masses, velocities, and spatial distributions are adopted from relativistic merger simulations. We find that energy deposition by neutrino annihilation can accelerate outflows with initially highmore » Lorentz factors along polar low-density funnels, but only in mergers with extremely low baryon pollution in the polar regions. NS–BH mergers, where polar mass ejection during the merging phase is absent, provide sufficiently baryon-poor environments to enable neutrino-powered, ultrarelativistic jets with terminal Lorentz factors above 100 and considerable dynamical collimation, favoring short gamma-ray bursts (sGRBs), although their typical energies and durations might be too small to explain the majority of events. In the case of NS–NS mergers, however, neutrino emission of the accreting and viscously spreading torus is too short and too weak to yield enough energy for the outflows to break out from the surrounding ejecta shell as highly relativistic jets. We conclude that neutrino annihilation alone cannot power sGRBs from NS–NS mergers.« less

GALACTIC WINDS DRIVEN BY ISOTROPIC AND ANISOTROPIC COSMIC-RAY DIFFUSION IN DISK GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pakmor, R.; Pfrommer, C.; Simpson, C. M.

2016-06-20

The physics of cosmic rays (CRs) is a promising candidate for explaining the driving of galactic winds and outflows. Recent galaxy formation simulations have demonstrated the need for active CR transport either in the form of diffusion or streaming to successfully launch winds in galaxies. However, due to computational limitations, most previous simulations have modeled CR transport isotropically. Here, we discuss high-resolution simulations of isolated disk galaxies in a 10{sup 11} M {sub ⊙} halo with the moving-mesh code Arepo that include injection of CRs from supernovae, advective transport, CR cooling, and CR transport through isotropic or anisotropic diffusion. Wemore » show that either mode of diffusion leads to the formation of strong bipolar outflows. However, they develop significantly later in the simulation with anisotropic diffusion compared to the simulation with isotropic diffusion. Moreover, we find that isotropic diffusion allows most of the CRs to quickly diffuse out of the disk, while in the simulation with anisotropic diffusion, most CRs remain in the disk once the magnetic field becomes dominated by its azimuthal component, which occurs after ∼300 Myr. This has important consequences for the gas dynamics in the disk. In particular, we show that isotropic diffusion strongly suppresses the amplification of the magnetic field in the disk compared to anisotropic or no diffusion models. We therefore conclude that reliable simulations which include CR transport inevitably need to account for anisotropic diffusion.« less

Formation and spatial distribution of hypervelocity stars in AGN outflows

NASA Astrophysics Data System (ADS)

Wang, Xiawei; Loeb, Abraham

2018-05-01

We study star formation within outflows driven by active galactic nuclei (AGN) as a new source of hypervelocity stars (HVSs). Recent observations revealed active star formation inside a galactic outflow at a rate of ∼ 15M⊙yr-1 . We verify that the shells swept up by an AGN outflow are capable of cooling and fragmentation into cold clumps embedded in a hot tenuous gas via thermal instabilities. We show that cold clumps of ∼ 103 M⊙ are formed within ∼ 105 yrs. As a result, stars are produced along outflow's path, endowed with the outflow speed at their formation site. These HVSs travel through the galactic halo and eventually escape into the intergalactic medium. The expected instantaneous rate of star formation inside the outflow is ∼ 4 - 5 orders of magnitude greater than the average rate associated with previously proposed mechanisms for producing HVSs, such as the Hills mechanism and three-body interaction between a star and a black hole binary. We predict the spatial distribution of HVSs formed in AGN outflows for future observational probe.

High-resolution Near-IR Spectral Mapping with H2 and [Fe II] Lines of Multiple Outflows around LkHα 234

NASA Astrophysics Data System (ADS)

Oh, Heeyoung; Pyo, Tae-Soo; Koo, Bon-Chul; Yuk, In-Soo; Kaplan, Kyle F.; Lee, Yong-Hyun; Sokal, Kimberly R.; Mace, Gregory N.; Park, Chan; Lee, Jae-Joon; Park, Byeong-Gon; Hwang, Narae; Kim, Hwihyun; Jaffe, Daniel T.

2018-05-01

We present a high-resolution, near-IR spectroscopic study of multiple outflows in the LkHα 234 star formation region using the Immersion GRating INfrared Spectrometer (IGRINS). Spectral mapping over the blueshifted emission of HH 167 allowed us to distinguish at least three separate, spatially overlapped outflows in H2 and [Fe II] emission. We show that the H2 emission represents not a single jet but rather complex multiple outflows driven by three known embedded sources: MM1, VLA 2, and VLA 3. There is a redshifted H2 outflow at a low velocity, V LSR <+50 km s‑1, with respect to the systemic velocity of V LSR = ‑11.5 km s‑1, that coincides with the H2O masers seen in earlier radio observations 2″ southwest of VLA 2. We found that the previously detected [Fe II] jet with | {V}LSR}| > 100 km s‑1 driven by VLA 3B is also detected in H2 emission and confirm that this jet has a position angle of about 240°. Spectra of the redshifted knots at 14″–65″ northeast of LkHα 234 are presented for the first time. These spectra also provide clues to the existence of multiple outflows. We detected high-velocity (50–120 km s‑1) H2 gas in the multiple outflows around LkHα 234. Since these gases move at speeds well over the dissociation velocity (>40 km s‑1), the emission must originate from the jet itself rather than H2 gas in the ambient medium. Also, position–velocity and excitation diagrams indicate that emission from knot C in HH 167 comes from two different phenomena, shocks and photodissociation.

Detectable radio flares following gravitational waves from mergers of binary neutron stars.

PubMed

Nakar, Ehud; Piran, Tsvi

2011-09-28

Mergers of neutron-star/neutron-star binaries are strong sources of gravitational waves. They can also launch subrelativistic and mildly relativistic outflows and are often assumed to be the sources of short γ-ray bursts. An electromagnetic signature that persisted for weeks to months after the event would strengthen any future claim of a detection of gravitational waves. Here we present results of calculations showing that the interaction of mildly relativistic outflows with the surrounding medium produces radio flares with peak emission at 1.4 gigahertz that persist at detectable (submillijansky) levels for weeks, out to a redshift of 0.1. Slower subrelativistic outflows produce flares detectable for years at 150 megahertz, as well as at 1.4 gigahertz, from slightly shorter distances. The radio transient RT 19870422 (ref. 11) has the properties predicted by our model, and its most probable origin is the merger of a compact neutron-star/neutron-star binary. The lack of radio detections usually associated with short γ-ray bursts does not constrain the radio transients that we discuss here (from mildly relativistic and subrelativistic outflows) because short γ-ray burst redshifts are typically >0.1 and the appropriate timescales (longer than weeks) have not been sampled.

Global Response to Local Ionospheric Mass Ejection

NASA Technical Reports Server (NTRS)

Moore, T. E.; Fok, M.-C.; Delcourt, D. C.; Slinker, S. P.; Fedder, J. A.

2010-01-01

We revisit a reported "Ionospheric Mass Ejection" using prior event observations to guide a global simulation of local ionospheric outflows, global magnetospheric circulation, and plasma sheet pressurization, and comparing our results with the observed global response. Our simulation framework is based on test particle motions in the Lyon-Fedder-Mobarry (LFM) global circulation model electromagnetic fields. The inner magnetosphere is simulated with the Comprehensive Ring Current Model (CRCM) of Fok and Wolf, driven by the transpolar potential developed by the LFM magnetosphere, and includes an embedded plasmaspheric simulation. Global circulation is stimulated using the observed solar wind conditions for the period 24-25 Sept 1998. This period begins with the arrival of a Coronal Mass Ejection, initially with northward, but later with southward interplanetary magnetic field. Test particles are launched from the ionosphere with fluxes specified by local empirical relationships of outflow to electrodynamic and particle precipitation imposed by the MIlD simulation. Particles are tracked until they are lost from the system downstream or into the atmosphere, using the full equations of motion. Results are compared with the observed ring current and a simulation of polar and auroral wind outflows driven globally by solar wind dynamic pressure. We find good quantitative agreement with the observed ring current, and reasonable qualitative agreement with earlier simulation results, suggesting that the solar wind driven global simulation generates realistic energy dissipation in the ionosphere and that the Strangeway relations provide a realistic local outflow description.

Four-fluid MHD simulations of the plasma and neutral gas environment of comet 67P/Churyumov-Gerasimenko near perihelion

NASA Astrophysics Data System (ADS)

Huang, Zhenguang; Tóth, Gábor; Gombosi, Tamas I.; Jia, Xianzhe; Rubin, Martin; Fougere, Nicolas; Tenishev, Valeriy; Combi, Michael R.; Bieler, Andre; Hansen, Kenneth C.; Shou, Yinsi; Altwegg, Kathrin

2016-05-01

The neutral and plasma environment is critical in understanding the interaction of the solar wind and comet 67P/Churyumov-Gerasimenko (CG), the target of the European Space Agency's Rosetta mission. To serve this need and support the Rosetta mission, we have developed a 3-D four-fluid model, which is based on BATS-R-US (Block-Adaptive Tree Solarwind Roe-type Upwind Scheme) within SWMF (Space Weather Modeling Framework) that solves the governing multifluid MHD equations and the Euler equations for the neutral gas fluid. These equations describe the behavior and interactions of the cometary heavy ions, the solar wind protons, the electrons, and the neutrals. This model incorporates different mass loading processes, including photoionization and electron impact ionization, charge exchange, dissociative ion-electron recombination, and collisional interactions between different fluids. We simulated the plasma and neutral gas environment near perihelion in three different cases: an idealized comet with a spherical body and uniform neutral gas outflow, an idealized comet with a spherical body and illumination-driven neutral gas outflow, and comet CG with a realistic shape model and illumination-driven neutral gas outflow. We compared the results of the three cases and showed that the simulations with illumination-driven neutral gas outflow have magnetic reconnection, a magnetic pileup region and nucleus directed plasma flow inside the nightside reconnection region, which have not been reported in the literature.

iPTF17cw: An Engine-driven Supernova Candidate Discovered Independent of a Gamma-Ray Trigger

NASA Astrophysics Data System (ADS)

Corsi, A.; Cenko, S. B.; Kasliwal, M. M.; Quimby, R.; Kulkarni, S. R.; Frail, D. A.; Goldstein, A. M.; Blagorodnova, N.; Connaughton, V.; Perley, D. A.; Singer, L. P.; Copperwheat, C. M.; Fremling, C.; Kupfer, T.; Piascik, A. S.; Steele, I. A.; Taddia, F.; Vedantham, H.; Kutyrev, A.; Palliyaguru, N. T.; Roberts, O.; Sollerman, J.; Troja, E.; Veilleux, S.

2017-09-01

We present the discovery, classification, and radio-to-X-ray follow-up observations of iPTF17cw, a broad-lined (BL) type Ic supernova (SN) discovered by the intermediate Palomar Transient Factory (iPTF). Although it is unrelated to the gravitational wave trigger, this SN was discovered as a happy by-product of the extensive observational campaign dedicated to the follow-up of Advanced LIGO event GW 170104. The spectroscopic properties and inferred peak bolometric luminosity of iPTF17cw are most similar to the gamma-ray-burst (GRB)-associated SN, SN 1998bw, while the shape of the r-band light curve is most similar to that of the relativistic SN, SN 2009bb. Karl G. Jansky Very Large Array (VLA) observations of the iPTF17cw field reveal a radio counterpart ≈10 times less luminous than SN 1998bw, and with a peak radio luminosity comparable to that of SN 2006aj/GRB 060218 and SN 2010bh/GRB 100316D. Our radio observations of iPTF17cw imply a relativistically expanding outflow. However, further late-time observations with the VLA in its most extended configuration are needed to confirm fading of the iPTF17cw radio counterpart at all frequencies. X-ray observations carried out with Chandra reveal the presence of an X-ray counterpart with a luminosity similar to that of SN 2010bh/GRB 100316D. Searching the Fermi catalog for possible γ-rays reveals that GRB 161228B is spatially and temporally compatible with iPTF17cw. The similarity to SN 1998bw and SN 2009bb, the radio and X-ray detections, and the potential association with GRB 161228B all point to iPTF17cw being a new candidate member of the rare sample of optically discovered engine-driven BL-Ic SNe associated with relativistic ejecta.

iPTF17cw: An Engine-driven Supernova Candidate Discovered Independent of a Gamma-Ray Trigger

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corsi, A.; Palliyaguru, N. T.; Cenko, S. B.

We present the discovery, classification, and radio-to-X-ray follow-up observations of iPTF17cw, a broad-lined (BL) type Ic supernova (SN) discovered by the intermediate Palomar Transient Factory (iPTF). Although it is unrelated to the gravitational wave trigger, this SN was discovered as a happy by-product of the extensive observational campaign dedicated to the follow-up of Advanced LIGO event GW 170104. The spectroscopic properties and inferred peak bolometric luminosity of iPTF17cw are most similar to the gamma-ray-burst (GRB)-associated SN, SN 1998bw, while the shape of the r -band light curve is most similar to that of the relativistic SN, SN 2009bb. Karl G.more » Jansky Very Large Array (VLA) observations of the iPTF17cw field reveal a radio counterpart ≈10 times less luminous than SN 1998bw, and with a peak radio luminosity comparable to that of SN 2006aj/GRB 060218 and SN 2010bh/GRB 100316D. Our radio observations of iPTF17cw imply a relativistically expanding outflow. However, further late-time observations with the VLA in its most extended configuration are needed to confirm fading of the iPTF17cw radio counterpart at all frequencies. X-ray observations carried out with Chandra reveal the presence of an X-ray counterpart with a luminosity similar to that of SN 2010bh/GRB 100316D. Searching the Fermi catalog for possible γ -rays reveals that GRB 161228B is spatially and temporally compatible with iPTF17cw. The similarity to SN 1998bw and SN 2009bb, the radio and X-ray detections, and the potential association with GRB 161228B all point to iPTF17cw being a new candidate member of the rare sample of optically discovered engine-driven BL-Ic SNe associated with relativistic ejecta.« less

Galactic Disk Winds Driven by Cosmic Ray Pressure

NASA Astrophysics Data System (ADS)

Mao, S. Alwin; Ostriker, Eve C.

2018-02-01

Cosmic ray pressure gradients transfer energy and momentum to extraplanar gas in disk galaxies, potentially driving significant mass loss as galactic winds. This may be particularly important for launching high-velocity outflows of “cool” (T ≲ 104 K) gas. We study cosmic ray-driven disk winds using a simplified semi-analytic model assuming streamlines follow the large-scale gravitational potential gradient. We consider scaled Milky Way–like potentials including a disk, bulge, and halo with a range of halo velocities V H = 50–300 km s-1 and streamline footpoints with radii in the disk R 0 = 1–16 kpc at a height of 1 kpc. Our solutions cover a wide range of footpoint gas velocity u 0, magnetic–to–cosmic ray pressure ratio, gas–to–cosmic ray pressure ratio, and angular momentum. Cosmic ray streaming at the Alfvén speed enables the effective sound speed C eff to increase from the footpoint to a critical point where C eff,c = u c ∼ V H; this differs from thermal winds, in which C eff decreases outward. The critical point is typically at a height of 1–6 kpc from the disk, increasing with V H, and the asymptotic wind velocity exceeds the escape speed of the halo. Mass-loss rates are insensitive to the footpoint values of the magnetic field and angular momentum. In addition to numerical parameter space exploration, we develop and compare to analytic scaling relations. We show that winds have mass-loss rates per unit area up to \\dot{Σ}∼ Π0VH-5/3u02/3, where Π0 is the footpoint cosmic ray pressure and u 0 is set by the upwelling of galactic fountains. The predicted wind mass-loss rate exceeds the star formation rate for V H ≲ 200 km s-1 and u 0 = 50 km s-1, a typical fountain velocity.

DEEP CHANDRA X-RAY IMAGING OF A NEARBY RADIO GALAXY 4C+29.30: X-RAY/RADIO CONNECTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siemiginowska, Aneta; Aldcroft, Thomas L.; Burke, D. J.

2012-05-10

We report results from our deep Chandra X-ray observations of a nearby radio galaxy, 4C+29.30 (z = 0.0647). The Chandra image resolves structures on sub-arcsec to arcsec scales, revealing complex X-ray morphology and detecting the main radio features: the nucleus, a jet, hotspots, and lobes. The nucleus is absorbed (N{sub H} {approx_equal} 3.95{sup +0.27}{sub -0.33} Multiplication-Sign 10{sup 23} cm{sup -2}) with an unabsorbed luminosity of L{sub 2-10keV} {approx_equal} (5.08 {+-} 0.52) Multiplication-Sign 10{sup 43} erg s{sup -1} characteristic of Type 2 active galactic nuclei. Regions of soft (<2 keV) X-ray emission that trace the hot interstellar medium (ISM) are correlatedmore » with radio structures along the main radio axis, indicating a strong relation between the two. The X-ray emission extends beyond the radio source and correlates with the morphology of optical-line-emitting regions. We measured the ISM temperature in several regions across the galaxy to be kT {approx_equal} 0.5 keV, with slightly higher temperatures (of a few keV) in the center and in the vicinity of the radio hotspots. Assuming that these regions were heated by weak shocks driven by the expanding radio source, we estimated the corresponding Mach number of 1.6 in the southern regions. The thermal pressure of the X-ray-emitting gas in the outermost regions suggests that the hot ISM is slightly underpressured with respect to the cold optical-line-emitting gas and radio-emitting plasma, which both seem to be in a rough pressure equilibrium. We conclude that 4C+29.30 displays a complex view of interactions between the jet-driven radio outflow and host galaxy environment, signaling feedback processes closely associated with the central active nucleus.« less

The signature of supernova ejecta in the X-ray afterglow of the gamma-ray burst 011211.

PubMed

Reeves, J N; Watson, D; Osborne, J P; Pounds, K A; O'Brien, P T; Short, A D T; Turner, M J L; Watson, M G; Mason, K O; Ehle, M; Schartel, N

2002-04-04

Now that gamma-ray bursts (GRBs) have been determined to lie at cosmological distances, their isotropic burst energies are estimated to be as high as 1054 erg (ref. 2), making them the most energetic phenomena in the Universe. The nature of the progenitors responsible for the bursts remains, however, elusive. The favoured models range from the merger of two neutron stars in a binary system to the collapse of a massive star. Spectroscopic studies of the afterglow emission could reveal details of the environment of the burst, by indicating the elements present, the speed of the outflow and an estimate of the temperature. Here we report an X-ray spectrum of the afterglow of GRB011211, which shows emission lines of magnesium, silicon, sulphur, argon, calcium and possibly nickel, arising in metal-enriched material with an outflow velocity of the order of one-tenth the speed of light. These observations strongly favour models where a supernova explosion from a massive stellar progenitor precedes the burst event and is responsible for the outflowing matter.

Searching for outflows in ultraluminous X-ray sources through high-resolution X-ray spectroscopy

NASA Astrophysics Data System (ADS)

Kosec, P.; Pinto, C.; Fabian, A. C.; Walton, D. J.

2018-02-01

Ultraluminous X-ray sources (ULXs) are non-nuclear point sources exceeding the Eddington luminosity of a 10 M⊙ black hole. Modern consensus for a majority of the ULX population is that they are powered by stellar-mass black holes or neutron stars accreting well above the Eddington limit. Theoretical models of super-Eddington accretion predict existence of powerful outflows of moderately ionized gas at mildly relativistic velocities. So far, these winds have been found in three systems: NGC 1313 X-1, NGC 5408 X-1 and NGC 55 ULX. In this work, we create a sample of all ULXs with usable archival high-resolution X-ray data, with 10 sources in total, in which we aim to find more signatures of outflows. We perform Gaussian line scans to find any narrow spectral signatures, and physical wind model scans where possible. We tentatively identify an outflow in NGC 5204 X-1, blueshifted to 0.34c, which produces emission features with a total significance of at least 3σ. Next we compare ULXs with similar hardness ratios. Holmberg IX X-1 shows absorption features that could be associated with a photoionized outflowing absorber, similar to that seen in NGC 1313 X-1. The spectrum of Holmberg II X-1 possesses features similar to NGC 5408 X-1 and NGC 6946 X-1 shows O VIII rest-frame emission. All other sources from the sample also show tentative evidence of spectral features in their high-resolution spectra. Further observations with the XMM-Newton and Chandra gratings will place stronger constraints. Future missions like XARM and Athena will be able to detect them at larger distances and increase our sample.

Evidence for a Variable Ultrafast Outflow in the Newly Discovered Ultraluminous Pulsar NGC 300 ULX-1

NASA Astrophysics Data System (ADS)

Kosec, P.; Pinto, C.; Walton, D. J.; Fabian, A. C.; Bachetti, M.; Brightman, M.; Fürst, F.; Grefenstette, B. W.

2018-06-01

Ultraluminous pulsars are a definite proof that persistent super-Eddington accretion occurs in nature. They support the scenario according to which most Ultraluminous X-ray Sources (ULXs) are super-Eddington accretors of stellar mass rather than sub-Eddington intermediate mass black holes. An important prediction of theories of supercritical accretion is the existence of powerful outflows of moderately ionized gas at mildly relativistic speeds. In practice, the spectral resolution of X-ray gratings such as RGS onboard XMM-Newton is required to resolve their observational signatures in ULXs. Using RGS, outflows have been discovered in the spectra of 3 ULXs (none of which are currently known to be pulsars). Most recently, the fourth ultraluminous pulsar was discovered in NGC 300. Here we report detection of an ultrafast outflow (UFO) in the X-ray spectrum of the object, with a significance of more than 3σ, during one of the two simultaneous observations of the source by XMM-Newton and NuSTAR in December 2016. The outflow has a projected velocity of 65000 km/s (0.22c) and a high ionisation factor with a log value of 3.9. This is the first direct evidence for a UFO in a neutron star ULX and also the first time that this its evidence in a ULX spectrum is seen in both soft and hard X-ray data simultaneously. We find no evidence of the UFO during the other observation of the object, which could be explained by either clumpy nature of the absorber or a slight change in our viewing angle of the accretion flow.

Wind-driven angular momentum loss in binary systems. I - Ballistic case

NASA Technical Reports Server (NTRS)

Brookshaw, Leigh; Tavani, Marco

1993-01-01

We study numerically the average loss of specific angular momentum from binary systems due to mass outflow from one of the two stars for a variety of initial injection geometries and wind velocities. We present results of ballistic calculations in three dimensions for initial mass ratios q of the mass-losing star to primary star in the range q between 10 exp -5 and 10. We consider injection surfaces close to the Roche lobe equipotential surface of the mass-losing star, and also cases with the mass-losing star underfilling its Roche lobe. We obtain that the orbital period is expected to have a negative time derivative for wind-driven secular evolution of binaries with q greater than about 3 and with the mass-losing star near filling its Roche lobe. We also study the effect of the presence of an absorbing surface approximating an accretion disk on the average final value of the specific angular momentum loss. We find that the effect of an accretion disk is to increase the wind-driven angular momentum loss. Our results are relevant for evolutionary models of high-mass binaries and low-mass X-ray binaries.

Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. II. Radiation-Gas Interactions and Outflows

NASA Astrophysics Data System (ADS)

Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron

2017-12-01

Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of turbulent star-forming clouds to analyze the detailed interaction between non-ionizing UV radiation and the cloud material. Our simulations trace the evolution of gas and star particles through self-gravitating collapse, star formation, and cloud destruction via radiation-driven outflows. These models are idealized in that we include only radiation feedback and adopt an isothermal equation of state. Turbulence creates a structure of dense filaments and large holes through which radiation escapes, such that only ˜50% of the radiation is (cumulatively) absorbed by the end of star formation. The surface density distribution of gas by mass as seen by the central cluster is roughly lognormal with {σ }{ln{{Σ }}}=1.3{--}1.7, similar to the externally projected surface density distribution. This allows low surface density regions to be driven outwards to nearly 10 times their initial escape speed {v}{esc}. Although the velocity distribution of outflows is broadened by the lognormal surface density distribution, the overall efficiency of momentum injection to the gas cloud is reduced because much of the radiation escapes. The mean outflow velocity is approximately twice the escape speed from the initial cloud radius. Our results are also informative for understanding galactic-scale wind driving by radiation, in particular, the relationship between velocity and surface density for individual outflow structures and the resulting velocity and mass distributions arising from turbulent sources.

AGN-enhanced outflows of low-ionization gas in star-forming galaxies at 1.7 < z < 4.6*

NASA Astrophysics Data System (ADS)

Talia, M.; Brusa, M.; Cimatti, A.; Lemaux, B. C.; Amorin, R.; Bardelli, S.; Cassarà, L. P.; Cucciati, O.; Garilli, B.; Grazian, A.; Guaita, L.; Hathi, N. P.; Koekemoer, A.; Le Fèvre, O.; Maccagni, D.; Nakajima, K.; Pentericci, L.; Pforr, J.; Schaerer, D.; Vanzella, E.; Vergani, D.; Zamorani, G.; Zucca, E.

2017-11-01

Fast and energetic winds are invoked by galaxy formation models as essential processes in the evolution of galaxies. These outflows can be powered either by star formation (SF) and/or active galactic nucleus (AGN) activity, but the relative dominance of the two mechanisms is still under debate. We use spectroscopic stacking analysis to study the properties of the low-ionization phase of the outflow in a sample of 1330 star-forming galaxies (SFGs) and 79 X-ray-detected (1042 < LX < 1045 erg s-1) Type 2 AGN at 1.7 < z < 4.6 selected from a compilation of deep optical spectroscopic surveys, mostly zCOSMOS-Deep and VIMOS Ultra Deep Survey (VUDS). We measure mean velocity offsets of ˜- 150 km s-1 in the SFGs, while in the AGN sample the velocity is much higher (˜- 950 km s-1), suggesting that the AGN is boosting the outflow up to velocities that could not be reached only with the SF contribution. The sample of X-ray AGN has on average a lower SF rate than non-AGN SFGs of similar mass: this, combined with the enhanced outflow velocity in AGN hosts, is consistent with AGN feedback in action. We further divide our sample of AGN into two X-ray luminosity bins: we measure the same velocity offsets in both stacked spectra, at odds with results reported for the highly ionized phase in local AGN, suggesting that the two phases of the outflow may be mixed only up to relatively low velocities, while the highest velocities can be reached only by the highly ionized phase.

Unification of X-ray Winds in Seyfert Galaxies: From Ultra-fast Outflows to Warm Absorbers

NASA Astrophysics Data System (ADS)

Tombesi, Francesco; Cappi, M.; Reeves, J.; Nemmen, R.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-04-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60%, consistent with previous studies. The fraction of sources with UFOs is >34%, >67% of which also show WAs. The large dynamic range obtained when considering all the absorbers together allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. The absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. This strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The observed parameters and correlations are consistent with both radiation pressure through Compton scattering and MHD processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, have a sufficiently high mechanical power to significantly contribute to the AGN feedback.

Comparing cosmological hydrodynamic simulations with observations of high- redshift galaxy formation

NASA Astrophysics Data System (ADS)

Finlator, Kristian Markwart

We use cosmological hydrodynamic simulations to study the impact of outflows and radiative feedback on high-redshift galaxies. For outflows, we consider simulations that assume (i) no winds, (ii) a "constant-wind" model in which the mass-loading factor and outflow speed are constant, and (iii) "momentum-driven" winds in which both parameters vary smoothly with mass. In order to treat radiative feedback, we develop a moment-based radiative transfer technique that operates in both post-processing and coupled radiative hydrodynamic modes. We first ask how outflows impact the broadband spectral energy distributions (SEDs) of six observed reionization-epoch galaxies. Simulations reproduce five regardless of the outflow prescription, while the sixth suggests an unusually bursty star formation history. We conclude that (i) simulations broadly account for available constraints on reionization-epoch galaxies, (ii) individual SEDs do not constrain outflows, and (iii) SED comparisons efficiently isolate objects that challenge simulations. We next study how outflows impact the galaxy mass metallicity relation (MZR). Momentum-driven outflows uniquely reproduce observations at z = 2. In this scenario, galaxies obey two equilibria: (i) The rate at which a galaxy processes gas into stars and outflows tracks its inflow rate; and (ii) The gas enrichment rate owing to star formation balances the dilution rate owing to inflows. Combining these conditions indicates that the MZR is dominated by the (instantaneous) variation of outflows with mass, with more-massive galaxies driving less gas into outflows per unit stellar mass formed. Turning to radiative feedback, we use post-processing simulations to study the topology of reionization. Reionization begins in overdensities and then "leaks" directly into voids, with filaments reionizing last owing to their high density and low emissivity. This result conflicts with previous findings that voids ionize last. We argue that it owes to the uniqely-biased emissivity field produced by our star formation prescriptions, which have previously been shown to reproduce numerous post-reionization constraints. Finally, preliminary results from coupled radiative hydrodynamic simulations indicate that reionization suppresses the star formation rate density by at most 10-20% by z = 5. This is much less than previous estimates, which we attribute to our unique reionization topology although confirmation will have to await more detailed modeling.

Properties of the molecular gas in the fast outflow in the Seyfert galaxy IC 5063

NASA Astrophysics Data System (ADS)

Oosterloo, Tom; Raymond Oonk, J. B.; Morganti, Raffaella; Combes, Françoise; Dasyra, Kalliopi; Salomé, Philippe; Vlahakis, Nektarios; Tadhunter, Clive

2017-12-01

We present a detailed study of the properties of the molecular gas in the fast outflow driven by the active galactic nucleus (AGN) in the nearby radio-loud Seyfert galaxy IC 5063. By using ALMA observations of a number of tracers of the molecular gas (12CO(1-0), 12CO(2-1), 12CO(3-2), 13CO(2-1) and HCO+(4-3)), we map the differences in excitation, density and temperature of the gas as function of position and kinematics. The results show that in the immediate vicinity of the radio jet, a fast outflow, with velocities up to 800 km s-1, is occurring of which the gas has high excitation with excitation temperatures in the range 30-55 K, demonstrating the direct impact of the jet on the ISM. The relative brightness of the 12CO lines, as well as that of 13CO(2-1) vs. 12CO(2-1), show that the outflow is optically thin. We estimate the mass of the molecular outflow to be at least 1.2 × 106 M⊙ and likely to be a factor between two and three larger than this value. This is similar to that of the outflow of atomic gas, but much larger than that of the ionised outflow, showing that the outflow in IC 5063 is dominated by cold gas. The total mass outflow rate we estimated to be 12 M⊙ yr-1. The mass of the outflow is much smaller than the total gas mass of the ISM of IC 5063. Therefore, although the influence of the AGN and its radio jet is very significant in the inner regions of IC 5063, globally speaking the impact will be very modest. We used RADEX non-LTE modelling to explore the physical conditions of the molecular gas in the outflow. Models with the outflowing gas being quite clumpy give the most consistent results and our preferred solutions have kinetic temperatures in the range 20-100 K and densities between 105 and 106 cm-3. The resulting pressures are 106-107.5 K cm-3, about two orders of magnitude higher than in the outer quiescent disk. The highest densities and temperatures are found in the regions with the fastest outflow. The results strongly suggest that the outflow in IC 5063 is driven by the radio plasma jet expanding into a clumpy gaseous medium and creating a cocoon of (shocked) gas which is pushed away from the jet axis resulting in a lateral outflow, very similar to what is predicted by numerical simulations.

CHANG-ES. VII. Magnetic Outflows from the Virgo Cluster Galaxy NGC 4388

NASA Astrophysics Data System (ADS)

Damas-Segovia, A.; Beck, R.; Vollmer, B.; Wiegert, T.; Krause, M.; Irwin, J.; Weżgowiec, M.; Li, J.; Dettmar, R.-J.; English, J.; Wang, Q. D.

2016-06-01

We investigate the effects of ram pressure on the ordered magnetic field of a galaxy hosting a radio halo and strong nuclear outflows. New radio images in total and polarized intensity of the edge-on Virgo galaxy NGC 4388 were obtained within the CHANG-ES EVLA project. The unprecedented noise level reached allows us to detect striking new features of the ordered magnetic field. The nuclear outflow extends far into the halo to about 5 kpc from the center and is spatially correlated with the {{H}}α and X-ray emission. For the first time, the southern outflow is detected. Above and below both spiral arms we find extended blobs of polarized emission with an ordered field oriented perpendicular to the disk. The synchrotron lifetime of the cosmic-ray electrons (CREs) in these regions yields a mean outflow velocity of 270+/- 70 {km} {{{s}}}-1, in agreement with a galactic wind scenario. The observed symmetry of the polarized halo features in NGC 4388 excludes a compression of the halo gas by the ram pressure of the intracluster medium (ICM). The assumption of equilibrium between the halo pressure and the ICM ram pressure yields an estimate of the ICM density that is consistent with both the ICM density derived from X-ray observations and the recent Planck Sunyaev-Zel’dovich measurements. The detection of a faint radio halo around cluster galaxies could thus be used for an estimate of ICM ram pressure.

Compact binary merger and kilonova: outflows from remnant disc

NASA Astrophysics Data System (ADS)

Yi, Tuan; Gu, Wei-Min; Liu, Tong; Kumar, Rajiv; Mu, Hui-Jun; Song, Cui-Ying

2018-05-01

Outflows launched from a remnant disc of compact binary merger may have essential contribution to the kilonova emission. Numerical calculations are conducted in this work to study the structure of accretion flows and outflows. By the incorporation of limited-energy advection in the hyper-accretion discs, outflows occur naturally from accretion flows due to imbalance between the viscous heating and the sum of the advective and radiative cooling. Following this spirit, we revisit the properties of the merger outflow ejecta. Our results show that around 10-3 ˜ 10-1 M⊙ of the disc mass can be launched as powerful outflows. The amount of unbound mass varies with the disc mass and the viscosity. The outflow-contributed peak luminosity is around 1040 ˜ 1041 erg s-1. Such a scenario can account for the observed kilonovae associated with short gamma-ray bursts, including the recent event AT2017gfo (GW170817).

Anatomy of the AGN in NGC 5548: Discovery of a fast and massive outflow

NASA Astrophysics Data System (ADS)

Kaastra, J.; Kriss, G.; Cappi, M.; Mehdipour, M.; Petrucci, P.; Steenbrugge, K.; Arav, N.; Behar, E.; Bianchi, S.; Boissay, R.; Branduardi-Raymont, G.; Chamberlain, C.; Costantini, E.; Ely, J.; Ebrero, J.; Di Gesu, L.; Harrison, F.; kaspi, S.; Malzac, J.; De Marco, B.; Matt, G.; Nandra, K.; Paltani, S.; Person, R.; Peterson, B.; Pinto, C.; Ponti, G.; Pozo Nuñez, F.; De Rosa, A.; Seta, H.; Ursini, F.; De Vries, C.; Walton, D.; Whewell, M.

2014-07-01

After a very succesfull multi-satellite campaign on Mrk 509 in 2009, we conducted a similar campaign on the AGN NGC 5548 in 2013. This archetype Seyfert 1 galaxy NGC 5548 has been studied for decades, and high-resolution X-ray and UV observations have previously shown an outflow with standard physical characteristics. However, our recent observing campaign with six space observatories (XMM-Newton, HST, Swift, NuSTAR, Chandra and INTEGRAL) shows the nucleus to be obscured by a stream of new ionized gas never seen before in this source. The gas with hydrogen column densities of 1E26-1E27 per m2 blocks 90% of the soft X-ray emission and causes deep and broad UV absorption troughs. The outflow velocities are up to five times faster than the persistent normal outflow. It is located at a distance of only a few light days from the nucleus close to the broad line region; this might indicate an origin from the accretion disk.

X-ray Evidence for Ultra-Fast Outflows in Local AGNs

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Sambruna, R. M.; Reeves, J. N.; Reynolds, C. S.; Braito, V.; Dadina, M.

2012-08-01

X-ray evidence for ultra-fast outflows (UFOs) has been recently reported in a number of local AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts and 5 Broad-Line Radio Galaxies (BLRGs) observed with XMM-Newton and Suzaku. We detect UFOs in ga 40% of the sources. Their outflow velocities are in the range ˜ 0.03-0.3c, with a mean value of ˜ 0.14c. The ionization is high, in the range logℰ ˜3-6rm erg s-1 cm, and also the associated column densities are large, in the interval ˜ 1022-1024rm cm-2. Overall, these results point to the presence of highly ionized and massive outflowing material in the innermost regions of AGNs. Their variability and location on sub-pc scales favor a direct association with accretion disk winds/outflows. This also suggests that UFOs may potentially play a significant role in the AGN cosmological feedback besides jets, and their study can provide important clues on the connection between accretion disks, winds, and jets.

Is there any evidence that ionized outflows quench star formation in type 1 quasars at z < 1?

NASA Astrophysics Data System (ADS)

Balmaverde, B.; Marconi, A.; Brusa, M.; Carniani, S.; Cresci, G.; Lusso, E.; Maiolino, R.; Mannucci, F.; Nagao, T.

2016-01-01

Aims: The aim of this paper is to test the basic model of negative active galactic nuclei (AGN) feedback. According to this model, once the central black hole accretes at the Eddington limit and reaches a certain critical mass, AGN driven outflows blow out gas, suppressing star formation in the host galaxy and self-regulating black hole growth. Methods: We consider a sample of 224 quasars selected from the Sloan Digital Sky Survey (SDSS) at z< 1 observed in the infrared band by the Herschel Space Observatory in point source photometry mode. We evaluate the star formation rate in relation to several outflow signatures traced by the [O III] λ4959, 5007 and [O II] λ3726, 3729 emission lines in about half of the sample with high quality spectra. Results: Most of the quasars show asymmetric and broad wings in [O III], which we interpret as outflow signatures. We separate the quasars in two groups, "weakly" and "strongly" outflowing, using three different criteria. When we compare the mean star formation rate in five redshift bins in the two groups, we find that the star formation rate (SFR) are comparable or slightly larger in the strongly outflowing quasars. We estimate the stellar mass from spectral energy distribution (SED) fitting and the quasars are distributed along the star formation main sequence, although with a large scatter. The scatter from this relation is uncorrelated with respect to the kinematic properties of the outflow. Moreover, for quasars dominated in the infrared by starburst or by AGN emission, we do not find any correlation between the star formation rate and the velocity of the outflow, a trend previously reported in the literature for pure starburst galaxies. Conclusions: We conclude that the basic AGN negative feedback scenario seems not to agree with our results. Although we use a large sample of quasars, we did not find any evidence that the star formation rate is suppressed in the presence of AGN driven outflows on large scale. A possibility is that feedback is effective over much longer timescales than those of single episodes of quasar activity.

(abstract) A Test of the Theoretical Models of Bipolar Outflows: The Bipolar Outflow in Mon R2

NASA Technical Reports Server (NTRS)

Xie, Taoling; Goldsmith, Paul; Patel, Nimesh

1993-01-01

We report some results of a study of the massive bipolar outflow in the central region of the relatively nearby giant molecular cloud Monoceros R2. We make a quantative comparison of our results with the Shu et al. outflow model which incorporates a radially directed wind sweeping up the ambient material into a shell. We find that this simple model naturally explains the shape of this thin shell. Although Shu's model in its simplest form predicts with reasonable parameters too much mass at very small polar angles, as previously pointed out by Masson and Chernin, it provides a reasonable good fit to the mass distribution at larger polar angles. It is possible that this discrepancy is due to inhomogeneities of the ambient molecular gas which is not considered by the model. We also discuss the constraints imposed by these results on recent jet-driven outflow models.

Can a Wind Model Mimic a Convection-Dominated Accretion Flow Model?

NASA Astrophysics Data System (ADS)

Chang, Heon-Young

2001-06-01

In this paper we investigate the properties of advection-dominated accretion flows(ADAFs) in case that outflows carry away infalling matter with its angular momentum and energy. Positive Bernoulli numbers in ADAFs allow a fraction of the gas to be ex-pelled in a form of outflows. The ADAFs are also unstable to convection. We present self-similar solutions for advection-dominated accretion flows in the presence of out-flows from the accretion flows (ADIOS). The axisymmetric flow is treated in variables integrated over polar sections and the effects of outflows on the accretion rlow are parameterized for possible configurations compatible with the one dimensional self-similar ADAF solution. We explicitly derive self-similar solutions of ADAFs in the presence of outflows and show that the strong outflows in the accretion flows result in a flatter density profile, which is similar to that of the convection-dominated accretion flows (CDAFs) in which convection transports the a! ngular momentum inward and the energy outward. These two different versions of the ADAF model should show similar behaviors in X-ray spectrum to some extent. Even though the two models may show similar behaviors, they should be distinguishable due to different physical properties. We suggest that for a central object of which mass is known these two different accretion flows should have different X-ray flux value due to deficient matter in the wind model.

Outflowing OH+ in Markarian 231: The Ionization Rate of the Molecular Gas

NASA Astrophysics Data System (ADS)

González-Alfonso, E.; Fischer, J.; Bruderer, S.; Ashby, M. L. N.; Smith, H. A.; Veilleux, S.; Müller, H. S. P.; Stewart, K. P.; Sturm, E.

2018-04-01

The oxygen-bearing molecular ions OH+, H2O+, and H3O+ are key species that probe the ionization rate of (partially) molecular gas that is ionized by X-rays and cosmic-rays permeating the interstellar medium. We report Herschel far-infrared and submillimeter spectroscopic observations of OH+ in Mrk 231, showing both ground-state P-Cygni profiles, and excited line profiles with blueshifted absorption wings extending up to ≈1000 km s‑1. In addition, OH+ probes an excited component peaking at central velocities, likely arising from the torus probed by the OH centimeter-wave megamaser. Four lines of H2O+ are also detected at systemic velocities, but H3O+ is undetected. Based on our earlier OH studies, we estimate an abundance ratio of {OH}/{OH}}+∼ 5{--}10 for the outflowing components and ≈20 for the torus, and an OH+ abundance relative to H nuclei of ≳10‑7. We also find high OH+/H2O+ and OH+/H3O+ ratios; both are ≳4 in the torus and ≳10–20 in the outflowing gas components. Chemical models indicate that these high OH+ abundances relative to OH, H2O+, and H3O+ are characteristic of gas with a high ionization rate per unit density, \\zeta /{n}{{H}}∼ (1{--}5)× {10}-17 cm3 s‑1 and ∼(1–2) × 10‑16 cm3 s‑1 for the above components, respectively, an ionization rate of ζ ∼ (0.5–2) × 10‑12 s‑1, and a low molecular fraction, {f}{{{H}}2}∼ 0.25. X-rays appear to be unable to explain the inferred ionization rate, and thus we suggest that low-energy (10–400 MeV) cosmic-rays are primarily responsible for the ionization, with {\\dot{M}}CR}∼ 0.01 M ⊙ yr‑1 and {\\dot{E}}CR}∼ {10}44 erg s‑1 the latter corresponds to ∼1% of the luminosity of the active galactic nucleus and is similar to the energetics of the molecular outflow. We suggest that cosmic-rays accelerated in the forward shock associated with the molecular outflow are responsible for the ionization, as they diffuse through the outflowing molecular phase downstream.

The Simbol-X Perspective on the Physics of Quasar Outflows

NASA Astrophysics Data System (ADS)

Giustini, M.; Cappi, M.; Vignali, C.; Palumbo, G. G. C.; Fiore, F.; Malaguti, G.

2009-05-01

There is increasing evidence that quasar outflows may play a key role in providing the feedback between AGN/QSOs and their surrounding (and feeding) media, in regulating the central supermassive black hole growth and the galaxy formation and, on larger scales, in shaping the growth of cosmic structures (see e.g. [1]). X-ray observations of quasar outflows are crucial to probe their innermost parts and assess the global energetics entrained in the outflow by studying its most extreme (in terms of velocity, ionization state, mass outflow rate) phases. Simbol-X-with its high effective area in the Fe K energy band and above-will allow the detection and the characterization of powerful outflows in bright, nearby AGN and notably also in moderately faint AGN, thus shedding light on feedback processes in these objects.

Optical and X-ray luminosities of expanding nebulae around ultraluminous X-ray sources

NASA Astrophysics Data System (ADS)

Siwek, Magdalena; Sądowski, Aleksander; Narayan, Ramesh; Roberts, Timothy P.; Soria, Roberto

2017-09-01

We have performed a set of simulations of expanding, spherically symmetric nebulae inflated by winds from accreting black holes in ultraluminous X-ray sources (ULXs). We implemented a realistic cooling function to account for free-free and bound-free cooling. For all model parameters we considered, the forward shock in the interstellar medium becomes radiative at a radius ˜100 pc. The emission is primarily in optical and UV, and the radiative luminosity is about 50 per cent of the total kinetic luminosity of the wind. In contrast, the reverse shock in the wind is adiabatic so long as the terminal outflow velocity of the wind vw ≳ 0.003c. The shocked wind in these models radiates in X-rays, but with a luminosity of only ˜1035 erg s-1. For wind velocities vw ≲ 0.001c, the shocked wind becomes radiative, but it is no longer hot enough to produce X-rays. Instead it emits in optical and UV, and the radiative luminosity is comparable to 100 per cent of the wind kinetic luminosity. We suggest that measuring the optical luminosities and putting limits on the X-ray and radio emission from shock-ionized ULX bubbles may help in estimating the mass outflow rate of the central accretion disc and the velocity of the outflow.

Analysis of the X-ray emission of nine Swift afterglows

NASA Astrophysics Data System (ADS)

Panaitescu, A.; Mészáros, P.; Gehrels, N.; Burrows, D.; Nousek, J.

2006-03-01

The X-ray light curves of nine Swift XRT afterglows (050126, 050128, 050219A, 050315, 050318, 050319, 050401, 050408 and 050505) display a complex behaviour: a steep t-3.0+/-0.3 decay until ~400 s, followed by a significantly slower t-0.65+/-0.20 fall-off, which at 0.2-2 day after the burst evolves into a t-1.7+/-0.5 decay. We consider three possible models for the geometry of relativistic blast-waves (spherical outflows, non-spreading jets and spreading jets), two possible dynamical regimes for the forward shock (adiabatic and fully radiative), and we take into account a possible angular structure of the outflow and delayed energy injection in the blast-wave to identify the models which reconcile the X-ray light-curve decay with the slope of the X-ray continuum for each of the above three afterglow phases. By piecing together the various models for each phase in a way that makes physical sense, we identify possible models for the entire X-ray afterglow. The major conclusion of this work is that a long-lived episode of energy injection in the blast-wave, during which the shock energy increases at t1.0+/-0.5, is required for five afterglows and could be at work in the other four as well. For some afterglows, there may be other mechanisms that can explain the t < 400 s fast falling-off X-ray light curve (e.g. the large-angle gamma-ray burst emission), the 400 s to 5 h slow decay (e.g. a structured outflow), or the steepening at 0.2-2 day (e.g. a jet-break, a collimated outflow transiting from a wind with a r-3 radial density profile to a homogeneous or outward-increasing density region). Optical observations in conjunction with the X-ray can distinguish among these various models. Our simple tests allow the determination of the location of the cooling frequency relative to the X-ray domain and, thus, of the index of the electron power-law distribution with energy in the blast-wave. The resulting indices are clearly inconsistent with a universal value.

XMM-Newton observations of the Galactic Centre Region - II. The soft-thermal emission

NASA Astrophysics Data System (ADS)

Heard, V.; Warwick, R. S.

2013-09-01

We have extended our earlier study of the X-ray emission emanating from the central 100 pc × 100 pc region of our Galaxy to an investigation of several features prominent in the soft X-ray (2-4.5 keV) band. We focus on three specific structures: a putative bipolar outflow from the vicinity of Sgr A*; a high surface brightness region located roughly 12 arcmin (25 pc) to the north-east of Sgr A* and a lower surface brightness extended loop feature seen to the south of Sgr A*. We show, unequivocally, that all three structures are thermal in nature and have similar temperatures (kT ≈ 1 keV). The inferred X-ray luminosities lie in the range (2-10) × 1034 erg s-1. In the case of the bipolar feature we suggest that the hot plasma is produced by the shock heating of the winds from massive stars within the Central Cluster, possibly collimated by the Circumnuclear Disc. Alternatively the outflow may be driven by outbursts on Sgr A*, which follow tidal disruption events occurring at a rate of roughly one every 4000 yr. The north-east enhancement is centred on a candidate pulsar wind nebula which has a relatively hard non-thermal X-ray spectrum. We suggest that the coincident soft-thermal emission traces the core of a new thermal-composite supernova remnant, designated as SNR G0.13-0.12. There is no clear evidence for an associated radio shell but such a feature may be masked by the bright emission of the nearby Radio Arc and other filamentary structures. SNR G0.13-0.12 is very likely interacting with the nearby molecular cloud, G0.11-0.11, and linked to the Fermi source, 2FGL J1746.4-2851c. Finally we explore a previous suggestion that the elliptically shaped X-ray loop to the south of Sgr A*, of maximum extent ˜45 pc, represents the shell of a superbubble located in the GC region. Although plausible, the interpretation of this feature in terms a coherent physical structure awaits confirmation.

The dependence of cosmic ray-driven galactic winds on halo mass

NASA Astrophysics Data System (ADS)

Jacob, Svenja; Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker; Pfrommer, Christoph

2018-03-01

Galactic winds regulate star formation in disc galaxies and help to enrich the circum-galactic medium. They are therefore crucial for galaxy formation, but their driving mechanism is still poorly understood. Recent studies have demonstrated that cosmic rays (CRs) can drive outflows if active CR transport is taken into account. Using hydrodynamical simulations of isolated galaxies with virial masses between 1010 and 1013 M⊙, we study how the properties of CR-driven winds depend on halo mass. CRs are treated in a two-fluid approximation and their transport is modelled through isotropic or anisotropic diffusion. We find that CRs are only able to drive mass-loaded winds beyond the virial radius in haloes with masses below 1012 M⊙. For our lowest examined halo mass, the wind is roughly spherical and has velocities of ˜20 km s-1. With increasing halo mass, the wind becomes biconical and can reach 10 times higher velocities. The mass loading factor drops rapidly with virial mass, a dependence that approximately follows a power law with a slope between -1 and -2. This scaling is slightly steeper than observational inferences, and also steeper than commonly used prescriptions for wind feedback in cosmological simulations. The slope is quite robust to variations of the CR injection efficiency or the CR diffusion coefficient. In contrast to the mass loading, the energy loading shows no significant dependence on halo mass. While these scalings are close to successful heuristic models of wind feedback, the CR-driven winds in our present models are not yet powerful enough to fully account for the required feedback strength.

Resolved atomic lines reveal outflows in two ultraluminous X-ray sources.

PubMed

Pinto, Ciro; Middleton, Matthew J; Fabian, Andrew C

2016-05-05

Ultraluminous X-ray sources are extragalactic, off-nucleus, point sources in galaxies, and have X-ray luminosities in excess of 3 × 10(39) ergs per second. They are thought to be powered by accretion onto a compact object. Possible explanations include accretion onto neutron stars with strong magnetic fields, onto stellar-mass black holes (of up to 20 solar masses) at or in excess of the classical Eddington limit, or onto intermediate-mass black holes (10(3)-10(5) solar masses). The lack of sufficient energy resolution in previous analyses has prevented an unambiguous identification of any emission or absorption lines in the X-ray band, thereby precluding a detailed analysis of the accretion flow. Here we report the presence of X-ray emission lines arising from highly ionized iron, oxygen and neon with a cumulative significance in excess of five standard deviations, together with blueshifted (about 0.2 times light velocity) absorption lines of similar significance, in the high-resolution X-ray spectra of the ultraluminous X-ray sources NGC 1313 X-1 and NGC 5408 X-1. The blueshifted absorption lines must occur in a fast-outflowing gas, whereas the emission lines originate in slow-moving gas around the source. We conclude that the compact object in each source is surrounded by powerful winds with an outflow velocity of about 0.2 times that of light, as predicted by models of accreting supermassive black holes and hyper-accreting stellar-mass black holes.

The Independence of Neutral and Ionized Gas Outflows in Low-z Galaxies

NASA Astrophysics Data System (ADS)

Bae, Hyun-Jin; Woo, Jong-Hak

2018-02-01

Using a large sample of emission line galaxies selected from the Sloan Digital Sky Survey, we investigate the kinematics of the neutral gas in the interstellar medium (ISM) based on the Na I λλ5890,5896 (Na D) doublet absorption line. By removing the Na D contribution from stellar atmospheres, we isolate the line profile of the Na D excess, which represents the neutral gas in the ISM. The kinematics traced by the Na D excess show high velocity and velocity dispersion for a fraction of galaxies, indicating the presence of neutral gas outflows. We find that the kinematics measured from the Na D excess are similar between AGNs and star-forming galaxies. Moreover, by comparing the kinematics traced by the Na D excess and those by the [O III] λ5007 line taken from Woo et al., which traces ionized outflows driven by AGNs, we find no correlation between them. These results demonstrate that the neutral gas in the ISM traced by the Na D excess and the ionized gas traced by [O III] are kinematically independent, and AGNs have no impact on the neutral gas outflows. In contrast to [O III], we find that the measured line-of-sight velocity shift and velocity dispersion of the Na D excess increase for more face-on galaxies due to the projection effect, supporting that Na D outflows are radially driven (i.e., perpendicular to the major axis of galaxies), presumably due to star formation.

Radiative cooling of swept up gas in AGN-driven galactic winds and its implications for molecular outflows

NASA Astrophysics Data System (ADS)

Richings, Alexander J.; Faucher-Giguére, Claude-André

2018-05-01

We recently used hydro-chemical simulations to demonstrate that molecular outflows observed in luminous quasars can be explained by molecule formation within the AGN wind. However, these simulations cover a limited parameter space, due to their computational cost. We have therefore developed an analytic model to follow cooling in the shocked ISM layer of an AGN wind. We explore different ambient densities (1-104 {cm}^{-3}), density profile slopes (0-1.5), AGN luminosities (1044-10^{47} {erg} {s}^{-1}), and metallicities (0.1-3 Z⊙). The swept up gas mostly cools within ˜1 Myr. Based on our previous simulations, we predict that this gas would produce observable molecular outflows. The instantaneous momentum boost initially increases as the outflow decelerates. However, it reaches a maximum of ≈20, due to work done against the gravitational potential. The predicted time-averaged observational estimate of the molecular outflow momentum boost reaches a maximum of ≈1 -2, partly due to our assumed molecular fraction, 0.2, but also because the instantaneous and observational, time-averaged definitions are not equivalent. Thus recent observational estimates of order unity momentum boosts do not necessarily rule out energy-driven outflows. Finally, we find that dust grains are likely to re-form by accretion of metals after the shocked ISM layer has cooled, assuming that a small fraction of dust grains swept up after this layer has cooled are able to mix into the cool phase, and assuming that grain growth remains efficient in the presence of the strong AGN radiation field. This would enable rapid molecule formation, as assumed in our models.

Zooming into local active galactic nuclei: the power of combining SDSS-IV MaNGA with higher resolution integral field unit observations

NASA Astrophysics Data System (ADS)

Wylezalek, Dominika; Schnorr Müller, Allan; Zakamska, Nadia L.; Storchi-Bergmann, Thaisa; Greene, Jenny E.; Müller-Sánchez, Francisco; Kelly, Michael; Liu, Guilin; Law, David R.; Barrera-Ballesteros, Jorge K.; Riffel, Rogemar A.; Thomas, Daniel

2017-05-01

Ionized gas outflows driven by active galactic nuclei (AGN) are ubiquitous in high-luminosity AGN with outflow speeds apparently correlated with the total bolometric luminosity of the AGN. This empirical relation and theoretical work suggest that in the range Lbol ˜ 1043-45 erg s-1 there must exist a threshold luminosity above which the AGN becomes powerful enough to launch winds that will be able to escape the galaxy potential. In this paper, we present pilot observations of two AGN in this transitional range that were taken with the Gemini North Multi-Object Spectrograph integral field unit (IFU). Both sources have also previously been observed within the Sloan Digital Sky Survey-IV (SDSS) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. While the MaNGA IFU maps probe the gas fields on galaxy-wide scales and show that some regions are dominated by AGN ionization, the new Gemini IFU data zoom into the centre with four times better spatial resolution. In the object with the lower Lbol we find evidence of a young or stalled biconical AGN-driven outflow where none was obvious at the MaNGA resolution. In the object with the higher Lbol we trace the large-scale biconical outflow into the nuclear region and connect the outflow from small to large scales. These observations suggest that AGN luminosity and galaxy potential are crucial in shaping wind launching and propagation in low-luminosity AGN. The transition from small and young outflows to galaxy-wide feedback can only be understood by combining large-scale IFU data that trace the galaxy velocity field with higher resolution, small-scale IFU maps.

Submillimeter array observations of NGC 2264-C: molecular outflows and driving sources

NASA Astrophysics Data System (ADS)

Cunningham, Nichol; Lumsden, Stuart L.; Cyganowski, Claudia J.; Maud, Luke T.; Purcell, Cormac

2016-05-01

We present 1.3 mm Submillimeter Array (SMA) observations at ˜3 arcsec resolution towards the brightest section of the intermediate/massive star-forming cluster NGC 2264-C. The millimetre continuum emission reveals ten 1.3 mm continuum peaks, of which four are new detections. The observed frequency range includes the known molecular jet/outflow tracer SiO (5-4), thus providing the first high-resolution observations of SiO towards NGC 2264-C. We also detect molecular lines of 12 additional species towards this region, including CH3CN, CH3OH, SO, H2CO, DCN, HC3N, and 12CO. The SiO (5-4) emission reveals the presence of two collimated, high-velocity (up to 30 km s-1 with respect to the systemic velocity) bipolar outflows in NGC 2264-C. In addition, the outflows are traced by emission from 12CO, SO, H2CO, and CH3OH. We find an evolutionary spread between cores residing in the same parent cloud. The two unambiguous outflows are driven by the brightest mm continuum cores, which are IR-dark, molecular line weak, and likely the youngest cores in the region. Furthermore, towards the Red MSX Source AFGL 989-IRS1, the IR-bright and most evolved source in NGC 2264-C, we observe no molecular outflow emission. A molecular line rich ridge feature, with no obvious directly associated continuum source, lies on the edge of a low-density cavity and may be formed from a wind driven by AFGL 989-IRS1. In addition, 229 GHz class I maser emission is detected towards this feature.

Self-consistent modelling of line-driven hot-star winds with Monte Carlo radiation hydrodynamics

NASA Astrophysics Data System (ADS)

Noebauer, U. M.; Sim, S. A.

2015-11-01

Radiative pressure exerted by line interactions is a prominent driver of outflows in astrophysical systems, being at work in the outflows emerging from hot stars or from the accretion discs of cataclysmic variables, massive young stars and active galactic nuclei. In this work, a new radiation hydrodynamical approach to model line-driven hot-star winds is presented. By coupling a Monte Carlo radiative transfer scheme with a finite volume fluid dynamical method, line-driven mass outflows may be modelled self-consistently, benefiting from the advantages of Monte Carlo techniques in treating multiline effects, such as multiple scatterings, and in dealing with arbitrary multidimensional configurations. In this work, we introduce our approach in detail by highlighting the key numerical techniques and verifying their operation in a number of simplified applications, specifically in a series of self-consistent, one-dimensional, Sobolev-type, hot-star wind calculations. The utility and accuracy of our approach are demonstrated by comparing the obtained results with the predictions of various formulations of the so-called CAK theory and by confronting the calculations with modern sophisticated techniques of predicting the wind structure. Using these calculations, we also point out some useful diagnostic capabilities our approach provides. Finally, we discuss some of the current limitations of our method, some possible extensions and potential future applications.

A SUPER-EDDINGTON, COMPTON-THICK WIND IN GRO J1655–40?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neilsen, J.; Homan, J.; Rahoui, F.

2016-05-01

During its 2005 outburst, GRO J1655–40 was observed at high spectral resolution with the Chandra High-Energy Transmission Grating Spectrometer, revealing a spectrum rich with blueshifted absorption lines indicative of an accretion disk wind—apparently too hot, too dense, and too close to the black hole to be driven by radiation pressure or thermal pressure (Miller et al.). However, this exotic wind represents just one piece of the puzzle in this outburst, as its presence coincides with an extremely soft and curved X-ray continuum spectrum, remarkable X-ray variability (Uttley and Klein-Wolt), and a bright, unexpected optical/infrared blackbody component that varies on themore » orbital period. Focusing on the X-ray continuum and the optical/infrared/UV spectral energy distribution, we argue that the unusual features of this “hypersoft state” are natural consequences of a super-Eddington Compton-thick wind from the disk: the optical/infrared blackbody represents the cool photosphere of a dense, extended outflow, while the X-ray emission is explained as Compton scattering by the relatively cool, optically thick wind. This wind obscures the intrinsic luminosity of the inner disk, which we suggest may have been at or above the Eddington limit.« less

Can a Double Component Outflow Explain the X-Ray and Optical Lightcurves of Swift Gamma-Ray Bursts?

NASA Technical Reports Server (NTRS)

De Pasquale, Massimiliano; Evans, P.; Oates, S.; Page, M.; Zane, S.; Schady, P.; Breeveld, A.; Holland, S.; Still, M.

2011-01-01

An increasing sample of Gamma-Ray Bursts (GRBs) observed by Swift show evidence of 'chromatic breaks', i.e. breaks that are present in the X-ray but not in the optical. We find that in a significant fraction of these GRB afterglows the X-ray and the optical emission cannot be produced by the same component. We propose that these afterglow lightcurves are the result of a two-component jet, in which both components undergo energy injection for the whole observation and the X-ray break is due to a jet break in the narrow outflow. Bursts with chromatic breaks also explain another surprising finding, the paucity of late achromatic breaks. We propose a model that may explain the behaviour of GRB emission in both X-ray and optical bands. This model can be a radical and noteworthy alternative to the current interpretation for the 'canonical' XRT and UVOT lightcurves, and it bears fundamental implications for GRB physics.

PLASMOID EJECTIONS AND LOOP CONTRACTIONS IN AN ERUPTIVE M7.7 SOLAR FLARE: EVIDENCE OF PARTICLE ACCELERATION AND HEATING IN MAGNETIC RECONNECTION OUTFLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Wei; Chen Qingrong; Petrosian, Vahe

2013-04-20

Where particle acceleration and plasma heating take place in relation to magnetic reconnection is a fundamental question for solar flares. We report analysis of an M7.7 flare on 2012 July 19 observed by SDO/AIA and RHESSI. Bi-directional outflows in forms of plasmoid ejections and contracting cusp-shaped loops originate between an erupting flux rope and underlying flare loops at speeds of typically 200-300 km s{sup -1} up to 1050 km s{sup -1}. These outflows are associated with spatially separated double coronal X-ray sources with centroid separation decreasing with energy. The highest temperature is located near the nonthermal X-ray loop-top source wellmore » below the original heights of contracting cusps near the inferred reconnection site. These observations suggest that the primary loci of particle acceleration and plasma heating are in the reconnection outflow regions, rather than the reconnection site itself. In addition, there is an initial ascent of the X-ray and EUV loop-top source prior to its recently recognized descent, which we ascribe to the interplay among multiple processes including the upward development of reconnection and the downward contractions of reconnected loops. The impulsive phase onset is delayed by 10 minutes from the start of the descent, but coincides with the rapid speed increases of the upward plasmoids, the individual loop shrinkages, and the overall loop-top descent, suggestive of an intimate relation of the energy release rate and reconnection outflow speed.« less

The Supermassive Black Hole—Galaxy Connection

NASA Astrophysics Data System (ADS)

King, Andrew

2014-09-01

The observed scaling relations imply that supermassive black holes (SMBH) and their host galaxies evolve together. Near-Eddington winds from the SMBH accretion discs explain many aspects of this connection. The wind Eddington factor should be in the range ˜1-30. A factor give black hole winds with velocities v˜0.1 c, observable in X-rays, just as seen in the most extreme ultrafast outflows (UFOs). Higher Eddington factors predict slower and less ionized winds, observable in the UV, as in BAL QSOs. In all cases the wind must shock against the host interstellar gas and it is plausible that these shocks should cool efficiently. There is detailed observational evidence for this in some UFOs. The wind sweeps up the interstellar gas into a thin shell and propels it outwards. For SMBH masses below a certain critical ( M- σ) value, all these outflows eventually stall and fall back, as the Eddington thrust of the wind is too weak to drive the gas to large radii. But once the SMBH mass reaches the critical M- σ value the global character of the outflow changes completely. The wind shock is no longer efficiently cooled, and the resulting thermal expansion drives the interstellar gas far from the black hole, which is unlikely to grow significantly further. Simple estimates of the maximum stellar bulge mass M b allowed by self-limited star formation show that the SMBH mass is typically about 10-3 M b at this point, in line with observation. The expansion-driven outflow reaches speeds v out≃1200 km s-1 and drives rates in cool (molecular) gas, giving a typical outflow mechanical energy L mech≃0.05 L Edd, where L Edd is the Eddington luminosity of the central SMBH. This is again in line with observation. These massive outflows may be what makes galaxies become red and dead, and can have several other potentially observable effects. In particular they have the right properties to enrich the intergalactic gas with metals. Our current picture of SMBH-galaxy coevolution is still incomplete, as there is no predictive theory of how the hole accretes gas from its surroundings. Recent progress in understanding how large-scale discs of gas can partially cancel angular momentum and promote dynamical infall offers a possible way forward.

FE K EMISSION AND ABSORPTION FEATURES IN THE XMM-EPIC SPECTRUM OF THE SEYFERT GALAXY IC 4329A

NASA Technical Reports Server (NTRS)

Markowitz, A.; Reeves, J. N.; Braito, V.

2001-01-01

We present a re-analysis of the XMM-Newton long-look of the X-ray bright Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two peaks, consistent with emission from neutral or near-neutral Fe Ka and KP. A relativistic diskline model whereby both peaks are the result of one doubly-peaked diskline profile is found to be a poor description of the data. Models using two relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Upper limits on Fe XXV and Fe XXVI emission and absorption at the systemic velocity of IC 4329a are obtained. We also present the results of RXTE monitoring of this source obtained so far; the combined XMM-Newton and RXTE data sets allow us to explore the time-resolved spectral behavior of this source on time scales ranging from hours to 2 years. We find no strong evidence for variability of the Fe Ka emission line on any time scale probed, likely due to the minimal level of continuum variability. We detect a narrow absorption line, at a energy of 7.68 keV in the rest frame of the source; its significance has been confirmed using Monte Carlo simulations. This feature is most likely due to absorption from Fe XXVI blueshifted to approximately 0.1c relative to the systemic velocity, making IC 4329a the lowest-redshift AGN known with a high-velocity, highly-ionized outflow component. As is often the case with similar outflows seen in high-luminosity quasars, the estimated mass outflow rate is larger than the inflow accretion rate, signaling that the outflow represents a substantial portion of the total energy budget of the AGN. The outflow could arise from a radiatively-driven disk wind, or it may be in the form of a discrete, transient blob of ejected material.

A large-scale dynamo and magnetoturbulence in rapidly rotating core-collapse supernovae.

PubMed

Mösta, Philipp; Ott, Christian D; Radice, David; Roberts, Luke F; Schnetter, Erik; Haas, Roland

2015-12-17

Magnetohydrodynamic turbulence is important in many high-energy astrophysical systems, where instabilities can amplify the local magnetic field over very short timescales. Specifically, the magnetorotational instability and dynamo action have been suggested as a mechanism for the growth of magnetar-strength magnetic fields (of 10(15) gauss and above) and for powering the explosion of a rotating massive star. Such stars are candidate progenitors of type Ic-bl hypernovae, which make up all supernovae that are connected to long γ-ray bursts. The magnetorotational instability has been studied with local high-resolution shearing-box simulations in three dimensions, and with global two-dimensional simulations, but it is not known whether turbulence driven by this instability can result in the creation of a large-scale, ordered and dynamically relevant field. Here we report results from global, three-dimensional, general-relativistic magnetohydrodynamic turbulence simulations. We show that hydromagnetic turbulence in rapidly rotating protoneutron stars produces an inverse cascade of energy. We find a large-scale, ordered toroidal field that is consistent with the formation of bipolar magnetorotationally driven outflows. Our results demonstrate that rapidly rotating massive stars are plausible progenitors for both type Ic-bl supernovae and long γ-ray bursts, and provide a viable mechanism for the formation of magnetars. Moreover, our findings suggest that rapidly rotating massive stars might lie behind potentially magnetar-powered superluminous supernovae.

Toward a Prescription for Feedback from Quasar Outflows

NASA Astrophysics Data System (ADS)

Ganguly, Rajib; Bourjaily, M.; Munsell, J.; Brotherton, M. S.; Bhattacharjee, A.; Runnoe, J.; Charlton, J. C.; Eracleous, M.

2011-01-01

Models have shown that quasars are a crucial ingredient in the evolution of massive galaxies. Outflows play a key role in the story of quasars and their host galaxies, by helping regulate the accretion process, the star-formation rate and mass of the host galaxy (i.e., feedback). The prescription for modeling outflows as a contributor to feedback requires knowledge of the outflow velocity, distance, geometry, and column density. In particular, we need to understand how these depend on physical parameters and how much is determined stochastically (and with what distribution). For this purpose, we are examining a sample of 14000 z=1.7-2.0 quasars from the Sloan Digital Sky Survey. This redshift range permits the following from the SDSS spectra: (1) separation of objects that do and do not exhibit outflows; (2) classification/measurement of outflow properties (ionization, velocity, velocity width); and (3) estimates of the quasar black hole mass. To this, we are adding photometry from GALEX, 2MASS, and ROSAT in an effort to characterize more fully the quasar SEDs. ROSAT photometry provides estimates of the level of soft X-ray absorption, which helps regulate the velocity of outflows. GALEX photometry samples the extreme ultraviolet range where several high ionization species, that may be present in the outflows, absorb light. 2MASS photometry samples the rest-frame optical, where the effects of absorption and dust reddening are minimal, yield better estimates of the bolometric luminosity (hence, Eddington ratio). In this poster, we will present preliminary measurements of the amount of absorption in the soft X-ray and extreme ultraviolet bands as a function of both outflow properties and quasar physical properties. This material is based upon work supported by the National Aeronautics and Space Administration under Grant No. 09-ADP09-0016 issued through the Astrophysics Data Analysis Program.

Understanding the Unusual X-Ray Emission Properties of the Massive, Close Binary WR 20a: A High Energy Window into the Stellar Wind Initiation Region

NASA Astrophysics Data System (ADS)

Montes, Gabriela; Ramirez-Ruiz, Enrico; De Colle, Fabio; Strickler, Rachel

2013-11-01

The problem of explaining the X-ray emission properties of the massive, close binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR 20a is composed of two nearly identical Wolf-Rayet stars of 82 and 83 solar masses orbiting with a period of only 3.7 days. Although Chandra observations were taken during the secondary optical eclipse, the X-ray light curve shows no signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous and softer during the optical eclipse, opposite to what has been observed in other binary systems. To aid in our interpretation of the data, we compare with the results of hydrodynamical simulations using the adaptive mesh refinement code Mezcal which includes radiative cooling and a radiative acceleration force term. It is shown that the X-ray emission can be successfully explained in models where the wind-wind collision interface in this system occurs while the outflowing material is still being accelerated. Consequently, WR 20a serves as a critical test-case for how radiatively driven stellar winds are initiated and how they interact. Our models not only procure a robust description of current Chandra data, which cover the orbital phases between 0.3 and 0.6, but also provide detailed predictions over the entire orbit.

X-ray evidence for ultra-fast outflows in Seyfert galaxies

NASA Astrophysics Data System (ADS)

Tombesi, Francesco; Braito, Valentina; Reeves, James; Cappi, Massimo; Dadina, Mauro

2012-07-01

X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts observed with XMM-Newton. Similar results are also obtained from a Suzaku analysis of 5 radio galaxies. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1}. The associated mechanical power is also high, in the range ˜10^{43}--10^{45} erg/s, which indicates that UFOs are capable to provide a significant contribution to the AGN cosmological feedback.

AGN feedback in action? - outflows and star formation in type 2 AGNs

NASA Astrophysics Data System (ADS)

Woo, Jong-Hak

2017-01-01

We present the statistical constraints on the ionized gas outflows and their connection to star formation, using a large sample of ~110,000 AGNs and star-forming galaxies at z < 0.3. First, we find a dramatic difference of the outflow signatures between AGNs and star-forming galaxies based on the [OIII] emission line kinematics. While the [OIII] velocity and velocity dispersion of star forming galaxies can be entirely accounted by the gravitational potential of host galaxies, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. Second, the distribution in the [OIII] velocity - velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the outflows are AGN-driven. Third, the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [OIII] profile. Interestingly, we find that the specific star formation of non-outflow AGNs is much lower than that of strong outflow AGNs, while the star formation rate of strong outflow AGNs is comparable to that of star forming galaxies. We interpret this trend as a delayed AGN feedback as it takes dynamical time for the outflows to suppress star formation in galactic scales.

Massive Outflows Associated with ATLASGAL Clumps

NASA Astrophysics Data System (ADS)

Yang, A. Y.; Thompson, M. A.; Urquhart, J. S.; Tian, W. W.

2018-03-01

We have undertaken the largest survey for outflows within the Galactic plane using simultaneously observed {}13{CO} and {{{C}}}18{{O}} data. Out of a total of 919 ATLASGAL clumps, 325 have data suitable to identify outflows, and 225 (69% ± 3%) show high-velocity outflows. The clumps with detected outflows show significantly higher clump masses ({M}clump}), bolometric luminosities ({L}bol}), luminosity-to-mass ratios ({L}bol}/{M}clump}), and peak H2 column densities ({N}{{{H}}2}) compared to those without outflows. Outflow activity has been detected within the youngest quiescent clump (i.e., 70 μ {{m}} weak) in this sample, and we find that the outflow detection rate increases with {M}clump}, {L}bol}, {L}bol}/{M}clump}, and {N}{{{H}}2}, approaching 90% in some cases (UC H II regions = 93% ± 3%; masers = 86% ± 4%; HC H II regions = 100%). This high detection rate suggests that outflows are ubiquitous phenomena of massive star formation (MSF). The mean outflow mass entrainment rate implies a mean accretion rate of ∼ {10}-4 {M}ȯ {yr}}-1, in full agreement with the accretion rate predicted by theoretical models of MSF. Outflow properties are tightly correlated with {M}clump}, {L}bol}, and {L}bol}/{M}clump} and show the strongest relation with the bolometric clump luminosity. This suggests that outflows might be driven by the most massive and luminous source within the clump. The correlations are similar for both low-mass and high-mass outflows over 7 orders of magnitude, indicating that they may share a similar outflow mechanism. Outflow energy is comparable to the turbulent energy within the clump; however, we find no evidence that outflows increase the level of clump turbulence as the clumps evolve. This implies that the origin of turbulence within clumps is fixed before the onset of star formation.

The very faint X-ray binary IGR J17062-6143: a truncated disc, no pulsations, and a possible outflow

NASA Astrophysics Data System (ADS)

van den Eijnden, J.; Degenaar, N.; Pinto, C.; Patruno, A.; Wette, K.; Messenger, C.; Hernández Santisteban, J. V.; Wijnands, R.; Miller, J. M.; Altamirano, D.; Paerels, F.; Chakrabarty, D.; Fabian, A. C.

2018-04-01

We present a comprehensive X-ray study of the neutron star low-mass X-ray binary IGR J17062-6143, which has been accreting at low luminosities since its discovery in 2006. Analysing NuSTAR, XMM-Newton, and Swift observations, we investigate the very faint nature of this source through three approaches: modelling the relativistic reflection spectrum to constrain the accretion geometry, performing high-resolution X-ray spectroscopy to search for an outflow, and searching for the recently reported millisecond X-ray pulsations. We find a strongly truncated accretion disc at 77^{+22}_{-18} gravitational radii (˜164 km) assuming a high inclination, although a low inclination and a disc extending to the neutron star cannot be excluded. The high-resolution spectroscopy reveals evidence for oxygen-rich circumbinary material, possibly resulting from a blueshifted, collisionally ionized outflow. Finally, we do not detect any pulsations. We discuss these results in the broader context of possible explanations for the persistent faint nature of weakly accreting neutron stars. The results are consistent with both an ultra-compact binary orbit and a magnetically truncated accretion flow, although both cannot be unambiguously inferred. We also discuss the nature of the donor star and conclude that it is likely a CO or O-Ne-Mg white dwarf, consistent with recent multiwavelength modelling.

Condensation onto grains in the outflows from mass-losing red giants

NASA Technical Reports Server (NTRS)

Jura, M.; Morris, M.

1985-01-01

In the outflows from red giants, grains are formed which are driven by radiation pressure. For the development of a model of the outflows, a detailed understanding of the interaction between the gas and dust is critical. The present investigation is concerned with condensation processes which occur after the grains nucleate near the stars. A physical process considered results from the cooling of the grains as they flow away from the star. Molecules which initially do not condense onto the grains can do so far from the star. It is shown that for some species this effect can be quite important in determining their gas-phase abundances in the outer circumstellar envelope. One of the major motivations of this investigation was provided by the desire to understand the physical conditions and molecular abundances in the outflows from the considered stars.

The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating Spectroscopy

NASA Astrophysics Data System (ADS)

Danehkar, Ashkbiz; Nowak, Michael A.; Lee, Julia C.; Kriss, Gerard A.; Young, Andrew J.; Hardcastle, Martin J.; Chakravorty, Susmita; Fang, Taotao; Neilsen, Joseph; Rahoui, Farid; Smith, Randall K.

2018-02-01

We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed a multi-wavelength ionizing spectral energy distribution using these observations and archival infrared data to create XSTAR photoionization models specific to the PG 1211+143 flux behavior during the epoch of our observations. Our analysis of the Chandra-HETGS spectra yields complex absorption lines from H-like and He-like ions of Ne, Mg, and Si, which confirm the presence of an ultra-fast outflow (UFO) with a velocity of approximately ‑17,300 km s‑1 (outflow redshift z out ∼ ‑0.0561) in the rest frame of PG 1211+143. This absorber is well described by an ionization parameter {log}ξ ∼ 2.9 {erg} {{{s}}}-1 {cm} and column density {log}{N}{{H}}∼ 21.5 {{cm}}-2. This corresponds to a stable region of the absorber’s thermal stability curve, and furthermore its implied neutral hydrogen column is broadly consistent with a broad Lyα absorption line at a mean outflow velocity of approximately ‑16,980 km s‑1 detected by our HST-COS observations. Our findings represent the first simultaneous detection of a UFO in both X-ray and UV observations. Our VLA observations provide evidence for an active jet in PG 1211+143, which may be connected to the X-ray and UV outflows; this possibility can be evaluated using very-long-baseline interferometric observations.

Comparison of ejection events in the jet and accretion disc outflows in 3C 111

NASA Astrophysics Data System (ADS)

Tombesi, F.; Sambruna, R. M.; Marscher, A. P.; Jorstad, S. G.; Reynolds, C. S.; Markowitz, A.

2012-07-01

We present a comparison of the parameters of accretion disc outflows and the jet of the broad-line radio galaxy 3C 111 on subparsec (sub-pc) scales. We make use of published X-ray observations of ultra-fast outflows (UFOs) and new 43-GHz Very Long Baseline Array images to track the jet knot ejection. We find that the superluminal jet coexists with the mildly relativistic outflows on sub-pc scales, possibly indicating a transverse stratification of a global flow. The two are roughly in pressure equilibrium, with the UFOs potentially providing additional support for the initial jet collimation. The UFOs are much more massive than the jet, but their kinetic power is probably about an order of magnitude lower, at least for the observations considered here. However, their momentum flux is equivalent and both of them are powerful enough to exert a concurrent feedback impact on the surrounding environment. A link between these components is naturally predicted in the context of magnetohydrodynamic models for jet/outflow formation. However, given the high radiation throughput of active galactic nuclei, radiation pressure should also be taken into account. From the comparison with the long-term 2-10 keV Rossi X-ray Timing Explorer light curve, we find that the UFOs are preferentially detected during periods of increasing flux. We also find the possibility to place the UFOs within the known X-ray dips-jet ejection cycles, which has been shown to be a strong proof of the disc-jet connection, in analogue with stellar mass black holes. However, given the limited number of observations presently available, these relations are only tentative and additional spectral monitoring is needed to test them conclusively.

Chandra Survey of Nearby Galaxies: Testing the Accretion Model for Low-luminosity AGNs

NASA Astrophysics Data System (ADS)

She, Rui; Ho, Luis C.; Feng, Hua; Cui, Can

2018-06-01

From a Chandra sample of active galactic nuclei (AGNs) in nearby galaxies, we find that for low-luminosity AGNs, either the intrinsic absorption column density, or the fraction of absorbed AGNs, positively scales with the Eddington ratio for L bol/L Edd ≲ 10‑2. Such a behavior, along with the softness of the X-ray spectrum at low luminosities, is in good agreement with the picture that they are powered by hot accretion flows surrounding supermassive black holes. Numerical simulations find that outflows are inevitable with hot accretion flows, and the outflow rate is correlated with the innermost accretion rate in the low-luminosity regime. This agrees well with our results, suggesting that the X-ray absorption originates from, or is associated with, the outflow material. Gas and dust on larger scales may also produce the observed correlation. Future correlation analyses may help differentiate the two scenarios.

A Search for Early High-Energy Afterglows in BATSE Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Giblin, Timothy W.

2003-01-01

The scope of this project was to perform a detailed search for the early high-energy afterglow component of gamma-ray bursts (GRBs) in the BATSE GRB data archive. GRBs are believed to be the product of shock waves generated in a relativistic outflow from the demise of extremely massive stars and/or binary neutron star mergers. The outflow undeniably encounters the ambient medium of the progenitor object and another shock wave is set up. A forward shock propagates into the medium and a reverse shock propagates through the ejecta. This "external" shock dissipates the kinetic energy of the ejecta in the form of radiation via synchrotron losses and slows the outflow eventually to a non-relativistic state. Radiation from the forward external shock is therefore expected to be long-lived, lasting days, weeks, and even months. This radiation is referred to as the 'afterglow'.

A mildly relativistic wide-angle outflow in the neutron-star merger event GW170817

NASA Astrophysics Data System (ADS)

Mooley, K. P.; Nakar, E.; Hotokezaka, K.; Hallinan, G.; Corsi, A.; Frail, D. A.; Horesh, A.; Murphy, T.; Lenc, E.; Kaplan, D. L.; de, K.; Dobie, D.; Chandra, P.; Deller, A.; Gottlieb, O.; Kasliwal, M. M.; Kulkarni, S. R.; Myers, S. T.; Nissanke, S.; Piran, T.; Lynch, C.; Bhalerao, V.; Bourke, S.; Bannister, K. W.; Singer, L. P.

2018-02-01

GW170817 was the first gravitational-wave detection of a binary neutron-star merger. It was accompanied by radiation across the electromagnetic spectrum and localized to the galaxy NGC 4993 at a distance of 40 megaparsecs. It has been proposed that the observed γ-ray, X-ray and radio emission is due to an ultra-relativistic jet being launched during the merger (and successfully breaking out of the surrounding material), directed away from our line of sight (off-axis). The presence of such a jet is predicted from models that posit neutron-star mergers as the drivers of short hard-γ-ray bursts. Here we report that the radio light curve of GW170817 has no direct signature of the afterglow of an off-axis jet. Although we cannot completely rule out the existence of a jet directed away from the line of sight, the observed γ-ray emission could not have originated from such a jet. Instead, the radio data require the existence of a mildly relativistic wide-angle outflow moving towards us. This outflow could be the high-velocity tail of the neutron-rich material that was ejected dynamically during the merger, or a cocoon of material that breaks out when a jet launched during the merger transfers its energy to the dynamical ejecta. Because the cocoon model explains the radio light curve of GW170817, as well as the γ-ray and X-ray emission (and possibly also the ultraviolet and optical emission), it is the model that is most consistent with the observational data. Cocoons may be a ubiquitous phenomenon produced in neutron-star mergers, giving rise to a hitherto unidentified population of radio, ultraviolet, X-ray and γ-ray transients in the local Universe.

A mildly relativistic wide-angle outflow in the neutron-star merger event GW170817.

PubMed

Mooley, K P; Nakar, E; Hotokezaka, K; Hallinan, G; Corsi, A; Frail, D A; Horesh, A; Murphy, T; Lenc, E; Kaplan, D L; De, K; Dobie, D; Chandra, P; Deller, A; Gottlieb, O; Kasliwal, M M; Kulkarni, S R; Myers, S T; Nissanke, S; Piran, T; Lynch, C; Bhalerao, V; Bourke, S; Bannister, K W; Singer, L P

2018-02-08

GW170817 was the first gravitational-wave detection of a binary neutron-star merger. It was accompanied by radiation across the electromagnetic spectrum and localized to the galaxy NGC 4993 at a distance of 40 megaparsecs. It has been proposed that the observed γ-ray, X-ray and radio emission is due to an ultra-relativistic jet being launched during the merger (and successfully breaking out of the surrounding material), directed away from our line of sight (off-axis). The presence of such a jet is predicted from models that posit neutron-star mergers as the drivers of short hard-γ-ray bursts. Here we report that the radio light curve of GW170817 has no direct signature of the afterglow of an off-axis jet. Although we cannot completely rule out the existence of a jet directed away from the line of sight, the observed γ-ray emission could not have originated from such a jet. Instead, the radio data require the existence of a mildly relativistic wide-angle outflow moving towards us. This outflow could be the high-velocity tail of the neutron-rich material that was ejected dynamically during the merger, or a cocoon of material that breaks out when a jet launched during the merger transfers its energy to the dynamical ejecta. Because the cocoon model explains the radio light curve of GW170817, as well as the γ-ray and X-ray emission (and possibly also the ultraviolet and optical emission), it is the model that is most consistent with the observational data. Cocoons may be a ubiquitous phenomenon produced in neutron-star mergers, giving rise to a hitherto unidentified population of radio, ultraviolet, X-ray and γ-ray transients in the local Universe.

Non-thermal Gamma-Ray Emission from Delayed Pair Breakdown in a Magnetized and Photon-rich Outflow

NASA Astrophysics Data System (ADS)

Gill, Ramandeep; Thompson, Christopher

2014-12-01

We consider delayed, volumetric heating in a magnetized outflow that has broken out of a confining medium and expanded to a high Lorentz factor (Γ ~ 102-103) and low optical depth to scattering (τ T ~ 10-3-10-2). The energy flux at breakout is dominated by the magnetic field, with a modest contribution from quasi-thermal gamma rays whose spectrum was calculated in Paper I. We focus on the case of extreme baryon depletion in the magnetized material, but allow for a separate baryonic component that is entrained from a confining medium. Dissipation is driven by relativistic motion between these two components, which develops once the photon compactness drops below 4 × 103(Ye /0.5)-1. We first calculate the acceleration of the magnetized component following breakout, showing that embedded MHD turbulence provides significant inertia, the neglect of which leads to unrealistically high estimates of flow Lorentz factor. After reheating begins, the pair and photon distributions are evolved self-consistently using a one-zone kinetic code that incorporates an exact treatment of Compton scattering, pair production and annihilation, and Coulomb scattering. Heating leads to a surge in pair creation, and the scattering depth saturates at τ T ~ 1-4. The plasma maintains a very low ratio of particle to magnetic pressure, and can support strong anisotropy in the charged particle distribution, with cooling dominated by Compton scattering. High-energy power-law spectra with photon indices in the range observed in gamma-ray bursts (GRBs; -3 < β < -3/2) are obtained by varying the ratio of heat input to the seed energy in quasi-thermal photons. We contrast our results with those for continuous heating across an expanding photosphere, and show that the latter model produces soft-to-hard evolution that is inconsistent with observations of GRBs.

Time-dependent Models for Blazar Emission with the Second-order Fermi Acceleration

NASA Astrophysics Data System (ADS)

Asano, Katsuaki; Takahara, Fumio; Kusunose, Masaaki; Toma, Kenji; Kakuwa, Jun

2014-01-01

The second-order Fermi acceleration (Fermi-II) driven by turbulence may be responsible for the electron acceleration in blazar jets. We test this model with time-dependent simulations. The hard electron spectrum predicted by the Fermi-II process agrees with the hard photon spectrum of 1ES 1101-232. For other blazars that show softer spectra, the Fermi-II model requires radial evolution of the electron injection rate and/or diffusion coefficient in the outflow. Such evolutions can yield a curved electron spectrum, which can reproduce the synchrotron spectrum of Mrk 421 from the radio to the X-ray regime. The photon spectrum in the GeV energy range of Mrk 421 is hard to fit with a synchrotron self-Compton model. However, if we introduce an external radio photon field with a luminosity of 4.9 × 1038 erg s-1, GeV photons are successfully produced via inverse Compton scattering. The temporal variability of the diffusion coefficient or injection rate causes flare emission. The observed synchronicity of X-ray and TeV flares implies a decrease of the magnetic field in the flaring source region.

A new candidate for a powerful wind detected in a bright IR-galaxy

NASA Astrophysics Data System (ADS)

Braito, V.; Reeves, J.; Severgnini, P.; Della Ceca, R.; Matzeu, G.; Ballo, L.; Nardini, E.

2017-10-01

We report the discovery of a new candidate for a powerful disk wind, in a nearby and bright starburst-AGN system: MCG-03-58-007. The winds strongly resembles the case of PDS456. MCG-03-58-007 is a relatively X-ray bright Seyfert 2 galaxy for which a deep Suzaku observation unveiled a highly curved spectrum due to a high column density absorber and an extremely steep intrinsic photon index (Gamma = 3). A detailed analysis showed that the steep spectrum is mainly driven by the presence of a deep absorption trough at 7.5-9 keV. This could be accounted for by the presence of a high ionisation, fast (v up to 0.2c) outflowing wind launched from within a few 100Rg from the black hole, whose kinetic output matches the prescription for significant feedback. New deep simultaneous XMM-Newton and NuSTAR observations provided the first direct measurement of the AGN luminosity and more importantly confirms the presence of a powerful X-ray wind. The new observations show rapid spectral variability, whose main driver appears to be the wind itself.

Galaxy evolution. Black hole feedback in the luminous quasar PDS 456.

PubMed

Nardini, E; Reeves, J N; Gofford, J; Harrison, F A; Risaliti, G; Braito, V; Costa, M T; Matzeu, G A; Walton, D J; Behar, E; Boggs, S E; Christensen, F E; Craig, W W; Hailey, C J; Matt, G; Miller, J M; O'Brien, P T; Stern, D; Turner, T J; Ward, M J

2015-02-20

The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband x-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10(46) ergs per second is enough to provide the feedback required by models of black hole and host galaxy coevolution. Copyright © 2015, American Association for the Advancement of Science.

Gas Flows in Dual Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Mueller Sanchez, Francisco; Comerford, Julia M.; Davies, Richard; Treister, Ezequiel; Privon, George C.; Nevin, Becky

2018-06-01

Dual Active Galactic Nuclei (AGN) are the Rosetta stone to understand the role of galaxy mergers in triggering nuclear activity and regulating black hole (BH) and galaxy growth. But very little is known about the physical processes required to effectively trigger AGN activity and regulate the growth of the two BHs. The work I will present here characterizes for the first time the properties of the stars, gas (molecular, ionized, and highly-ionized) and dust in all the confirmed dual AGN at z < 0.05, using Keck/OSIRIS, VLT/SINFONI, SOFIA/FORCAST, and HST data. I will focus on the interplay between the several complex processes observed in dual AGN, using as an example the prototypical merger system NGC 6240: vigorous star formation, two AGNs, outflowing winds of ionized gas, rippling dust and gas lanes, and tidal tails. In this galaxy, we observe for the first time a dual outflow of different species of gas: an AGN-driven outflow of highly-ionized gas to the northeast and a starburst-driven outflow of ionized hydrogen to the northwest. This shows that stellar feedback and supermassive black hole feedback can work in tandem to regulate the stellar growth of a galaxy after a merger event. These results open a new door to studies of dual AGN and AGN pairs in general, and enable dual AGN to be used, for the first time, for studies of galaxy evolution.

A frictionally and hydraulically constrained model of the convectively driven mean flow in partially enclosed seas

NASA Astrophysics Data System (ADS)

Maxworthy, T.

1997-08-01

A simple three-layer model of the dynamics of partially enclosed seas, driven by a surface buoyancy flux, is presented. It contains two major elements, a hydraulic constraint at the exit contraction and friction in the interior of the main body of the sea; both together determine the vertical structure and magnitudes of the interior flow variables, i.e. velocity and density. Application of the model to the large-scale dynamics of the Red Sea gives results that are not in disagreement with observation once the model is applied, also, to predict the dense outflow from the Gulf of Suez. The latter appears to be the agent responsible for the formation of dense bottom water in this system. Also, the model is reasonably successful in predicting the density of the outflow from the Persian Gulf, and can be applied to any number of other examples of convectively driven flow in long, narrow channels, with or without sills and constrictions at their exits.

Simulation of California's Major Reservoirs Outflow Using Data Mining Technique

NASA Astrophysics Data System (ADS)

Yang, T.; Gao, X.; Sorooshian, S.

2014-12-01

The reservoir's outflow is controlled by reservoir operators, which is different from the upstream inflow. The outflow is more important than the reservoir's inflow for the downstream water users. In order to simulate the complicated reservoir operation and extract the outflow decision making patterns for California's 12 major reservoirs, we build a data-driven, computer-based ("artificial intelligent") reservoir decision making tool, using decision regression and classification tree approach. This is a well-developed statistical and graphical modeling methodology in the field of data mining. A shuffled cross validation approach is also employed to extract the outflow decision making patterns and rules based on the selected decision variables (inflow amount, precipitation, timing, water type year etc.). To show the accuracy of the model, a verification study is carried out comparing the model-generated outflow decisions ("artificial intelligent" decisions) with that made by reservoir operators (human decisions). The simulation results show that the machine-generated outflow decisions are very similar to the real reservoir operators' decisions. This conclusion is based on statistical evaluations using the Nash-Sutcliffe test. The proposed model is able to detect the most influential variables and their weights when the reservoir operators make an outflow decision. While the proposed approach was firstly applied and tested on California's 12 major reservoirs, the method is universally adaptable to other reservoir systems.

The small observed scale of AGN-driven outflows, and inside-out disc quenching

NASA Astrophysics Data System (ADS)

Zubovas, Kastytis; King, Andrew

2016-11-01

Observations of massive outflows with detectable central active galactic nuclei (AGN) typically find them within radii ≲10 kpc. We show that this apparent size restriction is a natural result of AGN driving if this process injects total energy only of the order of the gas binding energy to the outflow, and the AGN varies over time (`flickers') as suggested in recent work. After the end of all AGN activity, the outflow continues to expand to larger radii, powered by the thermal expansion of the remnant-shocked AGN wind. We suggest that on average, outflows should be detected further from the nucleus in more massive galaxies. In massive gas-rich galaxies, these could be several tens of kpc in radius. We also consider the effect that pressure of such outflows has on a galaxy disc. In moderately gas-rich discs, with gas-to-baryon fraction <0.2, the outflow may induce star formation significant enough to be distinguished from quiescent by an apparently different normalization of the Kennicutt-Schmidt law. The star formation enhancement is probably stronger in the outskirts of galaxy discs, so coasting outflows might be detected by their effects upon the disc even after the driving AGN has shut off. We compare our results to the recent inference of inside-out quenching of star formation in galaxy discs.

Superposed epoch analysis of O+ auroral outflow during sawtooth events and substorms

NASA Astrophysics Data System (ADS)

Nowrouzi, N.; Kistler, L. M.; Lund, E. J.; Cai, X.

2017-12-01

Sawtooth events are repeated injection of energetic particles at geosynchronous orbit. Studies have shown that 94% of sawtooth events occurred during magnetic storm times. The main factor that causes a sawtooth event is still an open question. Simulations have suggested that heavy ions like O+ may play a role in triggering the injections. One of the sources of the O+ in the Earth's magnetosphere is the nightside aurora. O+ ions coming from the nightside auroral region have direct access to the near-earth magnetotail. A model (Brambles et al. 2013) for interplanetary coronal mass ejection driven sawtooth events found that nightside O+ outflow caused the subsequent teeth of the sawtooth event through a feedback mechanism. This work is a superposed epoch analysis to test whether the observed auroral outflow supports this model. Using FAST spacecraft data from 1997-2007, we examine the auroral O+ outflow as a function of time relative to an injection onset. Then we determine whether the profile of outflow flux of O+ during sawtooth events is different from the outflow observed during isolated substorms. The auroral region boundaries are estimated using the method of (Andersson et al. 2004). Subsequently the O+ outflow flux inside these boundaries are calculated and binned as a function of superposed epoch time for substorms and sawtooth "teeth". In this way, we will determine if sawtooth events do in fact have greater O+ outflow, and if that outflow is predominantly from the nightside, as suggested by the model results.

Density diagnostics of ionized outflows in active galacitc nuclei

NASA Astrophysics Data System (ADS)

Mao, J.; Kaastra, J.; Mehdipour, M.; Raassen, T.; Gu, L.

2017-10-01

Ionized outflows in Active Galactic Nuclei are thought to influence their nuclear and local galactic environment. However, the distance of outflows with respect to the central engine is poorly constrained, which limits our understanding of the kinetic power by the outflows. Therefore, the impact of AGN outflows on their host galaxies is uncertain. Given the density of the outflows, their distance can be immediately obtained by the definition of the ionization parameter. Here we carry out a theoretical study of density diagnostics of AGN outflows using absorption lines from metastable levels in Be-like to F-like ions. With the new self-consistent photoionization model (PION) in the SPEX code, we are able to calculate ground and metastable level populations. This enable us to determine under what physical conditions these levels are significantly populated. We then identify characteristic transitions from these metastable levels in the X-ray band. Firm detections of absorption lines from such metastable levels are challenging for current grating instruments. The next generation of spectrometers like X-IFU onboard Athena will certainly identify the presence/absence of these density- sensitive absorption lines, thus tightly constraining the location and the kinetic power of AGN outflows.

Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

PubMed

Rodriguez, J Alexis P; Kargel, Jeffrey S; Baker, Victor R; Gulick, Virginia C; Berman, Daniel C; Fairén, Alberto G; Linares, Rogelio; Zarroca, Mario; Yan, Jianguo; Miyamoto, Hideaki; Glines, Natalie

2015-09-08

Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System's most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet's upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected]. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

PubMed Central

Rodriguez, J. Alexis P.; Kargel, Jeffrey S.; Baker, Victor R.; Gulick, Virginia C.; Berman, Daniel C.; Fairén, Alberto G.; Linares, Rogelio; Zarroca, Mario; Yan, Jianguo; Miyamoto, Hideaki; Glines, Natalie

2015-01-01

Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System’s most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet’s upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform Boundary. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which was then completely submerged under a primordial northern plains ocean. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation. PMID:26346067

X-ray Properties of the Central kpc of AGN and Starbursts: The Latest News from Chandra

NASA Technical Reports Server (NTRS)

Weaver, Kimberly A.; White, Nicholas E. (Technical Monitor)

2001-01-01

The X-ray properties of 15 nearby (v less than 3,000 km/s) galaxies that possess AGN (active galactic nuclei) and/or starbursts are discussed. Two-thirds have nuclear extended emission on scales from approx. 0.5 to approx. 1.5 kpc that is either clearly associated with a nuclear outflow or morphologically resembles an outflow. Galaxies that are AGN-dominated tend to have linear structures while starburst-dominated galaxies tend to have plume-like structures. Significant X-ray absorption is present in the starburst regions, indicating that a circumnuclear starburst is sufficient to block an AGN at optical wavelengths. Galaxies with starburst activity possess more X-ray point sources within their central kpc than non-starbursts. Many of these sources are more luminous than typical X-ray binaries. The Chandra results are discussed in terms of the starburst-AGN connection, a revised unified model for AGN, and possible evolutionary scenarios.

Stratified Magnetically Driven Accretion-Disk Winds and Their Relations To Jets

NASA Technical Reports Server (NTRS)

Fukumura, Keigo; Tombesi, Francesco; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Contopoulos, Ioannis

2013-01-01

We explore the poloidal structure of two-dimensional magnetohydrodynamic (MHD) winds in relation to their potential association with the X-ray warm absorbers (WAs) and the highly ionized ultra-fast outflows (UFOs) in active galactic nuclei (AGNs), in a single unifying approach. We present the density n(r, theta), ionization parameter xi(r, theta), and velocity structure v(r, theta) of such ionized winds for typical values of their fluid-to-magnetic flux ratio, F, and specific angular momentum, H, for which wind solutions become super-Alfvenic. We explore the geometrical shape of winds for different values of these parameters and delineate the values that produce the widest and narrowest opening angles of these winds, quantities necessary in the determination of the statistics of AGN obscuration. We find that winds with smaller H show a poloidal geometry of narrower opening angles with their Alfv´en surface at lower inclination angles and therefore they produce the highest line of sight (LoS) velocities for observers at higher latitudes with the respect to the disk plane. We further note a physical and spatial correlation between the X-ray WAs and UFOs that form along the same LoS to the observer but at different radii, r, and distinct values of n, xi, and v consistent with the latest spectroscopic data of radio-quiet Seyfert galaxies. We also show that, at least in the case of 3C 111, the winds' pressure is sufficient to contain the relativistic plasma responsible for its radio emission. Stratified MHD disk winds could therefore serve as a unique means to understand and unify the diverse AGN outflows.

Stratified Magnetically Driven Accretion-disk Winds and Their Relations to Jets

NASA Astrophysics Data System (ADS)

Fukumura, Keigo; Tombesi, Francesco; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Contopoulos, Ioannis

2014-01-01

We explore the poloidal structure of two-dimensional magnetohydrodynamic (MHD) winds in relation to their potential association with the X-ray warm absorbers (WAs) and the highly ionized ultra-fast outflows (UFOs) in active galactic nuclei (AGNs), in a single unifying approach. We present the density n(r, θ), ionization parameter ξ(r, θ), and velocity structure v(r, θ) of such ionized winds for typical values of their fluid-to-magnetic flux ratio, F, and specific angular momentum, H, for which wind solutions become super-Alfvénic. We explore the geometrical shape of winds for different values of these parameters and delineate the values that produce the widest and narrowest opening angles of these winds, quantities necessary in the determination of the statistics of AGN obscuration. We find that winds with smaller H show a poloidal geometry of narrower opening angles with their Alfvén surface at lower inclination angles and therefore they produce the highest line of sight (LoS) velocities for observers at higher latitudes with the respect to the disk plane. We further note a physical and spatial correlation between the X-ray WAs and UFOs that form along the same LoS to the observer but at different radii, r, and distinct values of n, ξ, and v consistent with the latest spectroscopic data of radio-quiet Seyfert galaxies. We also show that, at least in the case of 3C 111, the winds' pressure is sufficient to contain the relativistic plasma responsible for its radio emission. Stratified MHD disk winds could therefore serve as a unique means to understand and unify the diverse AGN outflows.

Interannual variation, decadal trend, and future change in ozone outflow from East Asia

NASA Astrophysics Data System (ADS)

Zhu, Jia; Liao, Hong; Mao, Yuhao; Yang, Yang; Jiang, Hui

2017-03-01

We examine the past and future changes in the O3 outflow from East Asia using a global 3-D chemical transport model, GEOS-Chem. The simulations of Asian O3 outflow for 1986-2006 are driven by the assimilated GEOS-4 meteorological fields, and those for 2000-2050 are driven by the meteorological fields archived by the NASA Goddard Institute for Space Studies (GISS) general circulation model (GCM) 3 under the IPCC SRES A1B scenario. The evaluation of the model results against measurements shows that the GEOS-Chem model captures the seasonal cycles and interannual variations of tropospheric O3 concentrations fairly well with high correlation coefficients of 0.82-0.93 at four ground-based sites and 0.55-0.88 at two ozonesonde sites where observations are available. The increasing trends in surface-layer O3 concentrations in East Asia over the past 2 decades are captured by the model, although the modeled O3 trends have low biases. Sensitivity studies are conducted to examine the respective impacts of meteorological parameters and emissions on the variations in the outflow flux of O3. When both meteorological parameters and anthropogenic emissions varied from 1986-2006, the simulated Asian O3 outflow fluxes exhibited a statistically insignificant decadal trend; however, they showed large interannual variations (IAVs) with seasonal values of 4-9 % for the absolute percent departure from the mean (APDM) and an annual APDM value of 3.3 %. The sensitivity simulations indicated that the large IAVs in O3 outflow fluxes were mainly caused by variations in the meteorological conditions. The variations in meteorological parameters drove the IAVs in O3 outflow fluxes by altering the O3 concentrations over East Asia and by altering the zonal winds; the latter was identified to be the key factor, since the O3 outflow was highly correlated with zonal winds from 1986-2006. The simulations of the 2000-2050 changes show that the annual outflow flux of O3 will increase by 2.0, 7.9, and 12.2 % owing to climate change alone, emissions change alone, and changes in both climate and emissions, respectively. Therefore, climate change will aggravate the effects of the increases in anthropogenic emissions on future changes in the Asian O3 outflow. Future climate change is predicted to greatly increase the Asian O3 outflow in the spring and summer seasons as a result of the projected increases in zonal winds. The findings from the present study help us to understand the variations in tropospheric O3 in the downwind regions of East Asia on different timescales and have important implications for long-term air quality planning in the regions downwind of China, such as Japan and the US.

A Compton-thick Wind in the High Luminosity Quasar, PDS 456

NASA Technical Reports Server (NTRS)

Reeves, J. N.; O'Brien, P. T.; Behar, E.; Miller, L.; Turner, T. J.; Braito, V.; Fabian, A. C.; Kaspi, S.; Mushotzky, R.; Ward, M.

2009-01-01

PDS 456 is a nearby (z=0.184), luminous (L(sub bol) approximately equal to 10(exp 47) ergs(exp -1) type I quasar. A deep 190 ks Suzaku observation in February 2007 revealed the complex, broad band X-ray spectrum of PDS 456. The Suzaku spectrum exhibits highly statistically significant absorption features near 9 keV in the quasar rest-frame. We show that the most plausible origin of the absorption is from blue-shifted resonance (1s-2p) transitions of hydrogen-like iron (at 6.97 keV in the rest frame). This indicates that a highly ionized outflow may be present moving at near relativistic velocities (0.26-0.31c). A possible hard X-ray excess is detected above 15 keV with HXD (at 99.8% confidence), which may arise from high column density gas (N(sub H) greater than 10(exp 24)cm(exp -2) partially covering the X-ray emission, or through strong Compton reflection. Here we propose that the iron K-shell absorption in PDS 456 is associated with a thick, possibly clumpy outflow, covering about 20% of 4(pi) steradian solid angle. The outflow is likely launched from the inner accretion disk, within 15-100 gravitational radii of the black hole. The kinetic power of the outflow may be similar to the bolometric luminosity of PDS 456. Such a powerful wind could have a significant effect on the co-evolution of the host galaxy and its supermassive black hole, through feedback.

DISCOVERY OF RELATIVISTIC OUTFLOW IN THE SEYFERT GALAXY Ark 564

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, A.; Mathur, S.; Krongold, Y.

2013-07-20

We present Chandra High Energy Transmission Grating Spectra of the narrow-line Seyfert-1 galaxy Ark 564. The spectrum shows numerous absorption lines which are well modeled with low-velocity outflow components usually observed in Seyfert galaxies. There are, however, some residual absorption lines which are not accounted for by low-velocity outflows. Here, we present identifications of the strongest lines as K{alpha} transitions of O VII (two lines) and O VI at outflow velocities of {approx}0.1c. These lines are detected at 6.9{sigma}, 6.2{sigma}, and 4.7{sigma}, respectively, and cannot be due to chance statistical fluctuations. Photoionization models with ultra-high velocity components improve the spectralmore » fit significantly, providing further support for the presence of relativistic outflow in this source. Without knowing the location of the absorber, its mass and energy outflow rates cannot be well constrained; we find E-dot (outflow)/L{sub bol} lower limit of {>=}0.006% assuming a bi-conical wind geometry. This is the first time that absorption lines with ultra-high velocities are unambiguously detected in the soft X-ray band. The presence of outflows with relativistic velocities in active galactic nuclei (AGNs) with Seyfert-type luminosities is hard to understand and provides valuable constraints to models of AGN outflows. Radiation pressure is unlikely to be the driving mechanism for such outflows and magnetohydrodynamic may be involved.« less

The Suzaku View of Highly Ionized Outflows in AGN. 1; Statistical Detection and Global Absorber Properties

NASA Technical Reports Server (NTRS)

Gofford, Jason; Reeves, James N.; Tombesi, Francesco; Braito, Valentina; Turner, T. Jane; Miller, Lance; Cappi, Massimo

2013-01-01

We present the results of a new spectroscopic study of Fe K-band absorption in active galactic nuclei (AGN). Using data obtained from the Suzaku public archive we have performed a statistically driven blind search for Fe XXV Healpha and/or Fe XXVI Lyalpha absorption lines in a large sample of 51 Type 1.0-1.9 AGN. Through extensive Monte Carlo simulations we find that statistically significant absorption is detected at E greater than or approximately equal to 6.7 keV in 20/51 sources at the P(sub MC) greater than or equal tov 95 per cent level, which corresponds to approximately 40 per cent of the total sample. In all cases, individual absorption lines are detected independently and simultaneously amongst the two (or three) available X-ray imaging spectrometer detectors, which confirms the robustness of the line detections. The most frequently observed outflow phenomenology consists of two discrete absorption troughs corresponding to Fe XXV Healpha and Fe XXVI Lyalpha at a common velocity shift. From xstar fitting the mean column density and ionization parameter for the Fe K absorption components are log (N(sub H) per square centimeter)) is approximately equal to 23 and log (Xi/erg centimeter per second) is approximately equal to 4.5, respectively. Measured outflow velocities span a continuous range from less than1500 kilometers per second up to approximately100 000 kilometers per second, with mean and median values of approximately 0.1 c and approximately 0.056 c, respectively. The results of this work are consistent with those recently obtained using XMM-Newton and independently provides strong evidence for the existence of very highly ionized circumnuclear material in a significant fraction of both radio-quiet and radio-loud AGN in the local universe.

XMM-Newton Observations of NGC 253: Resolving the Emission Components in the Disk and Nuclear Area

NASA Technical Reports Server (NTRS)

Pietsch, W.; Borozdin, K. N.; Branduardi-Raymont, G.; Cappi, M.; Ehle, M.; Ferrando, P.; Freyberg, M. J.; Kahn, S. M.; Ponman, T. J.; Ptak, A.

2000-01-01

We describe the first XMM-Newton observations of the starburst galaxy NGC 253. As known from previous X-ray observations, NGC 253 shows a mixture of extended (disk and halo) and point-source emission. The high XMM-Newton throughput allows for the first time a detailed investigation of the spatial, spectral and variability properties of these components simultaneously. We detect a bright X-ray transient approx. 70 sec SSW of the nucleus and show the spectrum and light curve of the brightest point source (approx. 30 sec S of the nucleus, most likely a black-hole X-ray binary, BHXRB). The unprecedented combination of RGS and EPIC also sheds new light on the emission of the complex nuclear region, the X-ray plume and the disk diffuse emission. In particular, EPIC images reveal that the limb-brightening of the plume is mostly seen in higher ionization emission lines, while in the lower ionization lines, and below 0.5 keV, the plume is more homo- geneously structured, pointing to new interpretations as to the make up of the starburst-driven outflow. Assuming that type IIa supernova remnants (SNRs) are mostly responsible for the E greater than 4 keV emission, the detection with EPIC of the 6.7 keV line allows us to estimate a supernova rate within the nuclear starburst of 0.2 /yr.

Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies

NASA Astrophysics Data System (ADS)

Laha, S.; Guainazzi, M.; Dewangan, G.; Chakravorty, S.; Kembhavi, A.

2014-07-01

We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. We could put a strict lower limit on the detection fraction of 50%. We find a gap in the distribution of the ionisation parameter in the range 0.5

The Gaseous Environments of Quasars: Outflows, Feedback & Cold Mode Accretion

NASA Astrophysics Data System (ADS)

Chen, Chen; Hamann, Fred

2018-06-01

The early stages of massive galaxy evolution can involve galaxy-scale outflows driven by a starburst or a central quasar and cold-mode accretion (infall) that adds to the mass buildup in the galaxies. I will describe three related studies that use quasar absorption lines to measure outflows, infall, and the general gaseous environments of quasars across a range of spatial scales. The three studies are: 1) High-resolution spectroscopy with Keck-HIRES and VLT-UVES to study associated absorption lines (AALs) that have redshifts greater than the emission redshifts indicating infall and/or rich multi-component AAL complexes that might be interstellar clouds in the host galaxies that have been shredded and dispersed by a fast unseen quasar-driven wind. The data provide strong constraints on the gas kinematics, spatial structure, column densities, metallicities, and energetics. 2) A complete inventory of high-velocity CIV 1548,1550 mini-BAL outflows in quasars using high-resolution high signal-to-noise spectra in the public VLT-UVES and Keck-HIRES archives. This sensitive mini-BAL survey fills an important niche between previous work on narrow absorption lines (NALs) and the much-studied broad absorption lines (BALs) to build a more complete picture of quasar outflows. I will report of the mini-BAL statistics, the diversity of lines detected, and some tests for correlations with the quasar properties. We find, for example, that mini-BALs at v > 4000 km/s in at least 10% of 511 quasars studied, including 1% at v > 0.1 c. Finally, 3) Use the much larger database of NALs measured in 262,449 BOSS quasars by York et al. (in prep.) to study their potential relationships to the quasars and, specifically, their origins in quasar outflows. This involves primarily comparisons of the incidence and properties of NALs at different velocity shifts to other measured properties of the quasars such as BAL outflows, emission line characteristics, radio-loudness, and red colors. We find, for example, that the extreme high-velocity NALs (0.1 ‑ 0.2c) correlate strongly with AALs, indicating that a significant fraction of these NALs is ejected from the quasars.

Analytical modeling of Cosmic Winds and Jets

NASA Astrophysics Data System (ADS)

Vlahakis, Nektarios

1998-11-01

A widespread phenomenon in astrophysics is the outflow of plasma from the environment of stellar or galactic objects. This plasma outflows range from nonuniform winds to highly collimated jets which are common to many stages of stellar evolution. For example, collimated outflows are found around young stars (e.g., as in HH 30), older mass losing stars (as in eta-Carinae), symbiotic stars (e.g. in R Aqr), planetary nebulae nuclei (as in the hourglass nebula), black hole X-ray transients (as in GRS 1915+105 and GRO J1655-40), low- and high-mass X-ray binaries and recently also in cataclysmic variables (e.g. T Pyxidis). Similarly, they are also found emerging from the nuclei of many radio galaxies and quasars. Nevertheless, despite their abundance the questions of the formation, acceleration and propagation of nonuniform winds and jets have not been fully resolved. One of the main difficulties in dealing with the theoretical problem posed by cosmical outflows is that their dynamics needs to be described - even to lowest order - by the highly intractable set of the MHD equations. As is well known, this is a nonlinear system of partial differential equations with several critical points, and only very few classes of solutions are available for axisymmetric systems obtained by assuming a separation of variables in several key functions. This hypothesis allows an analysis in a 2-D geometry of the full MHD equations which reduce then to a system of ordinary differential equations. By a systematic method we construct general classes of exact and self-consistent axisymmetric MHD solutions. The unifying scheme contains three large groups of exact MHD outflow models, (I) meridionally self-similar ones with spherical critical surfaces, (II) radially self-similar models with conical critical surfaces and (III) generalized self-similar models with arbitrary shape critical surfaces. This classification includes known polytropic models, such as the classical Parker description of a stellar wind and the Blandford and Payne (1982) model of a disk-wind; it also contains nonpolytropic models, such as those of winds/jets in Sauty and Tsinganos (1994), Lima et al (1996) and Trussoni et al (1997). Besides the unification of all known cases under a common scheme, several new classes emerge and some are briefly analyzed; they could be explored for a further understanding of the physical properties of MHD outflows from various magnetized astrophysical rotators. We also propose a new class of exact and self-consistent MHD solutions which describe steady and axisymmetric hydromagnetic outflows from the magnetized atmosphere of a rotating gravitating central object with possibly an orbiting accretion disk. The plasma is driven by a thermal pressure gradient, as well as by magnetic rotator and radiative forces. At the Alfvenic and fast critical points the appropriate criticality conditions are applied. The outflows start almost radially but after the Alfven transition and before the fast critical surface is encountered the magnetic pinching force bends the poloidal streamlines into a cylindrical jet-type shape. The terminal speed, Alfven number, cross-sectional area of the jet, as well as its final pressure and density obtain uniform values at large distances from the source. The goal of the study is to give an analytical discussion of the two-dimensional interplay of the thermal pressure gradient, gravitational, Lorentz and inertial forces in accelerating and collimating an MHD flow. A parametric study of the model is given, as well as a brief sketch of its applicability to a self-consistent modeling of collimated outflows from various astrophysical objects. For example, the obtained characteristics of the collimated outflow in agreement with those in jets associated with YSO's. General theoretical arguments and various analytic self-similar solutions have recently shown that magnetized and rotating astrophysical outflows may become asymptotically cylindrical, in agreement with observations of cosmical jets. A notable common feature in all such self-consistent, self-similar MHD solutions is that before final cylindrical collimation is achieved, the jet passes from a stage of oscillations in its radius, Mach number and other physical parameters. It is shown that under rather general assumptions this oscillatory behaviour of collimated outflows is not restricted to the few specific models examined so far, but instead it seems to be a rather general physical property of an MHD outflow which starts noncylindrically before it reaches collimation. It is concluded thence that astrophysical jets are topologically stable to small amplitude, time-independent perturbations in their asymptotically cylindrical shape. Also, similarly to the familiar fluid instabilities these oscillations may give rise to brightness enhancements along jets.

The dark nemesis of galaxy formation: why hot haloes trigger black hole growth and bring star formation to an end

NASA Astrophysics Data System (ADS)

Bower, Richard G.; Schaye, Joop; Frenk, Carlos S.; Theuns, Tom; Schaller, Matthieu; Crain, Robert A.; McAlpine, Stuart

2017-02-01

Galaxies fall into two clearly distinct types: `blue-sequence' galaxies which are rapidly forming young stars, and `red-sequence' galaxies in which star formation has almost completely ceased. Most galaxies more massive than 3 × 1010 M⊙ follow the red sequence, while less massive central galaxies lie on the blue sequence. We show that these sequences are created by a competition between star formation-driven outflows and gas accretion on to the supermassive black hole at the galaxy's centre. We develop a simple analytic model for this interaction. In galaxies less massive than 3 × 1010 M⊙, young stars and supernovae drive a high-entropy outflow which is more buoyant than any tenuous corona. The outflow balances the rate of gas inflow, preventing high gas densities building up in the central regions. More massive galaxies, however, are surrounded by an increasingly hot corona. Above a halo mass of ˜1012 M⊙, the outflow ceases to be buoyant and star formation is unable to prevent the build-up of gas in the central regions. This triggers a strongly non-linear response from the black hole. Its accretion rate rises rapidly, heating the galaxy's corona, disrupting the incoming supply of cool gas and starving the galaxy of the fuel for star formation. The host galaxy makes a transition to the red sequence, and further growth predominantly occurs through galaxy mergers. We show that the analytic model provides a good description of galaxy evolution in the EAGLE hydrodynamic simulations. So long as star formation-driven outflows are present, the transition mass scale is almost independent of subgrid parameter choice.

A NOVEL PARADIGM FOR SHORT GAMMA-RAY BURSTS WITH EXTENDED X-RAY EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rezzolla, Luciano; Kumar, Pawan

2015-04-01

The merger of a binary of neutron stars provides natural explanations for many of the features of short gamma-ray bursts (SGRBs), such as the generation of a hot torus orbiting a rapidly rotating black hole, which can then build a magnetic jet and provide the energy reservoir to launch a relativistic outflow. However, this scenario has problems explaining the recently discovered long-term and sustained X-ray emission associated with the afterglows of a subclass of SGRBs. We propose a new model that explains how an X-ray afterglow can be sustained by the product of the merger and how the X-ray emissionmore » is produced before the corresponding emission in the gamma-band, though it is observed to follow it. Overall, our paradigm combines in a novel manner a number of well-established features of the emission in SGRBs and results from simulations. Because it involves the propagation of an ultra-relativistic outflow and its interaction with a confining medium, the paradigm also highlights a unifying phenomenology between short and long GRBs.« less

X-ray diving in the center of Sh2-129: looking for the driving source of Ou4

NASA Astrophysics Data System (ADS)

Grosso, Nicolas

2012-10-01

The outflow phenomenon is associated both with the early and the last phase of the stellar evolution. Recently, a unique bipolar outflow with an angular size of 1.2 degrees was discovered in the blister HII region Sh2-129. Ou4, nicknamed "The Giant Squid", is to our knowledge the bipolar outflow with the largest angular size ever found. We propose joint XMM-Newton/EPIC (35 ks) and Chandra/HRC-I (16 ks) observations to look for the driving source of Ou4 and to clarify the nature of this object.

Search for High-energy Neutrinos from Binary Neutron Star Merger GW170817 with ANTARES, IceCube, and the Pierre Auger Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albert, A.; André, M.; Anghinolfi, M.

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV–EeV energy range using the Antares, IceCube, and Pierre Auger Observatories. No neutrinos directionally coincidentmore » with the source were detected within ±500 s around the merger time. Additionally, no MeV neutrino burst signal was detected coincident with the merger. We further carried out an extended search in the direction of the source for high-energy neutrinos within the 14 day period following the merger, but found no evidence of emission. We used these results to probe dissipation mechanisms in relativistic outflows driven by the binary neutron star merger. The non-detection is consistent with model predictions of short GRBs observed at a large off-axis angle.« less

Search for High-energy Neutrinos from Binary Neutron Star Merger GW170817 with ANTARES, IceCube, and the Pierre Auger Observatory

DOE PAGES

Albert, A.; André, M.; Anghinolfi, M.; ...

2017-11-29

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV–EeV energy range using the Antares, IceCube, and Pierre Auger Observatories. No neutrinos directionally coincidentmore » with the source were detected within ±500 s around the merger time. Additionally, no MeV neutrino burst signal was detected coincident with the merger. We further carried out an extended search in the direction of the source for high-energy neutrinos within the 14 day period following the merger, but found no evidence of emission. We used these results to probe dissipation mechanisms in relativistic outflows driven by the binary neutron star merger. The non-detection is consistent with model predictions of short GRBs observed at a large off-axis angle.« less

Search for High-energy Neutrinos from Binary Neutron Star Merger GW170817 with ANTARES, IceCube, and the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Albert, A.; André, M.; Anghinolfi, M.; Ardid, M.; Aubert, J.-J.; Aublin, J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Belhorma, B.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M. C.; Brânzaş, H.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Cherkaoui El Moursli, R.; Chiarusi, T.; Circella, M.; Coelho, J. A. B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Díaz, A. F.; Deschamps, A.; De Bonis, G.; Distefano, C.; Di Palma, I.; Domi, A.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; El Khayati, N.; Elsässer, D.; Enzenhöfer, A.; Ettahiri, A.; Fassi, F.; Felis, I.; Fusco, L. A.; Gay, P.; Giordano, V.; Glotin, H.; Grégoire, T.; Ruiz, R. Gracia; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hofestädt, J.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Navas, S.; Nezri, E.; Organokov, M.; Păvălaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schüssler, F.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Turpin, D.; Tönnis, C.; Vallage, B.; Van Elewyck, V.; Versari, F.; Vivolo, D.; Vizzoca, A.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.; ANTARES Collaboration; Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Samarai, I. Al; Altmann, D.; Andeen, K.; Anderson, T.; Ansseau, I.; Anton, G.; Argüelles, C.; Auffenberg, J.; Axani, S.; Bagherpour, H.; Bai, X.; Barron, J. P.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; BenZvi, S.; Berley, D.; Bernardini, E.; Besson, D. Z.; Binder, G.; Bindig, D.; Blaufuss, E.; Blot, S.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Bourbeau, E.; Bourbeau, J.; Bradascio, F.; Braun, J.; Brayeur, L.; Brenzke, M.; Bretz, H.-P.; Bron, S.; Brostean-Kaiser, J.; Burgman, A.; Carver, T.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cross, R.; Day, M.; de André, J. P. A. M.; De Clercq, C.; DeLaunay, J. J.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dujmovic, H.; Dumm, J. P.; Dunkman, M.; Dvorak, E.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Eller, P.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Franckowiak, A.; Friedman, E.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Giang, W.; Glauch, T.; Glüsenkamp, T.; Goldschmidt, A.; Gonzalez, J. G.; Grant, D.; Griffith, Z.; Haack, C.; Hallgren, A.; Halzen, F.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Hokanson-Fasig, B.; Hoshina, K.; Huang, F.; Huber, M.; Hultqvist, K.; Hünnefeld, M.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Kalaczynski, P.; Kang, W.; Kappes, A.; Karg, T.; Karle, A.; Katz, U.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kheirandish, A.; Kim, J.; Kim, M.; Kintscher, T.; Kiryluk, J.; Kittler, T.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koschinsky, J. P.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, M.; Krückl, G.; Kunnen, J.; Kunwar, S.; Kurahashi, N.; Kuwabara, T.; Kyriacou, A.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lauber, F.; Lesiak-Bzdak, M.; Leuermann, M.; Liu, Q. R.; Lu, L.; Lünemann, J.; Luszczak, W.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mancina, S.; Maruyama, R.; Mase, K.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Micallef, J.; Momenté, G.; Montaruli, T.; Moore, R. W.; Moulai, M.; Nahnhauer, R.; Nakarmi, P.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; O’Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Peiffer, P.; Pepper, J. A.; Pérez de los Heros, C.; Pieloth, D.; Pinat, E.; Plum, M.; Pranav, D.; Price, P. B.; Przybylski, G. T.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Rea, I. C.; Reimann, R.; Relethford, B.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Rysewyk, D.; Sälzer, T.; Sanchez Herrera, S. E.; Sandrock, A.; Sandroos, J.; Santander, M.; Sarkar, S.; Sarkar, S.; Satalecka, K.; Schlunder, P.; Schmidt, T.; Schneider, A.; Schoenen, S.; Schöneberg, S.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soedingrekso, J.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stachurska, J.; Stamatikos, M.; Stanev, T.; Stasik, A.; Stettner, J.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strotjohann, N. L.; Stuttard, T.; Sullivan, G. W.; Sutherland, M.; Taboada, I.; Tatar, J.; Tenholt, F.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Tung, C. F.; Turcati, A.; Turley, C. F.; Ty, B.; Unger, E.; Usner, M.; Vandenbroucke, J.; Van Driessche, W.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Vehring, M.; Vogel, E.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandler, F. D.; Wandkowsky, N.; Waza, A.; Weaver, C.; Weiss, M. J.; Wendt, C.; Werthebach, J.; Westerhoff, S.; Whelan, B. J.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wolf, M.; Wood, J.; Wood, T. R.; Woolsey, E.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Yuan, T.; Zoll, M.; IceCube Collaboration; Aab, A.; Abreu, P.; Aglietta, M.; Albuquerque, I. F. M.; Albury, J. M.; Allekotte, I.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arsene, N.; Asorey, H.; Assis, P.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Barbato, F.; Barreira Luz, R. J.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Boháčová, M.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caruso, R.; Castellina, A.; Catalani, F.; Cataldi, G.; Cazon, L.; Chavez, A. G.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Cobos Cerutti, A. C.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Consolati, G.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; D’Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; Day, J. A.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; Debatin, J.; Deligny, O.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D’Olivo, J. C.; Dorosti, Q.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Farmer, J.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Feldbusch, F.; Fenu, F.; Fick, B.; Figueira, J. M.; Filipčič, A.; Freire, M. M.; Fujii, T.; Fuster, A.; Gaïor, R.; García, B.; Gaté, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gorgi, A.; Gottowik, M.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Halliday, R.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harvey, V. M.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Johnsen, J. A.; Josebachuili, M.; Jurysek, J.; Kääpä, A.; Kampert, K. H.; Keilhauer, B.; Kemmerich, N.; Kemp, J.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; Lago, B. L.; LaHurd, D.; Lang, R. G.; Lauscher, M.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lo Presti, D.; Lopes, L.; López, R.; López Casado, A.; Lorek, R.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Merenda, K.-D.; Michal, S.; Micheletti, M. I.; Middendorf, L.; Miramonti, L.; Mitrica, B.; Mockler, D.; Mollerach, S.; Montanet, F.; Morello, C.; Morlino, G.; Mostafá, M.; Müller, A. L.; Müller, G.; Muller, M. A.; Müller, S.; Mussa, R.; Naranjo, I.; Nellen, L.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Núñez, L. A.; Oikonomou, F.; Olinto, A.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pȩkala, J.; Pelayo, R.; Peña-Rodriguez, J.; Pereira, L. A. S.; Perlin, M.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Pierog, T.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Poh, J.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollan, R.; Rautenberg, J.; Ravignani, D.; Ridky, J.; Riehn, F.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Roncoroni, M. J.; Roth, M.; Roulet, E.; Rovero, A. C.; Ruehl, P.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Saleh, A.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarmento, R.; Sarmiento-Cano, C.; Sato, R.; Schauer, M.; Scherini, V.; Schieler, H.; Schimp, M.; Schmidt, D.; Scholten, O.; Schovánek, P.; Schröder, F. G.; Schröder, S.; Schulz, A.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Soriano, J. F.; Squartini, R.; Stanca, D.; Stanič, S.; Stasielak, J.; Stassi, P.; Stolpovskiy, M.; Strafella, F.; Streich, A.; Suarez, F.; Suarez Durán, M.; Sudholz, T.; Suomijärvi, T.; Supanitsky, A. D.; Šupík, J.; Swain, J.; Szadkowski, Z.; Taboada, A.; Taborda, O. A.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tomé, B.; Torralba Elipe, G.; Travnicek, P.; Trini, M.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Vázquez, R. A.; Veberič, D.; Ventura, C.; Vergara Quispe, I. D.; Verzi, V.; Vicha, J.; Villaseñor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiedeński, M.; Wiencke, L.; Wilczyński, H.; Wirtz, M.; Wittkowski, D.; Wundheiler, B.; Yang, L.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F.; The Pierre Auger Collaboration; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Atallah, D. V.; Aufmuth, P.; Aulbert, C.; AultONeal, K.; Austin, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonilla, E.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E.; Chassande-Mottin, E.; Chatterjee, D.; Cheeseboro, B. D.; Chen, H. Y.; Chen, X.; Chen, Y.; Cheng, H.-P.; Chia, H.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Cohen, D.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M., Jr.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Dálya, G.; Danilishin, S. L.; D’Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; De, S.; DeBra, D.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Demos, N.; Denker, T.; Dent, T.; De Pietri, R.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; De Rossi, C.; DeSalvo, R.; de Varona, O.; Devenson, J.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Dreissigacker, C.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dupej, P.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fee, C.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finstad, D.; Fiori, I.; Fiorucci, D.; Fishbach, M.; Fisher, R. P.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia-Quiros, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; Goncharov, B.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Gretarsson, E. M.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hreibi, A.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J.-M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña Hernandez, I.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McNeill, L.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, B. B.; Miller, J.; Millhouse, M.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moffa, D.; Moggi, A.; Mogushi, K.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Nevin, L.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; North, C.; Nuttall, L. K.; Oberling, J.; O’Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O’Reilly, B.; Ormiston, R.; Ortega, L. F.; O’Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Howard; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pirello, M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Pratten, G.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, A.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staats, K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, J. A.; Taylor, R.; Tewari, S. V.; Theeg, T.; Thies, F.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Weßels, P.; Westerweck, J.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Wilken, D.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, S.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zelenova, T.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.-H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration

2017-12-01

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV–EeV energy range using the ANTARES, IceCube, and Pierre Auger Observatories. No neutrinos directionally coincident with the source were detected within ±500 s around the merger time. Additionally, no MeV neutrino burst signal was detected coincident with the merger. We further carried out an extended search in the direction of the source for high-energy neutrinos within the 14 day period following the merger, but found no evidence of emission. We used these results to probe dissipation mechanisms in relativistic outflows driven by the binary neutron star merger. The non-detection is consistent with model predictions of short GRBs observed at a large off-axis angle.

Studying the outflow-core interaction with ALMA Cycle 1 observations of the HH 46/47 molecular outflow

NASA Astrophysics Data System (ADS)

Zhang, Yichen; Arce, Hector G.; Mardones, Diego; Dunham, Michael; Garay, Guido; Noriega-Crespo, Alberto; Corder, Stuartt; Offner, Stella; Cabrit, Sylvie

2016-01-01

We present ALMA Cycle 1 observations of the HH 46/47 molecular outflow which is driven by a low-mass Class 0/I protostar. Previous ALMA Cycle 0 12CO observation showed outflow cavities produced by the entrainment of ambient gas by the protostellar jet and wide-angle wind. Here we present analysis of observation of 12CO, 13CO, C18O and other species using combined 12m array and ACA observations. The improved angular resolution and sensitivity allow us to detect details of the outflow structure. Specially, we see that the outflow cavity wall is composed of two or more layers of outflowing gas, which separately connect to different shocked regions along the outflow axis inside the cavity, suggesting the outflow cavity wall is composed of multiple shells entrained by a series of jet bow-shock events. The new 13CO and C18O data also allow us to trace relatively denser and slower outflow material than that traced by the 12CO. These species are only detected within about 1 to 2 km/s from the cloud velocity, tracing the outflow to lower velocities than what is possible using only the 12CO emission. Interestingly, the cavity wall of the red lobe appears at very low outflow velocities (as low as ~0.2 km/s). In addition, 13CO and C18O allow us to correct for the CO optical depth, allowing us to obtain more accurate estimates of the outflow mass, momentum and kinetic energy. Applying the optical depth correction significantly increases the previous mass estimate by a factor of 14. The outflow kinetic energy distribution shows that even though the red lobe is mainly entrained by jet bow-shocks, most of the outflow energy is being deposited into the cloud at the base of the outflow cavity rather than around the heads of the bow shocks. The estimated total mass, momentum, and energy of the outflow indicate that the outflow has the ability to disperse the parent core. We found possible evidence for a slowly moving rotating outflow in CS. Our 13CO and C18O observations also trace a circumstellar envelope with both rotation and infall motions.

Double Neutron Star Mergers and Short Gamma-ray Bursts: Long-lasting High-energy Signatures and Remnant Dichotomy

NASA Astrophysics Data System (ADS)

Murase, Kohta; Toomey, Michael W.; Fang, Ke; Oikonomou, Foteini; Kimura, Shigeo S.; Hotokezaka, Kenta; Kashiyama, Kazumi; Ioka, Kunihito; Mészáros, Peter

2018-02-01

The recent detection of gravitational waves and electromagnetic counterparts from the double neutron star merger event GW+EM170817 supports the standard paradigm of short gamma-ray bursts (SGRBs) and kilonovae/macronovae. It is important to reveal the nature of the compact remnant left after the merger, either a black hole or neutron star, and their physical link to the origin of the long-lasting emission observed in SGRBs. The diversity of the merger remnants may also lead to different kinds of transients that can be detected in future. Here we study the high-energy emission from the long-lasting central engine left after the coalescence, under certain assumptions. In particular, we consider the X-ray emission from a remnant disk and the nonthermal nebular emission from disk-driven outflows or pulsar winds. We demonstrate that late-time X-ray and high-frequency radio emission can provide useful constraints on properties of the hidden compact remnants and their connections to long-lasting SGRB emission, and we discuss the detectability of nearby merger events through late-time observations at ∼30–100 days after the coalescence. We also investigate the GeV–TeV gamma-ray emission that occurs in the presence of long-lasting central engines and show the importance of external inverse Compton radiation due to upscattering of X-ray photons by relativistic electrons in the jet. We also search for high-energy gamma rays from GW170817 in the Fermi-LAT data and report upper limits on such long-lasting emission. Finally, we consider the implications of GW+EM170817 and discuss the constraints placed by X-ray and high-frequency radio observations.

Infall and outflow motions towards a sample of massive star-forming regions from the RMS survey

NASA Astrophysics Data System (ADS)

Cunningham, N.; Lumsden, S. L.; Moore, T. J. T.; Maud, L. T.; Mendigutía, I.

2018-06-01

We present the results of an outflow and infall survey towards a distance-limited sample of 31 massive star-forming regions drawn from the Red MSX source (RMS) survey. The presence of young, active outflows is identified from SiO (8-7) emission and the infall dynamics are explored using HCO+/H13CO+ (4-3) emission. We investigate if the infall and outflow parameters vary with source properties, exploring whether regions hosting potentially young active outflows show similarities or differences with regions harbouring more evolved, possibly momentum-driven, `fossil' outflows. SiO emission is detected towards approximately 46 per cent of the sources. When considering sources with and without an SiO detection (i.e. potentially active and fossil outflows, respectively), only the 12CO outflow velocity shows a significant difference between samples, indicating SiO is more prevalent towards sources with higher outflow velocities. Furthermore, we find the SiO luminosity increases as a function of the Herschel 70 μm to WISE 22 μm flux ratio, suggesting the production of SiO is prevalent in younger, more embedded regions. Similarly, we find tentative evidence that sources with an SiO detection have a smaller bolometric luminosity-to-mass ratio, indicating SiO (8-7) emission is associated with potentially younger regions. We do not find a prevalence towards sources displaying signatures of infall in our sample. However, the higher energy HCO+ transitions may not be the best suited tracer of infall at this spatial resolution in these regions.

YSO jets in the Galactic plane from UWISH2 - V. Jets and outflows in M17

NASA Astrophysics Data System (ADS)

Samal, M. R.; Chen, W. P.; Takami, M.; Jose, J.; Froebrich, D.

2018-07-01

Jets and outflows are the first signposts of stellar birth. Emission in the H2 1-0 S(1) line at 2.122- μm is a powerful tracer of shock excitation in these objects. Here we present the analysis of 2.0 × 0.8 deg2 data from the UK Wide-field Infrared Survey for H2 (UWISH2) in the 1-0 S(1) line to identify and characterize the outflows of the M17 complex. We uncover 48 probable outflows, of which 93 per cent are new discoveries. We identified driving source candidates for 60 per cent of outflows. Among the driving source candidate young stellar objects (YSOs), 90 per cent are protostars and the remaining 10 per cent are Class II YSOs. In comparison with results from other surveys, we suggest that H2 emission fades very quickly as the objects evolve from protostars to pre-main-sequence stars. We fit spectral energy distribution (SED) models to 14 candidate outflow-driving sources and conclude that the outflows of our sample are mostly driven by moderate-mass YSOs that are still actively accreting from their protoplanetary disc. We examined the spatial distribution of the outflows with the gas and dust distribution of the complex and observed that the filamentary dark cloud M17SWex, located on the south-western side of the complex, is associated with a greater number of outflows. We find that our results corroborate previous suggestions that, in the M17 complex, M17SWex is the most active site of star formation. Several of our newly identified outflow candidates are excellent targets for follow-up studies to understand better the very early phase of protostellar evolution.

Quasar outflows and AGN feedback in the extreme UV: HST/COS observations of HE 0238-1904

NASA Astrophysics Data System (ADS)

Arav, Nahum; Borguet, Benoit; Chamberlain, Carter; Edmonds, Doug; Danforth, Charles

2013-12-01

Spectroscopic observations of quasar outflows at rest-frame 500-1000 Å have immense diagnostic power. We present analyses of such data, where absorption troughs from O IV and O IV* allow us to obtain the distance of the outflows from the AGN and troughs from Ne VIII and Mg X reveal the warm absorber phase of the outflow. Their inferred column densities, combined with those of O VI, N IV and H I, yield two important results. (1) The outflow shows two ionization phases, where the high-ionization phase carries the bulk of the material. This is similar to the situation seen in X-ray warm absorber studies. Furthermore, the low-ionization phase is inferred to have a volume filling factor of 10-5-10-6. (2) We determine a distance of 3000 pc from the outflow to the central source using the O IV*/O IV column density ratio and the knowledge of the ionization parameter. Since this is a typical high-ionization outflow, we can determine robust values for the outflow's mass flux and kinetic luminosity of 40 M⊙ yr-1 and 1045 erg s-1, respectively, where the latter is roughly equal to 1 per cent of the bolometric luminosity. Such a large kinetic luminosity and mass flow rate measured in a typical high-ionization wind suggest that quasar outflows are a major contributor to AGN feedback mechanisms.

Associating Long-term Gamma-ray Variability with the Superorbital Period of LS I + 61 Deg. 303

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bonamente, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.;

Blowin' in the wind: both `negative' and `positive' feedback in an outflowing quasar at z~1.6

NASA Astrophysics Data System (ADS)

Cresci, Giovanni

2015-02-01

Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation, preventing massive galaxies to over-grow and producing the red colors of ellipticals. On the other hand, some models are also requiring `positive' AGN feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively-driven winds are available. We present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z=1.59 QSO, in which we clearly resolve a fast (1500 km/s) and extended (up to 13 kpc from the black hole) outflow in the [OIII] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Hα emission and the rest frame U band flux show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. The outflow is therefore removing the gas from the host galaxy (`negative feedback'), but also triggering star formation by outflow induced pressure at the edges (`positive feedback'). XID2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work.

X-ray evidence for ultra-fast outflows in AGNs

NASA Astrophysics Data System (ADS)

Tombesi, Francesco; Sambruna, Rita; Braito, Valentina; Reeves, James; Reynolds, Christopher; Cappi, Massimo

2012-07-01

X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts and 5 radio galaxies observed with XMM-Newton and Suzaku. We assessed the global detection significance of the absorption lines and performed a detailed photo-ionization modeling. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1} and the associated mechanical power is high, in the range ˜10^{43}--10^{45} erg/s. Therefore, UFOs are capable to provide a significant contribution to the AGN cosmological feedback and their study can provide important clues on the connection between accretion disks, winds and jets.

A Global Three-Dimensional Radiation Hydrodynamic Simulation of a Self-Gravitating Accretion Disk

NASA Astrophysics Data System (ADS)

Phillipson, Rebecca; Vogeley, Michael S.; McMillan, Stephen; Boyd, Patricia

2018-01-01

We present three-dimensional, radiation hydrodynamic simulations of initially thin accretion disks with self-gravity using the grid-based code PLUTO. We produce simulated light curves and spectral energy distributions and compare to observational data of X-ray binary (XRB) and active galactic nuclei (AGN) variability. These simulations are of interest for modeling the role of radiation in accretion physics across decades of mass and frequency. In particular, the characteristics of the time variability in various bandwidths can probe the timescales over which different physical processes dominate the accretion flow. For example, in the case of some XRBs, superorbital periods much longer than the companion orbital period have been observed. Smoothed particle hydrodynamics (SPH) calculations have shown that irradiation-driven warping could be the mechanism underlying these long periods. In the case of AGN, irradiation-driven warping is also predicted to occur in addition to strong outflows originating from thermal and radiation pressure driving forces, which are important processes in understanding feedback and star formation in active galaxies. We compare our simulations to various toy models via traditional time series analysis of our synthetic and observed light curves.

A High Definition View of AGN Feedback: Chandra Imaging of Nearby Seyfert Galaxies

NASA Astrophysics Data System (ADS)

Wang, Junfeng; Fabbiano, G.; Risaliti, G.; Elvis, M.; Karovska, M.; Zezas, A.; Mundell, C. G.

2010-03-01

To improve the physics of AGN feedback, it is crucial to evaluate the true role of outflows on galaxy evolution observationally. I will present new results from Chandra spectral imaging of nearby Seyfert galaxies, which offer unique opportunities to examine feedback in action in much greater detail than at high redshift. Exploiting Chandra's highest possible resolution, we are able to study structures in NGC 4151 on spatial scales of 0.5 arcsec (30 pc), showing an extended X-ray morphology overall consistent with the optical NLR. We find that most of the NLR clouds in NGC 4151 have [OIII] to soft X-ray ratio consistent with the values observed in NLRs of some Seyfert 2 galaxies, which indicates a uniform ionization parameter even at large radii. We examine various X-ray emission mechanisms of the radio jet and consider thermal emission from interaction between radio outflow and the NLR clouds the most probable origin for the X-ray emission associated with the jet.

An Axisymmetric Hydrodynamical Model for the Torus Wind in AGN. 2; X-ray Excited Funnel Flow

NASA Technical Reports Server (NTRS)

Dorodnitsyn, A.; Kallman, T.; Proga, D.

2008-01-01

We have calculated a series of models of outflows from the obscuring torus in active galactic nuclei (AGN). Our modeling assumes that the inner face of a rotationally supported torus is illuminated and heated by the intense X-rays from the inner accretion disk and black hole. As a result of such heating a strong biconical outflow is observed in our simulations. We calculate 3-dimensional hydrodynamical models, assuming axial symmetry, and including the effects of X-ray heating, ionization, and radiation pressure. We discuss the behavior of a large family of these models, their velocity fields, mass fluxes and temperature, as functions of the torus properties and X-ray flux. Synthetic warm absorber spectra are calculated, assuming pure absorption, for sample models at various inclination angles and observing times. We show that these models have mass fluxes and flow speeds which are comparable to those which have been inferred from observations of Seyfert 1 warm absorbers, and that they can produce rich absorption line spectra.

Chandra Detection of a Parsec Scale Wind in the Broad Line Radio Galaxy 3C 382

NASA Technical Reports Server (NTRS)

Reeves, J. N.; Sambruna, R. M.; Braito, V.; Eracleous, Michael

2009-01-01

We present unambiguous evidence for a parsec scale wind in the Broad-Line Radio Galaxy (BLRG) 3C 382, the first radio-loud AGN whereby an outflow has been measured with X-ray grating spectroscopy. A 118 ks Chandra grating (HETG) observation of 3C 382 has revealed the presence of several high ionization absorption lines in the soft X-ray band, from Fe, Ne, Mg and Si. The absorption lines are blue-shifted with respect to the systemic velocity of 3C 382 by -840+/-60 km/s and are resolved by Chandra with a velocity width of sigma = 340+/-70 km/s. The outflow appears to originate from a single zone of gas of column density N(sub H) = 1.3 x 10(exp 21)/sq cm and ionization parameter log(E/erg/cm/s) = 2.45. From the above measurements we calculate that the outflow is observed on parsec scales, within the likely range from 10-1000 pc, i.e., consistent with an origin in the Narrow Line Region. Finally we also discuss the possibility of a much faster (0.1c) outflow component, based on a blue-shifted iron K(alpha) emission line in the Suzaku observation of 3C 382, which could have an origin in an accretion disk wind.

Depressed emission between magnetic arcades near a sunspot

NASA Astrophysics Data System (ADS)

Ryabov, B. I.; Shibasaki, K.

The locations of the depressed emission in microwaves, EUV and soft X-rays are compared with each other and with the location of the plasma outflow in the active region (AR) 8535 on the Sun. We found that two open-field regions overlap the regions of depressed emission near the AR's sunspot. These two open-field regions are simulated with the potential-field source-surface (PFSS) model under radial distances of RSS = 1.8 R⊙ and RSS = 2.5 R⊙. Each open-field region is located between the arcades of the loops of the same magnetic polarity. The former open-field region covers the region of the plasma outflow, which is thus useful for the tests on connection to the heliosphere. The utmost microwave depression of the intensity in the ordinary mode (the Very Large Array 15 GHz observations) also overlaps the region of the plasma outflow and thus indicates this outflow. The lasting for eight days depression in soft X-rays and the SOHO EIT 2.84× 10-8 m images are attributed to the evacuation of as hot coronal plasma as T≥ 2× 106 K from the extended in height (``open") magnetic structures. We conclude that the AR 8535 presents the sunspot atmosphere affected by the large-scale magnetic fields.

Galactic cluster winds in presence of a dark energy

NASA Astrophysics Data System (ADS)

Bisnovatyi-Kogan, G. S.; Merafina, M.

2013-10-01

We obtain a solution for the hydrodynamic outflow of the polytropic gas from the gravitating centre, in the presence of the uniform dark energy (DE). The antigravity of DE is enlightening the outflow and makes the outflow possible at smaller initial temperature, at the same density. The main property of the wind in the presence of DE is its unlimited acceleration after passing the critical point. In application of this solution to the winds from galaxy clusters, we suggest that collision of the strongly accelerated wind with another galaxy cluster, or with another galactic cluster wind, could lead to the formation of a highest energy cosmic rays.

CHANDRA Detects Relativistic Broad Absorption Lines from APM 08279+5255

NASA Astrophysics Data System (ADS)

Chartas, G.; Brandt, W. N.; Gallagher, S. C.; Garmire, G. P.

2002-11-01

We report the discovery of X-ray broad absorption lines (BALs) from the BAL quasar APM 08279+5255 originating from material moving at relativistic velocities with respect to the central source. The large flux magnification by a factor of ~100 provided by the gravitational lens effect combined with the large redshift (z=3.91) of the quasar have facilitated the acquisition of the first high signal-to-noise X-ray spectrum of a quasar containing X-ray BALs. Our analysis of the X-ray spectrum of APM 08279+5255 places the rest-frame energies of the two observed absorption lines at 8.1 and 9.8 keV. The detection of each of these lines is significant at a greater than 99.9% confidence level based on the F-test. Assuming that the absorption lines are from Fe XXV Kα, the implied bulk velocities of the X-ray BALs are ~0.2c and ~0.4c, respectively. The observed high bulk velocities of the X-ray BALs combined with the relatively short recombination timescales of the X-ray-absorbing gas imply that the absorbers responsible for the X-ray BALs are located at radii of <~2×1017 cm, within the expected location of the UV absorber. With this implied geometry, the X-ray gas could provide the necessary shielding to prevent the UV absorber from being completely ionized by the central X-ray source, consistent with hydrodynamical simulations of line-driven disk winds. Estimated mass-outflow rates for the gas creating the X-ray BALs are typically less than a solar mass per year. Our spectral analysis also indicates that the continuum X-ray emission of APM 08279+5255 is consistent with that of a typical radio-quiet quasar with a spectral slope of Γ=1.72+0.06-0.05.

Demographics and Case Studies of Galactic Outflows in the Local Universe

NASA Astrophysics Data System (ADS)

Rupke, David

2017-07-01

Galactic outflows driven by both star formation and active black holes are an important driver of galaxy evolution. The local universe is a sensitive laboratory for understanding the scaling relations that characterize these winds and the physics that govern them. I will review what we know from statistical studies about the prevalance and properties of nearby galactic winds and how these properties depend on those of the host galaxy or power source. I will also highlight detailed case studies of key objects that illustrate the multiphase structure of these winds.

OBSERVATIONS OF MOLECULAR OUTFLOW IN CAR 291.6-01.9

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saul, M.; Saul, L., E-mail: msaul@phys.unsw.edu.au, E-mail: luke.saul@space.unibe.ch

We report the first observations of a dense molecular gas nebula and bipolar outflow in Car 291.6-01.9, showing characteristics of an embedded young stellar object (YSO). Using the Mopra radio telescope near Coonabarabaran, Australia, we image the kinematic structure of several emission features to examine physical properties within a molecular clump of mass {approx}3.2 {+-} 0.6 Multiplication-Sign 10{sup 3} M{sub Sun} in which a stellar cluster may be forming. Motivated by acquiring a more thorough understanding of star formation we ask what may have initiated collapse in the clump; observed outflow alignment is suggestive of {approx}1.0 pc distant massive starmore » HD 308280 radiative-driven compression as a formation trigger for the dense core. An outflow derived age of <10{sup 6} years, together with significant C{sup 18}O and SO core depletion, support the case for the core as the host of an extremely YSO cluster.« less

Observations of Superwinds in Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Marlowe, A. T.; Heckman, T. M.; Wyse, R.; Schommer, R.

1993-12-01

Dwarf galaxies are important in developing our understanding of the formation and evolution of galaxies, and of the structure in the universe. The concept of supernova-driven mass outflows is a vital ingredient in theories of the structure and evolution of dwarfs galaxies. We have begun a detailed multi-waveband search for outflows in starbursting dwarf galaxies, and have obtained Fabry-Perot images and Echelle spectra of 20 nearby actively-star-forming dwarf galaxies. In about half the sample, the Fabry-Perot Hα images show loops and filaments with sizes of one to a few kpc. The Echelle spectra taken through the loops and filaments show kinematics consistent with expanding bubble-like structures. We describe these data, and present seven dwarfs in our sample that have the strongest evidence of outflows.

On the stability of radiation-pressure-dominated cavities

NASA Astrophysics Data System (ADS)

Kuiper, R.; Klahr, H.; Beuther, H.; Henning, Th.

2012-01-01

Context. When massive stars exert a radiation pressure onto their environment that is higher than their gravitational attraction (super-Eddington condition), they launch a radiation-pressure-driven outflow, which creates cleared cavities. These cavities should prevent any further accretion onto the star from the direction of the bubble, although it has been claimed that a radiative Rayleigh-Taylor instability should lead to the collapse of the outflow cavity and foster the growth of massive stars. Aims: We investigate the stability of idealized radiation-pressure-dominated cavities, focusing on its dependence on the radiation transport approach used in numerical simulations for the stellar radiation feedback. Methods: We compare two different methods for stellar radiation feedback: gray flux-limited diffusion (FLD) and ray-tracing (RT). Both methods are implemented in our self-gravity radiation hydrodynamics simulations for various initial density structures of the collapsing clouds, eventually forming massive stars. We also derive simple analytical models to support our findings. Results: Both methods lead to the launch of a radiation-pressure-dominated outflow cavity. However, only the FLD cases lead to prominent instability in the cavity shell. The RT cases do not show such instability; once the outflow has started, it precedes continuously. The FLD cases display extended epochs of marginal Eddington equilibrium in the cavity shell, making them prone to the radiative Rayleigh-Taylor instability. In the RT cases, the radiation pressure exceeds gravity by 1-2 orders of magnitude. The radiative Rayleigh-Taylor instability is then consequently suppressed. It is a fundamental property of the gray FLD method to neglect the stellar radiation temperature at the location of absorption and thus to underestimate the opacity at the location of the cavity shell. Conclusions: Treating the stellar irradiation in the gray FLD approximation underestimates the radiative forces acting on the cavity shell. This can lead artificially to situations that are affected by the radiative Rayleigh-Taylor instability. The proper treatment of direct stellar irradiation by massive stars is crucial for the stability of radiation-pressure-dominated cavities. Movies are available in electronic form at http://www.aanda.org

NuSTAR Observations of the Magnetar 1E 2259+586

NASA Technical Reports Server (NTRS)

Vogel, Julia K.; Hascoet, Romain; Kaspi, Victoria M.; An, Hongjun; Archibald, Robert; Beloborodov, Andrei M.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Gotthelf, Eric V.;

Positron annihilation in the nuclear outflows of the Milky Way

NASA Astrophysics Data System (ADS)

Panther, Fiona H.; Crocker, Roland M.; Birnboim, Yuval; Seitenzahl, Ivo R.; Ruiter, Ashley J.

2018-02-01

Observations of soft gamma rays emanating from the Milky Way from SPI/INTEGRAL reveal the annihilation of ˜2 × 1043 positrons every second in the Galactic bulge. The origin of these positrons, which annihilate to produce a prominent emission line centred at 511 keV, has remained mysterious since their discovery almost 50 yr ago. A plausible origin for the positrons is in association with the intense star formation ongoing in the Galactic centre. Moreover, there is strong evidence for a nuclear outflow in the Milky Way. We find that advective transport and subsequent annihilation of positrons in such an outflow cannot simultaneously replicate the observed morphology of positron annihilation in the Galactic bulge and satisfy the requirement that 90 per cent of positrons annihilate once the outflow has cooled to 104 K.

Radio Observations as a Tool to Investigate Shocks and Asymmetries in Accreting White Dwarf Binaries

NASA Astrophysics Data System (ADS)

Weston, Jennifer Helen Seng; E-Nova Project

2017-01-01

In this dissertation, I use radio observations with the Karl G. Jansky Very Large Array (VLA) to reveal that colliding flows within the ejecta from nova explosions can lead to shocks that accelerate particles and produce radio synchrotron emission. In both novae V1723 Aql and V5589 Sgr, radio emission within the first one to two months deviated strongly from the classic thermal model for radio emission from novae. Three years of radio observations of V1723 Aql show that multiple outflows from the system collided to create non-thermal shocks with a brightness temperature of >106 K. After these shocks faded, the radio light curve became roughly consistent with an expanding thermal shell. However, resolved images of V1723 Aql show elongated material that apparently rotates its major axis over the course of 15 months. In the case of nova V5589 Sgr, I show that the early radio emission is dominated by a shock-powered non-thermal flare that produces strong (kTx > 33 keV) X-rays. These findings have important implications for understanding how normal novae generate GeV gamma-rays.Additionally, I present VLA observations of the symbiotic star CH Cyg and two small surveys of symbiotic binaries. Radio observations of CH Cyg tie the ejection of a collimated jet to a change of state in the accretion disk, strengthening the link between bipolar outflows from accreting white dwarfs and other types of accreting compact objects. Next, I use a survey of eleven accretion-driven symbiotic binaries to determine that the radio brightness of a symbiotic system could potentially be used as an indicator of whether it is powered predominantly by shell burning on the surface of the white dwarf or by accretion. This survey also produces the first radio detections of seven of the target systems. In the second survey of seventeen symbiotic binaries, I spatially resolve extended radio emission in several systems for the first time. The results from these surveys provide some support for the model of radio emission where the red giant wind is photoionized by the white dwarf, and suggest that there may be a greater population of radio faint, accretion driven symbiotic systems.

Correlated fast X-ray and optical variability in the black-hole candidate XTE J1118+480.

PubMed

Kanbach, G; Straubmeier, C; Spruit, H C; Belloni, T

2001-11-08

Black holes become visible when they accrete gas, a common source of which is a close stellar companion. The standard theory for this process (invoking a 'thin accretion disk') does not explain some spectacular phenomena associated with these systems, such as their X-ray variability and relativistic outflows, indicating some lack of understanding of the actual physical conditions. Simultaneous observations at multiple wavelengths can provide strong constraints on these conditions. Here we report simultaneous high-time-resolution X-ray and optical observations of the transient source XTE J1118+480, which show a strong but puzzling correlation between the emissions. The optical emission rises suddenly following an increase in the X-ray output, but with a dip 2-5 seconds in advance of the X-rays. This result is not easy to understand within the simplest model of the optical emission, where the light comes from reprocessed X-rays. It is probably more consistent with an earlier suggestion that the optical light is cyclosynchrotron emission that originates in a region about 20,000 km from the black hole. We propose that the time dependence is evidence for a relatively slow (<0.1c), magnetically controlled outflow.

Broadband observations of the naked-eye gamma-ray burst GRB 080319B.

PubMed

Racusin, J L; Karpov, S V; Sokolowski, M; Granot, J; Wu, X F; Pal'shin, V; Covino, S; van der Horst, A J; Oates, S R; Schady, P; Smith, R J; Cummings, J; Starling, R L C; Piotrowski, L W; Zhang, B; Evans, P A; Holland, S T; Malek, K; Page, M T; Vetere, L; Margutti, R; Guidorzi, C; Kamble, A P; Curran, P A; Beardmore, A; Kouveliotou, C; Mankiewicz, L; Melandri, A; O'Brien, P T; Page, K L; Piran, T; Tanvir, N R; Wrochna, G; Aptekar, R L; Barthelmy, S; Bartolini, C; Beskin, G M; Bondar, S; Bremer, M; Campana, S; Castro-Tirado, A; Cucchiara, A; Cwiok, M; D'Avanzo, P; D'Elia, V; Valle, M Della; de Ugarte Postigo, A; Dominik, W; Falcone, A; Fiore, F; Fox, D B; Frederiks, D D; Fruchter, A S; Fugazza, D; Garrett, M A; Gehrels, N; Golenetskii, S; Gomboc, A; Gorosabel, J; Greco, G; Guarnieri, A; Immler, S; Jelinek, M; Kasprowicz, G; La Parola, V; Levan, A J; Mangano, V; Mazets, E P; Molinari, E; Moretti, A; Nawrocki, K; Oleynik, P P; Osborne, J P; Pagani, C; Pandey, S B; Paragi, Z; Perri, M; Piccioni, A; Ramirez-Ruiz, E; Roming, P W A; Steele, I A; Strom, R G; Testa, V; Tosti, G; Ulanov, M V; Wiersema, K; Wijers, R A M J; Winters, J M; Zarnecki, A F; Zerbi, F; Mészáros, P; Chincarini, G; Burrows, D N

2008-09-11

Long-duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of massive stars. Previous early optical observations of even the most exceptional GRBs (990123 and 030329) lacked both the temporal resolution to probe the optical flash in detail and the accuracy needed to trace the transition from the prompt emission within the outflow to external shocks caused by interaction with the progenitor environment. Here we report observations of the extraordinarily bright prompt optical and gamma-ray emission of GRB 080319B that provide diagnostics within seconds of its formation, followed by broadband observations of the afterglow decay that continued for weeks. We show that the prompt emission stems from a single physical region, implying an extremely relativistic outflow that propagates within the narrow inner core of a two-component jet.

Magnetic Origin of Black Hole Winds Across the Mass Scale

NASA Technical Reports Server (NTRS)

Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Tombesi, Francesco; Contopoulos, Ioannis

2017-01-01

Black hole accretion disks appear to produce invariably plasma outflows that result in blue-shifted absorption features in their spectra. The X-ray absorption-line properties of these outflows are quite diverse, ranging in velocity from non-relativistic (approx. 300 km/sec) to sub-relativistic (approx. 0.1c where c is the speed of light) and a similarly broad range in the ionization states of the wind plasma. We report here that semi-analytic, self-similar magnetohydrodynamic (MHD) wind models that have successfully accounted for the X-ray absorber properties of supermassive black holes, also fit well the high-resolution X-ray spectrum of the accreting stellar-mass black hole, GRO J1655-40. This provides an explicit theoretical argument of their MHD origin (aligned with earlier observational claims) and supports the notion of a universal magnetic structure of the observed winds across all known black hole sizes.

Quasar Outflows and AGN Feedback in the Extreme UV: HST/COS Observations of QSO HE0238-1904

NASA Astrophysics Data System (ADS)

Arav, Nahum; Borguet, B.; Chamberlain, C.; Edmonds, D.; Danforth, C.

2014-01-01

Spectroscopic observations of quasar outflows at rest-frame 500-1000 Angstrom have immense diagnostic power. We present analyses of such data, where absorption troughs from three important ions are measured: first, O IV and O IV* that allow us to obtain the distance of high ionization outflows from the AGN; second, Ne VIII and Mg X that are sensitive to the very high ionization phase of the outflow. Their inferred column densities, combined with those of troughs from O VI, N IV, and H I, yield two important results: 1) The outflow shows two ionization phases, where the high ionization phase carries the bulk of the material. This is similar to the situation seen in x-ray warm absorber studies. Furthermore, the low ionization phase is inferred to have a volume filling factor of 10^(-5)-10^(-6). 2) From the O IV to O IV* column density ratio, and the knowledge of the ionization parameter, we determine a distance of 3000 pc. from the outflow to the central source. Since this is a typical high ionization outflow, we can determine robust values for the mass flux and kinetic luminosity of the outflow: 40 solar masses per year and 10^45 ergs/s, respectively, where the latter is roughly equal to 1% of the bolometric luminosity. Such a large kinetic luminosity and mass flow rate measured in a typical high ionization wind suggests that quasar outflows are a major contributor to AGN feedback mechanisms.

Time-dependent models for blazar emission with the second-order Fermi acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asano, Katsuaki; Takahara, Fumio; Toma, Kenji

The second-order Fermi acceleration (Fermi-II) driven by turbulence may be responsible for the electron acceleration in blazar jets. We test this model with time-dependent simulations. The hard electron spectrum predicted by the Fermi-II process agrees with the hard photon spectrum of 1ES 1101–232. For other blazars that show softer spectra, the Fermi-II model requires radial evolution of the electron injection rate and/or diffusion coefficient in the outflow. Such evolutions can yield a curved electron spectrum, which can reproduce the synchrotron spectrum of Mrk 421 from the radio to the X-ray regime. The photon spectrum in the GeV energy range ofmore » Mrk 421 is hard to fit with a synchrotron self-Compton model. However, if we introduce an external radio photon field with a luminosity of 4.9 × 10{sup 38} erg s{sup –1}, GeV photons are successfully produced via inverse Compton scattering. The temporal variability of the diffusion coefficient or injection rate causes flare emission. The observed synchronicity of X-ray and TeV flares implies a decrease of the magnetic field in the flaring source region.« less

A Unified View of X-ray Absorbers in AGNs and XRBs with MHD Winds

NASA Astrophysics Data System (ADS)

Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris R.; Tombesi, Francesco; Behar, Ehud; Contopoulos, John

2016-01-01

The presence of UV and X-ray absorbers (aka. warm absorbers or WAs) has been long known for decades from extensive spectroscopic studies across diverse AGN populations such as nearby Seyfert galaxies and distant quasars. Furthermore, another class of seemingly distinct type of absorbers, ultra-fast outflows or UFOs, is becoming increasingly known today. Nonetheless, a physical identification of such absorbers, such as geometrical property and physical conditions, is very elusive to date despite the recent state-of-the-art observations. We develop a coherent scenario in which the detected absorbers are driven primarily (if not exclusively) by the action of global magnetic fields originating from a black hole accretion disk. In the context of MHD disk-wind of density profile of n~1/r, it is found that the properties of the observed WAs/UFOs are successfully described assuming a characteristic SED. As a case study, we analyze PG1211+143 and GRO J1655-40 to demonstrate that our wind model can systematically unify apparently diverse absorbers in both AGNs and XRBs in terms of explaining their global behavior as well as individual spectral lines.

Ultra-Fast Outflows in Radio-Loud AGN: New Constraints on Jet-Disk Connection

NASA Astrophysics Data System (ADS)

Sambruna, Rita

There is strong observational and theoretical evidence that outflows/jets are coupled to accretion disks in black hole accreting systems, from Galactic to extragalactic sizes. While in radio-quiet AGN there is ample evidence for the presence of Ultra-Fast Outflows (UFOs) from the presence of blue-shifted absorption features in their 4-10~keV spectra, sub-relativistic winds are expected on theoretical basis in radio-loud AGN but have not been observed until now. Our recent Suzaku observations of 5 bright Broad- Line Radio Galaxies (BLRGs, the radio-loud counterparts of Seyferts) has started to change this picture. We found strong evidence for UFOs in 3 out of 5 BLRGs, with ionization parameters, column densities, and velocities of the absorber similar to Seyferts. Moreover, the outflows in BLRGs are likely to be energetically very significant: from the Suzaku data of the three sources, outflow masses similar to the accretion masses and kinetic energies of the wind similar to the X-ray luminosity and radio power of the jet are inferred. Clearly, UFOs in radio-loud AGN represent a new key ingredient to understand their central engines and in particular, the jet-disk linkage. Our discovery of UFOs in a handful of BLRGs raises the questions of how common disk winds are in radio-loud AGN, what the absorber physical and dynamical characteristics are, and what is the outflow role in broader picture of galaxy-black hole connection for radio sources, i.e., for large-scale feedback models. To address these and other issues, we propose to use archival XMM-Newton and Suzaku spectra to search for Ultra-Fast Outflows in a large number of radio sources. Over a period of two years, we will conduct a systematic, uniform analysis of the archival X-ray data, building on our extensive experience with a similar previous project for Seyferts, and using robust analysis and statistical methodologies. As an important side product, we will also obtain accurate, self- consistent measurements of the broad-band X-ray spectra of radio-loud AGN for comparison to radio-quiet, addressing the origin of the division between the two classes. In addition, the upcoming Astro-H mission will greatly benefit from the outcomes of this project, which will provide templates for realistic simulations to define the scientific requirements of the calorimeter, and a list of targets to design a sample for the core AGN projects of the team.

CSO CO (2–1) and Spitzer IRAC observations of a bipolar outflow in high-mass star-forming region IRAS 22506+5944

NASA Astrophysics Data System (ADS)

Xie, Ze-Qiang; Qiu, Ke-Ping

2018-02-01

We present Caltech Submillimeter Observatory CO (2–1) and Spitzer IRAC observations toward IRAS 22506+5944, which is a 104 L ⊙ massive star-forming region. The CO (2–1) maps show an east-west bipolar molecular outflow originating from the 3 mm dust continuum peak. The Spitzer IRAC color-composite image reveals a pair of bow-shaped tips which are prominent in excess 4.5μm emission and are located at the leading fronts of the bipolar outflow, providing compelling evidence for the existence of bow-shocks as the driving agents of the molecular outflow. By comparing our CO (2–1) observations with previously published CO (1–0) data, we find that the CO (2–1)/(1–0) line ratio increases from low (∼5 kms‑1) to moderate (∼8–12 kms‑1) velocities, and then decreases at higher velocities. This is qualitatively consistent with the scenario that the molecular outflow is driven by multiple bow-shocks. We also revisit the position-velocity diagram of the CO (1–0) data, and find two spur structures along the outflow axis, which are further evidence for the presence of multiple jet bowshocks. Finally, power-law fittings to the mass spectrum of the outflow gives power law indexes more consistent with the jet bow-shock model than the wide-angle wind model.

Nature versus Nurture: The Origin of Soft Gamma-Ray Repeaters and Anomalous X-Ray Pulsars

NASA Astrophysics Data System (ADS)

Marsden, D.; Lingenfelter, R. E.; Rothschild, R. E.; Higdon, J. C.

2001-03-01

Soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are young and radio-quiet X-ray pulsars that have been rapidly spun-down to slow spin periods clustered in the range 5-12 s. Most of these unusual pulsars also appear to be associated with supernova shell remnants (SNRs) with typical ages less than 30 kyr. By examining the sizes of these remnants versus their ages, we demonstrate that the interstellar media that surrounded the SGR and AXP progenitors and their SNRs were unusually dense compared to the environments around most young radio pulsars and SNRs. We explore the implications of this evidence on magnetar and propeller-based models for the rapid spin-down of SGRs and AXPs. We find that evidence of dense environments is not consistent with the magnetar model unless a causal link can be shown between the development of magnetars and the external interstellar medium. Propeller-driven spin-down by fossil accretion disks for SGRs and AXPs appears to be consistent with dense environments since the environment can facilitate the formation of such a disk. This may occur in two ways: (1) formation of a ``pushback'' disk from the innermost ejecta pushed back by prompt reverse shocks from supernova remnant interactions with massive progenitor wind material stalled in dense surrounding gas or (2) acquisition of disks by a high-velocity neutron stars, which may be able to capture sufficient amounts of comoving outflowing ejecta slowed by the prompt reverse shocks in dense environments.

Outflow-driven Transients from the Birth of Binary Black Holes. I. Tidally Locked Secondary Supernovae

NASA Astrophysics Data System (ADS)

Kimura, Shigeo S.; Murase, Kohta; Mészáros, Peter

2017-12-01

We propose a new type of electromagnetic transient associated with the birth of binary black holes (BBHs), which may lead to merger events accompanied by gravitational waves in ∼ 0.1{--}1 {Gyr}. We consider the newborn BBHs formed through the evolution of isolated massive stellar binaries. For a close massive binary, consisting of a primary black hole (BH) and a secondary Wolf–Rayet (WR) star that are orbiting around each other, the spin period of the WR star can be tidally synchronized to its orbital period. Then the angular momentum of the outer material of the WR star is large enough to form an accretion disk around a newborn, secondary BH, following its core-collapse. This disk may produce an energetic outflow with a kinetic energy of ∼ {10}50{--}{10}52 {erg} and an outflow velocity of ∼ {10}10 {cm} {{{s}}}-1, resulting in an optical transient with an absolute magnitude from approximately ‑14 to approximatley ‑17 with a duration of around a day. This type of transient also produces detectable radio signals ∼ 1{--}10 years after the birth of BBHs, via synchrotron emission from nonthermal electrons accelerated at external shocks. The predicted optical transients have a shorter duration than ordinary core-collapse supernovae. Dedicated optical transient surveys can detect them and distinguish them from ordinary SNe using the different features of its light curve and late-time spectrum. In this paper (Paper I), we investigate disk-driven outflows from the secondary BH, whereas possible signals from the primary BH will be discussed in Paper II.

The SAMI Galaxy Survey: understanding observations of large-scale outflows at low redshift with EAGLE simulations

NASA Astrophysics Data System (ADS)

Tescari, E.; Cortese, L.; Power, C.; Wyithe, J. S. B.; Ho, I.-T.; Crain, R. A.; Bland-Hawthorn, J.; Croom, S. M.; Kewley, L. J.; Schaye, J.; Bower, R. G.; Theuns, T.; Schaller, M.; Barnes, L.; Brough, S.; Bryant, J. J.; Goodwin, M.; Gunawardhana, M. L. P.; Lawrence, J. S.; Leslie, S. K.; López-Sánchez, Á. R.; Lorente, N. P. F.; Medling, A. M.; Richards, S. N.; Sweet, S. M.; Tonini, C.

2018-01-01

This work presents a study of galactic outflows driven by stellar feedback. We extract main-sequence disc galaxies with stellar mass 109 ≤ M⋆/ M⊙ ≤ 5.7 × 1010 at redshift z = 0 from the highest resolution cosmological simulation of the Evolution and Assembly of GaLaxies and their Environments (EAGLE) set. Synthetic gas rotation velocity and velocity dispersion (σ) maps are created and compared to observations of disc galaxies obtained with the Sydney-AAO (Australian Astronomical Observatory) Multi-object Integral field spectrograph (SAMI), where σ-values greater than 150 km s-1 are most naturally explained by bipolar outflows powered by starburst activity. We find that the extension of the simulated edge-on (pixelated) velocity dispersion probability distribution depends on stellar mass and star formation rate surface density (ΣSFR), with low-M⋆/low-ΣSFR galaxies showing a narrow peak at low σ (∼30 km s-1) and more active, high-M⋆/high-ΣSFR galaxies reaching σ > 150 km s-1. Although supernova-driven galactic winds in the EAGLE simulations may not entrain enough gas with T <105 K compared to observed galaxies, we find that gas temperature is a good proxy for the presence of outflows. There is a direct correlation between the thermal state of the gas and its state of motion as described by the σ-distribution. The following equivalence relations hold in EAGLE: (i) low-σ peak ⇔ disc of the galaxy ⇔ gas with T <105 K; (ii) high-σ tail ⇔ galactic winds ⇔ gas with T ≥105 K.

Associating long-term γ-ray variability with the superorbital period of LS I +61°303

DOE PAGES

Ackermann, M.; Ajello, M.; Ballet, J.; ...

2013-08-07

Gamma-ray binaries are stellar systems for which the spectral energy distribution (discounting the thermal stellar emission) peaks at high energies. Detected from radio to TeV gamma rays, the γ-ray binary LS I +61°303 is highly variable across all frequencies. One aspect of this system's variability is the modulation of its emission with the timescale set by the ~26.4960 day orbital period. Here we show that, during the time of our observations, the γ-ray emission of LS I +61°303 also presents a sinusoidal variability consistent with the previously known superorbital period of 1667 days. This modulation is more prominently seen atmore » orbital phases around apastron, whereas it does not introduce a visible change close to periastron. It is also found in the appearance and disappearance of variability at the orbital period in the power spectrum of the data. This behavior could be explained by a quasi-cyclical evolution of the equatorial outflow of the Be companion star, whose features influence the conditions for generating gamma rays. Furthermore, these findings open the possibility to use γ-ray observations to study the outflows of massive stars in eccentric binary systems.« less

ASSOCIATING LONG-TERM {gamma}-RAY VARIABILITY WITH THE SUPERORBITAL PERIOD OF LS I +61 Degree-Sign 303

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackermann, M.; Buehler, R.; Ajello, M.

2013-08-20

Gamma-ray binaries are stellar systems for which the spectral energy distribution (discounting the thermal stellar emission) peaks at high energies. Detected from radio to TeV gamma rays, the {gamma}-ray binary LS I +61 Degree-Sign 303 is highly variable across all frequencies. One aspect of this system's variability is the modulation of its emission with the timescale set by the {approx}26.4960 day orbital period. Here we show that, during the time of our observations, the {gamma}-ray emission of LS I +61 Degree-Sign 303 also presents a sinusoidal variability consistent with the previously known superorbital period of 1667 days. This modulation ismore » more prominently seen at orbital phases around apastron, whereas it does not introduce a visible change close to periastron. It is also found in the appearance and disappearance of variability at the orbital period in the power spectrum of the data. This behavior could be explained by a quasi-cyclical evolution of the equatorial outflow of the Be companion star, whose features influence the conditions for generating gamma rays. These findings open the possibility to use {gamma}-ray observations to study the outflows of massive stars in eccentric binary systems.« less

Supernova-driven outflows and chemical evolution of dwarf spheroidal galaxies

PubMed Central

Qian, Yong-Zhong; Wasserburg, G. J.

2012-01-01

We present a general phenomenological model for the metallicity distribution (MD) in terms of [Fe/H] for dwarf spheroidal galaxies (dSphs). These galaxies appear to have stopped accreting gas from the intergalactic medium and are fossilized systems with their stars undergoing slow internal evolution. For a wide variety of infall histories of unprocessed baryonic matter to feed star formation, most of the observed MDs can be well described by our model. The key requirement is that the fraction of the gas mass lost by supernova-driven outflows is close to unity. This model also predicts a relationship between the total stellar mass and the mean metallicity for dSphs in accord with properties of their dark matter halos. The model further predicts as a natural consequence that the abundance ratios [E/Fe] for elements such as O, Mg, and Si decrease for stellar populations at the higher end of the [Fe/H] range in a dSph. We show that, for infall rates far below the net rate of gas loss to star formation and outflows, the MD in our model is very sharply peaked at one [Fe/H] value, similar to what is observed in most globular clusters. This result suggests that globular clusters may be end members of the same family as dSphs. PMID:22411827

Supernova-driven outflows and chemical evolution of dwarf spheroidal galaxies.

PubMed

Qian, Yong-Zhong; Wasserburg, G J

2012-03-27

We present a general phenomenological model for the metallicity distribution (MD) in terms of [Fe/H] for dwarf spheroidal galaxies (dSphs). These galaxies appear to have stopped accreting gas from the intergalactic medium and are fossilized systems with their stars undergoing slow internal evolution. For a wide variety of infall histories of unprocessed baryonic matter to feed star formation, most of the observed MDs can be well described by our model. The key requirement is that the fraction of the gas mass lost by supernova-driven outflows is close to unity. This model also predicts a relationship between the total stellar mass and the mean metallicity for dSphs in accord with properties of their dark matter halos. The model further predicts as a natural consequence that the abundance ratios [E/Fe] for elements such as O, Mg, and Si decrease for stellar populations at the higher end of the [Fe/H] range in a dSph. We show that, for infall rates far below the net rate of gas loss to star formation and outflows, the MD in our model is very sharply peaked at one [Fe/H] value, similar to what is observed in most globular clusters. This result suggests that globular clusters may be end members of the same family as dSphs.

Particle-in-Cell Simulation of Collisionless Driven Reconnection with Open Boundaries

NASA Technical Reports Server (NTRS)

Kimas, Alex; Hesse, Michael; Zenitani, Seiji; Kuznetsova, Maria

2010-01-01

First results are discussed from an ongoing study of driven collisionless reconnection using a 2 1/2-dimensional electromagnetic particle-in-cell simulation model with open inflow and outflow boundaries. An extended electron diffusion region (EEDR) is defined as that region surrounding a reconnecting neutral line in which the out-of-plane nonideal electric field is positive. It is shown that the boundaries of this region in the directions of the outflow jets are at the positions where the electrons make the transition from unfrozen meandering motion in the current sheet to outward drifting with the magnetic field in the outflow jets; a turning length scale is defined to mark these positions, The initial width of the EEDR in the inflow directions is comparable to the electron bounce width. Later. as shoulders develop to form a two-scale structure. thc EEDR width expands to the ion bounce width scale. The inner portion of the EEDR or the electron diffusion region proper remains at the electron bounce width. Two methods are introduced for predicting the reconnection electric field using the dimensions of the EEDR. These results are interpreted as further evidence that the EEDR is the region that is relevant to understanding the electron role in the neutral line vicinity.

BAT AGN Spectroscopic Survey - III. An Observed Link Between AGN Eddington Ratio and Narrow-Emission-Line Ratios

NASA Technical Reports Server (NTRS)

Oh, Kyuseok; Schawinski, Kevin; Koss, Michael; Trakhtenbrot, Benny; Lamperti, Isabella; Ricci, Claudio; Mushotzky, Richard; Veilleux, Sylvain; Berney, Simon; Crenshaw, D. Michael;

Multi-phase Nature of a Radiation-driven Fountain with Nuclear Starburst in a Low-mass Active Galactic Nucleus

NASA Astrophysics Data System (ADS)

Wada, Keiichi; Schartmann, Marc; Meijerink, Rowin

2016-09-01

The structures and dynamics of molecular, atomic, and ionized gases are studied around a low-luminosity active galactic nucleus (AGN) with a small (2× {10}6{M}⊙ ) black hole using three-dimensional (3D) radiation-hydrodynamic simulations. We studied, for the first time, the non-equilibrium chemistry for the X-ray-dominated region in the “radiation-driven fountain” with supernova feedback. A double hollow cone structure is naturally formed without postulating a thick “torus” around a central source. The cone is occupied with an inhomogeneous, diffuse ionized gas and surrounded by a geometrically thick (h/r≳ 1) atomic gas. Dense molecular gases are distributed near the equatorial plane, and energy feedback from supernovae enhances their scale height. Molecular hydrogen exists in a hot phase (>1000 K) as well as in a cold (\\lt 100 {{K}}), dense (\\gt {10}3 {{cm}}-3) phase. The velocity dispersion of H2 in the vertical direction is comparable to the rotational velocity, which is consistent with near-infrared observations of nearby Seyfert galaxies. Using 3D radiation transfer calculations for the dust emission, we find polar emission in the mid-infrared band (12 μm), which is associated with bipolar outflows, as suggested in recent interferometric observations of nearby AGNs. If the viewing angle for the nucleus is larger than 75°, the spectral energy distribution is consistent with that of the Circinus galaxy. The multi-phase interstellar medium observed in optical/infrared and X-ray observations is also discussed.

Unification of X-ray Winds in Seyfert Galaxies: From Ultra-fast Outflows to Warm Absorbers

NASA Technical Reports Server (NTRS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Nemmen, R. S.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-01-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent with previous studies. The fraction of sources with UFOs is >34 per cent, >67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show a sufficiently high mechanical power (at least approx 0.5 per cent of the bolometric luminosity) to provide a significant contribution to active galactic nuclei (AGN) feedback and thus to the evolution of the host galaxy. In this regard, we find possible evidence for the interaction of the AGN wind with the surrounding environment on large scales.

Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Nemmen, R. S.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-04-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent with previous studies. The fraction of sources with UFOs is >34 per cent, >67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show a sufficiently high mechanical power (at least ˜0.5 per cent of the bolometric luminosity) to provide a significant contribution to active galactic nuclei (AGN) feedback and thus to the evolution of the host galaxy. In this regard, we find possible evidence for the interaction of the AGN wind with the surrounding environment on large scales.

Multi-fluid simulations of the coupled solar wind-magnetosphere-ionsphere system

NASA Astrophysics Data System (ADS)

Lyon, J.

2011-12-01

This paper will review recent work done with the multi-fluid version of the Lyon-Fedder-Mobarry (MF-LFM) global MHD simulation code. We will concentrate on O+ outflow from the ionosphere and its importance for magnetosphere-ionosphere (MI) coupling and also the importance of ionospheric conditions in determining the outflow. While the predominant method of coupling between the magnetosphere and ionosphere is electrodynamic, it has become apparent the mass flows from the ionosphere into the magnetosphere can have profound effects on both systems. The earliest models to attempt to incorporate this effect used very crude clouds of plasma near the Earth. The earliest MF-LFM results showed that depending on the details of the outflow - where, how much, how fast - very different magnetospheric responses could be found. Two approaches to causally driven models for the outflow have been developed for use in global simulations, the Polar Wind Outflow Model (PWOM), started at the Univ. of Michigan, and the model used by Bill Lotko and co-workers at Dartmouth. We will give a quick review of this model which is based on the empirical relation between outflow fluence and Poynting flux discovered by Strangeway. An additional factor used in this model is the precipitating flux of electrons, which is presumed to correlate with the scale height of the upwelling ions. parameters such as outflow speed and density are constrained by the total fluence. The effects of the outflow depend on the speed. Slower outflow tends to land in the inner magnetosphere increasing the strength of the ring current. Higher speed flow out in the tail. Using this model, simulations have shown that solar wind dynamic pressure has a profound effect on the amount of fluence. The most striking result has been the simulation of magnetospheric sawtooth events. We will discuss future directions for this research, emphasizing the need for better physical models for the outflow process and its coupling to the ionosphere.

A Suzaku, NuSTAR and XMMNewton} view on variable absorption and relativistic reflection in NGC 4151

NASA Astrophysics Data System (ADS)

Beuchert, T.; Markowitz, A.; Dauser, T.; Garcia, J.; Keck, M.; Wilms, J.; Kadler, M.; Brenneman, L.; Zdziarski, A.

2017-10-01

We disentangle X-ray disk reflection from complex line-of-sight absorption in NGC 4151 using Suzaku, NuSTAR, and XMMNewton}. Extending upon Keck et al. (2015), we develop a physically-motivated baseline model using the latest lamp-post reflection code relxillCp_lp, which includes a Comptonization continuum. We identify two components at heights of 1.2 and 15.0 gravitational radii using a long-look simultaneous Suzaku/NuSTAR observation but argue for a vertically extended corona as opposed to distinct primary sources. We also find two neutral absorbers (one full-covering and one partial-covering), an ionized absorber (log ξ=2.8), and a highly-ionized ultra-fast outflow, all reported previously. All analyzed spectra are well described by this baseline model. The bulk of the spectral variability on time-scales from days to years can be attributed to changes of both neutral absorbers, which are inversely correlated with the hard X-ray continuum flux. The observed evolution is either consistent with changes in the absorber structure (clumpy absorber in the outer BLR or a dusty radiatively driven wind) or a geometrically stable neutral absorber that becomes increasingly ionized at a rising flux level. The soft X-rays below 1 keV are dominated by photoionized emission from extended gas, which may act as a warm mirror for the nuclear radiation.

A Brown Dwarf Joins the Jet-Set

NASA Astrophysics Data System (ADS)

2007-05-01

Jets of matter have been discovered around a very low mass 'failed star', mimicking a process seen in young stars. This suggests that these 'brown dwarfs' form in a similar manner to normal stars but also that outflows are driven out by objects as massive as hundreds of millions of solar masses down to Jupiter-sized objects. The brown dwarf with the name 2MASS1207-3932 is full of surprises [1]. Its companion, a 5 Jupiter-mass giant, was the first confirmed exoplanet for which astronomers could obtain an image (see ESO 23/04 and 12/05), thereby opening a new field of research - the direct detection of alien worlds. It was then later found (see ESO 19/06) that the brown dwarf has a disc surrounding it, not unlike very young stars. ESO PR Photo 24/07 ESO PR Photo 24/07 Jets from a Brown Dwarf (Artist's Impression) Now, astronomers using ESO's Very Large Telescope (VLT) have found that the young brown dwarf is also spewing jets, a behaviour again quite similar to young stars. The mass of the brown dwarf is only 24 Jupiter-masses. Hence, it is by far the smallest object known to drive an outflow. "This leads us to the tantalizing prospect that young giant planets could also be associated with outflows," says Emma Whelan, the lead-author of the paper reporting the results. The outflows were discovered using an amazing technique known as spectro-astrometry, based on high resolution spectra taken with UVES on the VLT. Such a technique was required due to the difficulty of the task. While in normal young stars - known as T-Tauri stars for the prototype of their class - the jets are large and bright enough to be seen directly, this is not the case around brown dwarfs: the length scale of the jets, recovered with spectro-astrometry is only about 0.1 arcsecond long, that is, the size of a two Euro coin seen from 40 km away. The jets stretch about 1 billion kilometres and the material is rushing away from the brown dwarf with a speed of a few kilometres per second. The astronomers had to rely on the power of the VLT because the observed emission is extremely faint and only UVES on the VLT could provide both the sensitivity and the spectral resolution they required. "Discoveries like these are purely reliant on excellent telescopes and instruments, such as the VLT," says Whelan. "Our result also highlights the incredible level of quality which is available today to astronomers: the first telescopes built by Galileo were used to observe the moons of Jupiter. Today, the largest ground-based telescopes can be used to observe a Jupiter size object at a distance of 200 light-years and find it has outflows!" Using the same technique and the same telescope, the team had previously discovered outflows in another young brown dwarf. The new discovery sets a record for the lowest mass object in which jets are seen [2]. Outflows are ubiquitous in the Universe, as they are observed rushing away from the active nuclei of galaxies - AGNs - but also emerging from young stars. The present observations show they even arise in still lower mass objects. The outflow mechanism is thus very robust over an enormous range of masses, from several tens of millions of solar mass (for AGNs) down to a few tens of Jupiter masses (for brown dwarfs). More Information These results were reported in a Letter to the Editor in the Astrophysical Journal (vol. 659, p. L45): "Discovery of a Bipolar Outflow from 2MASSW J1207334-393254 a 24 MJup Brown Dwarf", by E.T. Whelan et al. The team is composed of Emma Whelan and Tom Ray (Dublin Institute for Advanced Studies, Ireland), Ray Jayawardhana (University of Toronto, Canada), Francesca Bacciotti, Antonella Natta and Sofia Randich (Osservatorio Astrofisico di Arcetri, Italy), Leonardo Testi (ESO), and Subu Mohanty (Harvard-Smithsonian CfA, USA).

Outflow activities in the young high-mass stellar object G23.44-0.18

NASA Astrophysics Data System (ADS)

Ren, Jeremy Zhiyuan; Liu, Tie; Wu, Yuefang; Li, Lixin

2011-07-01

We present an observational study towards the young high-mass star-forming region G23.44-0.18 using the Submillimeter Array. Two massive, radio-quiet dusty cores MM1 and MM2 are observed in 1.3-mm continuum emission and dense molecular gas tracers including thermal CH3OH, CH3CN, HNCO, SO, and OCS lines. The 12CO (2-1) line reveals a strong bipolar outflow originating from MM2. The outflow consists of a low-velocity component with wide-angle quasi-parabolic shape and a more compact and collimated high-velocity component. The overall geometry resembles the outflow system observed in the low-mass protostar which has a jet-driven fast flow and entrained gas shell. The outflow has a dynamical age of 6 × 103 yr and a mass loss rate ˜10-3 M ⊙ yr-1. A prominent shock emission in the outflow is observed in SO and OCS, and also detected in CH3OH and HNCO. We investigated the chemistry of MM1, MM2 and the shocked region. The dense core MM2 have molecular abundances of three to four times higher than those in MM1. The abundance excess, we suggest, can be a net effect of the stellar evolution and embedded shocks in MM2 that calls for further inspection.

Magnetic field amplification via protostellar disc dynamos

NASA Astrophysics Data System (ADS)

Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Koldoba, A. V.; Wasserman, I.

2018-06-01

We numerically investigate the generation of a magnetic field in a protostellar disc via an αΩ-dynamo and the resulting magnetohydrodynamic (MHD) driven outflows. We find that for small values of the dimensionless dynamo parameter αd, the poloidal field grows exponentially at a rate σ ∝ Ω _K √{α _d}, before saturating to a value ∝ √{α _d}. The dynamo excites dipole and octupole modes, but quadrupole modes are suppressed, because of the symmetries of the seed field. Initial seed fields too weak to launch MHD outflows are found to grow sufficiently to launch winds with observationally relevant mass fluxes of the order of 10^{-9} M_{⊙} yr^{-1} for T Tauri stars. This suggests that αΩ-dynamos may be responsible for generating magnetic fields strong enough to launch observed outflows.

Stellar physics. Observing the onset of outflow collimation in a massive protostar.

PubMed

Carrasco-González, C; Torrelles, J M; Cantó, J; Curiel, S; Surcis, G; Vlemmings, W H T; van Langevelde, H J; Goddi, C; Anglada, G; Kim, S-W; Kim, J-S; Gómez, J F

2015-04-03

The current paradigm of star formation through accretion disks, and magnetohydrodynamically driven gas ejections, predicts the development of collimated outflows, rather than expansion without any preferential direction. We present radio continuum observations of the massive protostar W75N(B)-VLA 2, showing that it is a thermal, collimated ionized wind and that it has evolved in 18 years from a compact source into an elongated one. This is consistent with the evolution of the associated expanding water-vapor maser shell, which changed from a nearly circular morphology, tracing an almost isotropic outflow, to an elliptical one outlining collimated motions. We model this behavior in terms of an episodic, short-lived, originally isotropic ionized wind whose morphology evolves as it moves within a toroidal density stratification. Copyright © 2015, American Association for the Advancement of Science.

The COS revolution of AGN outflow science

NASA Astrophysics Data System (ADS)

Arav, Nahum

2016-10-01

HST/COS has opened a new discovery space for quasar outflow science. Specifically, it provides high quality FUV spectra covering the diagnostic-rich 500A-1050A rest-frame of medium redshift objects. We have published three refereed papers based on the analysis of such data that were supported by our concluded COS archive program, in which we reported: a) a new population of very high ionization outflows, b) robust cases of two-ionization-phase outflows, which are the missing link between UV AGN outflows and x-ray warm absorbers, and most importantly c) spectral diagnostics that allowed us to determine the distance of the outflows from the central source. The latter is a cardinal issue in the field as many researchers believe that most outflows are situated close to the accretion disk ( 0.01 pc) while the few reliable measurements show distances of 10-10,000 pc. Therefore, every empirical distance measurement is of importance. Our archive based publication also demonstrates that quasar outflows have sufficient energy to match theoretical predictions for AGN feedback influencing galaxy evolution.We propose to continue this successful archive program. Thus far we've analyzed about 300 COS G130M and G160M orbits of AGN observations. There are roughly 900 additional orbits that satisfy our criteria and will be available within a year. Based on our published survey, we expect that these 900 orbits will yield about 20-30 additional very-high ionization outflows and 4-6 cases of distance and kinetic luminosity determinations, all in cosmologically important luminous-quasars.

Circulation in the Chesapeake Bay entrance region: Estuary-shelf interaction

NASA Technical Reports Server (NTRS)

Boicourt, W. C.

1981-01-01

Current meters and temperature-salinity recorders confirm the assumption that the upper layers of the continental shelf waters off Chesapeake Bay can be banded in summer, such that the coastal boundary layer (consisting of the Bay outflow) and the outer shelf flow southward while the inner shelf flows to the north, driven by the prevailing southerly winds. These measurements show that the estuary itself may also be banded in its lower reaches such that the inflow is confined primarily to the deep channel, while the upper layer outflow is split into two flow maxima on either side of this channel.

Directly Driven Ion Outflow

NASA Technical Reports Server (NTRS)

Elliott, H. A.; Comfort, R. H.; Craven, P. D.; Moore, T. E.; Russell, C. T.; Rose, M. Franklin (Technical Monitor)

2001-01-01

We examine ionospheric outflows in the high altitude magnetospheric polar cap during the POLAR satellite's apogee on April 19, 1996 using the Thermal Ion Dynamics Experiment (TIDE) instrument. The elevated levels of O(+) observed in this pass may be due to the geophysical conditions during and prior to the apogee pass. In addition to the high abundance of O(+) relative to H(+), several other aspects of this data are noteworthy. We observe relationships between the density, velocity, and temperature which appear to be associated with perpendicular heating and the mirror force, rather than adiabatic expansion. The H(+) outflow is at a fairly constant flux which is consistent with being source limited by charge exchange at lower altitudes. Local centrifugal acceleration in the polar cap is found to be insufficient to account for the main variations we observe in the outflow velocity. The solar wind speed is high during this pass approximately 700 kilometers per second, and there are Alfve'n waves present in the solar wind such that the solar wind speed and IMF Bx are correlated. In this pass both the H(+) and O(+) outflow velocities correlate with both the solar wind speed and IMF fluctuations. Polar cap magnetometer and Hydra electron data show the same long period wave structure as found in the solar wind and polar cap ion outflow. In addition, the polar cap Poynting flux along the magnetic field direction correlates well with the H(+) temperature (R=0.84). We conclude that the solar wind can drive polar cap ion outflow particularly during polar squalls by setting up a parallel drop that is tens of eV which then causes the ion outflow velocity of O(+) and H(+), the electrons, and magnetic perturbations to vary in a similar fashion.

An ultra-relativistic outflow from a neutron star accreting gas from a companion.

PubMed

Fender, Rob; Wu, Kinwah; Johnston, Helen; Tzioumis, Tasso; Jonker, Peter; Spencer, Ralph; Van Der Klis, Michiel

2004-01-15

Collimated relativistic outflows-also known as jets-are amongst the most energetic phenomena in the Universe. They are associated with supermassive black holes in distant active galactic nuclei, accreting stellar-mass black holes and neutron stars in binary systems and are believed to be responsible for gamma-ray bursts. The physics of these jets, however, remains something of a mystery in that their bulk velocities, compositions and energetics remain poorly determined. Here we report the discovery of an ultra-relativistic outflow from a neutron star accreting gas within a binary stellar system. The velocity of the outflow is comparable to the fastest-moving flows observed from active galactic nuclei, and its strength is modulated by the rate of accretion of material onto the neutron star. Shocks are energized further downstream in the flow, which are themselves moving at mildly relativistic bulk velocities and are the sites of the observed synchrotron emission from the jet. We conclude that the generation of highly relativistic outflows does not require properties that are unique to black holes, such as an event horizon.

Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona

NASA Astrophysics Data System (ADS)

Slemzin, V.; Harra, L.; Urnov, A.; Kuzin, S.; Goryaev, F.; Berghmans, D.

2013-08-01

The identification of solar-wind sources is an important question in solar physics. The existing solar-wind models ( e.g., the Wang-Sheeley-Arge model) provide the approximate locations of the solar wind sources based on magnetic field extrapolations. It has been suggested recently that plasma outflows observed at the edges of active regions may be a source of the slow solar wind. To explore this we analyze an isolated active region (AR) adjacent to small coronal hole (CH) in July/August 2009. On 1 August, Hinode/EUV Imaging Spectrometer observations showed two compact outflow regions in the corona. Coronal rays were observed above the active-region coronal hole (ARCH) region on the eastern limb on 31 July by STEREO-A/EUVI and at the western limb on 7 August by CORONAS- Photon/TESIS telescopes. In both cases the coronal rays were co-aligned with open magnetic-field lines given by the potential field source surface model, which expanded into the streamer. The solar-wind parameters measured by STEREO-B, ACE, Wind, and STEREO-A confirmed the identification of the ARCH as a source region of the slow solar wind. The results of the study support the suggestion that coronal rays can represent signatures of outflows from ARs propagating in the inner corona along open field lines into the heliosphere.

Off-axis Gamma-ray Burst Afterglow Modeling Based on a Two-dimensional Axisymmetric Hydrodynamics Simulation

NASA Astrophysics Data System (ADS)

van Eerten, Hendrik; Zhang, Weiqun; MacFadyen, Andrew

2010-10-01

Starting as highly relativistic collimated jets, gamma-ray burst outflows gradually slow down and become nonrelativistic spherical blast waves. Although detailed analytical solutions describing the afterglow emission received by an on-axis observer during both the early and late phases of the outflow evolution exist, a calculation of the received flux during the intermediate phase and for an off-axis observer requires either a more simplified analytical model or direct numerical simulations of the outflow dynamics. In this paper, we present light curves for off-axis observers covering the long-term evolution of the blast wave, calculated from a high-resolution two-dimensional relativistic hydrodynamics simulation using a synchrotron radiation model. We compare our results to earlier analytical work and calculate the consequence of the observer angle with respect to the jet axis both for the detection of orphan afterglows and for jet break fits to the observational data. We confirm earlier results in the literature finding that only a very small number of local type Ibc supernovae can harbor an orphan afterglow. For off-axis observers, the observable jet break can be delayed up to several weeks, potentially leading to overestimation of the beaming-corrected total energy. In addition we find that, when using our off-axis light curves to create synthetic Swift X-ray data, jet breaks are likely to remain hidden in the data.

Theory of High-Energy Emission from the Pulsar/Be Star System PSR 1259-63. I. Radiation Mechanisms and Interaction Geometry

NASA Astrophysics Data System (ADS)

Tavani, Marco; Arons, Jonathan

1997-03-01

We study the physical processes in the system containing the 47 ms radio pulsar PSR B1259-63 orbiting around a Be star in a highly eccentric orbit. This system is the only known binary where a radio pulsar is observed to interact with gaseous material from a Be star. A rapidly rotating radio pulsar such as PSR B1259-63 is expected to produce a wind of electromagnetic emission and relativistic particles, and this binary is an ideal astrophysical laboratory to study the mass outflow/pulsar interaction in a highly time-variable environment. Motivated by the results of a recent multiwavelength campaign during the 1994 January periastron passage of PSR B1259-63, we discuss several issues regarding the mechanism of high-energy emission. Unpulsed power-law emission from the PSR B1259-63 system was detected near periastron in the energy range 1-200 keV. The observed X-ray/soft γ-ray emission is characterized by moderate luminosity, small and constant column density, lack of detectable pulsations, and peculiar spectral and intensity variability. In principle, high-energy (X-ray and gamma-ray) emission from the system can be produced by different mechanisms including (1) mass accretion onto the surface of the neutron star, (2) ``propeller''-like magnetospheric interaction at a small pulsar distance, and (3) shock-powered emission in a pulsar wind termination shock at a large distance from the pulsar. We carry out a series of calculations aimed at modeling the high-energy data of the PSR B1259-63 system throughout its orbit and especially near periastron. We find that the observed high-energy emission from the PSR B1259-63 system is not compatible with accretion or propeller-powered emission. This conclusion is supported by a model based on standard properties of Be stars and for plausible assumptions about the pulsar/outflow interaction geometry. We find that shock-powered high-energy emission produced by the pulsar/outflow interaction is consistent with all the characteristics of the high-energy emission of the PSR B1259-63 system. This opens the possibility of obtaining for the first time constraints on the physical properties of the PSR B1259-63 pulsar wind and its interaction properties in a strongly time-variable nebular environment. By studying the time evolution of the pulsar cavity, we can constrain the magnitude and geometry of the mass outflow as the PSR B1259-63 orbits around its Be star companion. The pulsar/outflow interaction is most likely mediated by a collisionless shock at the internal boundary of the pulsar cavity. The system shows all the characteristics of a binary plerion being diffuse and compact near apastron and periastron, respectively. The PSR B1259-63 system is subject to different radiative regimes depending on whether synchrotron or inverse-Compton (IC) cooling dominates the radiation of electron/positron pairs (e+/- pairs) advected away from the inner boundary of the pulsar cavity. The highly nonthermal nature of the observed X-ray/soft γ-ray emission from the PSR B1259-63 system near periastron establishes the existence of an efficient particle acceleration mechanism within a timescale shown to be less than ~102-103 s. A synchrotron/IC model of emission of e+/- pairs accelerated at the inner shock front of the pulsar cavity and adiabatically expanding in the MHD flow provides an excellent explanation of the observed time-variable X-ray flux and spectrum from the PSR B1259-63 system. We find that the best model for the PSR B1259-63 system is consistent with the pulsar orbital plane being misaligned with the plane of a thick equatorial Be star outflow. The angular width of the equatorially enhanced Be star outflow is constrained to be ~50° at the pulsar distance, and the misalignment angle is >~25°. We calculate the intensity and spectrum of the high-energy emission for the whole PSR B1259-63 orbit and predict the characteristics of the emission near the apastron region based on the periastron results. The mass-loss rate is deduced to be approximately constant in time during a ~2 yr period. Our results for the Be star outflow of the PSR B1259-63 system are consistent with models of the radio eclipses near periastron. The consequences of our analysis have general validity. Our study of the PSR B1259-63 system shows that X-ray emission can be caused by a mechanism alternative to accretion in a system containing an energetic pulsar interacting with nebular material. This fact can have far-reaching consequences for the interpretation of galactic astrophysical systems showing nonthermal X-ray and γ-ray emission. We show that a binary system such as PSR B1259-63 offers a novel way to study the acceleration process of relativistic plasmas subject to strongly time variable radiative environments.

The X-ray evolution of inflows and outflows in active galactic nuclei

NASA Astrophysics Data System (ADS)

Saez, Cristian

The evolution of the space density of AGNs might have spectral counterparts which could be observable in X-rays. The main objective of this thesis is to study the spectral properties of AGNs in X-rays in order to increase our current knowledge of AGN evolution. In chapter 2, we present results from a statistical analysis of 173 bright radio-quiet AGNs selected from the Chandra Deep Field-North and Chandra Deep Field-South surveys (hereafter, CDFs) in the redshift range of 0.1 ≲z≲ 4. We find that the X-ray power-law photon index (Gamma) of radio-quiet AGNs is correlated with their 2--10 keV rest-frame X-ray luminosity ( LX) at the > 99.5% confidence level in two redshift bins, 0.3 ≲z≲ 0.96, and 1.5 ≲z≲ 3.3 and is slightly less significant in the redshift bin 0.96 ≲z≲ 1.5. The X-ray spectral slope steepens as the X-ray luminosity increases for AGNs in the luminosity range 1042 to 1045 erg s-1. Combining our results from the CDFs with those from previous studies in the redshift range 1.5 ≲z≲ 3.3, we find that the Gamma -- L X correlation has a null-hypothesis probability of 1.6 x 10 -9. We investigate the redshift evolution of the correlation between the power-law photon index and the hard X-ray luminosity and find that the slope and offset of a linear fit to the correlation change significantly (at the > 99.9% confidence level) between redshift bins of 0.3 ≲z≲ 0.96 and 1.5 ≲z≲ 3.3. We explore physical scenarios explaining the origin of this correlation and its possible evolution with redshift in the context of steady corona models focusing on its dependency on variations of the properties of the hot corona with redshift. In chapter 3, we present results from three Suzaku observations of the z = 3.91 gravitationally lensed broad absorption line quasar APM 08279+5255. We detect strong and broad absorption at rest-frame energies of ≲ 2 keV (low-energy) and 7--12 keV (high-energy). The detection of these features confirms the results of previous long-exposure (80--90 ks) Chandra and XMM-Newton observations. The low and high-energy absorption is detected in both the back-illuminated (BI) and front-illuminated (FI) Suzaku XIS spectra (with an F-test significance of ≳ 99%). We interpret the low-energy absorption as arising from a low-ionization absorber with log (NH/cm-2) ˜ 23 and the high-energy absorption as due to lines arising from highly ionized (2.75 ≲ log xi ≲ 4.0; where xi is the ionization parameter) iron in a near-relativistic outflowing wind. Assuming this interpretation we find that the velocities in the outflow range between 0.1c and 0.6c. We constrain the angle between the outflow direction of the X-ray absorber and our line of sight to be ≲ 36°. We also detect likely variability of the absorption lines (at the ≳ 99.9% and ≳ 98% significance levels in the FI and BI spectra, respectively) with a rest-frame time scale of ˜1 month. Assuming that the detected high-energy absorption features arise from Fe XXV, we estimate that the fraction of the total bolometric energy injected over the quasar's lifetime into the intergalactic medium in the form of kinetic energy to be ≳ 10%. In chapter 4, we present an expansion of our previous work on the study of X-ray outflows on APM 08279+5255. The main conclusions from our multi-epoch spectral analysis of Chandra, XMM-Newton and Suzaku observations of the z = 3.91 gravitationally lensed broad absorption line (BAL) quasar APM 08279+5255 are: (1) In every observation we confirm the presence of two strong features, one at rest-frame energies between 1--4 keV, and the other between 7--18 keV. (2) The low-energy absorption is interpreted as arising (1--4 keV rest-frame) from a low-ionization absorber with log (N H/cm-2) ˜ 23 and the high-energy absorption (7--18 keV rest-frame) as due to lines arising from highly ionized (3 ≲ log xi ≲ 4; where xi is the ionization parameter) iron in a near-relativistic outflowing wind. Assuming this interpretation, we find that the velocities on the outflow could get up to ˜ 0.7c. We also present results obtained from fits to all the long exposure observations of APM 08279+5255 with a new outflow model. (Abstract shortened by UMI.)

The two-way relationship between ionospheric outflow and the ring current

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welling, Daniel T.; Jordanova, Vania Koleva; Glocer, Alex

It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first-principles-based numerical models to test the dependence of ionospheric outflow on ring current-driven region 2 field-aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptivemore » Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), a polar wind model (Polar Wind Outflow Model), and a bounce-averaged kinetic ring current model (ring current atmosphere interaction model with self-consistent magnetic field, RAM-SCB). Initially, each code is two-way coupled to all others except for RAM-SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS-R-US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the non-coupled results. The additional outflow further energizes the ring current, establishing an ionosphere-magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere-magnetosphere-ring current system.« less

The two-way relationship between ionospheric outflow and the ring current

DOE PAGES

Welling, Daniel T.; Jordanova, Vania Koleva; Glocer, Alex; ...

2015-06-01

It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first-principles-based numerical models to test the dependence of ionospheric outflow on ring current-driven region 2 field-aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptivemore » Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), a polar wind model (Polar Wind Outflow Model), and a bounce-averaged kinetic ring current model (ring current atmosphere interaction model with self-consistent magnetic field, RAM-SCB). Initially, each code is two-way coupled to all others except for RAM-SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS-R-US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the non-coupled results. The additional outflow further energizes the ring current, establishing an ionosphere-magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere-magnetosphere-ring current system.« less

Optimizing gene transfer to conventional outflow cells in living mouse eyes

PubMed Central

Li, G; Gonzalez, P; Camras, LJ; Navarro, I; Qiu, J; Challa, P; Stamer, WD

2013-01-01

The mouse eye has physiological and genetic advantages to study conventional outflow function. However, its small size and shallow anterior chamber presents technical challenges to efficient intracameral delivery of genetic material to conventional outflow cells. The goal of this study was to optimize methods to overcome this technical hurdle, without damaging ocular structures or compromising outflow function. Gene targeting was monitored by immunofluorescence microscopy after transduction of adenovirus encoding green fluorescent protein driven by a CMV promoter. Guided by a micromanipulator and stereomicroscope, virus was delivered intracamerally to anesthetized mice by bolus injection using 33 gauge needle attached to Hamilton syringe or infusion with glass micropipette connected to syringe pump. The total number of particles introduced remained constant, while volume of injected virus solution (3–10 µl) was varied for each method and time of infusion (3–40 min) tested. Outflow facility and intraocular pressure were monitored invasively using established techniques. Unlike bolus injections or slow infusions, introduction of virus intracamerally during rapid infusions (3 min) at any volume tested preferentially targeted trabecular meshwork and Schlemm's canal cells, with minimal transduction of neighboring cells. While infusions resulted in transient intraocular pressure spikes (commensurate with volume infused, Δ40–70 mmHg), eyes typically recovered within 60 minutes. Transduced eyes displayed normal outflow facility and tissue morphology 3–6 days after infusions. Taken together, fast infusion of virus solution in small volumes intracamerally is a novel and effective method to selectively deliver agents to conventional outflow cells in living mice. PMID:23337742

Shining a light on star formation driven outflows: the physical conditions within galactic outflows

NASA Astrophysics Data System (ADS)

Chisholm, John P.; Tremonti, Christina A.; Leitherer, Claus; Wofford, Aida; Chen, Yanmei

2016-01-01

Stellar feedback drives energy and momentum into the surrounding gas, which drives gas and metals out of galaxies through a galactic outflow. Unfortunately, galactic outflows are difficult to observe and characterize because they are extremely diffuse, and contain gas at many different temperatures. Here we present results from a sample of 37 nearby (z < 0.27) star forming galaxies observed in the ultraviolet with the Cosmic Origins Spectrograph on the Hubble Space Telescope. The sample covers over three decades in stellar mass and star formation rate, probing different morphologies such as dwarf irregulars and high-mass merging systems. Using four different UV absorption lines (O I, Si II, Si III and Si IV) that trace a wide range of temperatures (ionization potentials between 13.6 eV and 45 eV), we find shallow correlations between the outflow velocity or the equivalent width of absorption lines with stellar mass or star formation rate. Absorption lines probing different temperature phases have similar centroid velocities and line widths, indicating that they are comoving. Using the equivalent width ratios of the four different transitions, we find the ratios to be consistent with photo-ionized outflows, with moderately strong ionization parameters. By constraining the ionization mechanism we model the ionization fractions for each transition, but find the ionization fractions depend crucially on input model parameters. The shallow velocity scalings imply that low-mass galaxies launch outflows capable of escaping their galactic potential, while higher mass galaxies retain all of their gas, unless they undergo a merger.

Comparison of Ejection Events in the Jet and Accretion Disc Outflows in 3C 111

NASA Technical Reports Server (NTRS)

Tombesi, F.; Sambruna, R. M.; Marscher, A. P.; Jorstad, S. G.; Reynolds, C. S.; Markowtiz, A.

2012-01-01

We present a comparison of the parameters of accretion disc outflows and the jet of the broad-line radio galaxy 3C 111 on sub-pc scales. We make use of published X-ray observations of ultra-fast outflows (UFOs) and new 43 GHz VLBA images to track the jet knots ejection. We find that the superluminal jet coexists with the mildly relativistic outflows on sub-pc scales, possibly indicating a transverse stratification of a global flow. The two are roughly in pressure equilibrium, with the UFOs potentially providing additional support for the initial jet collimation. The UFOs are much more massive than the jet, but their kinetic power is probably about an order of magnitude lower, at least for the observations considered here. However, their momentum flux is equivalent and both of them are powerful enough to exert a concurrent feedback impact on the surrounding environment. A link between these components is naturally predicted in the context of MHD models for jet/outflow formation. However, given the high radiation throughput of AGNs, radiation pressure should also be taken into account. From the comparison with the long-term 2-10 keV RXTE light curve we find that the UFOs are preferentially detected during periods of increasing flux. We also find the possibility to place the UFOs within the known X-ray dips-jet ejection cycles, which has been shown to be a strong proof of the disc-jet connection, in analogue with stellar-mass black holes. However, given the limited number of observations presently available, these relations are only tentative and additional spectral monitoring is needed to test them conclusively.

Discovery of Ultra-fast Outflows in a Sample of Broad-line Radio Galaxies Observed with Suzaku

NASA Astrophysics Data System (ADS)

Tombesi, F.; Sambruna, R. M.; Reeves, J. N.; Braito, V.; Ballo, L.; Gofford, J.; Cappi, M.; Mushotzky, R. F.

2010-08-01

We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines are detected with high significance according to both the F-test and extensive Monte Carlo simulations. Their likely interpretation as blueshifted Fe XXV and Fe XXVI K-shell resonance lines implies an origin from highly ionized gas outflowing with mildly relativistic velocities, in the range v ~= 0.04-0.15c. A fit with specific photoionization models gives ionization parameters in the range log ξ ~= 4-5.6 erg s-1 cm and column densities of N H ~= 1022-1023 cm-2. These characteristics are very similar to those of the ultra-fast outflows (UFOs) previously observed in radio-quiet AGNs. Their estimated location within ~0.01-0.3 pc of the central super-massive black hole suggests a likely origin related with accretion disk winds/outflows. Depending on the absorber covering fraction, the mass outflow rate of these UFOs can be comparable to the accretion rate and their kinetic power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, these UFOs can play a significant role in the expected feedback from the AGN to the surrounding environment and can give us further clues on the relation between the accretion disk and the formation of winds/jets in both radio-quiet and radio-loud AGNs.

The Production of Cold Gas Within Galaxy Outflows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scannapieco, Evan

2017-03-01

I present a suite of three-dimensional simulations of the evolution of initially hot material ejected by starburst-driven galaxy outflows. The simulations are conducted in a comoving frame that moves with the material, tracking atomic/ionic cooling, Compton cooling, and dust cooling and destruction. Compton cooling is the most efficient of these processes, while the main role of atomic/ionic cooling is to enhance density inhomogeneities. Dust, on the other hand, has little effect on the outflow evolution, and is rapidly destroyed in all the simulations except for the case with the smallest mass flux. I use the results to construct a simplemore » steady-state model of the observed UV/optical emission from each outflow. The velocity profiles in this case are dominated by geometric effects, and the overall luminosities are extremely strong functions of the properties of the host system, as observed in ultra-luminous infrared galaxies (ULIRGs). Furthermore the luminosities and maximum velocities in several models are consistent with emission-line observations of ULIRGs, although the velocities are significantly greater than observed in absorption-line studies. It may be that absorption line observations of galaxy outflows probe entrained cold material at small radii, while emission-line observations probe cold material condensing from the initially hot medium at larger distances.« less

Large-Scale Star Formation-Driven Outflows at 1

NASA Astrophysics Data System (ADS)

Lundgren, Britt; Brammer, G.; Van Dokkum, P. G.; Bezanson, R.; Franx, M.; Fumagalli, M.; Momcheva, I. G.; Nelson, E.; Skelton, R.; Wake, D.; Whitaker, K. E.; da Cunha, E.; Erb, D.; Fan, X.; Kriek, M.; Labbe, I.; Marchesini, D.; Patel, S.; Rix, H.; Schmidt, K.; van der Wel, A.

2013-01-01

We present evidence of large-scale outflows from three low-mass star-forming galaxies observed at z=1.24, z=1.35 and z=1.75 in the 3D-HST Survey. Each of these galaxies is located within a projected physical distance of 60 kpc around the sight line to the quasar SDSS J123622.93+621526.6, which exhibits well-separated strong (W>0.8A) MgII absorption systems matching precisely to the redshifts of the three galaxies. We derive the star formation surface densities from the H-alpha emission in the WFC3 G141 grism observations for the galaxies and find that in each case the star formation surface density well-exceeds 0.1 solar mass / yr / kpc^2, the typical threshold for starburst galaxies in the local Universe. From a small but complete parallel census of the 0.650.8A MgII covering fraction of star-forming galaxies at 10.4A MgII absorbing gas around star-forming galaxies may evolve from 2 to the present, consistent with recent observations of an increasing collimation of star formation-driven outflows with time from 3.

Large-scale Star-formation-driven Outflows at 1 < z < 2 in the 3D-HST Survey

NASA Astrophysics Data System (ADS)

Lundgren, Britt F.; Brammer, Gabriel; van Dokkum, Pieter; Bezanson, Rachel; Franx, Marijn; Fumagalli, Mattia; Momcheva, Ivelina; Nelson, Erica; Skelton, Rosalind E.; Wake, David; Whitaker, Katherine; da Cunha, Elizabete; Erb, Dawn K.; Fan, Xiaohui; Kriek, Mariska; Labbé, Ivo; Marchesini, Danilo; Patel, Shannon; Rix, Hans Walter; Schmidt, Kasper; van der Wel, Arjen

2012-11-01

We present evidence of large-scale outflows from three low-mass (log(M */M ⊙) ~ 9.75) star-forming (SFR > 4 M ⊙ yr-1) galaxies observed at z = 1.24, z = 1.35, and z = 1.75 in the 3D-HST Survey. Each of these galaxies is located within a projected physical distance of 60 kpc around the sight line to the quasar SDSS J123622.93+621526.6, which exhibits well-separated strong (W λ2796 r >~ 0.8 Å) Mg II absorption systems matching precisely to the redshifts of the three galaxies. We derive the star formation surface densities from the Hα emission in the WFC3 G141 grism observations for the galaxies and find that in each case the star formation surface density well exceeds 0.1 M ⊙ yr-1 kpc-2, the typical threshold for starburst galaxies in the local universe. From a small but complete parallel census of the 0.65 < z < 2.6 galaxies with H 140 <~ 24 proximate to the quasar sight line, we detect Mg II absorption associated with galaxies extending to physical distances of 130 kpc. We determine that the Wr > 0.8 Å Mg II covering fraction of star-forming galaxies at 1 < z < 2 may be as large as unity on scales extending to at least 60 kpc, providing early constraints on the typical extent of starburst-driven winds around galaxies at this redshift. Our observations additionally suggest that the azimuthal distribution of Wr > 0.4 Å Mg II absorbing gas around star-forming galaxies may evolve from z ~ 2 to the present, consistent with recent observations of an increasing collimation of star-formation-driven outflows with time from z ~ 3.

Rarefaction acceleration of ultrarelativistic magnetized jets in gamma-ray burst sources

NASA Astrophysics Data System (ADS)

Komissarov, Serguei S.; Vlahakis, Nektarios; Königl, Arieh

2010-09-01

When a magnetically dominated superfast-magnetosonic long/soft gamma-ray burst (GRB) jet leaves the progenitor star, the external pressure support will drop and the jet may enter the regime of ballistic expansion, during which additional magnetic acceleration becomes ineffective. However, recent numerical simulations by Tchekhovskoy et al. have suggested that the transition to this regime is accompanied by a spurt of acceleration. We confirm this finding numerically and attribute the acceleration to a sideways expansion of the jet, associated with a strong magnetosonic rarefaction wave that is driven into the jet when it loses pressure support, which induces a conversion of magnetic energy into kinetic energy of bulk motion. This mechanism, which we dub rarefaction acceleration, can only operate in a relativistic outflow because in this case the total energy can still be dominated by the magnetic component even in the superfast-magnetosonic regime. We analyse this process using the equations of relativistic magnetohydrodynamics and demonstrate that it is more efficient at converting internal energy into kinetic energy when the flow is magnetized than in a purely hydrodynamic outflow, as was found numerically by Mizuno et al. We show that, just as in the case of the magnetic acceleration of a collimating jet that is confined by an external pressure distribution - the collimation-acceleration mechanism - the rarefaction-acceleration process in a magnetized jet is a consequence of the fact that the separation between neighbouring magnetic flux surfaces increases faster than their cylindrical radius. However, whereas in the case of effective collimation-acceleration the product of the jet opening angle and its Lorentz factor does not exceed ~1, the addition of the rarefaction-acceleration mechanism makes it possible for this product to become >>1, in agreement with the inference from late-time panchromatic breaks in the afterglow light curves of long/soft GRBs.

Signatures of hypermassive neutron star lifetimes on r-process nucleosynthesis in the disc ejecta from neutron star mergers

NASA Astrophysics Data System (ADS)

Lippuner, Jonas; Fernández, Rodrigo; Roberts, Luke F.; Foucart, Francois; Kasen, Daniel; Metzger, Brian D.; Ott, Christian D.

2017-11-01

We investigate the nucleosynthesis of heavy elements in the winds ejected by accretion discs formed in neutron star mergers. We compute the element formation in disc outflows from hypermassive neutron star (HMNS) remnants of variable lifetime, including the effect of angular momentum transport in the disc evolution. We employ long-term axisymmetric hydrodynamic disc simulations to model the ejecta, and compute r-process nucleosynthesis with tracer particles using a nuclear reaction network containing ∼8000 species. We find that the previously known strong correlation between HMNS lifetime, ejected mass and average electron fraction in the outflow is directly related to the amount of neutrino irradiation on the disc, which dominates mass ejection at early times in the form of a neutrino-driven wind. Production of lanthanides and actinides saturates at short HMNS lifetimes (≲10 ms), with additional ejecta contributing to a blue optical kilonova component for longer-lived HMNSs. We find good agreement between the abundances from the disc outflow alone and the solar r-process distribution only for short HMNS lifetimes (≲10 ms). For longer lifetimes, the rare-earth and third r-process peaks are significantly underproduced compared to the solar pattern, requiring additional contributions from the dynamical ejecta. The nucleosynthesis signature from a spinning black hole (BH) can only overlap with that from an HMNS of moderate lifetime (≲60 ms). Finally, we show that angular momentum transport not only contributes with a late-time outflow component, but that it also enhances the neutrino-driven component by moving material to shallower regions of the gravitational potential, in addition to providing additional heating.

A Molecular-line Study of the Interstellar Bullet Engine IRAS05506+2414

NASA Astrophysics Data System (ADS)

Sahai, Raghvendra; Lee, Chin-Fei; Sánchez Contreras, Carmen; Patel, Nimesh; Morris, Mark R.; Claussen, Mark

2017-12-01

We present interferometric and single-dish molecular line observations of the interstellar bullet-outflow source IRAS 05506+2414, whose wide-angle bullet spray is similar to the Orion BN/KL explosive outflow and likely arises from an entirely different mechanism than the classical accretion-disk-driven bipolar flows in young stellar objects. The bullet-outflow source is associated with a large pseudo-disk and three molecular outflows—a high-velocity outflow (HVO), a medium-velocity outflow (MVO), and a slow, extended outflow (SEO). The size (mass) of the pseudo-disk is 10,350 au × 6400 au (0.64-0.17 M ⊙) from a model-fit assuming infall and rotation, we derive a central stellar mass of 8-19 M ⊙. The HVO (MVO) has an angular size ˜5180 (˜3330) au and a projected outflow velocity of ˜140 km s-1 (˜30 km s-1). The SEO size (outflow speed) is ˜0.9 pc (˜6 km s-1). The HVO’s axis is aligned with (orthogonal to) that of the SEO (pseudo-disk). The velocity structure of the MVO is unresolved. The scalar momenta in the HVO and SEO are very similar, suggesting that the SEO has resulted from the HVO interacting with ambient-cloud material. The bullet spray shares a common axis with the pseudo-disk and has an age comparable to that of MVO (few hundred years), suggesting that these three structures are intimately linked. We discuss several models for the outflows in IRAS 05506+2414 (including dynamical decay of a stellar cluster, chance encounter of a runaway star with a dense cloud, and close passage of two protostars), and conclude that second-epoch imaging to derive proper motions of the bullets and nearby stars can help to discriminate between them.

Sub-arcsecond imaging of Arp 299-A at 150 MHz with LOFAR: Evidence for a starburst-driven outflow

NASA Astrophysics Data System (ADS)

Ramírez-Olivencia, N.; Varenius, E.; Pérez-Torres, M.; Alberdi, A.; Pérez, E.; Alonso-Herrero, A.; Deller, A.; Herrero-Illana, R.; Moldón, J.; Barcos-Muñoz, L.; Martí-Vidal, I.

2018-03-01

We report on the first sub-arcsecond (0.44 × 0.41 arcsec2) angular resolution image at 150 MHz of the A-nucleus in the luminous infrared galaxy Arp 299, from International Low Frequency Array (LOFAR) Telescope observations. The most remarkable finding is that of an intriguing two-sided, filamentary structure emanating from the A-nucleus, which we interpret as an outflow that extends up to at least 14 arcsec from the A-nucleus in the N-S direction ( ≈5 kpc deprojected size) and accounts for almost 40% of the extended emission of the entire galaxy system. We also discuss HST/NICMOS [FeII] 1.64 μm and H2 2.12 μm images of Arp 299-A, which show similar features to those unveiled by our 150 MHz LOFAR observations, providing strong morphological support for the outflow scenario. Finally, we discuss unpublished Na I D spectra that confirm the outflow nature of this structure. From energetic arguments, we rule out the low-luminosity active galactic nucleus in Arp 299-A as a driver for the outflow. On the contrary, the powerful, compact starburst in the central regions of Arp 299-A provides plenty of mechanical energy to sustain an outflow, and we conclude that the intense supernova (SN) activity in the nuclear region of Arp 299-A is driving the observed outflow. We estimate that the starburst wind can support a mass-outflow rate in the range (11-63 M⊙ yr-1) at speeds of up to 370-890 km s-1, and is relatively young, with an estimated kinematic age of 3-7 Myr. Those results open an avenue to the use of low-frequency (150 MHz), sub-arcsecond imaging with LOFAR to detect outflows in the central regions of local luminous infrared galaxies.

Evidence for ultrafast outflows in radio-quiet AGNs - III. Location and energetics

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

2012-05-01

Using the results of a previous X-ray photoionization modelling of blueshifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this Letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ˜0.0003-0.03 pc (˜ 102-104rs) from the central black hole, consistent with what is expected for accretion disc winds/outflows. The mass outflow rates are constrained between ˜0.01 and 1 M⊙ yr-1, corresponding to >rsim5-10 per cent of the accretion rates. The average lower/upper limits on the mechanical power are log? 42.6-44.6 erg s-1. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN cosmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyfert galaxies.

Far-ultraviolet Observations of Outflows from Infrared-luminous Galaxies

NASA Astrophysics Data System (ADS)

Leitherer, Claus; Chandar, Rupali; Tremonti, Christy A.; Wofford, Aida; Schaerer, Daniel

2013-08-01

We obtained medium-resolution ultraviolet (UV) spectra between 1150 and 1450 Å of the four UV-bright, infrared-luminous starburst galaxies IRAS F08339+6517, NGC 3256, NGC 6090, and NGC 7552 using the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The selected sightlines toward the starburst nuclei probe the properties of the recently formed massive stars and the physical conditions in the starburst-driven galactic superwinds. Despite being metal-rich and dusty, all four galaxies are strong Lyα emitters with equivalent widths ranging between 2 and 13 Å. The UV spectra show strong P Cygni-type high-ionization features indicative of stellar winds and blueshifted low-ionization lines formed in the interstellar and circumgalactic medium. We detect outflowing gas with bulk velocities of ~400 km s-1 and maximum velocities of almost 900 km s-1. These are among the highest values found in the local universe and comparable to outflow velocities found in luminous Lyman-break galaxies at intermediate and high redshift. The outflow velocities are unlikely to be high enough to cause escape of material from the galactic gravitational potential. However, the winds are significant for the evolution of the galaxies by transporting heavy elements from the starburst nuclei and enriching the galaxy halos. The derived mass outflow rates of ~100 M ⊙ yr-1 are comparable to or even higher than the star formation rates. The outflows can quench star formation and ultimately regulate the starburst as has been suggested for high-redshift galaxies.

Delayed or No Feedback? Gas Outflows in Type 2 AGNs. III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woo, Jong-Hak; Son, Donghoon; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr, E-mail: hjbae@galaxy.yonsei.ac.kr

2017-04-20

We present gas kinematics based on the [O iii] λ 5007 line and their connection to galaxy gravitational potential, active galactic nucleus (AGN) energetics, and star formation, using a large sample of ∼110,000 AGNs and star-forming (SF) galaxies at z < 0.3. Gas and stellar velocity dispersions are comparable to each other in SF galaxies, indicating that the ionized gas kinematics can be accounted by the gravitational potential of host galaxies. In contrast, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. The [O iii] velocity–velocity dispersion (VVD) diagrammore » dramatically expands toward high values as a function of AGN luminosity, implying that the outflows are AGN-driven, while SF galaxies do not show such a trend. We find that the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [O iii] profile. AGNs with strong outflow signatures show on average similar specific star formation rates (sSFRs) to those of star-forming galaxies. In contrast, AGNs with weak or no outflows have an order of magnitude lower sSFRs, suggesting that AGNs with current strong outflows do now show any negative AGN feedback and that it may take dynamical time to impact on star formation over galactic scales.« less

Exploring the making of a galactic wind in the starbursting dwarf irregular galaxy IC 10 with LOFAR

NASA Astrophysics Data System (ADS)

Heesen, V.; Rafferty, D. A.; Horneffer, A.; Beck, R.; Basu, A.; Westcott, J.; Hindson, L.; Brinks, E.; ChyŻy, K. T.; Scaife, A. M. M.; Brüggen, M.; Heald, G.; Fletcher, A.; Horellou, C.; Tabatabaei, F. S.; Paladino, R.; Nikiel-Wroczyński, B.; Hoeft, M.; Dettmar, R.-J.

2018-05-01

Low-mass galaxies are subject to strong galactic outflows, in which cosmic rays may play an important role; they can be best traced with low-frequency radio continuum observations, which are less affected by spectral ageing. We present a study of the nearby starburst dwarf irregular galaxy IC 10 using observations at 140 MHz with the Low-Frequency Array (LOFAR), at 1580 MHz with the Very Large Array (VLA), and at 6200 MHz with the VLA and the 100-m Effelsberg telescope. We find that IC 10 has a low-frequency radio halo, which manifests itself as a second component (thick disc) in the minor axis profiles of the non-thermal radio continuum emission at 140 and 1580 MHz. These profiles are then fitted with 1D cosmic ray transport models for pure diffusion and advection. We find that a diffusion model fits best, with a diffusion coefficient of D = (0.4-0.8) × 1026(E/GeV)0.5 cm2 s-1, which is at least an order of magnitude smaller than estimates both from anisotropic diffusion and the diffusion length. In contrast, advection models, which cannot be ruled out due to the mild inclination, while providing poorer fits, result in advection speeds close to the escape velocity of ≈ 50 km s- 1, as expected for a cosmic ray-driven wind. Our favoured model with an accelerating wind provides a self-consistent solution, where the magnetic field is in energy equipartition with both the warm neutral and warm ionized medium with an important contribution from cosmic rays. Consequently, cosmic rays can play a vital role for the launching of galactic winds in the disc-halo interface.

High-energy Emission from Nonrelativistic Radiative Shocks: Application to Gamma-Ray Novae

NASA Astrophysics Data System (ADS)

Vurm, Indrek; Metzger, Brian D.

2018-01-01

The observation of GeV gamma-rays from novae by Fermi/LAT demonstrates that the nonrelativistic radiative shocks in these systems can accelerate particles to energies of at least ∼10 GeV. The low-energy extension of the same nonthermal particle distribution inevitably gives rise to emission in the hard X-ray band. Above ≳ 10 {keV}, this radiation can escape the system without significant absorption/attenuation, and can potentially be detected by NuSTAR. We present theoretical models for hard X-ray and gamma-ray emission from radiative shocks in both leptonic and hadronic scenarios, accounting for the rapid evolution of the downstream properties due to the fast cooling of thermal plasma. We find that due to strong Coulomb losses, only a fraction of {10}-4{--}{10}-3 of the gamma-ray luminosity is radiated in the NuSTAR band; nevertheless, this emission could be detectable simultaneously with the LAT emission in bright gamma-ray novae with a ∼50 ks exposure. The spectral slope in hard X-rays is α ≈ 0 for typical nova parameters, thus serving as a testable prediction of the model. Our work demonstrates how combined hard X-ray and gamma-ray observations can be used to constrain properties of the nova outflow (velocity, density, and mass outflow rate) and particle acceleration at the shock. A very low X-ray to gamma-ray luminosity ratio ({L}{{X}}/{L}γ ≲ 5× {10}-4) would disfavor leptonic models for the gamma-ray emission. Our model can also be applied to other astrophysical environments with radiative shocks, including SNe IIn and colliding winds in massive star binaries.

RELATIVISTIC ELECTRONS PRODUCED BY RECONNECTING ELECTRIC FIELDS IN A LASER-DRIVEN BENCH-TOP SOLAR FLARE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, J. Y.; Zhang, K.; Yuan, D. W.

2016-08-01

Laboratory experiments have been carried out to model the magnetic reconnection process in a solar flare with powerful lasers. Relativistic electrons with energy up to megaelectronvolts are detected along the magnetic separatrices bounding the reconnection outflow, which exhibit a kappa-like distribution with an effective temperature of ∼10{sup 9} K. The acceleration of non-thermal electrons is found to be more efficient in the case with a guide magnetic field (a component of a magnetic field along the reconnection-induced electric field) than in the case without a guide field. Hardening of the spectrum at energies ≥500 keV is observed in both cases, which remarkably resembles themore » hardening of hard X-ray and γ -ray spectra observed in many solar flares. This supports a recent proposal that the hardening in the hard X-ray and γ -ray emissions of solar flares is due to a hardening of the source-electron spectrum. We also performed numerical simulations that help examine behaviors of electrons in the reconnection process with the electromagnetic field configurations occurring in the experiments. The trajectories of non-thermal electrons observed in the experiments were well duplicated in the simulations. Our numerical simulations generally reproduce the electron energy spectrum as well, except for the hardening of the electron spectrum. This suggests that other mechanisms such as shock or turbulence may play an important role in the production of the observed energetic electrons.« less

Momentum and energy balance in late-type stellar winds

NASA Technical Reports Server (NTRS)

Macgregor, K. B.

1981-01-01

Observations at ultraviolet and X-ray wavelengths indicate that the classical picture of a static stellar atmosphere containing a radiative equilibrium temperature distribution is inapplicable to the majority of late type stars. Mass loss and the presence of atmospheric regions characterized by gas temperatures in excess of the stellar effective temperature appear to be almost ubiquitous throughout the HR diagram. Evidence pertaining to the thermal and dynamical structure of the outer envelopes of cool stars is summarized. These results are compared with the predictions of several theoretical models which were proposed to account for mass loss from latetype stars. Models in which the outflow is thermally radiatively, or wave driven are considered for identification of the physical processes responsible for the observed wind properties. The observed variation of both the wind, thermal and dynamical structure as one proceeds from the supergiant branch toward the main sequence in the cool portion of the HR diagram give consideration to potential mechanisms for heating and cooling the flow from low gravity stars.

Magnetorotational instability in decretion disks of critically rotating stars and the outer structure of Be and Be/X-ray disks

NASA Astrophysics Data System (ADS)

Krtička, J.; Kurfürst, P.; Krtičková, I.

2015-01-01

Context. Evolutionary models of fast-rotating stars show that the stellar rotational velocity may approach the critical speed. Critically rotating stars cannot spin up more, therefore they lose their excess angular momentum through an equatorial outflowing disk. The radial extension of such disks is unknown, partly because we lack information about the radial variations of the viscosity. Aims: We study the magnetorotational instability, which is considered to be the origin of anomalous viscosity in outflowing disks. Methods: We used analytic calculations to study the stability of outflowing disks submerged in the magnetic field. Results: The magnetorotational instability develops close to the star if the plasma parameter is large enough. At large radii the instability disappears in the region where the disk orbital velocity is roughly equal to the sound speed. Conclusions: The magnetorotational instability is a plausible source of anomalous viscosity in outflowing disks. This is also true in the region where the disk radial velocity approaches the sound speed. The disk sonic radius can therefore be roughly considered as an effective outer disk radius, although disk material may escape from the star to the insterstellar medium. The radial profile of the angular momentum-loss rate already flattens there, consequently, the disk mass-loss rate can be calculated with the sonic radius as the effective disk outer radius. We discuss a possible observation determination of the outer disk radius by using Be and Be/X-ray binaries.

Reversing cooling flows with AGN jets: shock waves, rarefaction waves and trailing outflows

NASA Astrophysics Data System (ADS)

Guo, Fulai; Duan, Xiaodong; Yuan, Ye-Fei

2018-01-01

The cooling flow problem is one of the central problems in galaxy clusters, and active galactic nucleus (AGN) feedback is considered to play a key role in offsetting cooling. However, how AGN jets heat and suppress cooling flows remains highly debated. Using an idealized simulation of a cool-core cluster, we study the development of central cooling catastrophe and how a subsequent powerful AGN jet event averts cooling flows, with a focus on complex gasdynamical processes involved. We find that the jet drives a bow shock, which reverses cooling inflows and overheats inner cool-core regions. The shocked gas moves outward in a rarefaction wave, which rarefies the dense core and adiabatically transports a significant fraction of heated energy to outer regions. As the rarefaction wave propagates away, inflows resume in the cluster core, but a trailing outflow is uplifted by the AGN bubble, preventing gas accumulation and catastrophic cooling in central regions. Inflows and trailing outflows constitute meridional circulations in the cluster core. At later times, trailing outflows fall back to the cluster centre, triggering central cooling catastrophe and potentially a new generation of AGN feedback. We thus envisage a picture of cool cluster cores going through cycles of cooling-induced contraction and AGN-induced expansion. This picture naturally predicts an anti-correlation between the gas fraction (or X-ray luminosity) of cool cores and the central gas entropy, which may be tested by X-ray observations.

Modeling mass loss from B(e) stars

NASA Technical Reports Server (NTRS)

Cassinelli, J. P.; Schulte-Ladbeck, R. E.; Abbott, M.; Poe, C. H.

1989-01-01

It was suggested by Zickgraf et al. (1986) that the outer atmospheres of some B(e) stars have a two-component structure: a fast, radiation-driven wind from the pole, and a dense, slow outflow from the equator. Poe et al. (1989) developed this theory to explain the momentum problem associated with WR stars. This paper uses the multiforce wind theory of Poe et al. to model the B(e) outflow phenomenon. Two general questions are investigated: (1) whether B(e) stars can be rotating near critical speed, and if so, (2) what constraints can be placed on the parameters that determine the two-component flow structure.

On the origin of jets from disc-accreting magnetized stars

NASA Astrophysics Data System (ADS)

Lovelace, Richard V. E.; Romanova, Marina M.; Lii, Patrick; Dyda, Sergei

2014-09-01

A brief review of the origin of jets from disc-accreting rotating magnetized stars is given. In most models, the interior of the disc is characterized by a turbulent viscosity and magnetic diffusivity ("alpha" discs) whereas the coronal region outside the disc is treated using ideal magnetohydrodynamics (MHD). Extensive MHD simulations have established the occurrence of long-lasting outflows in the case of both slowly and rapidly rotating stars. (1) Slowly rotating stars exhibit a new type of outflow, conical winds. Conical winds are generated when stellar magnetic flux is bunched up by the inward motion of the accretion disc. Near their region of origin, the winds have a thin conical shell shape with half opening angle of ˜30°. At large distances, their toroidal magnetic field collimates the outflow forming current carrying, matter dominated jets. These winds are predominantly magnetically and not centrifugally driven. About 10-30% of the disc matter from the inner disc is launched in the conical wind. Conical winds may be responsible for episodic as well as long lasting outflows in different types of stars. (2) Rapidly rotating stars in the "propeller regime" exhibit two-component outflows. One component is similar to the matter dominated conical wind, where a large fraction of the disc matter may be ejected in this regime. The second component is a high-velocity, low-density magnetically dominated axial jet where matter flows along the open polar field lines of the star. The axial jet has a mass flux of about 10% that of the conical wind, but its energy flux, due to the Poynting flux, can be as large as for the conical wind. The jet's magnetically dominated angular momentum flux causes the star to spin down rapidly. Propeller-driven outflows may be responsible for protostellar jets and their rapid spin-down. When the artificial requirement of symmetry about the equatorial plane is dropped, the conical winds are found to come alternately from one side of the disc and then the other, even for the case where the stellar magnetic field is a centered axisymmetric dipole. Recent MHD simulations of disc accretion to rotating stars in the propeller regime have been done with no turbulent viscosity and no diffusivity. The strong turbulence observed is due to the magneto-rotational instability. This turbulence drives accretion in the disc and leads to episodic conical winds and jets.

A Deep Chandra ACIS Study of NGC 4151. III. The Line Emission and Spectral Analysis of the Ionization Cone

NASA Astrophysics Data System (ADS)

Wang, Junfeng; Fabbiano, Giuseppina; Elvis, Martin; Risaliti, Guido; Karovska, Margarita; Zezas, Andreas; Mundell, Carole G.; Dumas, Gaelle; Schinnerer, Eva

2011-11-01

This paper is the third in a series in which we present deep Chandra ACIS-S imaging spectroscopy of the Seyfert 1 galaxy NGC 4151, devoted to study its complex circumnuclear X-ray emission. Emission features in the soft X-ray spectrum of the bright extended emission (L 0.3-2 keV ~ 1040 erg s-1) at r > 130 pc (2'') are consistent with blended brighter O VII, O VIII, and Ne IX lines seen in the Chandra HETGS and XMM-Newton RGS spectra below 2 keV. We construct emission line images of these features and find good morphological correlations with the narrow-line region clouds mapped in [O III] λ5007. Self-consistent photoionization models provide good descriptions of the spectra of the large-scale emission, as well as resolved structures, supporting the dominant role of nuclear photoionization, although displacement of optical and X-ray features implies a more complex medium. Collisionally ionized emission is estimated to be lsim12% of the extended emission. Presence of both low- and high-ionization spectral components and extended emission in the X-ray image perpendicular to the bicone indicates leakage of nuclear ionization, likely filtered through warm absorbers, instead of being blocked by a continuous obscuring torus. The ratios of [O III]/soft X-ray flux are approximately constant (~15) for the 1.5 kpc radius spanned by these measurements, indicating similar relative contributions from the low- and high-ionization gas phases at different radial distances from the nucleus. If the [O III] and X-ray emission arise from a single photoionized medium, this further implies an outflow with a wind-like density profile. Using spatially resolved X-ray features, we estimate that the mass outflow rate in NGC 4151 is ~2 M ⊙ yr-1 at 130 pc and the kinematic power of the ionized outflow is 1.7 × 1041 erg s-1, approximately 0.3% of the bolometric luminosity of the active nucleus in NGC 4151.

The origin of fast molecular outflows in quasars: molecule formation in AGN-driven galactic winds

NASA Astrophysics Data System (ADS)

Richings, Alexander J.; Faucher-Giguère, Claude-André

2018-03-01

We explore the origin of fast molecular outflows that have been observed in active galactic nuclei (AGNs). Previous numerical studies have shown that it is difficult to create such an outflow by accelerating existing molecular clouds in the host galaxy, as the clouds will be destroyed before they can reach the high velocities that are observed. In this work, we consider an alternative scenario where molecules form in situ within the AGN outflow. We present a series of hydro-chemical simulations of an isotropic AGN wind interacting with a uniform medium. We follow the time-dependent chemistry of 157 species, including 20 molecules, to determine whether molecules can form rapidly enough to produce the observed molecular outflows. We find H2 outflow rates up to 140 M_{⊙} yr^{-1}, which is sensitive to density, AGN luminosity, and metallicity. We compute emission and absorption lines of CO, OH, and warm (a few hundred K) H2 from the simulations in post-processing. The CO-derived outflow rates and OH absorption strengths at solar metallicity agree with observations, although the maximum line-of-sight velocities from the model CO spectra are a factor ≈2 lower than is observed. We derive a CO (1-0) to H2 conversion factor of α _{CO (1-0)} = 0.13 M_{⊙} (K km s^{-1} pc2)^{-1}, 6 times lower than is commonly assumed in observations of such systems. We find strong emission from the mid-infrared lines of H2. The mass of H2 traced by this infrared emission is within a few per cent of the total H2 mass. This H2 emission may be observable by James Webb Space Telescope.

How stellar feedback simultaneously regulates star formation and drives outflows

NASA Astrophysics Data System (ADS)

Hayward, Christopher C.; Hopkins, Philip F.

2017-02-01

We present an analytic model for how momentum deposition from stellar feedback simultaneously regulates star formation and drives outflows in a turbulent interstellar medium (ISM). Because the ISM is turbulent, a given patch of ISM exhibits sub-patches with a range of surface densities. The high-density patches are 'pushed' by feedback, thereby driving turbulence and self-regulating local star formation. Sufficiently low-density patches, however, are accelerated to above the escape velocity before the region can self-adjust and are thus vented as outflows. When the gas fraction is ≳ 0.3, the ratio of the turbulent velocity dispersion to the circular velocity is sufficiently high that at any given time, of the order of half of the ISM has surface density less than the critical value and thus can be blown out on a dynamical time. The resulting outflows have a mass-loading factor (η ≡ dot{M}_{out}/M_{star }) that is inversely proportional to the gas fraction times the circular velocity. At low gas fractions, the star formation rate needed for local self-regulation, and corresponding turbulent Mach number, declines rapidly; the ISM is 'smoother', and it is actually more difficult to drive winds with large mass-loading factors. Crucially, our model predicts that stellar-feedback-driven outflows should be suppressed at z ≲ 1 in M⋆ ≳ 1010 M⊙ galaxies. This mechanism allows massive galaxies to exhibit violent outflows at high redshifts and then 'shut down' those outflows at late times, thereby enabling the formation of a smooth, extended thin stellar disc. We provide simple fitting functions for η that should be useful for sub-resolution and semi-analytic models.

Formation of Hydrocarbons in the Outflows from Red Giants

NASA Technical Reports Server (NTRS)

Roberge, Wayne; Kress, Monika; Tielens, Alexander G.

1995-01-01

The formation of hydrocarbons in the oxygen-rich outflows from red giants was studied. The existence of organic molecules in such outflows has been known for several years; however, their surprisingly high abundances has been a mystery since all of the carbon had been thought to be irretrievably locked up in CO, the most strongly bound molecule. CO is the first molecule to form from the atoms present in the star's extended atmosphere, and as strong stellar winds drive a cooling outflow, dust grains condense out. In oxygen-rich outflows, the dust is thought to be composed mainly of silicates and other metal oxides. Perhaps the noble metals can condense out in metallic form, in particular the relatively abundant transition metals iron and nickel. We proposed that perhaps the carbon reservoir held as CO can be accessed through a catalytic process involving the chemisorption of CO and H2 onto grains rich in metallic iron. CO and H2 are the two most abundant molecules in circumstellar outflows, and they both are known to dissociate on transition metal surfaces at elevated temperatures, freeing carbon to form organic molecules such as methane. We believe methane is a precursor molecule to the organics observed in oxygen-rich red giants. We have developed a nonequilibrium numerical model of a surface chemical (catalytic) process. Based on this model, we believe that methane can be formed under the conditions present in circumstellar outflows. Although the methane formation rates are exceptionally low under these conditions, over dynamical timescales, a significant amount of CO can be converted to methane and driven further out in the envelope, explaining the presence of organics there.

Life and Times of the X-Ray Gas in Elliptical Galaxies

NASA Astrophysics Data System (ADS)

Renzini, Alvio

2000-09-01

The global gas flows in elliptical galaxies are initiated by stellar mass loss and their diagnostics rely on X-ray observations. The flows are controlled by a number of factors, including supernova heating, the depth and shape of the potential well as determined by the amount and distribution of bright and dark matter, AGN fueling and its feedback effects, interaction with the intracluster medium, and star formation. As a result no steady-state solution can satisfactorily describe the complex, evolutionary behavior of the gas flows, which can experience supersonic wind, subsonic outflow, and inflow phases, and transitions between one such flow regime to another. Having identified heating by Type Ia SN's as one of the key factors controlling the flows, constraints on its evolution with cosmological time are derived by considering the total amount of iron contained in whole clusters of galaxies, while the iron abundance in individual galaxy flows can set constraints on the present rate of SNIa's in ellipticals. The central issue of the problem remains the fate of the gas. It is argued that in one way or another, via SN-driven winds, ram pressure stripping, or AGN violent ejection, most of the gas is ultimately expelled from galaxies thus joining the intracluster medium.

A compact, metal-rich, kpc-scale outflow in FBQS J0209-0438: detailed diagnostics from HST/COS extreme UV observations

NASA Astrophysics Data System (ADS)

Finn, Charles W.; Morris, Simon L.; Crighton, Neil H. M.; Hamann, Fred; Done, Chris; Theuns, Tom; Fumagalli, Michele; Tejos, Nicolas; Worseck, Gabor

2014-06-01

We present HST/COS observations of highly ionized absorption lines associated with a radio-loud quasar (QSO) at z = 1.1319. The absorption system has multiple velocity components, with an overall width of ≈600 km s-1, tracing gas that is largely outflowing from the QSO at velocities of a few 100 km s-1. There is an unprecedented range in ionization, with detections of H I, N III, N IV, N V, O IV, O IV*, O V, O VI, Ne VIII, Mg X, S V and Ar VIII. We estimate the total hydrogen number density from the column density ratio N(OIV*) / N(OIV) to be log(nH/cm-3)˜3. Combined with constraints on the ionization parameter in the O IV bearing gas from photoionization equilibrium models, we derive a distance to the absorbing complex of 2.3≲R≲6.0kpc from the centre of the QSO. A range in ionization parameter, covering ˜two orders of magnitude, suggest absorption path lengths in the range 10-4.5≲labs≲1pc. In addition, the absorbing gas only partially covers the background emission from the QSO continuum, which suggests clouds with transverse sizes ltrans≲10-2.5 pc. Widely differing absorption path lengths, combined with covering fractions less than unity across all ions pose a challenge to models involving simple cloud geometries in associated absorption systems. These issues may be mitigated by the presence of non-equilibrium effects, which can be important in small, dynamically unstable clouds, together with the possibility of multiple gas temperatures. The dynamics and expected lifetimes of the gas clouds suggest that they do not originate from close to the active galactic nuclei, but are instead formed close to their observed location. Their inferred distance, outflow velocities and gas densities are broadly consistent with scenarios involving gas entrainment or condensations in winds driven by either supernovae, or the supermassive black hole accretion disc. In the case of the latter, the present data most likely does not trace the bulk of the outflow by mass, which could instead manifest itself as an accompanying warm absorber, detectable in X-rays.

Electron-positron outflow from black holes.

PubMed

van Putten, M H

2000-04-24

Cosmological gamma-ray bursts (GRBs) appear as the brightest transient phenomena in the Universe. The nature of their central engine is a missing link in the theory of fireballs to stellar mass progenitors, and may be associated with low mass black holes. In contact with an external magnetic field B, black hole spin produces a gravitational potential on the wave function of charged particles. We show that a rapidly rotating black hole of mass M produces outflow from initially electrostatic equilibrium with normalized isotropic emission approximately 10(48)(B/B(c))(2)(M/7M)(2)sin (2) theta erg/s, where B(c) = 4.4x10(13) G. The half-opening angle satisfies theta >or = square root[B(c)/3B]. The outflow proposed as input to GRB fireball models.

Arcus: exploring the formation and evolution of clusters, galaxies, and stars

NASA Astrophysics Data System (ADS)

Smith, R. K.; Abraham, M.; Allured, R.; Bautz, M.; Bookbinder, J.; Bregman, J.; Brenneman, L.; Brickhouse, N. S.; Burrows, D.; Burwitz, V.; Cheimets, P. N.; Costantini, E.; Dawson, S.; DeRoo, C.; Falcone, A.; Foster, A. R.; Gallo, L.; Grant, C. E.; Günther, H. M.; Heilmann, R. K.; Hertz, E.; Hine, B.; Huenemoerder, D.; Kaastra, J. S.; Kreykenbohm, I.; Madsen, K. K.; McEntaffer, R.; Miller, E.; Miller, J.; Morse, E.; Mushotzky, R.; Nandra, K.; Nowak, M.; Paerels, F.; Petre, R.; Poppenhaeger, K.; Ptak, A.; Reid, P.; Sanders, J.; Schattenburg, M.; Schulz, N.; Smale, A.; Temi, P.; Valencic, L.; Walker, S.; Willingale, R.; Wilms, J.; Wolk, S. J.

2017-08-01

Arcus, a Medium Explorer (MIDEX) mission, was selected by NASA for a Phase A study in August 2017. The observatory provides high-resolution soft X-ray spectroscopy in the 12-50Å bandpass with unprecedented sensitivity: effective areas of >450 cm2 and spectral resolution >2500. The Arcus key science goals are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, groups, and clusters, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback and (3) to explore how stars, circumstellar disks and exoplanet atmospheres form and evolve. Arcus relies upon the same 12m focal length grazing-incidence silicon pore X-ray optics (SPO) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. The power and telemetry requirements on the spacecraft are modest. Mission operations are straightforward, as most observations will be long ( 100 ksec), uninterrupted, and pre-planned, although there will be capabilities to observe sources such as tidal disruption events or supernovae with a 3 day turnaround. Following the 2nd year of operation, Arcus will transition to a proposal-driven guest observatory facility.

ROSAT observations of NGC 2146: Evidence for a starburst-driven superwind

NASA Technical Reports Server (NTRS)

Armus, L.; Heckman, T. M.; Weaver, K. A.; Lehnert, M. D.

1995-01-01

We have imaged the edge-on starburst galaxy NGC 2146 with the Position Sensitive Proportional Counter (PSPC) and the High Resolution Imager (HRI) on board ROSAT and have compared these data to optical images and long-slit spectra. NGC 2146 possesses a very large X-ray nebula with a half-light radius of 1 min (4 kpc) and a maximum diameter of approximately 4 min, or 17 kpc. The X-ray emission is resolved by the PSPC and preferentially oriented along the minor axis, with a total flux of 1.1 x 10(exp -12) ergs/sq cm/s over 0.2 - 2.4 keV and a luminosity of approximately 3 x 10(exp 40) ergs/s. The inner X-ray nebula is resolved by the HRI into at least four bright knots together with strong diffuse emission responsible for at least 50% of the flux within a radius of 0.5 min (approximately 2 kpc). The brightest knot has a luminosity of (2 - 3) x 10(exp 39) ergs/s. The X-ray nebula has a spatial extent much larger than the starburst ridge seen at centimeter wavelengths by Kronberg & Biermann (1981) and is oriented in a `X-like' pattern along the galaxy minor axis at a position angle of approximately 30 degrees. This minor-axis X-ray emission is associated with a region of H alpha and dust filaments seen in optical images. Optical spectra show that the emission-line gas along the minor axis is characterized by relatively broad lines (approximately 250 km/s full width half-maximum (FWHM)) and by `shocklike' emission-line flux ratios. Together with the blue-asymmetric nuclear emission-line and NaD interstellar absorption-line profiles, these optical data strongly suggest the presence of a starburst-driven superwind. The X-ray spectrum extracted from the central 5 min contains a strong Fe L emission-line complex at 0.6 - 1.0 keV and a hard excess above 1.0 keV. The spectrum is best described with a two-component model, containing a soft (kT approximately 400 - 500 eV) Raymond-Smith thermal plasma together with either a Gamma = 1.7 power-law or a kT greater than 2.2 keV bremsstrahlung component. The soft thermal component provides approximately 30% of the total luminosity over 0.2 - 2.4 keV, or approximately 10(exp 40) ergs/s. The pressure derived from the soft component of the X-ray spectrum is consistent with that predicted from a starburst-driven superwind if the filling factor of the warm gas is approximately 1% - 10 %. If the hard X-ray component is thermal gas associated with the galactic outflow, the filling factor must be close to unity. Predictions of the luminosity, temperature, and size of an adiabatic starburst-generated windblown bubble are consistent with those measured for the soft thermal X-ray emission in NGC 2146. The hard X-ray component, however, has a luminosity much larger than predicted by the superwind model if this component is thermal emission from gas heated by an internal shock in the expanding bubble. We briefly review various possibilities as to the nature of the hard X-ray component in NGC 2146.

The Prevalence of Ionized Gas Outflow Signatures in SDSS-IV MaNGA Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Flores, Anthony M.; Wylezalek, Dominika; Zakamska, Nadia

2018-01-01

Actively accreting supermassive black holes (AGN) can have a variety of effects on their host galaxies, from generating large regions of hot, photoionized gas, to driving AGN feedback in the form of galaxy wide outflows that may affect the evolution of the galaxy over time by quenching their star formation and by thus setting limits to the total mass of their host galaxy. The focus of this work is to assess the prevalence of AGN-driven outflows in low-redshift AGN of moderate power using IFU observations of 2778 galaxies available through SDSS-IV MaNGA.SDSS-IV MaNGA is an optical spectroscopic IFU survey which will have obtained spatially resolved spectroscopic observations of ~10,000 galaxies at z ≤ 0.1 and with stellar masses >10^9 solar masses over the next three years, allowing us to describe the kinematic properties of a large galaxy sample across different spatial regions.We have re-mapped the kinematics of the [O III] emission line to account for asymmetries and secondary kinematic components in the emission line brought on by potential AGN-driven outflows. Using all galaxies currently in the MaNGA survey, we implement a new fitting procedure to help determine the prevalence of these secondary components. Specifically, we use the non-parametric W80 value as a proxy for velocity dispersion, which we expect to be affected especially in the case of asymmetries and broadening of the emission lines. Separating these galaxies into two samples of independently identified AGN candidates and non-AGN, I will show that broad secondary components are twice as common in MaNGA-selected AGN compared to galaxies in MaNGA not classified as AGN. Moreover, when the underlying distribution of W80 values are compared between samples, I will show that the differences in these distributions are statistically significant. This demonstrates that large IFU survey like SDSS-IV MaNGA will uncover many previously unknown AGN and AGN feedback signatures. Outflows and feedback from low- and intermediate-luminosity AGN might have been underestimated in the past but can potentially significantly contribute to the AGN/host-galaxy self-regulation.

Using He I λ10830 to Diagnose Mass Flows Around Herbig Ae/Be Stars

NASA Astrophysics Data System (ADS)

Cauley, Paul W.; Johns-Krull, Christopher M.

2015-01-01

The pre-main sequence Herbig Ae/Be stars (HAEBES) are the intermediate mass cousins of the low mass T Tauri stars (TTSs). However, it is not clear that the same accretion and mass outflow mechanisms operate identically in both mass regimes. Classical TTSs (CTTSs) accrete material from their disks along stellar magnetic field lines in a scenario called magnetospheric accretion. Magnetospheric accretion requires a strong stellar dipole field in order to truncate the inner gas disk. These fields are either absent or very weak on a large majority of HAEBES, challenging the view that magnetospheric accretion is the dominant accretion mechanism. If magnetospheric accretion does not operate similarly around HAEBES as it does around CTTSs, then strong magnetocentrifugal outflows, which are directly linked to accretion and are ubiquitous around CTTSs, may be driven less efficiently from HAEBE systems. Here we present high resolution spectroscopic observations of the He I λ10830 line in a sample of 48 HAEBES. He I λ10830 is an excellent tracer of both mass infall and outflow which is directly manifested as red and blue-shifted absorption in the profile morphologies. These features, among others, are common in our sample. The occurrence of both red and blue-shifted absorption profiles is less frequent, however, than is found in CTTSs. Statistical contingency tests confirm this difference at a significant level. In addition, we find strong evidence for smaller disk truncation radii in the objects displaying red-shifted absorption profiles. This is expected for HAEBES experiencing magnetospheric accretion based on their large rotation rates and weak magnetic field strengths. Finally, the low incidence of blue-shifted absorption in our sample compared to CTTSs and the complete lack of simultaneous red and blue-shifted absorption features suggests that magnetospheric accretion in HAEBES is less efficient at driving strong outflows. The stellar wind-like outflows that are observed are likely driven, at least in part, by boundary layer accretion. The smaller (or absent) disk truncation radii in HAEBES may have consequences for the frequency of planets in close orbits around main sequence B and A stars.

Dynamic Fluid-Kinetic (DyFK) Simulations of Storm-Enhanced Density Supply of Cleft Ion Fountain Outflows

NASA Astrophysics Data System (ADS)

Horwitz, J. L.; Zeng, W.; Foster, J. C.; Strangeway, R. J.; Adrian, M. L.; Moore, T. E.

2008-12-01

Elevated ionospheric density regions frequently appear to be convected from the subauroral plasmaspheric region toward noon, in association with convection of plasmaspheric tails in the dayside magnetosphere, typically during large geomagnetic storms. In this presentation, we explore the possibility that these Storm Enhanced Density (SED) regions could provide ionospheric plasma source populations for cleft ion fountain outflows. We use our Dynamic Fluid Kinetic (DyFK) code to simulate the entry of a high-density "plasmasphere-like" flux tube entering the cleft region and subjected to an episode of wave-driven transverse ion heating. The results of including different proportions of SED and soft electron precipitation levels, together with transverse ion heating effects on the resulting outflows, will be presented, including the O+ and H+ ion density and related parameter profiles for the simulated SED involved events. We will also compare these modeling results with SED-outflow observations from GPS TEC, and the FAST and IMAGE spacecraft. Foster, J. C., P. J. Erickson, A. J. Coster, J. Goldstein, and F. J. Rich, Ionospheric signatures of plasmaspheric tails, Geophys. Res. Lett., 29(13), 1623, doi:10.1029/2002GL015067, 2002.

Mapping the Extent of M82's outlfows with VIRUS-P

NASA Astrophysics Data System (ADS)

Indahl, Briana; Hill, Gary J.; Drory, Niv; McLinden, Emily

2017-06-01

Starburst-driven outflows (SBDOs) and other feedback processes play a critical role in the evolution of galaxies through the regulation and disruption of star formation. However, our ability to observe and quantify feedback from SBDOs directly has been limited by the inability to obtain the spectroscopy needed for physical diagnostics over the large areas of local SBDOs. We present integral field spectroscopy taken with the George and Cynthia Mitchell Spectrograph (VIRUS-P) on the 2.7 meter Harlan J. Smith Telescope at McDonald Observatory mapping the full extent of M82’s northern outflow out to ~12kpc covering ~139 square arcminutes. We measured line ratios ([OIII]/Hβ, [OI]/Hα, [NII]/Hα), [SII]/Hα) for each spaxel in our fields. Using Ionization Diagnostic Diagrams (IDDs) we spatially map shock dominated regions which we show trace the biconical structure of the outflow. M82 is a local galaxy (z~0.000677) and the classical example of a starburst galaxy with vigorous outflows. As a result it has been comprehensively studied for nearly 50 years. However, we present the most sensitive and extensive map of the warm ionized gas to date from the disk to the Hα cap at ~12kpc.

Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs: III - Location and Energetics

NASA Technical Reports Server (NTRS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

2012-01-01

Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval approx.0.0003-0.03pc (approx.10(exp 2)-10(exp 4)tau(sub s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are constrained between approx.0.01- 1 Stellar Mass/y, corresponding to approx. or >5-10% of the accretion rates. The average lower-upper limits on the mechanical power are logE(sub K) approx. or = 42.6-44.6 erg/s. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN r.osmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyferts galaxies .

Detection of blueshifted emission and absorption and a relativistic iron line in the X-ray spectrum of ESO323-G077

NASA Astrophysics Data System (ADS)

Jiménez-Bailón, E.; Krongold, Y.; Bianchi, S.; Matt, G.; Santos-Lleó, M.; Piconcelli, E.; Schartel, N.

2008-12-01

We report on the X-ray observation of the Seyfert 1 galaxy ESO323-G077 performed with XMM-Newton. The EPIC spectra show a complex spectrum with conspicuous absorption and emission features. The continuum emission can be modelled with a power law with an index of 1.99 +/- 0.02 in the whole XMM-Newton energy band, marginally consistent with typical values of type I objects. An absorption component with an uncommonly high equivalent hydrogen column (nH = 5.82+0.12-0.11 × 1022cm-2) is affecting the soft part of the spectrum. Additionally, two warm absorption components are also present in the spectrum. The lower ionized one, mainly imprinting the soft band of the spectrum, has an ionization parameter of logU = 2.14+0.06-0.07 and an outflowing velocity of v = 3200+600-200kms-1. Two absorption lines located at ~6.7 and ~7.0keV can be modelled with the highly ionized absorber. The ionization parameter and outflowing velocity of the gas measured are logU = 3.26+0.19-0.15 and v = 1700+600-400kms-1, respectively. Four emission lines were also detected in the soft energy band. The most likely explanation for these emission lines is that they are associated with an outflowing gas with a velocity of ~2000kms-1. The data suggest that the same gas which is causing the absorption could also being responsible of these emission features. Finally, the XMM-Newton spectrum shows the presence of a relativistic iron emission line likely originated in the accretion disc of a Kerr black hole with an inclination of ~25°. We propose a model to explain the observed X-ray properties which invokes the presence of a two-phase outflow with cone-like structure and a velocity of the order of 2000- 4000kms-1. The inner layer of the cone would be less ionized, or even neutral, than the outer layer. The inclination angle of the source would be lower than the opening angle of the outflowing cone. Partially based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. E-mail: elena@astroscu.unam.mx

Simulating Gamma-Ray Emission in Star-forming Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pfrommer, Christoph; Pakmor, Rüdiger; Simpson, Christine M.

Star-forming galaxies emit GeV and TeV gamma-rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving-mesh code Arepo to perform magnetohydrodynamical galaxy formation simulations with self-consistent CR physics. Our galaxy models exhibit a first burst of star formation that injects CRs at supernovae. Once CRs have sufficiently accumulated in our Milky Way–like galaxy, their buoyancy force overcomes the magnetic tension of the toroidal disk field. As field lines open up, they enable anisotropically diffusing CRs to escape into the halo and to accelerate amore » bubble-like, CR-dominated outflow. However, these bubbles are invisible in our simulated gamma-ray maps of hadronic pion-decay and secondary inverse-Compton emission because of low gas density in the outflows. By adopting a phenomenological relation between star formation rate (SFR) and far-infrared emission and assuming that gamma-rays mainly originate from decaying pions, our simulated galaxies can reproduce the observed tight relation between far-infrared and gamma-ray emission, independent of whether we account for anisotropic CR diffusion. This demonstrates that uncertainties in modeling active CR transport processes only play a minor role in predicting gamma-ray emission from galaxies. We find that in starbursts, most of the CR energy is “calorimetrically” lost to hadronic interactions. In contrast, the gamma-ray emission deviates from this calorimetric property at low SFRs due to adiabatic losses, which cannot be identified in traditional one-zone models.« less

Simulating Gamma-Ray Emission in Star-forming Galaxies

NASA Astrophysics Data System (ADS)

Pfrommer, Christoph; Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker

2017-10-01

Star-forming galaxies emit GeV and TeV gamma-rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving-mesh code Arepo to perform magnetohydrodynamical galaxy formation simulations with self-consistent CR physics. Our galaxy models exhibit a first burst of star formation that injects CRs at supernovae. Once CRs have sufficiently accumulated in our Milky Way-like galaxy, their buoyancy force overcomes the magnetic tension of the toroidal disk field. As field lines open up, they enable anisotropically diffusing CRs to escape into the halo and to accelerate a bubble-like, CR-dominated outflow. However, these bubbles are invisible in our simulated gamma-ray maps of hadronic pion-decay and secondary inverse-Compton emission because of low gas density in the outflows. By adopting a phenomenological relation between star formation rate (SFR) and far-infrared emission and assuming that gamma-rays mainly originate from decaying pions, our simulated galaxies can reproduce the observed tight relation between far-infrared and gamma-ray emission, independent of whether we account for anisotropic CR diffusion. This demonstrates that uncertainties in modeling active CR transport processes only play a minor role in predicting gamma-ray emission from galaxies. We find that in starbursts, most of the CR energy is “calorimetrically” lost to hadronic interactions. In contrast, the gamma-ray emission deviates from this calorimetric property at low SFRs due to adiabatic losses, which cannot be identified in traditional one-zone models.

RADIO OBSERVATIONS OF THE STAR FORMATION ACTIVITIES IN THE NGC 2024 FIR 4 REGION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Minho; Kang, Miju; Lee, Jeong-Eun, E-mail: minho@kasi.re.kr

Star formation activities in the NGC 2024 FIR 4 region were studied by imaging centimeter continuum sources and water maser sources using several archival data sets from the Very Large Array. The continuum source VLA 9 is elongated in the northwest–southeast direction, consistent with the FIR 4 bipolar outflow axis, and has a flat spectrum in the 6.2–3.6 cm interval. The three water maser spots associated with FIR 4 are also distributed along the outflow axis. One of the spots is located close to VLA 9, and another one is close to an X-ray source. Examinations of the positions ofmore » compact objects in this region suggest that the FIR 4 cloud core contains a single low-mass protostar. VLA 9 is the best indicator of the protostellar position. VLA 9 may be a radio thermal jet driven by this protostar, and it is unlikely that FIR 4 contains a high-mass young stellar object (YSO). A methanol 6.7 GHz maser source is located close to VLA 9, at a distance of about 100 AU. The FIR 4 protostar must be responsible for the methanol maser action, which suggests that methanol class II masers are not necessarily excited by high-mass YSOs. Also discussed are properties of other centimeter continuum sources in the field of view and the water masers associated with FIR 6n. Some of the continuum sources are radio thermal jets, and some are magnetically active young stars.« less

High energy power-law tail in X-ray binaries and bulk Comptonization due to an outflow from a disk

NASA Astrophysics Data System (ADS)

Kumar, Nagendra

2018-02-01

We study the high energy power-law tail emission of X-ray binaries (XRBs) by a bulk Comptonization process which is usually observed in the very high soft (VHS) state of black hole (BH) XRBs and the high soft (HS) state of the neutron star (NS) and BH XRBs. Earlier, to generate the power-law tail in bulk Comptonization framework, a free-fall converging flow into BH or NS had been considered as a bulk region. In this work, for a bulk region we consider mainly an outflow geometry from the accretion disk which is bounded by a torus surrounding the compact object. We have two choices for an outflow geometry: (i) collimated flow and (ii) conical flow of opening angle θ _b and the axis is perpendicular to the disk. We also consider an azimuthal velocity of the torus fluids as a bulk motion where the fluids are rotating around the compact object (a torus flow). We find that the power-law tail can be generated in a torus flow having large optical depth and bulk speed (>0.75 c), and in conical flow with θ _b > ˜ 30° for a low value of Comptonizing medium temperature. Particularly, in conical flow the low opening angle is more favourable to generate the power-law tail in both the HS state and the VHS state. We notice that when the outflow is collimated, then the emergent spectrum does not have power-law component for a low Comptonizing medium temperature.

Wave propagation in pulsar magnetospheres - Refraction of rays in the open flux zone

NASA Technical Reports Server (NTRS)

Barnard, J. J.; Arons, J.

1986-01-01

The propagation of waves through a relativistically outflowing electron-positron plasma in a very strong dipolar magnetic field, conditions expected in pulsar magnetospheres, is investigated. Halmilton's equations is derived for the propagation of rays through a plasma which is inhomogeneous in density, magnetic field directions, and Lorentz factor. These equations are solved for rays propagating through the plasmas outflowing along the 'open' dipolar field lines in which the density decreases inversely as the radius cubed and in the case where gradients transverse to the radial direction exist. In the radial case, the effects of refraction on pulse profiles, spectrum, and polarization are examined, and the effects of a transverse gradient are indicated. Attention is given to models in which the observed broad bandwidth in the radio emission has its origin in a radius to frequency map. Models with broad-band emission at a single radius are also studied. These are compared to observations of pulse width and pulse component separation as a function of frequency. The origin of 'orthogonal modes' is discussed.

A New Relativistic Component of the Accretion Disk Wind in PDS 456

NASA Astrophysics Data System (ADS)

Reeves, J. N.; Braito, V.; Nardini, E.; Lobban, A. P.; Matzeu, G. A.; Costa, M. T.

2018-02-01

Past X-ray observations of the nearby luminous quasar PDS 456 (at z = 0.184) have revealed a wide angle accretion disk wind, with an outflow velocity of ∼‑0.25c. Here, we unveil a new, relativistic component of the wind through hard X-ray observations with NuSTAR and XMM-Newton, obtained in 2017 March when the quasar was in a low-flux state. This very fast wind component, with an outflow velocity of ‑0.46 ± 0.02c, is detected in the iron K band, in addition to the ‑0.25c wind zone. The relativistic component may arise from the innermost disk wind, launched from close to the black hole at a radius of ∼10 gravitational radii. The opacity of the fast wind also increases during a possible obscuration event lasting for 50 ks. We suggest that the very fast wind may only be apparent during the lowest X-ray flux states of PDS 456, becoming overly ionized as the luminosity increases. Overall, the total wind power may even approach the Eddington value.

Constraints on Galactic Cosmic-Ray Origins from Elemental Composition Measurements

NASA Astrophysics Data System (ADS)

Binns, W. R.; Christian, E. R.; Cummings, A. C.; Denolfo, G. A.; Israel, M. H.; Lave, K. A.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; von Rosenvinge, T. T.; Wiedenbeck, M. E.

2017-01-01

We present measurements of the abundances of ultra-heavy (Z>29) cosmic rays made by the CRIS instrument on NASA's Advanced Composition Explorer satellite. The data set corresponds to 6413 days of data collection between December 4, 1997 and May 31, 2016. The charge resolution that we obtain is excellent, exhibiting essentially complete separation of adjacent charges in the Z>28 range. We detected 196 events over the charge range of Z =30-40. Our measured abundances show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to a mix of massive star outflow and SN ejecta with normal ISM, rather than pure ISM. Additionally, the refractory and volatile elements have similar slopes and refractory elements are preferentially accelerated by a factor of 4. The measured abundances support a model in which 20% of cosmic ray source material is from massive star outflow and ejecta and 80% is from normal ISM. Our abundances show generally good agreement with the TIGER and SuperTIGER results. This research is supported by NASA under Grant # NNX13AH66G.

The WISSH quasars project. I. Powerful ionised outflows in hyper-luminous quasars

NASA Astrophysics Data System (ADS)

Bischetti, M.; Piconcelli, E.; Vietri, G.; Bongiorno, A.; Fiore, F.; Sani, E.; Marconi, A.; Duras, F.; Zappacosta, L.; Brusa, M.; Comastri, A.; Cresci, G.; Feruglio, C.; Giallongo, E.; La Franca, F.; Mainieri, V.; Mannucci, F.; Martocchia, S.; Ricci, F.; Schneider, R.; Testa, V.; Vignali, C.

2017-02-01

Models and observations suggest that both the power and effects of AGN feedback should be maximised in hyper-luminous (LBol > 1047 erg s-1) quasars, I.e. objects at the brightest end of the AGN luminosity function. In this paper, we present the first results of a multiwavelength observing programme, focusing on a sample of WISE/SDSS selected hyper-luminous (WISSH) broad-line quasars at z ≈ 1.5-5. The WISSH quasars project has been designed to reveal the most energetic AGN-driven outflows, estimate their occurrence at the peak of quasar activity, and extend the study of correlations between outflows and nuclear properties up to poorly investigated, extreme AGN luminosities, I.e. LBol 1047 - 1048 erg s-1. We present near-infrared, long-slit LBT/LUCI1 spectroscopy of five WISSH quasars at z ≈ 2.3 - 3.5, showing prominent [OIII] emission lines with broad (FWHM 1200-2200 km s-1) and skewed profiles. The luminosities of these broad [OIII] wings are the highest measured so far, with L[OIII]broad ≳ 5 × 1044 erg s-1, and reveal the presence of powerful ionised outflows with associated mass outflow rates Ṁ ≳ 1700M⊙ yr-1 and kinetic powers Ėkin ≳ 1045 erg s-1. Although these estimates are affected by large uncertainties because of the use of [OIII] as a tracer of ionised outflows and the very basic outflow model adopted here, these results suggest that in our hyper-luminous targets the AGN is highly efficient at pushing large amounts of ionised gas outwards. Furthermore, the mechanical outflow luminosities measured for WISSH quasars correspond to higher percentages ( 1-3%) of LBol than those derived for AGN with lower LBol. Our targets host very massive (MBH ≳ 2 × 109M⊙) black holes that are still accreting at a high rate (I.e. a factor of 0.4-3 of the Eddington limit). These findings clearly demonstrate that WISSH quasars offer the opportunity to probe the extreme end of both luminosity and supermassive black holes (SMBH) mass functions and revealing powerful ionised outflows that are able to affect the evolution of their host galaxies.

An In-depth Chandra ACIS View Of The Circumnuclear Region Of NGC 4151: The Jet, The Biconical Outflow, And A Leaky Torus

NASA Astrophysics Data System (ADS)

Wang, Junfeng; Fabbiano, G.; Elvis, M.; Risaliti, G.; Karovska, M.; Zezas, A.; Mundell, C. G.

2011-05-01

We report on the imaging analysis of 200 ks Chandra ACIS-S observations of the nearby Seyfert 1 galaxy NGC 4151. Structured soft X-ray emission is observed to extend from 30 pc to 1.5 kpc. We find strong evidence for jet-gas cloud interaction in the inner 150 pc region, confirming our previous HRC results. Self-consistent photoionization models provide good descriptions of the spectra of the optical bi-cone, supporting the dominant role of nuclear photoionization. Presence of both low and high ionization spectral components and extended emission in the X-ray image perpendicular to the bi-cone indicates leakage of nuclear ionization. Using spatially resolved features, we estimate the kinematic power of the outflow in NGC 4151 to be 0.3% of its bolometric luminosity. This work is supported by NASA grant GO8-9101X and GO1-12009X.

Dramatically Variable C IV Mini-Broad Absorption Line System in the Quasar HS 1603+3820

NASA Astrophysics Data System (ADS)

Misawa, T.; Eracleous, M.; Charlton, J. C.; Chartas, G.; Kashikawa, N.

2008-10-01

We observed the quasar HS 1603+3820 (z_{em} = 2.542, first discovered by Dobrzycki et al. 1996) six times over an interval of 4.2 yrs (1.2 yrs in the quasar rest frame) using the High Dispersion Spectrograph on Subaru telescope. The purpose was to study the mini-broad absorption line (mini-BAL; FWHM ˜ 1,000 km s^{-1}) that is blue-shifted from the quasar by ˜ 9,500 km s^{-1}. We found significant time variability, which supported the physical association of the mini-BAL gas with an outflow from the quasar. We have narrowed down the cause of the variability to two possible scenarios. We also used archival Chandra x-ray data to study the x-ray properties of this quasar. The results constrain the location of the absorbing gas relative to the overall outflow.

Chandra HETGs Observation of the Warm Absorber in Mrk 290

NASA Astrophysics Data System (ADS)

Zhang, Shuinai; Marshall, H. L.; Ji, L. L.

2009-01-01

Four Chandra High Energy Transmission Grating spectra of Mrk 290, a bright Seyfert 1, were carried out in 2003 with a total integration time of 251 ks. The nuclear X-ray spectrum is best described by a absorbed power law of photon index Γ 1.83 plus a black body model with a temperature of 90 eV. Using the combined spectra, we detect significant absorption lines due to intervening ionized outflowing gas. Some absorption lines show a discrete velocity structure. The outflow velocity 500 km/s is comparable with that in ultraviolet band. Support for this work was provided by the National Aeronautic Space Administration through the Smithonian Astrophysics of Observation contract SV3-73016 to MIT for support of the Chandra X-ray Center, which is operated by SAO for and on behalf of NASA under contract NAS8-03060.

Unifying X-ray winds in radio galaxies with Chandra HETG

NASA Astrophysics Data System (ADS)

Tombesi, Francesco

2013-09-01

X-ray winds are routinely observed in the spectra of Seyfert galaxies. They can be classified as warm absorbers (WAs), with v~100-1,000km/s, and ultra-fast outflows (UFOs), with v>10,000km/s. In stark contrast, the lack of sensitive enough observations allowed the detection of WAs or UFOs only in very few radio galaxies. Therefore, we propose to observe a small sample of three radio galaxies with the Chandra HETG - 3C111 for 150ks, 3C390.3 for 150ks and 3C120 for 200ks - to detect and study in detail their WAs. We will quantify the importance of mechanical feedback from winds in radio galaxies and compare them to the radio jet power. We will also test whether WAs and UFOs can be unified in a single, multi-phase and multi-scale outflow, as recently reported for Seyferts.

The effect of pair cascades on the high-energy spectral cut-off in gamma-ray bursts

NASA Astrophysics Data System (ADS)

Gill, Ramandeep; Granot, Jonathan

2018-03-01

The highly luminous and variable prompt emission in gamma-ray bursts (GRBs) arises in an ultra-relativistic outflow. The exact underlying radiative mechanism shaping its non-thermal spectrum is still uncertain, making it hard to determine the outflow's bulk Lorentz factor Γ. GRBs with spectral cut-off due to pair production (γγ → e+e-) at energies Ec ≳ 10 MeV are extremely useful for inferring Γ. We find that when the emission region has a high enough compactness, then as it becomes optically thick to scattering, Compton downscattering by non-relativistic e±-pairs can shift the spectral cut-off energy well below the self-annihilation threshold, Esa = Γmec2/(1 + z). We treat this effect numerically and show that Γ obtained assuming Ec = Esa can underpredict its true value by as much as an order of magnitude.

Prompt Ion Outflows and Artificial Ducts during High-Power HF Heating at HAARP: Effect of Suprathermal Electrons?

NASA Astrophysics Data System (ADS)

Mishin, E. V.; Milikh, G. M.

2014-12-01

In situ observations from the DMSP and Demeter satellites established that high-power HF heating of the ionosphere F-region results in significant ion outflows associated with 10-30% density enhancements in the topside ionosphere magnetically-conjugate to the heated region. As follows from the SAMI2 two-fluid model calculations, their formation time should exceed 5-7 minutes. However, specially designed DMSP-HAARP experiments have shown that artificial ducts and ion outflows appear on the topside within 2 minutes. We describe the results of these observations and present a semi-quantitative explanation of the fast timescale due to suprathermal electrons accelerated by HF-induced plasma turbulence. There are two possible effects of suprathermal electrons: (1) the increase of the ambipolar electric field over the usual thermal ambipolar diffusion and (2) excitation of heat flux-driven plasma instability resulting in an anomalous electron-ion momentum exchange. Both effects result in faster upward ion flows.

Collimated Outflow Formation via Binary Stars: Three-Dimensional Simulations of Asymptotic Giant Branch Wind and Disk Wind Interactions

NASA Astrophysics Data System (ADS)

García-Arredondo, F.; Frank, Adam

2004-01-01

We present three-dimensional hydrodynamic simulations of the interaction of a slow wind from an asymptotic giant branch (AGB) star and a jet blown by an orbiting companion. The jet or ``collimated fast wind'' is assumed to originate from an accretion disk that forms via Bondi accretion of the AGB wind or Roche lobe overflow. We present two distinct regimes in the wind-jet interaction determined by the ratio of the AGB wind to jet momentum flux. Our results show that when the wind momentum flux overwhelms the flux in the jet, a more disordered outflow results with the jet assuming a corkscrew pattern and multiple shock structures driven into the AGB wind. In the opposite regime, the jet dominates and will drive a highly collimated, narrow-waisted outflow. We compare our results with scenarios described by Soker & Rappaport and extrapolate to the structures observed in planetary nebulae (PNs) and symbiotic stars.

Current and Future X-ray Studies of High-Redshift AGNs and the First Supermassive Black Holes

NASA Astrophysics Data System (ADS)

Brandt, Niel

2016-01-01

X-ray observations of high-redshift AGNs at z = 4-7 have played a critical role in understanding the physical processes at work inthese objects as well as their basic demographics. Since 2000, Chandra and XMM-Newton have provided new X-ray detections for more than 120 such objects, and well-defined samples of z > 4 AGNs now allow reliable X-ray population studies. Once luminosity effectsare considered, the basic X-ray continuum properties of most high-redshift AGNs appear remarkably similar to those of local AGNs, although there are some notable apparent exceptions (e.g., highly radio-loud quasars). Furthermore, the X-ray absorption found in some objects has been used as a diagnostic of outflowing winds and circumnuclear material. Demographically, the X-ray data now support an exponential decline in the number density of luminous AGNs above z ~ 3, and quantitative space-density comparisons for optically selected and X-ray selected quasars indicate basic statistical agreement.The current X-ray discoveries point the way toward the future breakthroughs that will be possible with, e.g., Athena and the X-raySurveyor. These missions will execute powerful blank-field surveys to elucidate the demographics of the first growing supermassive black holes (SMBHs), including highly obscured systems, up to z ~ 10. They will also carry out complementary X-ray spectroscopic and variability investigations of high-redshift AGNs by targeting the most-luminous z = 7-10 quasars found in wide-field surveys by, e.g., Euclid, LSST, and WFIRST. X-ray spectroscopic and variability studies of the X-ray continuum and reflection signatures will help determine Eddington ratios and disk/corona properties; measuring these will clarify how the first quasars grew so quickly. Furthermore, absorption line/edge studies will reveal how outflows from the first SMBHs influenced the growth of the first galaxies. I will suggest some efficient observational strategies for Athena and the X-ray Surveyor.

Magnetized Disk Winds in NGC 3783

NASA Technical Reports Server (NTRS)

Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Tombesi, Francesco; Contopoulos, Ioannis

2018-01-01

We analyze a 900 kilosecond stacked Chandra/HETG (High-Energy Transmission Grating) spectrum of NGC 3783 in the context of magnetically driven accretion-disk wind models in an effort to provide tight constraints on the global conditions of the underlying absorbers. Motivated by the earlier measurements of its absorption measure distribution (AMD) indicating X-ray-absorbing ionic columns that decrease slowly with decreasing ionization parameter, we employ 2-dimension (2-D) magnetohydrodynamic (MHD) disk wind models to describe the global outflow. We compute its photoionization structure along with the wind kinematic properties, allowing us to further calculate in a self-consistent fashion the shapes of the major X-ray absorption lines. With the wind radial density profile determined by the AMD, the profiles of the ensemble of the observed absorption features are determined by the two global parameters of the MHD wind; i.e., disk inclination theta (sub obs) and wind density normalization n (sub o). Considering the most significant absorption features in the approximately 1.8-20 angstrom range, we show that the MHD wind is best described by n(r) approximately equal to 6.9 times 10 (sup 11) (r/r (sub o)) (sup - 1.15) cubic centimeters and theta (sub obs). We argue that winds launched by X-ray heating or radiation pressure, or even MHD winds but with steeper radial density profiles, are strongly disfavored by data. Considering the properties of Fe K-band absorption features (i.e., Fe XXV and Fe XXVI), while typically prominent in the active galactic nucleus X-ray spectra, they appear to be weak in NGC 3783. For the specific parameters of our model obtained by fitting the AMD and the rest of the absorption features, these features are found to be weak, in agreement with observations.

Magnetized Disk Winds in NGC 3783

NASA Astrophysics Data System (ADS)

Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Tombesi, Francesco; Contopoulos, Ioannis

2018-01-01

We analyze a 900 ks stacked Chandra/HETG spectrum of NGC 3783 in the context of magnetically driven accretion-disk wind models in an effort to provide tight constraints on the global conditions of the underlying absorbers. Motivated by the earlier measurements of its absorption measure distribution (AMD) indicating X-ray-absorbing ionic columns that decrease slowly with decreasing ionization parameter, we employ 2D magnetohydrodynamic (MHD) disk wind models to describe the global outflow. We compute its photoionization structure along with the wind kinematic properties, allowing us to further calculate in a self-consistent fashion the shapes of the major X-ray absorption lines. With the wind radial density profile determined by the AMD, the profiles of the ensemble of the observed absorption features are determined by the two global parameters of the MHD wind; i.e., disk inclination {θ }{obs} and wind density normalization n o . Considering the most significant absorption features in the ∼1.8–20 Å range, we show that the MHD wind is best described by n{(r)∼ 6.9× {10}11(r/{r}o)}-1.15 cm‑3 and {θ }{obs}=44^\\circ . We argue that winds launched by X-ray heating or radiation pressure, or even MHD winds but with steeper radial density profiles, are strongly disfavored by data. Considering the properties of Fe K-band absorption features (i.e., Fe XXV and Fe XXVI), while typically prominent in the active galactic nucleus X-ray spectra, they appear to be weak in NGC 3783. For the specific parameters of our model obtained by fitting the AMD and the rest of the absorption features, these features are found to be weak, in agreement with observations.

Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert galaxies - I. A global view and frequency of occurrence of warm absorbers.

NASA Astrophysics Data System (ADS)

Laha, Sibasish; Guainazzi, Matteo; Dewangan, Gulab C.; Chakravorty, Susmita; Kembhavi, Ajit K.

2014-07-01

We present results from a homogeneous analysis of the broad-band 0.3-10 keV CCD resolution as well as of the soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. Our goal is to characterize warm absorbers (WAs) along the line of sight to the active nucleus. We significantly detect WAs in 65 per cent of the sample sources. Our results are consistent with WAs being present in at least half of the Seyfert galaxies in the nearby Universe, in agreement with previous estimates. We find a gap in the distribution of the ionization parameter in the range 0.5 < log ξ < 1.5 which we interpret as a thermally unstable region for WA clouds. This may indicate that the WA flow is probably constituted by a clumpy distribution of discrete clouds rather than a continuous medium. The distribution of the WA column densities for the sources with broad Fe Kα lines are similar to those sources which do not have broadened emission lines. Therefore, the detected broad Fe Kα emission lines are bona fide and not artefacts of ionized absorption in the soft X-rays. The WA parameters show no correlation among themselves, with the exception of the ionization parameter versus column density. The shallow slope of the log ξ versus log vout linear regression (0.12 ± 0.03) is inconsistent with the scaling laws predicted by radiation or magnetohydrodynamic-driven winds. Our results also suggest that WA and ultra fast outflows do not represent extreme manifestation of the same astrophysical system.

Evidence for hot clumpy accretion flow in the transitional millisecond pulsar PSR J1023+0038

NASA Astrophysics Data System (ADS)

Shahbaz, T.; Dallilar, Y.; Garner, A.; Eikenberry, S.; Veledina, A.; Gandhi, P.

2018-06-01

We present simultaneous optical and near-infrared (IR) photometry of the millisecond pulsar PSR J1023+0038 during its low-mass X-ray binary phase. The r΄- and Ks-band light curves show rectangular, flat-bottomed dips, similar to the X-ray mode-switching (active-passive state transitions) behaviour observed previously. The cross-correlation function (CCF) of the optical and near-IR data reveals a strong, broad negative anticorrelation at negative lags, a broad positive correlation at positive lags, with a strong, positive narrow correlation superimposed. The shape of the CCF resembles the CCF of black hole X-ray binaries but the time-scales are different. The features can be explained by reprocessing and a hot accretion flow close to the neutron star's magnetospheric radius. The optical emission is dominated by the reprocessed component, whereas the near-IR emission contains the emission from plasmoids in the hot accretion flow and a reprocessed component. The rapid active-passive state transition occurs when the hot accretion flow material is channelled on to the neutron star and is expelled from its magnetosphere. During the transition the optical reprocessing component decreases resulting in the removal of a blue spectral component. The accretion of clumpy material through the magnetic barrier of the neutron star produces the observed near-IR/optical CCF and variability. The dip at negative lags corresponds to the suppression of the near-IR synchrotron component in the hot flow, whereas the broad positive correlation at positive lags is driven by the increased synchrotron emission of the outflowing plasmoids. The narrow peak in the CCF is due to the delayed reprocessed component, enhanced by the increased X-ray emission.

Downscattering due to Wind Outflows in Compact X-ray Sources: Theory and Interpretation

NASA Technical Reports Server (NTRS)

Titarchuk, Lev; Shrader, Chris

2004-01-01

A number of recent lines of evidence point towards the presence of hot, outflowing plasma from the central regions of compact Galactic and extragalactic X-ray sources. Additionally, it has long been noted that many of these sources exhibit an "excess" continuum component, above approx. 10 keV, usually attributed to Compton Reflection from a static medium. Motivated by these facts, as well as by recent observational constraints on the Compton reflection models - specifically apparently discrepant variability timescales for line and continuum components in some cases - we consider possible of effects of out-flowing plasma on the high-energy continuum spectra of accretion powered compact objects. We present a general formulation for photon downscattering diffusion which includes recoil and Comptonization effects due to divergence of the flow. We then develop an analytical theory for the spectral formation in such systems that allows us to derive formulae for the emergent spectrum. Finally we perform the analytical model fitting on several Galactic X-ray binaries. Objects which have been modeled with high-covering-fraction Compton reflectors, such as GS1353-64 are included in our analysis. In addition, Cyg X-3, is which is widely believed to be characterized by dense circumstellar winds with temperature of order 10(exp 6) K, provides an interesting test case. Data from INTEGRAL and RXTE covering the approx. 3 - 300 keV range are used in our analysis. We further consider the possibility that the widely noted distortion of the power-law continuum above 10 keV may in some cases be explained by these spectral softening effects.

Chandra Observation of Luminous and Ultraluminous X-ray Binaries in M101

NASA Technical Reports Server (NTRS)

Mukai, K.; Pence, W. D.; Snowden, S. L.; Kuntz, K. D.; White, Nicholas E. (Technical Monitor)

2002-01-01

X-ray binaries in the Milky Way are among the brightest objects on the X-ray sky. With the increasing sensitivity of recent missions, it is now possible to study X-ray binaries in nearby galaxies. We present data on six ultraluminous binaries in the nearby spiral galaxy, M101, obtained with Chandra ACIS-S. Of these, five appear to be similar to ultraluminous sources in other galaxies, while the brightest source, P098, shows some unique characteristics. We present our interpretation of the data in terms of an optically thick outflow, and discuss implications.

Quasar Feedback in the Ultraluminous Infrared Galaxy F11119+3257: Connecting the Accretion Disk Wind with the Large-scale Molecular Outflow

NASA Astrophysics Data System (ADS)

Veilleux, S.; Bolatto, A.; Tombesi, F.; Meléndez, M.; Sturm, E.; González-Alfonso, E.; Fischer, J.; Rupke, D. S. N.

2017-07-01

In Tombesi et al., we reported the first direct evidence for a quasar accretion disk wind driving a massive (>100 M ⊙ yr-1) molecular outflow. The target was F11119+3257, an ultraluminous infrared galaxy (ULIRG) with unambiguous type 1 quasar optical broad emission lines. The energetics of the accretion disk wind and molecular outflow were found to be consistent with the predictions of quasar feedback models where the molecular outflow is driven by a hot energy-conserving bubble inflated by the inner quasar accretion disk wind. However, this conclusion was uncertain because the mass outflow rate, momentum flux, and mechanical power of the outflowing molecular gas were estimated from the optically thick OH 119 μm transition profile observed with Herschel. Here, we independently confirm the presence of the molecular outflow in F11119+3257, based on the detection of ˜±1000 km s-1 blue- and redshifted wings in the CO(1-0) emission line profile derived from deep ALMA observations obtained in the compact array configuration (˜2.″8 resolution). The broad CO(1-0) line emission appears to be spatially extended on a scale of at least ˜7 kpc from the center. Mass outflow rate, momentum flux, and mechanical power of (80-200) {R}7-1 M ⊙ yr-1, (1.5-3.0) {R}7-1 L AGN/c, and (0.15-0.40)% {R}7-1 {L}{AGN}, respectively, are inferred from these data, assuming a CO-to-H2 conversion factor appropriate for a ULIRG (R 7 is the radius of the outflow normalized to 7 kpc, and L AGN is the AGN luminosity). These rates are time-averaged over a flow timescale of 7 × 106 yr. They are similar to the OH-based rates time-averaged over a flow timescale of 4 × 105 yr, but about a factor of 4 smaller than the local (“instantaneous” ≲105 yr) OH-based estimates cited in Tombesi et al. The implications of these new results are discussed in the context of time-variable quasar-mode feedback and galaxy evolution. The need for an energy-conserving bubble to explain the molecular outflow is also reexamined.

Relativistic baryonic jets from an ultraluminous supersoft X-ray source.

PubMed

Liu, Ji-Feng; Bai, Yu; Wang, Song; Justham, Stephen; Lu, You-Jun; Gu, Wei-Min; Liu, Qing-Zhong; Di Stefano, Rosanne; Guo, Jin-Cheng; Cabrera-Lavers, Antonio; Álvarez, Pedro; Cao, Yi; Kulkarni, Shri

2015-12-03

The formation of relativistic jets by an accreting compact object is one of the fundamental mysteries of astrophysics. Although the theory is poorly understood, observations of relativistic jets from systems known as microquasars (compact binary stars) have led to a well established phenomenology. Relativistic jets are not expected to be produced by sources with soft or supersoft X-ray spectra, although two such systems are known to produce relatively low-velocity bipolar outflows. Here we report the optical spectra of an ultraluminous supersoft X-ray source (ULS) in the nearby galaxy M81 (M81 ULS-1; refs 9, 10). Unexpectedly, the spectra show blueshifted, broad Hα emission lines, characteristic of baryonic jets with relativistic speeds. These time-variable emission lines have projected velocities of about 17 per cent of the speed of light, and seem to be similar to those from the prototype microquasar SS 433 (refs 11, 12). Such relativistic jets are not expected to be launched from white dwarfs, and an origin from a black hole or a neutron star is hard to reconcile with the persistence of M81 ULS-1's soft X-rays. Thus the unexpected presence of relativistic jets in a ULS challenges canonical theories of jet formation, but might be explained by a long-speculated, supercritically accreting black hole with optically thick outflows.

NGC 5195 IN M51: FEEDBACK “BURPS” AFTER A MASSIVE MEAL?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlegel, E. M.; Jones, C.; Machacek, M.

2016-06-01

We describe a double-arc-like X-ray structure lying ∼15″–30″ (∼0.8–1.7 kpc) south of the NGC 5195 nucleus, visible in the merged exposures of long Chandra pointings of M51. The curvature and orientation of the arcs argues for a nuclear origin. The arcs are radially separated by ∼15″ (∼1 kpc), but are rotated relative to each other by ∼30°. From an archival image, we find a slender H α -emitting region just outside the outer edge of the outer X-ray arc, suggesting that the X-ray-emitting gas plowed up and displaced the H α -emitting material from the galaxy core. Star formation maymore » have commenced in that arc. H α emission is present at the inner arc, but appears more complex in structure. In contrast to an explosion expected to be azimuthally symmetric, the X-ray arcs suggest a focused outflow. We interpret the arcs as episodic outbursts from the central super-massive black hole (SMBH). We conclude that NGC 5195 represents the nearest galaxy exhibiting on-going, large-scale outflows of gas, in particular, two episodes of a focused outburst of the SMBH. The arcs represent a clear demonstration of feedback.« less

The Variable Fast Soft X-Ray Wind in PG 1211+143

NASA Astrophysics Data System (ADS)

Reeves, J. N.; Lobban, A.; Pounds, K. A.

2018-02-01

The analysis of a series of seven observations of the nearby (z = 0.0809) QSO PG 1211+143, taken with the Reflection Grating Spectrometer (RGS) onboard XMM-Newton in 2014, are presented. The high-resolution soft X-ray spectrum, with a total exposure exceeding 600 ks, shows a series of blueshifted absorption lines from the He and H-like transitions of N, O, and Ne, as well as from L-shell Fe. The strongest absorption lines are all systematically blueshifted by ‑0.06c, originating in two absorption zones from low- and high-ionization gas. Both zones are variable on timescales of days, with the variations in absorber opacity effectively explained by either column density changes or the absorber ionization responding directly to the continuum flux. We find that the soft X-ray absorbers probably exist in a two-phase wind at a radial distance of ∼1017–1018 cm from the black hole with the lower-ionization gas as denser clumps embedded within a higher-ionization outflow. The overall mass outflow rate of the soft X-ray wind may be as high as 2{M}ȯ yr‑1, close to the Eddington rate for PG 1211+143 and similar to that previously deduced from the Fe K absorption.

Chemical reaction path modeling of hydrothermal processes on Mars: Preliminary results

NASA Technical Reports Server (NTRS)

Plumlee, Geoffrey S.; Ridley, W. Ian

1992-01-01

Hydrothermal processes are thought to have had significant roles in the development of surficial mineralogies and morphological features on Mars. For example, a significant proportion of the Martian soil could consist of the erosional products of hydrothermally altered impact melt sheets. In this model, impact-driven, vapor-dominated hydrothermal systems hydrothermally altered the surrounding rocks and transported volatiles such as S and Cl to the surface. Further support for impact-driven hydrothermal alteration on Mars was provided by studies of the Ries crater, Germany, where suevite deposits were extensively altered to montmorillonite clays by inferred low-temperature (100-130 C) hydrothermal fluids. It was also suggested that surface outflow from both impact-driven and volcano-driven hydrothermal systems could generate the valley networks, thereby eliminating the need for an early warm wet climate. We use computer-driven chemical reaction path calculation to model chemical processes which were likely associated with postulated Martian hydrothermal systems.

Outflows in low-mass galaxies at z >1

NASA Astrophysics Data System (ADS)

Maseda, Michael V.; MUSE GTO Consortium

2017-03-01

Star formation histories of local dwarf galaxies, derived through resolved stellar populations, appear complex and varied. The general picture derived from hydrodynamical simulations is one of cold gas accretion and bursty star formation, followed by feedback from supernovae and winds that heat and eject the central gas reservoirs. This ejection halts star formation until the material cools and re-accretes, resulting in an episodic SFH, particularly at stellar masses below ~ 109 M⊙. Such feedback has often been cited as the driving force behind the observed slowly-rising rotation curves in local dwarfs, due to an under-density of dark matter compared to theoretical models, which is one of the primary challenges to LCDM cosmology. However, these events have not yet been directly observed at high-redshift. Recently, using HST imaging and grism spectroscopy, we have uncovered an abundant population of low-mass galaxies (M* < 109 M⊙) at z = 1 - 2 that are undergoing strong bursts of star formation, in agreement with the theoretical predictions. These Extreme Emission Line Galaxies, with high specific SFRs and shallow gravitational potential wells, are ideal places to test the theoretical prediction of strong feedback-driven outflows. Here we use deep MUSE spectroscopy to search these galaxies for signatures of outflowing material, namely kinematic offsets between absorption lines (in the restframe optical and UV), which trace cool gas, and the nebular emission lines, which define the systemic redshift of the galaxy. Although the EELGs are intrinsically very faint, stacked spectra reveal blueshifted velocity centroids for Fe II absorption, which is indicative of outflowing cold gas. This represents the first constraint on outflows in M* < 109 M⊙ galaxies at z = 1 - 2. These outflows should regulate the star formation histories of low-mass galaxies at early cosmic times and thus play a crucial role in galaxy growth and evolution.

Driving gas shells with radiation pressure on dust in radiation-hydrodynamic simulations

NASA Astrophysics Data System (ADS)

Costa, Tiago; Rosdahl, Joakim; Sijacki, Debora; Haehnelt, Martin G.

2018-01-01

We present radiation-hydrodynamic simulations of radiatively-driven gas shells launched by bright active galactic nuclei (AGN) in isolated dark matter haloes. Our goals are (1) to investigate the ability of AGN radiation pressure on dust to launch galactic outflows and (2) to constrain the efficiency of infrared (IR) multiscattering in boosting outflow acceleration. Our simulations are performed with the radiation-hydrodynamic code RAMSES-RT and include both single- and multiscattered radiation pressure from an AGN, radiative cooling and self-gravity. Since outflowing shells always eventually become transparent to the incident radiation field, outflows that sweep up all intervening gas are likely to remain gravitationally bound to their halo even at high AGN luminosities. The expansion of outflowing shells is well described by simple analytic models as long as the shells are mildly optically thick to IR radiation. In this case, an enhancement in the acceleration of shells through IR multiscattering occurs as predicted, i.e. a force \\dot{P} ≈ τ_IR L/c is exerted on the gas. For high optical depths τIR ≳ 50, however, momentum transfer between outflowing optically thick gas and IR radiation is rapidly suppressed, even if the radiation is efficiently confined. At high τIR, the characteristic flow time becomes shorter than the required trapping time of IR radiation such that the momentum flux \\dot{P} ≪ τ_IR L/c. We argue that while unlikely to unbind massive galactic gaseous haloes, AGN radiation pressure on dust could play an important role in regulating star formation and black hole accretion in the nuclei of massive compact galaxies at high redshift.

Blowin' in the Wind: Both "Negative" and "Positive" Feedback in an Obscured High-z Quasar

NASA Astrophysics Data System (ADS)

Cresci, G.; Mainieri, V.; Brusa, M.; Marconi, A.; Perna, M.; Mannucci, F.; Piconcelli, E.; Maiolino, R.; Feruglio, C.; Fiore, F.; Bongiorno, A.; Lanzuisi, G.; Merloni, A.; Schramm, M.; Silverman, J. D.; Civano, F.

2015-01-01

Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, preventing massive galaxies to overgrow and producing the red colors of ellipticals. On the other hand, some models are also requiring "positive" active galactic nucleus feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively driven winds are available. Here we present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z = 1.59 QSO detected in the XMM-COSMOS survey, in which we clearly resolve a fast (1500 km s-1) and extended (up to 13 kpc from the black hole) outflow in the [O III] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Hα emission and the rest frame U-band flux from Hubble Space Telescope/Advanced Camera for Surveys imaging enable to map the current star formation in the host galaxy: both tracers independently show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. The outflow is therefore removing the gas from the host galaxy ("negative feedback"), but also triggering star formation by outflow induced pressure at the edges ("positive feedback"). XID2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work.

Density diagnostics of ionized outflows in active galactic nuclei. X-ray and UV absorption lines from metastable levels in Be-like to C-like ions

NASA Astrophysics Data System (ADS)

Mao, Junjie; Kaastra, J. S.; Mehdipour, M.; Raassen, A. J. J.; Gu, Liyi; Miller, J. M.

2017-11-01

Context. Ionized outflows in active galactic nuclei (AGNs) are thought to influence their nuclear and local galactic environment. However, the distance of the outflows with respect to the central engine is poorly constrained, which limits our understanding of their kinetic power as a cosmic feedback channel. Therefore, the impact of AGN outflows on their host galaxies is uncertain. However, when the density of the outflows is known, their distance can be immediately obtained from their modeled ionization parameters. Aims: We perform a theoretical study of density diagnostics of ionized outflows using absorption lines from metastable levels in Be-like to C-like cosmic abundant ions. Methods: With the new self-consistent PhotoIONization (PION) model in the SPEX code, we are able to calculate detailed level populations, including the ground and metastable levels. This enables us to determine under what physical conditions the metastable levels are significantly populated. We then identify characteristic lines from these metastable levels in the 1-2000 Å wavelength range. Results: In the broad density range of nH ∈ (106, 1020) m-3, the metastable levels 2s2p (3P0-2) in Be-like ions can be significantly populated. For B-like ions, merely the first excited level 2s22p (2P3/2) can be used as a density probe. For C-like ions, the first two excited levels 2s22p2 (3P1 and 3P2) are better density probes than the next two excited levels 2s22p2 (1S0 and 1D2). Different ions in the same isoelectronic sequence cover not only a wide range of ionization parameters, but also a wide range of density values. On the other hand, within the same isonuclear sequence, those less ionized ions probe lower density and smaller ionization parameters. Finally, we reanalyzed the high-resolution grating spectra of NGC 5548 observed with Chandra in January 2002 using a set of PION components to account for the ionized outflow. We derive lower (or upper) limits of plasma density in five out of six PION components based on the presence (or absence) of the metastable absorption lines. Once atomic data from N-like to F-like ions are available, combined with the next generation of spectrometers that cover both X-ray and UV wavelength ranges with higher spectral resolution and larger effective areas, tight constraints on the density and thus the location and kinetic power of AGN outflows can be obtained.

Development of a miniature motor-driven pulsatile LVAD driven by a fuzzy controller.

PubMed

Okamoto, Eiji; Makino, Tsutomu; Tanaka, Shuji; Yasuda, Takahiko; Akasaka, Yuta; Tani, Makiko; Inoue, Yusuke; Mitoh, Ayumu; Mitamura, Yoshinori

2007-01-01

We have been developing a small, lightweight motor-driven pulsatile left ventricular assist device (LVAD) with a ball screw. The motor-driven LVAD consists of a brushless DC motor and a ball screw. The attractive magnetic force between Nd-Fe-B magnets (with a diameter of 5 mm and a thickness of 1.5 mm) mounted in holes in a silicone rubber sheet (thickness 2 mm) and an iron plate adhered onto the a diaphragm of the blood pump can provide optimum active blood filling during the pump filling phase. The LVAD has a stroke volume of 55 ml and an overall volume of 285 ml; it weighs 360 g. The controller mainly consists of a fuzzy logic position and velocity controller to apply doctors' and engineers' knowledge to control the LVAD. Each unit of the controller consists of a functionally independent program module for easy improvement of the controller's performance. The LVAD was evaluated in in vitro experiments using a mock circulation. A maximum pump outflow of 5.1 l/min was obtained at a drive rate of 95 bpm against an afterload of 95 mmHg, and active filling using the attractive magnetic force provided a pump output of 3.6 l/min at a drive rate of 75 bpm under a preload of 0 mmHg. The operating efficiency of the LVAD was measured at between 8% and 10.5%. While the LVAD can provide adequate pump outflow for cardiac assistance, further upgrading of the software and improvement of the blood pump are required to improve pump performance and efficiency.

Revealing the ultrafast outflow in IRAS 13224-3809 through spectral variability

NASA Astrophysics Data System (ADS)

Parker, M. L.; Alston, W. N.; Buisson, D. J. K.; Fabian, A. C.; Jiang, J.; Kara, E.; Lohfink, A.; Pinto, C.; Reynolds, C. S.

2017-08-01

We present an analysis of the long-term X-ray variability of the extreme narrow-line Seyfert 1 galaxy IRAS 13224-3809 using principal component analysis (PCA) and fractional excess variability (Fvar) spectra to identify model-independent spectral components. We identify a series of variability peaks in both the first PCA component and Fvar spectrum which correspond to the strongest predicted absorption lines from the ultrafast outflow (UFO) discovered by Parker et al. (2017). We also find higher order PCA components, which correspond to variability of the soft excess and reflection features. The subtle differences between RMS and PCA results argue that the observed flux-dependence of the absorption is due to increased ionization of the gas, rather than changes in column density or covering fraction. This result demonstrates that we can detect outflows from variability alone and that variability studies of UFOs are an extremely promising avenue for future research.

Radiative GRMHD simulations of accretion and outflow in non-magnetized neutron stars and ultraluminous X-ray sources

NASA Astrophysics Data System (ADS)

Abarca, David; Kluźniak, Wlodek; Sądowski, Aleksander

2018-06-01

We run two GRRMHD simulations of super-Eddington accretion disks around a black hole and a non-magnetized, non-rotating neutron star. The neutron star was modeled using a reflective inner boundary condition. We observe the formation of a transition layer in the inner region of the disk in the neutron star simulation which leads to a larger mass outflow rate and a lower radiative luminosity over the black hole case. Sphereization of the flow leads to an observable luminosity at infinity around the Eddington value when viewed from all directions for the neutron star case, contrasting to the black hole case where collimation of the emission leads to observable luminosities about an order of magnitude higher when observed along the disk axis. We find the outflow to be optically thick to scattering, which would lead to the obscuring of any neutron star pulsations observed in corresponding ULXs.

Physical Processes for Driving Ionospheric Outflows in Global Simulations

NASA Technical Reports Server (NTRS)

Moore, Thomas Earle; Strangeway, Robert J.

2009-01-01

We review and assess the importance of processes thought to drive ionospheric outflows, linking them as appropriate to the solar wind and interplanetary magnetic field, and to the spatial and temporal distribution of their magnetospheric internal responses. These begin with the diffuse effects of photoionization and thermal equilibrium of the ionospheric topside, enhancing Jeans' escape, with ambipolar diffusion and acceleration. Auroral outflows begin with dayside reconnexion and resultant field-aligned currents and driven convection. These produce plasmaspheric plumes, collisional heating and wave-particle interactions, centrifugal acceleration, and auroral acceleration by parallel electric fields, including enhanced ambipolar fields from electron heating by precipitating particles. Observations and simulations show that solar wind energy dissipation into the atmosphere is concentrated by the geomagnetic field into auroral regions with an amplification factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Internal plasmas thus enable electromagnetic driving via coupling to the plasma, neutral gas and by extension, the entire body " We assess the Importance of each of these processes in terms of local escape flux production as well as global outflow, and suggest methods for their implementation within multispecies global simulation codes. We complete 'he survey with an assessment of outstanding obstacles to this objective.

Magnetospheric space plasma investigations

NASA Technical Reports Server (NTRS)

Comfort, Richard H.; Horwitz, James L.

1996-01-01

The discussion in this final report is limited to a summary of important accomplishments. These accomplishments include the generalized semikinetic (GSK) model, O(+) outflows in the F-region ionosphere, field-aligned flows and trapped ion distributions, ULF wave ray-tracing, and plasmasphere-ionosphere coupling.

Thermal Pollution Mathematical Model. Volume 5: User's Manual for Three-Dimensional Rigid-Lid Model. [environment impact of thermal discharges from power plants

NASA Technical Reports Server (NTRS)

Lee, S. S.; Sengupta, S.; Nwadike, E. V.; Sinha, S. K.

1980-01-01

A user's manual for a three dimensional, rigid lid model used for hydrothermal predictions of closed basins subjected to a heated discharge together with various other inflows and outflows is presented. The model has the capability to predict (1) wind driven circulation; (2) the circulation caused by inflows and outflows to the domain; and (3) the thermal effects in the domain, and to combine the above processes. The calibration procedure consists of comparing ground truth corrected airborne radiometer data with surface isotherms predicted by the model. The model was verified for accuracy at various sites and results are found to be fairly accurate in all verification runs.

Suzaku Observations of Near-Relativistic Outflows in the BAL Quasar APM 08279+5255

NASA Astrophysics Data System (ADS)

Saez, C.; Chartas, G.; Brandt, W. N.

2009-05-01

We present results from three Suzaku observations of the z = 3.91 gravitationally lensed broad absorption line quasar APM 08279+5255. We detect strong and broad absorption at rest-frame energies of lsim2 keV (low energy) and 7-12 keV (high energy). The detection of these features confirms the results of previous long-exposure (80-90 ks) Chandra and XMM-Newton observations. The low- and high-energy absorption is detected in both the back-illuminated (BI) and front-illuminated (FI) Suzaku X-ray Imaging Spectrometer spectra (with an F-test significance of gsim99%). We interpret the low-energy absorption as arising from a low-ionization absorber with log N H ~ 23 and the high-energy absorption as due to lines arising from highly ionized (2.75 lsim logξ lsim 4.0, where ξ is the ionization parameter) iron in a near-relativistic outflowing wind. Assuming this interpretation we find that the velocities in the outflow range between 0.1c and 0.6c. We constrain the angle between the outflow direction of the X-ray absorber and our line of sight to be lsim36°. We also detect likely variability of the absorption lines (at the gsim99.9% and gsim98% significance levels in the FI and BI spectra, respectively) with a rest-frame timescale of ~1 month. Assuming that the detected high-energy absorption features arise from Fe XXV, we estimate that the fraction of the total bolometric energy injected over the quasar's lifetime into the intergalactic medium in the form of kinetic energy to be gsim10%.

The high-energy view of the broad-line radio galaxy 3C 111

NASA Astrophysics Data System (ADS)

Ballo, L.; Braito, V.; Reeves, J. N.; Sambruna, R. M.; Tombesi, F.

2011-12-01

We present the analysis of Suzaku and XMM-Newton observations of the broad-line radio galaxy (BLRG) 3C 111. Its high-energy emission shows variability, a harder continuum with respect to the radio-quiet active galactic nucleus population, and weak reflection features. Suzaku found the source in a minimum flux level; a comparison with the XMM-Newton data implies an increase of a factor of 2.5 in the 0.5-10 keV flux, in the 6 months separating the two observations. The iron K complex is detected in both data sets, with rather low equivalent width(s). The intensity of the iron K complex does not respond to the change in continuum flux. An ultrafast, high-ionization outflowing gas is clearly detected in the Suzaku/X-ray Imaging Spectrometer data; the absorber is most likely unstable. Indeed, during the XMM-Newton observation, which was 6 months after, the absorber was not detected. No clear rollover in the hard X-ray emission is detected, probably due to the emergence of the jet as a dominant component in the hard X-ray band, as suggested by the detection above ˜100 keV with the GSO onboard Suzaku, although the present data do not allow us to firmly constrain the relative contribution of the different components. The fluxes observed by the γ-ray satellites CGRO and Fermi would be compatible with the putative jet component if peaking at energies E˜ 100 MeV. In the X-ray band, the jet contribution to the continuum starts to be significant only above 10 keV. If the detection of the jet component in 3C 111 is confirmed, then its relative importance in the X-ray energy band could explain the different observed properties in the high-energy emission of BLRGs, which are otherwise similar in their other multiwavelength properties. Comparison between X-ray and γ-ray data taken at different epochs suggests that the strong variability observed for 3C 111 is probably driven by a change in the primary continuum.

Revisiting the `forbidden' region: AGN radiative feedback with radiation trapping

NASA Astrophysics Data System (ADS)

Ishibashi, W.; Fabian, A. C.; Ricci, C.; Celotti, A.

2018-06-01

Active galactic nucleus (AGN) feedback, driven by radiation pressure on dust, is an important mechanism for efficiently coupling the accreting black hole to the surrounding environment. Recent observations confirm that X-ray selected AGN samples respect the effective Eddington limit for dusty gas in the plane defined by the observed column density versus the Eddington ratio, the so-called NH - λ plane. A `forbidden' region occurs in this plane, where obscuring clouds cannot be long-lived, due to the action of radiation pressure on dust. Here we compute the effective Eddington limit by explicitly taking into account the trapping of reprocessed radiation (which has been neglected in previous works), and investigate its impact on the NH - λ plane. We show that the inclusion of radiation trapping leads to an enhanced forbidden region, such that even Compton-thick material can potentially be disrupted by sub-Eddington luminosities. We compare our model results to the most complete sample of local AGNs with measured X-ray properties, and find good agreement. Considering the anisotropic emission from the accretion disc, we also expect the development of dusty outflows along the polar axis, which may naturally account for the polar dust emission recently detected in several AGNs from mid-infrared observations. Radiative feedback thus appears to be the key mechanism regulating the obscuration properties of AGNs, and we discuss its physical implications in the context of co-evolution scenarios.

GLOBAL SIMULATIONS OF GALACTIC WINDS INCLUDING COSMIC-RAY STREAMING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruszkowski, Mateusz; Yang, H.-Y. Karen; Zweibel, Ellen, E-mail: mateuszr@umich.edu, E-mail: hsyang@astro.umd.edu, E-mail: zweibel@astro.wisc.edu

2017-01-10

Galactic outflows play an important role in galactic evolution. Despite their importance, a detailed understanding of the physical mechanisms responsible for the driving of these winds is lacking. In an effort to gain more insight into the nature of these flows, we perform global three-dimensional magnetohydrodynamical simulations of an isolated Milky Way-size starburst galaxy. We focus on the dynamical role of cosmic rays (CRs) injected by supernovae, and specifically on the impact of the streaming and anisotropic diffusion of CRs along the magnetic fields. We find that these microphysical effects can have a significant effect on the wind launching andmore » mass loading factors, depending on the details of the plasma physics. Due to the CR streaming instability, CRs propagating in the interstellar medium scatter on self-excited Alfvén waves and couple to the gas. When the wave growth due to the streaming instability is inhibited by some damping process, such as turbulent damping, the coupling of CRs to the gas is weaker and their effective propagation speed faster than the Alfvén speed. Alternatively, CRs could scatter from “extrinsic turbulence” that is driven by another mechanism. We demonstrate that the presence of moderately super-Alfvénic CR streaming enhances the efficiency of galactic wind driving. Cosmic rays stream away from denser regions near the galactic disk along partially ordered magnetic fields and in the process accelerate more tenuous gas away from the galaxy. For CR acceleration efficiencies broadly consistent with the observational constraints, CRs reduce the galactic star formation rates and significantly aid in launching galactic winds.« less

Standing on the shoulders of giants: Star and planet formation in 2010-2020 - The Kenneth Greisen Lecture

NASA Astrophysics Data System (ADS)

McCaughrean, Mark

2008-04-01

Despite centuries of theoretical hypotheses on the origin of our own Sun and its planets, it is only in the past thirty years that we have begun to develop an empirical, observational picture of how stars and planets are forming today throughout our Galaxy and beyond. Driven largely by the advent of infrared and millimetre astronomy in the 1970s and 1980s, progress in the field has accelerated considerably in the past 10 years through the combination of powerful ground- and space-telescopes covering the X-ray, optical, infrared and millimetre, in addition to considerable improvements in theoretical simulations. In this talk, I shall present an overview of recent observational and theoretical work on the birth and early evolution of stars, brown dwarfs, circumstellar disks, jets, outflows, and planetary systems. In doing so, I shall also identify key problems which future facilities, including the next generation of extremely large ground-based telescopes and the NASA/ESA/CSA James Webb Space Telescope, will play vital roles in helping to unravel over the coming decade.

The soft x ray halo of the spiral galaxy NGC4631

NASA Technical Reports Server (NTRS)

Walterbos, Rene A. M.; Steakley, Michael F.; Wang, Q. Daniel; Norman, Colin A.; Braun, Robert

1994-01-01

ROSAT PSPC observations of the close to edge-on spiral galaxy NGC4631 are presented. This vigorously star forming galaxy shows extented x ray emission perpendicular to the plane, out to about 6 to 8 kpc. The spatial extent is largest at soft x ray energies. The total x ray luminosity of hot gas can be easily supplied by star formation in the disk, and it is likely that the halo is due to outflow of hot gas from the inner disk. Spectral analysis of the x ray data shows that part of the halo emission may be quite cool, well below 10(exp 6)K. Implications of these results are briefly discussed.

GBT Detection of Polarization-Dependent HI Absorption and HI Outflows in Local ULIRGs and Quasars

NASA Technical Reports Server (NTRS)

Teng, Stacy H.; Veilleux, Sylvain; Baker, Andrew J.

2013-01-01

We present the results of a 21-cm HI survey of 27 local massive gas-rich late-stage mergers and merger remnants with the Green Bank Telescope (GBT). These remnants were selected from the Quasar/ULIRG Evolution Study (QUEST) sample of ultraluminous infrared galaxies (ULIRGs; L(sub 8 - 1000 micron) > 10(exp 12) solar L) and quasars; our targets are all bolometrically dominated by active galactic nuclei (AGN) and sample the later phases of the proposed ULIRG-to-quasar evolutionary sequence. We find the prevalence of HI absorption (emission) to be 100% (29%) in ULIRGs with HI detections, 100% (88%) in FIR-strong quasars, and 63% (100%) in FIR-weak quasars. The absorption features are associated with powerful neutral outflows that change from being mainly driven by star formation in ULIRGs to being driven by the AGN in the quasars. These outflows have velocities that exceed 1500 km/s in some cases. Unexpectedly, we find polarization-dependent HI absorption in 57% of our spectra (88% and 63% of the FIR-strong and FIR-weak quasars, respectively). We attribute this result to absorption of polarized continuum emission from these sources by foreground HI clouds. About 60% of the quasars displaying polarized spectra are radio-loud, far higher than the approx 10% observed in the general AGN population. This discrepancy suggests that radio jets play an important role in shaping the environments in these galaxies. These systems may represent a transition phase in the evolution of gas-rich mergers into "mature" radio galaxies.

The Valley Networks on Mars

NASA Astrophysics Data System (ADS)

Gulick, V. C.

2002-12-01

Despite three decades of exploration, the valley networks on Mars still seem to raise more questions than they answer. Valley systems have formed in the southern highlands, along some regions of the dichotomy boundary and the south rim of Valles Marineris, around the rim of some impact craters, and on the flanks of some volcanoes. They are found on some of the oldest and youngest terrains as well as on intermediate aged surfaces. There is surprisingly little consensus as to the formation and the paleoclimatic implications of the valley networks. Did the valleys require a persistent solar-driven atmospheric hydrological cycle involving precipitation, surface runoff, infiltration and groundwater outflow as they typically do on Earth? Or are they the result of magmatic or impact-driven thermal cycling of ground water involving persistent outflow and subsequent runoff? Are they the result of some other process(es)? Ground-water sapping, surface-water runoff, debris flows, wind erosion, and formation mechanisms involving other fluids have been proposed. Until such basic questions as these are definitively answered, their significance for understanding paleoclimatic change on Mars remains cloudy. I will review what is known about valley networks using data from both past and current missions. I will discuss what we have learned about their morphology, environments in which they formed, their spatial and temporal associations, possible formation mechanisms, relation to outflow channel and gully formation, as well as the possible implications for past climate change on Mars. Finally I will discuss how future, meter to submeter scale imaging and other remote sensing observations may shed new light on the debate over the origin of these enigmatic features.

Characterizing Quasar Outflows I: Sample, Spectral Measurements

NASA Astrophysics Data System (ADS)

Ganguly, Rajib; Christenson, D. H.; Richmond, J. M.; Derseweh, J. A.; Robbins, J. M.; Townsend, S. L.; Stark, M. A.

2012-05-01

Galaxy evolution models have shown that quasars are a crucial ingredient in the evolution of massive galaxies. Outflows play a key role in the story of quasars and their host galaxies, by helping regulate the accretion process, the star-formation rate and mass of the host galaxy (i.e., feedback). The prescription for modeling outflows as a contributor to feedback requires knowledge of the outflow velocity, geometry, and column density. In particular, we need to understand how these depend on physical parameters and how much is determined stochastically (and with what distribution). For this purpose, we are examining a sample of 11000 z=1.7-2.0 quasars from the Sloan Digital Sky Survey. This redshift range permits the following from the SDSS spectra: (1) separation of objects that do and do not exhibit outflows; (2) classification/measurement of outflow properties (ionization, velocity, velocity width); and (3) measurements of UV emission line and continuum parameters. In this poster, we subjectively divide these quasars into four categories: broad absorption-line quasars (2700 objects), associated absorption-line quasars (1700 objects), reddened quasars (160 objects), and unabsorbed/unreddened quasars (6300 objects). We present measurements of the absorption (velocities, velocity widths, equivalent widths), composite spectral profiles of outflows as a function of velocity, as well as measurements of the continuum and CIV, MgII, and FeII emission-line properties. In accompanying posters, we add photometry from the rest-frame X-ray (ROSAT and Chandra), EUV (GALEX), optical (2MASS), and infrared (WISE) bands to complete the SED. The continuum and emission-line measurements from the SDSS spectra and accompanying photometry provides estimates on the black hole masses, bolometric luminsosities, and SED. We consider empirically how these affect the outflow properties. This material is based upon work supported by the National Aeronautics and Space Administration under Grant No. 09-ADP09-0016 issued through the Astrophysics Data Analysis Program.

Coronal Structures in Cool Stars

NASA Technical Reports Server (NTRS)

Oliversen, Ronald (Technical Monitor); Dupree, Andrea K.

2005-01-01

We have extended our study of the structure of coronas in cool stars to very young stars still accreting from their surrounding disks. In addition we are pursing the connection between coronal X-rays and a powerful diagnostic line in the infrared, the He I 10830Angstrom transition of helium. Highlights of these are summarized below including publications during this reporting period and presentations. Spectroscopy of the infrared He I (lambda10830) line with KECK/NIRSPEC and IRTF/CSHELL and of the ultraviolet C III (lambda977) and O VI (lambda1032) emission with FUSE reveals that the classical T Tauri star TW Hydrae exhibits P Cygni profiles, line asymmetries, and absorption indicative of a continuous, fast (approximately 400 kilometers per second), hot (approximately 300,000 K) accelerating outflow with a mass loss rate approximately 10(exp -11)-10(exp -12) solar mass yr(sup -1) or larger. Spectra of T Tauri N appear consistent with such a wind. The source of the emission and outflow seems restricted to the stars themselves. Although the mass accretion rate is an order of magnitude less for TW Hya than for T Tau, the outflow reaches higher velocities at chromospheric temperatures in TW Hya. Winds from young stellar objects may be substantially hotter and faster than previously thought. The ultraviolet emission lines, when corrected for absorption are broad. Emission associated with the accretion flow and shock is likely to show turbulent broadening. We note that the UV line widths are significantly larger than the X-ray line widths. If the X-rays from TW Hya are generated at the accretion shock, the UV lines may not be directly associated with the shock. On the other hand, studies of X-ray emission in young star clusters, suggest that the strength of the X-ray emission is correlated with stellar rotation, thus casting doubt on an accretion origin for the X-rays. We are beginning to access the infrared spectral region where the He I 108308Angstroms transition occurs. This line is particularly useful as a diagnostic of coronal radiation since it is formed by recombination following photoionization of neutral helium by coronal X-rays. Because the lower level of the transition is metastable, infrared radiation from the stellar photosphere is absorbed which provides a diagnostic of atmospheric dynamics. This transition is useful both in young stars in the T Tauri phase and in active cool star binaries. We will investigate the influence of coronal x-rays on the strength of this transition.

Magnetic reconnection driven by Gekko XII lasers with a Helmholtz capacitor-coil target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pei, X. X.; University of Chinese Academy of Sciences, Beijing 100049; Zhong, J. Y., E-mail: jyzhong@bnu.edu.cn, E-mail: gzhao@bao.ac.cn

2016-03-15

We demonstrate a novel plasma device for magnetic reconnection, driven by Gekko XII lasers irradiating a double-turn Helmholtz capacitor-coil target. Optical probing revealed an accumulated plasma plume near the magnetic reconnection outflow. The background electron density and magnetic field were measured to be approximately 10{sup 18 }cm{sup −3} and 60 T by using Nomarski interferometry and the Faraday effect, respectively. In contrast with experiments on magnetic reconnection constructed by the Biermann battery effect, which produced high beta values, our beta value was much lower than one, which greatly extends the parameter regime of laser-driven magnetic reconnection and reveals its potential in astrophysicalmore » plasma applications.« less

The dynamic ejecta of compact object mergers and eccentric collisions.

PubMed

Rosswog, Stephan

2013-06-13

Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds, and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers indeed produce gamma-ray bursts, there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties, and therefore plays a different role for nucleosynthesis and for the electromagnetic (EM) transients that go along with compact object encounters. Here, we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject approximately 1 per cent of a Solar mass of extremely neutron-rich material. The exact amount, as well as the ejection velocity, depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the 'heavy' (A>130) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass, and therefore cannot occur frequently without overproducing gala- ctic r-process matter. We also discuss the EM transients that are powered by radioactive decays within the ejecta ('macronovae'), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium.

Swift and Fermi observations of the early afterglow of the short gamma-ray burst 090510

DOE PAGES

De Pasquale, M.

2010-01-14

Here, we present the observations of GRB090510 performed by the Fermi Gamma-Ray Space Telescope and the Swift observatory. In a GeV range, we detected a bright, short burst that shows an extended emission. Furthermore, its optical emission initially rises, a feature so far observed only in long bursts, while the X-ray flux shows an initial shallow decrease, followed by a steeper decay. This exceptional behavior enables us to investigate the physical properties of the gamma-ray burst outflow, poorly known in short bursts. Here, we discuss internal and external shock models for the broadband energy emission of this object.

A tenuous X-ray corona enveloping AE Aquarii

NASA Astrophysics Data System (ADS)

Venter, L. A.; Meintjes, P. J.

2007-06-01

In this paper we propose that the observed unpulsed X-ray emission in AE Aquarii is the result of a very tenuous hot corona associated with the secondary star, which is pumped magnetohydrodynamically by the propeller action of the fast rotating white dwarf. It is shown that the closed coronal field of the secondary star envelops a substantial portion of the binary system, including the fast rotating magnetized white dwarf. This implies that the propeller outflow of material in AE Aquarii is initiated inside an enveloping magnetic cavity. The outflow crossing the secondary dead-zone field constitutes a βgen = (8πρv2esc/B2) >> 1 plasma, acting as a magnetohydrodynamic generator resulting in the induction of field-aligned currents in these closed magnetospheric circuits where βcir = (8πnkT/B2) << 1. The Ohmic heating of the coronal circuit can readily account for a Tx >= 107 K plasma in the coronal flux tubes connecting the generator and the stellar surface. Further, the bremsstrahlung losses of the thermal electrons in the coronal circuit can readily drive the observed unpulsed X-ray luminosity of Lx ~ 1031 ergs -1, which correlates with the luminosity and relatively large source implied by recent XMM-Newton observations.

The disc-jet symbiosis emerges: modelling the emission of Sagittarius A* with electron thermodynamics

NASA Astrophysics Data System (ADS)

Ressler, S. M.; Tchekhovskoy, A.; Quataert, E.; Gammie, C. F.

2017-05-01

We calculate the radiative properties of Sagittarius A* - spectral energy distribution, variability and radio-infrared images - using the first 3D, physically motivated black hole accretion models that directly evolve the electron thermodynamics in general relativistic MHD simulations. These models reproduce the coupled disc-jet structure for the emission favoured by previous phenomenological analytic and numerical works. More specifically, we find that the low frequency radio emission is dominated by emission from a polar outflow while the emission above 100 GHz is dominated by the inner region of the accretion disc. The latter produces time variable near-infrared (NIR) and X-ray emission, with frequent flaring events (including IR flares without corresponding X-ray flares and IR flares with weak X-ray flares). The photon ring is clearly visible at 230 GHz and 2 μm, which is encouraging for future horizon-scale observations. We also show that anisotropic electron thermal conduction along magnetic field lines has a negligible effect on the radiative properties of our model. We conclude by noting limitations of our current generation of first-principles models, particularly that the outflow is closer to adiabatic than isothermal and thus underpredicts the low frequency radio emission.

Correlation Analysis of Prompt Emission from Gamma Ray Bursts

NASA Astrophysics Data System (ADS)

Pothapragada, Sriharsha

Prompt emission from gamma-ray bursts (GRBs) exhibits very rapid, complicated temporal and spectral evolution. This diverse variability in the light-curves reflects the complicated nature of the underlying physics, in which inter-penetrating relativistic shells in the outflow are believed to generate strong magnetic fields that vary over very small scales. We use the theory of jitter radiation to model the emission from such regions and the resulting overall prompt gamma ray emission from a series of relativistic collisionless shocks. We present simulated GRB light-curves developed as a series of "pulses" corresponding to instantaneously illuminated "thin-shell" regions emitting via the jitter radiation mechanism. The effects of various geometries, viewing angles, and bulk Lorentz factor profiles of the radiating outflow jets on the spectral features and evolution of these light-curves are explored. Our results demonstrate how an anisotropic jitter radiation pattern, in conjunction with relativistic shock kinematics, can produce certain features observed in the GRB prompt emission spectra, such as the occurrence of hard, synchrotron violating spectra, the "tracking" of observed flux with spectral parameters, and spectral softening below peak energy within individual episodes of the light curve. We highlight predictions in the light of recent advances in the observational sphere of GRBs.

Outflow channel sources, reactivation, and chaos formation, Xanthe Terra, Mars

USGS Publications Warehouse

Rodriguez, J.A.P.; Sasaki, S.; Kuzmin, R.O.; Dohm, J.M.; Tanaka, K.L.; Miyamoto, H.; Kurita, K.; Komatsu, G.; Fairen, A.G.; Ferris, J.C.

2005-01-01

The undulating, warped, and densely fractured surfaces of highland regions east of Valles Marineris (located north of the eastern Aureum Chaos, east of the Hydraotes Chaos, and south of the Hydaspis Chaos) resulted from extensional surface warping related to ground subsidence, caused when pressurized water confined in subterranean caverns was released to the surface. Water emanations formed crater lakes and resulted in channeling episodes involved in the excavation of Ares, Tiu, and Simud Valles of the eastern part of the circum-Chryse outflow channel system. Progressive surface subsidence and associated reduction of the subsurface cavernous volume, and/or episodes of magmatic-driven activity, led to increases of the hydrostatic pressure, resulting in reactivation of both catastrophic and non-catastrophic outflow activity. Ancient cratered highland and basin materials that underwent large-scale subsidence grade into densely fractured terrains. Collapse of rock materials in these regions resulted in the formation of chaotic terrains, which occur in and near the headwaters of the eastern circum-Chryse outflow channels. The deepest chaotic terrain in the Hydaspis Chaos region resulted from the collapse of pre-existing outflow channel floors. The release of volatiles and related collapse may have included water emanations not necessarily linked to catastrophic outflow. Basal warming related to dike intrusions, thermokarst activity involving wet sediments and/or dissected ice-enriched country rock, permafrost exposed to the atmosphere by extensional tectonism and channel incision, and/or the injection of water into porous floor material, may have enhanced outflow channel floor instability and subsequent collapse. In addition to the possible genetic linkage to outflow channel development dating back to at least the Late Noachian, clear disruption of impact craters with pristine ejecta blankets and rims, as well as preservation of fine tectonic fabrics, suggest that plateau subsidence and chaos formation may have continued well into the Amazonian Period. The geologic and paleohydrologic histories presented here have important implications, as new mechanisms for outflow channel formation and other fluvial activity are described, and new reactivation mechanisms are proposed for the origin of chaotic terrain as contributors to flooding. Detailed geomorphic analysis indicates that subterranean caverns may have been exposed during chaos formation, and thus chaotic terrains mark prime locations for future geologic, hydrologic, and possible astrobiologic exploration. ?? 2004 Elsevier Inc. All rights reserved.

The origin of blueshifted absorption features in the X-ray spectrum of PG 1211+143: outflow or disc

NASA Astrophysics Data System (ADS)

Gallo, L. C.; Fabian, A. C.

2013-07-01

In some radio-quiet active galactic nuclei (AGN), high-energy absorption features in the X-ray spectra have been interpreted as ultrafast outflows (UFOs) - highly ionized material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativistic velocities. In some cases, these outflows can carry energy in excess of the binding energy of the host galaxy. Needless to say, these features demand our attention as they are strong signatures of AGN feedback and will influence galaxy evolution. For the same reason, alternative models need to be discussed and refuted or confirmed. Gallo and Fabian proposed that some of these features could arise from resonance absorption of the reflected spectrum in a layer of ionized material located above and corotating with the accretion disc. Therefore, the absorbing medium would be subjected to similar blurring effects as seen in the disc. A priori, the existence of such plasma above the disc is as plausible as a fast wind. In this work, we highlight the ambiguity by demonstrating that the absorption model can describe the ˜7.6 keV absorption feature (and possibly other features) in the quasar PG 1211+143, an AGN that is often described as a classic example of a UFO. In this model, the 2-10 keV spectrum would be largely reflection dominated (as opposed to power law dominated in the wind models) and the resonance absorption would be originating in a layer between about 6 and 60 gravitational radii. The studies of such features constitute a cornerstone for future X-ray observatories like Astro-H and Athena+. Should our model prove correct, or at least important in some cases, then absorption will provide another diagnostic tool with which to probe the inner accretion flow with future missions.

Searching for the UV counterpart of the extraordinary X-ray UFO in the NLSy1 IRAS17020+4544

NASA Astrophysics Data System (ADS)

Krongold, Yair

2017-08-01

We recently reported the first unambiguous discovery in high resolution X-ray data of an ultra fast outflow (UFO) with velocity .1c. This wind, in Narrow Line Seyfert 1 galaxy IRAS17020+4544, represents so far the most compelling detection of an UFO, with many different absorption lines that give rise to very high significance detections. The charge states that form the wind clearly indicate a large range of ionization states in the gas, and significant absorption by Ly alpha, C IV, Si IV and N V (among other ions) is expected in the UV band. The goal of our proposed program is to observe an characterize the best X-ray detected UFO in the UV. These observations are crucial to study in great detail the UFO phenomenon, and understand its nature and its relation to the narrow absorption line low velocity systems. Only through detection of Ly alpha absorption in the UV data, measurements of the metallicity of these winds will be possible. The proposed program will help guide new theoretical models of UFOs origins, beyond the simple actual picture that predicts only very high ionization Fe absorption. UV data are required to understand the wind nature and launching mechanism (whether due to radiation pressure via line or continuum opacity, or magnetic forces). Fully characterizing the wind properties will put stronger constraints in the mass outflow and kinetic outflow rates of these systems, as well as in their geometry. Such estimates will give a much clearer picture of UFOs feedback potential, and will provide clues on the feedback mode in action (e.g. energy conserving vs. momentum conserving).

Discovery of very high energy gamma rays associated with an x-ray binary.

PubMed

Aharonian, F; Akhperjanian, A G; Aye, K-M; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Berghaus, P; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Breitling, F; Brown, A M; Bussons Gordo, J; Chadwick, P M; Chounet, L-M; Cornils, R; Costamante, L; Degrange, B; Dickinson, H J; Djannati-Ataï, A; Drury, L O'c; Dubus, G; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Fleury, P; Fontaine, G; Fuchs, Y; Funk, S; Gallant, Y A; Giebels, B; Gillessen, S; Glicenstein, J F; Goret, P; Hadjichristidis, C; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; Jacholkowska, A; de Jager, O C; Khélifi, B; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemière, A; Lemoine-Goumard, M; Leroy, N; Lohse, T; Marcowith, A; Martin, J-M; Martineau-Huynh, O; Masterson, C; McComb, T J L; de Naurois, M; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Raux, J; Rayner, S M; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V; Saugé, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Spangler, D; Steenkamp, R; Stegmann, C; Tavernet, J-P; Terrier, R; Théoret, C G; Tluczykont, M; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J

2005-07-29

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

High Resolution Studies of Mass Loss from Massive Binary Stars

NASA Astrophysics Data System (ADS)

Corcoran, Michael F.; Gull, Theodore R.; Hamaguchi, Kenji; Richardson, Noel; Madura, Thomas; Post Russell, Christopher Michael; Teodoro, Mairan; Nichols, Joy S.; Moffat, Anthony F. J.; Shenar, Tomer; Pablo, Herbert

2017-01-01

Mass loss from hot luminous single and binary stars has a significant, perhaps decisive, effect on their evolution. The combination of X-ray observations of hot shocked gas embedded in the stellar winds and high-resolution optical/UV spectra of the cooler mass in the outflow provides unique ways to study the unstable process by which massive stars lose mass both through continuous stellar winds and rare, impulsive, large-scale mass ejections. The ability to obtain coordinated observations with the Hubble Space Telescope Imaging Spectrograph (HST/STIS) and the Chandra High-Energy Transmission Grating Spectrometer (HETGS) and other X-ray observatories has allowed, for the first time, studies of resolved line emisssion over the temperature range of 104- 108K, and has provided observations to confront numerical dynamical models in three dimensions. Such observations advance our knowledge of mass-loss asymmetries, spatial and temporal variabilities, and the fundamental underlying physics of the hot shocked outflow, providing more realistic constraints on the amount of mass lost by different luminous stars in a variety of evolutionary stages. We discuss the impact that these joint observational studies have had on our understanding of dynamical mass outflows from massive stars, with particular emphasis on two important massive binaries, Delta Ori Aa, a linchpin of the mass luminosity relation for upper HRD main sequence stars, and the supermassive colliding wind binary Eta Carinae.

The O VI Mystery: Mismatch between X-Ray and UV Column Densities

NASA Astrophysics Data System (ADS)

Mathur, S.; Nicastro, F.; Gupta, A.; Krongold, Y.; McLaughlin, B. M.; Brickhouse, N.; Pradhan, A.

2017-12-01

The UV spectra of Galactic and extragalactic sightlines often show O VI absorption lines at a range of redshifts, and from a variety of sources from the Galactic circumgalactic medium to active galactic nuclei (AGN) outflows. Inner shell O VI absorption is also observed in X-ray spectra (at λ =22.03 Å), but the column density inferred from the X-ray line was consistently larger than that from the UV line. Here we present a solution to this discrepancy for the z = 0 systems. The O II Kβ line {}4{S}0\\to {(}3D)3{p}4P at 562.40 eV (≡22.04 Å) is blended with the O VI Kα line in X-ray spectra. We estimate the strength of this O II line in two different ways, and show that in most cases the O II line accounts for the entire blended line. The small amount of O VI equivalent width present in some cases has column density entirely consistent with the UV value. This solution to the O VI discrepancy, however, does not apply to high column-density systems like AGN outflows. We discuss other possible causes to explain their UV/X-ray mismatch. The O VI and O II lines will be resolved by gratings on board the proposed mission Arcus and the concept mission Lynx, and would allow the detection of weak O VI lines not just at z = 0, but also at higher redshift.

New places and phases of CO-poor/CI-rich molecular gas in the Universe

NASA Astrophysics Data System (ADS)

Papadopoulos, Padelis P.; Bisbas, Thomas G.; Zhang, Zhiyu

2018-04-01

In this work we extend the work on the recently discovered role of Cosmic Rays (CRs) in regulating the average CO/H_2 abundance ratio in molecular clouds (and thus their CO line visibility) in starburst galaxies, and find that it can lead to a CO-poor/CI-rich H_2 gas phase even in environments with Galactic or in only modestly enhanced CR backgrounds expected in ordinary star-forming galaxies. Furthermore, the same CR-driven astro-chemistry raises the possibility of a widespread phase transition of molecular gas towards a CO-poor/CI-rich phase in: a) molecular gas outflows found in star-forming galaxies, b) active galactic nuclei (AGNs), and c) near synchrotron-emitting radio jets and the radio-loud cores of powerful radio galaxies. For main sequence galaxies we find that CRs can render some of their molecular gas mass CO-invisible, compounding the effects of low metallicities. Imaging the two fine structure lines of atomic carbon with resolution high enough to search beyond the CI/CO-bright line regions associated with central starbursts can reveal such a CO-poor/CI-rich molecular gas phase, provided that relative brightness sensitivity levels of Tb(CI 1 - 0)/Tb(CO J = 1 - 0) ˜0.15 are reached. The capability to search for such gas in the Galaxy is now at hand with the new high-frequency survey telescope HEAT deployed in Antarctica and future ones to be deployed in Dome A. ALMA can search for such gas in star-forming spiral disks, galactic molecular gas outflows and the CR-intense galactic and circumgalactic gas-rich environments of radio-loud objects.

Early Soft X-Ray to UV Emission from Double Neutron Star Mergers: Implications from the Long-term Observations of GW170817

NASA Astrophysics Data System (ADS)

Wang, Xiang-Yu; Huang, Zhi-Qiu

2018-01-01

Recent long-term radio follow-up observations of GW170817 reveal a simple power-law rising light curve, with a slope of {t}0.78, up to 93 days after the merger. The latest X-ray detection at 109 days is also consistent with such a temporal slope. Such a shallow rise behavior requires a mildly relativistic outflow with a steep velocity gradient profile, so that slower material with larger energy catches up with the decelerating ejecta and re-energizes it. It has been suggested that this mildly relativistic outflow may represent a cocoon of material. We suggest that the velocity gradient profile may form during the stage that the cocoon is breaking out of the merger ejecta, resulting from shock propagation down a density gradient. The cooling of the hot relativistic cocoon material immediately after it breaks out should have produced soft X-ray to UV radiation at tens of seconds to hours after the merger. The soft X-ray emission has a luminosity of {L}{{X}}∼ {10}45 {erg} {{{s}}}-1 over a period of tens of seconds for a merger event like GW170817. The UV emission shows a rise initially and peaks at about a few hours with a luminosity of {L}{UV}∼ {10}42 {erg} {{{s}}}-1. The soft X-ray transients could be detected by future wide-angle X-ray detectors, such as the Chinese mission Einstein Probe. This soft X-ray/UV emission would serve as one of the earliest electromagnetic counterparts of gravitation waves from double neutron star mergers and could provide the earliest localization of the sources.

Determining inclinations of active galactic nuclei via their narrow-line region kinematics

NASA Astrophysics Data System (ADS)

Fischer, Travis Cody

Active Galactic Nuclei (AGN) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight. However, except for a few special cases, the specific inclinations of individual AGN are unknown. We have developed a promising technique for determining the inclinations of nearby AGN by mapping the kinematics of their narrow-line regions (NLRs), which are easily resolved with Hubble Space Telescope (HST) [O III] imaging and long-slit spectra from the Space Telescope Imaging Spectrograph (STIS). Our studies indicate that NLR kinematics dominated by radial outflow can be fit with simple biconical outflow models that can be used to determine the inclination of the bicone axis, and hence the obscuring torus, with respect to our line of sight. We present NLR analysis of 53 Seyfert galaxies and resultant inclinations from models of 17 individual AGN with clear signatures of biconical outflow. From these AGN, which we can for the first time assess the effect of inclination on other observable properties in radio-quiet AGN, including the discovery of a distinct correlation between AGN inclination and X-ray column density. INDEX WORDS: AGN, Seyfert galaxies, NLR, Outflows, Kinematics, Bicones, Unified Model Graduation.

Imaging the molecular outflows of the prototypical ULIRG NGC 6240 with ALMA

NASA Astrophysics Data System (ADS)

Saito, T.; Iono, D.; Ueda, J.; Espada, D.; Sliwa, K.; Nakanishi, K.; Lu, N.; Xu, C. K.; Michiyama, T.; Kaneko, H.; Yamashita, T.; Ando, M.; Yun, M. S.; Motohara, K.; Kawabe, R.

2018-03-01

We present 0.97 × 0.53 arcsec2 (470 pc × 250 pc) resolution CO (J = 2-1) observations towards the nearby luminous merging galaxy NGC 6240 with the Atacama Large Millimeter/submillimeter Array. We confirmed a strong CO concentration within the central 700 pc, which peaks between the double nuclei, surrounded by extended CO features along the optical dust lanes (˜11 kpc). We found that the CO emission around the central, a few kpc, has extremely broad velocity wings with full width at zero intensity ˜ 2000 km s-1, suggesting a possible signature of molecular outflow(s). In order to extract and visualize the high-velocity components in NGC 6240, we performed a multiple Gaussian fit to the CO data cube. The distribution of the broad CO components shows four extremely large line width regions (˜1000 km s-1) located 1-2 kpc away from both nuclei. Spatial coincidence of the large line width regions with H α, near-IR H2, and X-ray suggests that the broad CO (2-1) components are associated with nuclear outflows launched from the double nuclei.

Sgr A* envelope explosion and the young stars in the centre of the Milky Way

NASA Astrophysics Data System (ADS)

Nayakshin, Sergei; Zubovas, Kastytis

2018-05-01

Sgr A* is the super massive black hole residing in the centre of the Milky Way. There is plenty of observational evidence that a massive gas cloud fell into the central parsec of the Milky Way ˜6 million years ago, triggering formation of a disc of young stars and activating Sgr A* . In addition to the disc, there is an unexplained population of young stars on randomly oriented orbits. Here we hypothesize that these young stars were formed by fragmentation of a massive quasi-spherical gas shell driven out from Sgr A* potential well by an energetic outflow. To account for the properties of the observed stars, the shell must be more massive than 105 Solar masses, be launched from inside ˜0.01 pc, and the feedback outflow has to be highly super-Eddington albeit for a brief period of time, producing kinetic energy of at least 1055 erg. The young stars in the central parsec of the Galaxy may be a unique example of stars formed from atomic rather than molecular hydrogen, and forged by extreme pressure of black hole outflows.

Magmatic Intrusions and a Hydrothermal Origin for Fluvial Valleys on Mars

NASA Technical Reports Server (NTRS)

Gulick, Virginia C

1998-01-01

Numerical models of Martian hydrothermal systems demonstrate that systems associated with magmatic intrusions greater than several hundred cubic kilometers can provide sufficient groundwater outflow to form the observed fluvial valleys, if subsurface permeability exceeds about 1.0 darcy. Groundwater outflow increases with increasing intrusion volume and subsurface permeability and is relatively insensitive to intrusion depth and subsurface porosity within the range considered here. Hydrothermally-derived fluids can melt through 1 to 2 km thick ice-rich permafrost layers in several thousand years. Hydrothermal systems thus provide a viable alternative to rainfall for providing surface water for valley formation. This mechanism can form fluvial valleys not only during the postulated early warm, wet climatic epoch, but also during more recent epochs when atmospheric conditions did not favor atmospheric cycling of water. The clustered distribution of the valley networks on a given geologic surface or terrain unit of Mars may also be more compatible with localized, hydrothermally-driven groundwater outflow than regional rainfall. Hydrothermal centers on Mars may have provided appropriate environments for the initiation of life or final oases for the long-term persistence of life.

The Lighthouse nebula: a run-away pulsar, its PWN, jets and parent SNR

NASA Astrophysics Data System (ADS)

Pavan, L.; Bordas, P.; Puhlhofer, G.; et al.

2016-06-01

Some 10-20 kyr ago a pulsar was born from a core collapse event, receiving right away a strong kick. Nowadays this pulsar is powering the Lighthouse Nebula (IGR J11014-6103): a complex system of outflows comprising the bow-shock PWN, and two well collimated jets extending perpendicularly to the pulsar's direction of motion. Whereas sharing some clear commonalities with the well known Guitar Nebula, the Lighthouse nebula is the only such system where the parent supernova remnant is well visible and bright in X-rays. I will describe the results from our recent Chandra X-ray campaign, and follow-up optical and radio observations, analyse the properties of the PWN, and possible interpretations on the nature of the long helicoidal jets and of the other outflows that we identified. I will also discuss the link between this system and its parent supernova remnant MSH 11-61A, which could help shedding a light on the processes that give birth to such peculiar systems.

Fine Structure in Quasar Flows Revealed by Lens-Aided Multi-Angle Spectroscopy (LAMAS)

NASA Astrophysics Data System (ADS)

Green, Paul J.

2006-09-01

Spectral differences between lensed quasar image components are common. Since lensing is intrinsically achromatic, these differences are typically explained as the effect of either microlensing, or as light path time delays sampling intrinsic quasar spectral variability. In some cases, neither explanation seems sufficient. Here we advance a novel third hypothesis: some spectral differences are due to small line-of- sight differences through quasar disk wind outflows, taking the widest separation lens SDSSJ1004+4112 as a key example. We show that small changes in sightline may traverse streams with significantly differing columns. The implications are many. Fine structure in these outflows may change the observed spectra on arcsec scales. Though difficult to detect observationally, high ionization, high velocity-width streams may sculpt the optical and X-ray spectra of most quasars. We discuss existing multi-epoch optical/UV spectroscopy and results from X-ray observations both by Chandra and XMM in this context, and sketch further possible tests. The author gratefully acknowledges support through NASA contract NAS8-03060 (CXC).

Novel molecular insights into RhoA GTPase-induced resistance to aqueous humor outflow through the trabecular meshwork

PubMed Central

Zhang, Min; Maddala, Rupalatha; Rao, Ponugoti Vasantha

2008-01-01

Impaired drainage of aqueous humor through the trabecular meshwork (TM) culminating in increased intraocular pressure is a major risk factor for glaucoma, a leading cause of blindness worldwide. Regulation of aqueous humor drainage through the TM, however, is poorly understood. The role of RhoA GTPase-mediated actomyosin organization, cell adhesive interactions, and gene expression in regulation of aqueous humor outflow was investigated using adenoviral vector-driven expression of constitutively active mutant of RhoA (RhoAV14). Organ-cultured anterior segments from porcine eyes expressing RhoAV14 exhibited significant reduction of aqueous humor outflow. Cultured TM cells expressing RhoAV14 exhibited a pronounced contractile morphology, increased actin stress fibers, and focal adhesions and increased levels of phosphorylated myosin light chain (MLC), collagen IV, fibronectin, and laminin. cDNA microarray analysis of RNA extracted from RhoAV14-expressing human TM cells revealed a significant increase in the expression of genes encoding extracellular matrix (ECM) proteins, cytokines, integrins, cytoskeletal proteins, and signaling proteins. Conversely, various ECM proteins stimulated robust increases in phosphorylation of MLC, paxillin, and focal adhesion kinase and activated Rho GTPase and actin stress fiber formation in TM cells, indicating a potential regulatory feedback interaction between ECM-induced mechanical strain and Rho GTPase-induced isometric tension in TM cells. Collectively, these data demonstrate that sustained activation of Rho GTPase signaling in the aqueous humor outflow pathway increases resistance to aqueous humor outflow through the trabecular pathway by influencing the actomyosin assembly, cell adhesive interactions, and the expression of ECM proteins and cytokines in TM cells. PMID:18799648

X-ray diagnostics of massive star winds

NASA Astrophysics Data System (ADS)

Oskinova, L. M.; Ignace, R.; Huenemoerder, D. P.

2017-11-01

Observations with powerful X-ray telescopes, such as XMM-Newton and Chandra, significantly advance our understanding of massive stars. Nearly all early-type stars are X-ray sources. Studies of their X-ray emission provide important diagnostics of stellar winds. High-resolution X-ray spectra of O-type stars are well explained when stellar wind clumping is taking into account, providing further support to a modern picture of stellar winds as non-stationary, inhomogeneous outflows. X-ray variability is detected from such winds, on time scales likely associated with stellar rotation. High-resolution X-ray spectroscopy indicates that the winds of late O-type stars are predominantly in a hot phase. Consequently, X-rays provide the best observational window to study these winds. X-ray spectroscopy of evolved, Wolf-Rayet type, stars allows to probe their powerful metal enhanced winds, while the mechanisms responsible for the X-ray emission of these stars are not yet understood.

Scaling Relations of Starburst-driven Galactic Winds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanner, Ryan; Cecil, Gerald; Heitsch, Fabian, E-mail: rytanner@augusta.edu

2017-07-10

Using synthetic absorption lines generated from 3D hydrodynamical simulations, we explore how the velocity of a starburst-driven galactic wind correlates with the star formation rate (SFR) and SFR density. We find strong correlations for neutral and low ionized gas, but no correlation for highly ionized gas. The correlations for neutral and low ionized gas only hold for SFRs below a critical limit set by the mass loading of the starburst, above which point the scaling relations flatten abruptly. Below this point the scaling relations depend on the temperature regime being probed by the absorption line, not on the mass loading.more » The exact scaling relation depends on whether the maximum or mean velocity of the absorption line is used. We find that the outflow velocity of neutral gas can be up to five times lower than the average velocity of ionized gas, with the velocity difference increasing for higher ionization states. Furthermore, the velocity difference depends on both the SFR and mass loading of the starburst. Thus, absorption lines of neutral or low ionized gas cannot easily be used as a proxy for the outflow velocity of the hot gas.« less

Watching AGN feedback at its birth: HST observations of nascent outflow host IC860

NASA Astrophysics Data System (ADS)

Alatalo, Katherine

2016-10-01

IC860 is a nearby IR-luminous early-type spiral with a unique set of properties: it is a shocked, poststarburst galaxy that hosts an AGN-driven neutral wind and a compact core of molecular gas. IC860 can serve as a rosetta stone for the early stages of triggering AGN feedback. We propose to use WFC3 on HST to obtain NUV, optical and near-IR imaging of IC860. We will create a spatially-resolved history of star formation quenching through SED-fitting of 7 requested broadband filters, and compare the spatially resolved star formation histories to in different positions within the underlying stellar features (such as spiral structure) that might define a narrative of how star formation is quenching in IC860. These observations will also resolve the super-star cluster sites to trace the most recent star formation. Finally, these observations will trace the mass of the outflow by building an absorption map of the dust. IC860 presents a unique opportunity to study a galaxy at an early stage of transitioning from blue spiral to red early-type galaxy, that also hosts an AGN-driven neutral wind and a compact, turbulent molecular gas core.

Stellar-mass black holes and ultraluminous x-ray sources.

PubMed

Fender, Rob; Belloni, Tomaso

2012-08-03

We review the likely population, observational properties, and broad implications of stellar-mass black holes and ultraluminous x-ray sources. We focus on the clear empirical rules connecting accretion and outflow that have been established for stellar-mass black holes in binary systems in the past decade and a half. These patterns of behavior are probably the keys that will allow us to understand black hole feedback on the largest scales over cosmological time scales.

Post-merger evolution of a neutron star-black hole binary with neutrino transport

NASA Astrophysics Data System (ADS)

Foucart, Francois; O'Connor, Evan; Roberts, Luke; Duez, Matthew D.; Haas, Roland; Kidder, Lawrence E.; Ott, Christian D.; Pfeiffer, Harald P.; Scheel, Mark A.; Szilagyi, Bela

2015-06-01

We present a first simulation of the post-merger evolution of a black hole-neutron star binary in full general relativity using an energy-integrated general-relativistic truncated moment formalism for neutrino transport. We describe our implementation of the moment formalism and important tests of our code, before studying the formation phase of an accretion disk after a black hole-neutron star merger. We use as initial data an existing general-relativistic simulation of the merger of a neutron star of mass 1.4 M⊙ with a black hole of mass 7 M⊙ and dimensionless spin χBH=0.8 . Comparing with a simpler leakage scheme for the treatment of the neutrinos, we find noticeable differences in the neutron-to-proton ratio in and around the disk, and in the neutrino luminosity. We find that the electron neutrino luminosity is much lower in the transport simulations, and that both the disk and the disk outflows are less neutron rich. The spatial distribution of the neutrinos is significantly affected by relativistic effects, due to large velocities and curvature in the regions of strongest emission. Over the short time scale evolved, we do not observe purely neutrino-driven outflows. However, a small amount of material (3 ×10-4M⊙ ) is ejected in the polar region during the circularization of the disk. Most of that material is ejected early in the formation of the disk, and is fairly neutron rich (electron fraction Ye˜0.15 - 0.25 ). Through r-process nucleosynthesis, that material should produce high-opacity lanthanides in the polar region, and could thus affect the light curve of radioactively powered electromagnetic transients. We also show that by the end of the simulation, while the bulk of the disk remains neutron rich (Ye˜0.15 - 0.2 and decreasing), its outer layers have a higher electron fraction: 10% of the remaining mass has Ye>0.3 . As that material would be the first to be unbound by disk outflows on longer time scales, and as composition evolution is slower at later times, the changes in Ye experienced during the formation phase of the disk could have an impact on nucleosynthesis outputs from neutrino-driven and viscously driven outflows. Finally, we find that the effective viscosity due to momentum transport by neutrinos is unlikely to have a strong effect on the growth of the magnetorotational instability in the post-merger accretion disk.

The steady state solutions of radiatively driven stellar winds for a non-Sobolev, pure absorption model

NASA Technical Reports Server (NTRS)

Poe, C. H.; Owocki, S. P.; Castor, J. I.

1990-01-01

The steady state solution topology for absorption line-driven flows is investigated for the condition that the Sobolev approximation is not used to compute the line force. The solution topology near the sonic point is of the nodal type with two positive slope solutions. The shallower of these slopes applies to reasonable lower boundary conditions and realistic ion thermal speed v(th) and to the Sobolev limit of zero of the usual Castor, Abbott, and Klein model. At finite v(th), this solution consists of a family of very similar solutions converging on the sonic point. It is concluded that a non-Sobolev, absorption line-driven flow with a realistic values of v(th) has no uniquely defined steady state. To the extent that a pure absorption model of the outflow of stellar winds is applicable, radiatively driven winds should be intrinsically variable.

The X-ray and ultraviolet absorbing outflow in 3C 351

NASA Astrophysics Data System (ADS)

Mathur, Smita; Wilkes, Belinda; Elvis, Martin; Fiore, Fabrizio

1994-10-01

3C 351 (z = 0.371), and X-ray-'quiet' quasar, is one of the few quasars showing signs of a 'warm absorber' in its X-ray spectrum; i.e., partially ionized absorbing material in the line of sight whose opacity depends on its ionization structure. The main feature in the X-ray spectrum is a K-edge due to O VII or O VIII. 3C 351 also shows unusually strong, blueshifted, associated, absorption lines in the ultraviolet (Bahcall et al. 1993) including O VI (lambda lambda 1031, 1037). This high ionization state strongly suggests an identification with the X-ray absorber and a site within the active nucleus. In this paper we demonstrate that the X-ray and UV absorption is due to the same material. This is the first confirmed UV/X-ray absorber. Physical conditions of the absorber are determined through the combination of constraints derived from both the X-ray and UV analysis. This highly ionized, outflowing, low-density, high-column density absorber situated outside the broad emission line region (BELR) is a previously unknown component of nuclear material. We rule out the identification of the absorber with a BELR cloud as the physical conditions in the two regions are inconsistent with one another. The effect of the X-ray quietness and IR upturn in the 3C 351 continuum on the BELR is also investigated. The strengths of the high-ionization lines of C IV lambda-1549 and O VI lambda-1034 with respect to Lyman-alpha are systematically lower (up to a factor of 10) in the material ionized by the 3C 351 continuum as compared to those produced by the 'standard' quasar continuum, the strongest effect being on the strength of O VI lambda-1034. We find that for a 3C 351-like continuum, C III) lambda-1909 ceases to be a density indicator.

Rotation and Mass Loss

NASA Astrophysics Data System (ADS)

Owocki, S.

2008-06-01

Stellar rotation can play an important role in structuring and enhancing the mass loss from massive stars. Initial 1D models focussed on the expected centrifugal enhancement of the line-driven mass flux from the equator of a rotating star, but the review here emphasizes that the loss of centrifugal support away from the stellar surface actually limits the steady mass flux to just the point-star CAK value, with models near critical rotation characterized by a slow, subcritical acceleration. Recent suggestions that such slow outflows might have high enough density to explain disks in Be or B[e] stars are examined in the context of 2D simulations of the ``Wind Compressed Disk'' (WCD) paradigm, together with a review of the tendency for poleward components of the line-driving force to inhibit WCD formation. When one accounts for equatorial gravity darkening, the net tendency is in fact for the relatively bright regions at higher latitude to drive a faster, denser ``bipolar'' outflow. I discuss the potential relevance for the bipolar form of nebulae from LBV stars like η Carinae, but emphasize that, since the large mass loss associated with the eruption of eta Carinae's Homunculus would heavily saturate line-driving, explaining its bipolar form requires development of analogous models for continuum-driven mass loss. I conclude with a discussion of how radiation seems inherently ill-suited to supporting or driving a geometrically thin, but optically thick disk or disk outflow. The disks inferred in Be and B[e] stars may instead be centrifugally ejected, with radiation inducing an ablation flow from the disk surface, and thus perhaps playing a greater role in destroying (rather than creating) an orbiting, circumstellar disk.

GREEN BANK TELESCOPE DETECTION OF POLARIZATION-DEPENDENT H I ABSORPTION AND H I OUTFLOWS IN LOCAL ULIRGs AND QUASARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teng, Stacy H.; Veilleux, Sylvain; Baker, Andrew J., E-mail: stacy.h.teng@nasa.gov

2013-03-10

We present the results of a 21 cm H I survey of 27 local massive gas-rich late-stage mergers and merger remnants with the Robert C. Byrd Green Bank Telescope. These remnants were selected from the Quasar/ULIRG Evolution Study sample of ultraluminous infrared galaxies (ULIRGs; L{sub 8{sub -{sub 1000{sub {mu}m}}}} > 10{sup 12} L{sub Sun }) and quasars; our targets are all bolometrically dominated by active galactic nuclei (AGNs) and sample the later phases of the proposed ULIRG-to-quasar evolutionary sequence. We find the prevalence of H I absorption (emission) to be 100% (29%) in ULIRGs with H I detections, 100% (88%)more » in FIR-strong quasars, and 63% (100%) in FIR-weak quasars. The absorption features are associated with powerful neutral outflows that change from being mainly driven by star formation in ULIRGs to being driven by the AGN in the quasars. These outflows have velocities that exceed 1500 km s{sup -1} in some cases. Unexpectedly, we find polarization-dependent H I absorption in 57% of our spectra (88% and 63% of the FIR-strong and FIR-weak quasars, respectively). We attribute this result to absorption of polarized continuum emission from these sources by foreground H I clouds. About 60% of the quasars displaying polarized spectra are radio-loud, far higher than the {approx}10% observed in the general AGN population. This discrepancy suggests that radio jets play an important role in shaping the environments in these galaxies. These systems may represent a transition phase in the evolution of gas-rich mergers into ''mature'' radio galaxies.« less

Fast luminous blue transients from newborn black holes

NASA Astrophysics Data System (ADS)

Kashiyama, Kazumi; Quataert, Eliot

2015-08-01

Newborn black holes in collapsing massive stars can be accompanied by a fallback disc. The accretion rate is typically super-Eddington and strong disc outflows are expected. Such outflows could be directly observed in some failed explosions of compact (blue supergiants or Wolf-Rayet stars) progenitors, and may be more common than long-duration gamma-ray bursts. Using an analytical model, we show that the fallback disc outflows produce blue UV-optical transients with a peak bolometric luminosity of ˜ 1042-43 erg s- 1 (peak R-band absolute AB magnitudes of -16 to -18) and an emission duration of ˜ a few to ˜10 d. The spectra are likely dominated intermediate mass elements, but will lack much radioactive nuclei and iron-group elements. The above properties are broadly consistent with some of the rapid blue transients detected by Panoramic Survey Telescope & Rapid Response System and Palomar Transient Factory. This scenario can be distinguished from alternative models using radio observations within a few years after the optical peak.

Monte Carlo Simulations of the Photospheric Emission in Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Bégué, D.; Siutsou, I. A.; Vereshchagin, G. V.

2013-04-01

We studied the decoupling of photons from ultra-relativistic spherically symmetric outflows expanding with constant velocity by means of Monte Carlo simulations. For outflows with finite widths we confirm the existence of two regimes: photon-thick and photon-thin, introduced recently by Ruffini et al. (RSV). The probability density function of the last scattering of photons is shown to be very different in these two cases. We also obtained spectra as well as light curves. In the photon-thick case, the time-integrated spectrum is much broader than the Planck function and its shape is well described by the fuzzy photosphere approximation introduced by RSV. In the photon-thin case, we confirm the crucial role of photon diffusion, hence the probability density of decoupling has a maximum near the diffusion radius well below the photosphere. The time-integrated spectrum of the photon-thin case has a Band shape that is produced when the outflow is optically thick and its peak is formed at the diffusion radius.

MONTE CARLO SIMULATIONS OF THE PHOTOSPHERIC EMISSION IN GAMMA-RAY BURSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Begue, D.; Siutsou, I. A.; Vereshchagin, G. V.

2013-04-20

We studied the decoupling of photons from ultra-relativistic spherically symmetric outflows expanding with constant velocity by means of Monte Carlo simulations. For outflows with finite widths we confirm the existence of two regimes: photon-thick and photon-thin, introduced recently by Ruffini et al. (RSV). The probability density function of the last scattering of photons is shown to be very different in these two cases. We also obtained spectra as well as light curves. In the photon-thick case, the time-integrated spectrum is much broader than the Planck function and its shape is well described by the fuzzy photosphere approximation introduced by RSV.more » In the photon-thin case, we confirm the crucial role of photon diffusion, hence the probability density of decoupling has a maximum near the diffusion radius well below the photosphere. The time-integrated spectrum of the photon-thin case has a Band shape that is produced when the outflow is optically thick and its peak is formed at the diffusion radius.« less

Transparency Parameters from Relativistically Expanding Outflows

NASA Astrophysics Data System (ADS)

Bégué, D.; Iyyani, S.

2014-09-01

In many gamma-ray bursts a distinct blackbody spectral component is present, which is attributed to the emission from the photosphere of a relativistically expanding plasma. The properties of this component (temperature and flux) can be linked to the properties of the outflow and have been presented in the case where there is no sub-photospheric dissipation and the photosphere is in coasting phase. First, we present the derivation of the properties of the outflow for finite winds, including when the photosphere is in the accelerating phase. Second, we study the effect of localized sub-photospheric dissipation on the estimation of the parameters. Finally, we apply our results to GRB 090902B. We find that during the first epoch of this burst the photosphere is most likely to be in the accelerating phase, leading to smaller values of the Lorentz factor than the ones previously estimated. For the second epoch, we find that the photosphere is likely to be in the coasting phase.

Grain formation around carbon stars. 1: Stationary outflow models

NASA Technical Reports Server (NTRS)

Egan, Michael P.; Leung, Chun Ming

1995-01-01

Asymptotic giant branch (AGB) stars are known to be sites of dust formation and undergo significant mass loss. The outflow is believed to be driven by radiation pressure on grains and momentum coupling between the grains and gas. While the physics of shell dynamics and grain formation are closely coupled, most previous models of circumstellar shells have treated the problem separately. Studies of shell dynamics typically assume the existence of grains needed to drive the outflow, while most grain formation models assume a constant veolcity wind in which grains form. Furthermore, models of grain formation have relied primarily on classical nucleation theory instead of using a more realistic approach based on chemical kinetics. To model grain formation in carbon-rich AGB stars, we have coupled the kinetic equations governing small cluster growth to moment equations which determine the growth of large particles. Phenomenological models assuming stationary outflow are presented to demonstrate the differences between the classical nucleation approach and the kinetic equation method. It is found that classical nucleation theory predicts nucleation at a lower supersaturation ratio than is predicted by the kinetic equations, resulting in significant differences in grain properties. Coagulation of clusters larger than monomers is unimportant for grain formation in high mass-loss models but becomes more important to grain growth in low mass-loss situations. The properties of the dust grains are altered considerably if differential drift velocities are ignored in modeling grain formation. The effect of stellar temperature, stellar luminosity, and different outflow velocities are investigated. The models indicate that changing the stellar temperature while keeping the stellar luminosity constant has little effect on the physical parameters of the dust shell formed. Increasing the stellar luminosity while keeping the stellar temperature constant results in large differences in grain properties. For small outflow velocities, grains form at lower supersaturation ratios and close to the stellar photosphere, resulting in larger but fewer grains. The reverse is true when grains form under high outflow velocities, i.e., they form at higher supersaturation ratios, farther from the star, and are much smaller but at larger quantities.

A Fully GPU-Based Ray-Driven Backprojector via a Ray-Culling Scheme with Voxel-Level Parallelization for Cone-Beam CT Reconstruction.

PubMed

Park, Hyeong-Gyu; Shin, Yeong-Gil; Lee, Ho

2015-12-01

A ray-driven backprojector is based on ray-tracing, which computes the length of the intersection between the ray paths and each voxel to be reconstructed. To reduce the computational burden caused by these exhaustive intersection tests, we propose a fully graphics processing unit (GPU)-based ray-driven backprojector in conjunction with a ray-culling scheme that enables straightforward parallelization without compromising the high computing performance of a GPU. The purpose of the ray-culling scheme is to reduce the number of ray-voxel intersection tests by excluding rays irrelevant to a specific voxel computation. This rejection step is based on an axis-aligned bounding box (AABB) enclosing a region of voxel projection, where eight vertices of each voxel are projected onto the detector plane. The range of the rectangular-shaped AABB is determined by min/max operations on the coordinates in the region. Using the indices of pixels inside the AABB, the rays passing through the voxel can be identified and the voxel is weighted as the length of intersection between the voxel and the ray. This procedure makes it possible to reflect voxel-level parallelization, allowing an independent calculation at each voxel, which is feasible for a GPU implementation. To eliminate redundant calculations during ray-culling, a shared-memory optimization is applied to exploit the GPU memory hierarchy. In experimental results using real measurement data with phantoms, the proposed GPU-based ray-culling scheme reconstructed a volume of resolution 28032803176 in 77 seconds from 680 projections of resolution 10243768 , which is 26 times and 7.5 times faster than standard CPU-based and GPU-based ray-driven backprojectors, respectively. Qualitative and quantitative analyses showed that the ray-driven backprojector provides high-quality reconstruction images when compared with those generated by the Feldkamp-Davis-Kress algorithm using a pixel-driven backprojector, with an average of 2.5 times higher contrast-to-noise ratio, 1.04 times higher universal quality index, and 1.39 times higher normalized mutual information. © The Author(s) 2014.

A High-definition View Of The Circum-nuclear Regions In Nearby Seyferts With Chandra And HST

NASA Astrophysics Data System (ADS)

Wang, Junfeng; Fabbiano, G.; Elvis, M.; Risaliti, G.; Karovska, M.; Zezas, A.; Mundell, C. G.

2011-09-01

To improve our understanding of AGN feedback, it is crucial to evaluate the true role of outflows on galaxy evolution observationally. I will present new results from the CHandra survey of Extended Emission-line Regions in nearby Seyfert galaxies (CHEERS), which aims to examine feedback in action in much greater detail than at high redshift. Findings from Chandra studies of the circum-nuclear region in the archetypal Seyfert 1 galaxy NGC 4151 will be discussed in detail. Exploiting Chandra's highest possible resolution, we find evidence for X-ray emission from interaction between radio outflow and the optical narrow-line region clouds, in addition to the emission from photoionized gas.

Origin of the bright prompt optical emission in the naked eye burst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hascoeet, R.; Daigne, F.; Mochkovitch, R.

The huge optical brightness of GRB 080319B (the 'Naked Eye Burst') makes this event really challenging for models of the prompt GRB emission. In the framework of the internal shock model, we investigate a scenario where the dominant radiative process is synchrotron emission and the high optical flux is due to the dynamical properties of the relativistic outflow : if the initial Lorentz factor distribution in the jet is highly variable, many internal shocks will form within the outflow at various radii. The most violent shocks will produce the main gamma-ray component while the less violent ones will contribute atmore » lower energy, including the optical range.« less

Quasar feedback revealed by giant molecular outflows

NASA Astrophysics Data System (ADS)

Feruglio, C.; Maiolino, R.; Piconcelli, E.; Menci, N.; Aussel, H.; Lamastra, A.; Fiore, F.

2010-07-01

In the standard scenario for galaxy evolution young star-forming galaxies transform into red bulge-dominated spheroids, where star formation has been quenched. To explain this transformation, a strong negative feedback generated by accretion onto a central super-massive black hole is often invoked. The depletion of gas resulting from quasar-driven outflows should eventually stop star-formation across the host galaxy and lead the black hole to “suicide” by starvation. Direct observational evidence for a major quasar feedback onto the host galaxy is still missing, because outflows previously observed in quasars are generally associated with the ionized component of the gas, which only accounts for a minor fraction of the total gas content, and typically occurrs in the central regions. We used the IRAM PdB Interferometer to observe the CO(1-0) transition in Mrk 231, the closest quasar known. Thanks to the wide band we detected broad wings of the CO line, with velocities of up to 750 km s-1 and spatially resolved on the kpc scale. These broad CO wings trace a giant molecular outflow of about 700 M_⊙/year, far larger than the ongoing star-formation rate (~200 M_⊙/year) observed in the host galaxy. This wind will totally expel the cold gas reservoir in Mrk 231 in about 107 yrs, therefore halting the star-formation activity on the same timescale. The inferred kinetic energy in the molecular outflow is ~1.2 × 1044 erg/s, corresponding to a few percent of the AGN bolometric luminosity, which is very close to the fraction expected by models ascribing quasar feedback to highly supersonic shocks generated by radiatively accelerated nuclear winds. Instead, the contribution by the SNe associated with the starburst fall short by several orders of magnitude to account for the kinetic energy observed in the outflow. The direct observational evidence for quasar feedback reported here provides solid support to the scenarios ascribing the observed properties of local massive galaxies to quasar-induced large-scale winds.

Does an Intrinsic Magnetic Field Inhibit or Enhance Planetary Ionosphere Outflow and Loss?

NASA Astrophysics Data System (ADS)

Strangeway, R. J.; Russell, C. T.; Luhmann, J. G.; Moore, T. E.; Foster, J. C.; Barabash, S. V.; Nilsson, H.

2017-12-01

A characteristic feature of the planets Earth, Venus and Mars is the observation of the outflow of ionospheric ions, most notably oxygen. The oxygen ion outflow is frequently assumed to be a proxy for the loss of water from the planetary atmosphere. In terms of global outflow rates for the Earth the rate varies from 1025 to 1026 s-1, depending on geomagnetic activity. For both Venus and Mars global rates of the order 5x1024 s-1 have been reported. Venus and Mars do not have a large-scale intrinsic magnetic field, and there are several pathways for atmospheric and ionospheric loss. At Mars, because of its low gravity, neutral oxygen can escape through dissociative recombination. At Venus only processes related to the solar wind interaction with the planet such as sputtering and direct scavenging of the ionosphere by the solar wind can result in oxygen escape. At the Earth the intrinsic magnetic field forms a barrier to the solar wind, but reconnection of the Earth's magnetic field with the Interplanetary Magnetic Field allows solar wind energy and momentum to be transferred into the magnetosphere, resulting in ionospheric outflows. Observations of oxygen ions at the dayside magnetopause suggest that at least some of these ions escape. In terms of the evolution of planetary atmospheres how the solar-wind driven escape rates vary for magnetized versus umagnetized planets is also not clear. An enhanced solar wind dynamic pressure will increase escape from the unmagnetized planets, but it may also result in enhanced reconnection at the Earth, increasing outflow and loss rates for the Earth as well. Continued improvement in our understanding of the different pathways for ionospheric and atmospheric loss will allow us to determine how effective an intrinsic planetary field is in preserving a planetary atmosphere, or if we have to look for other explanations as to why the atmospheres of Venus and Mars have evolved to their desiccated state.

Complex X-ray Absorption and the Fe K(alpha) Profile in NGC 3516

NASA Technical Reports Server (NTRS)

Turner, T. J.; Kraemer, S. B.; George, I. M.; Reeves, J. N.; Botorff, M. C.

2004-01-01

We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and November. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, one which is consistent with our previous model of the UV/X-ray absorber while the other, which is outflowing at a velocity of approximately 1100 kilometers per second, has a larger column density and is much more highly ionized. The broad-band spectral characteristics of the X-ray continuum observed with XMM during 2001 April, reveal the presence of a third layer of absorption consisting of a very large column (approximately 2.5 x 10(exp 23) per square centimeter) of highly ionized gas with a covering fraction approximately 50%. This low covering fraction suggests that the absorber lies within a few 1t-days of the X-ray source and/or is filamentary in structure. Interestingly, these absorbers are not in thermal equilibrium with one another. The two new components are too highly ionized to be radiatively accelerated, which we suggest is evidence for a hydromagnetic origin for the outflow. Applying our model to the November dataset, we can account for the spectral variability primarily by a drop in the ionization states of the absorbers, as expected by the change in the continuum flux. When this complex absorption is accounted for we find the underlying continuum to be typical of Seyfert 1 galaxies. The spectral curvature attributed to the high column absorber, in turn, reduces estimates of the flux and extent of any broad Fe emission line from the accretion disk.

Lens-Aided Multi-Angle Spectroscopy (LAMAS) Reveals Small-Scale Outflow Structure in Quasars

NASA Astrophysics Data System (ADS)

Green, Paul J.

2006-06-01

Spectral differences between lensed quasar image components are common. Since lensing is intrinsically achromatic, these differences are typically explained as the effect of either microlensing, or as light path time delays sampling intrinsic quasar spectral variability. Here we advance a novel third hypothesis: some spectral differences are due to small line-of-sight differences through quasar disk wind outflows. In particular, we propose that variable spectral differences seen only in component A of the widest separation lens SDSS J1004+4112 are due to differential absorption along the sight lines. The absorber properties required by this hypothesis are akin to known broad absorption line (BAL) outflows but must have a broader, smoother velocity profile. We interpret the observed C IV emission-line variability as further evidence for spatial fine structure transverse to the line of sight. Since outflows are likely to be rotating, such absorber fine structure can consistently explain some of the UV and X-ray variability seen in AGNs. The implications are many: (1) Spectroscopic differences in other lensed objects may be due to this ``lens-aided multi-angle spectroscopy'' (LAMAS). (2) Outflows have fine structure on size scales of arcseconds, as seen from the nucleus. (3) Assuming either broad absorption line region sizes proposed in recent wind models, or typically assumed continuum emission region sizes, LAMAS and/or variability provide broadly consistent absorber size scale estimates of ~1015 cm. (4) Very broad smooth absorption may be ubiquitous in quasar spectra, even when no obvious troughs are seen.

Multi-wavelength campaign on NGC 7469. II. Column densities and variability in the X-ray spectrum

NASA Astrophysics Data System (ADS)

Peretz, U.; Behar, E.; Kriss, G. A.; Kaastra, J.; Arav, N.; Bianchi, S.; Branduardi-Raymont, G.; Cappi, M.; Costantini, E.; De Marco, B.; Di Gesu, L.; Ebrero, J.; Kaspi, S.; Mehdipour, M.; Middei, R.; Paltani, S.; Petrucci, P. O.; Ponti, G.; Ursini, F.

2018-01-01

We have investigated the ionic column density variability of the ionized outflows associated with NGC 7469, to estimate their location and power. This could allow a better understanding of galactic feedback of AGNs to their host galaxies. Analysis of seven XMM-Newton grating observations from 2015 is reported. We used an individual-ion spectral fitting approach, and compared different epochs to accurately determine variability on timescales of years, months, and days. We find no significant column density variability in a ten-year period implying that the outflow is far from the ionizing source. The implied lower bound on the ionization equilibrium time, ten years, constrains the lower limit on the distance to be at least 12 pc, and up to 31 pc, much less but consistent with the 1 kpc wide starburst ring. The ionization distribution of column density is reconstructed from measured column densities, nicely matching results of two 2004 observations, with one large high ionization parameter (ξ) component at 2 < log ξ< 3.5, and one at 0.5 < log ξ< 1 in cgs units. The strong dependence of the expression for kinetic power, ∝ 1 /ξ, hampers tight constraints on the feedback mechanism of outflows with a large range in ionization parameter, which is often observed and indicates a non-conical outflow. The kinetic power of the outflow is estimated here to be within 0.4 and 60% of the Eddington luminosity, depending on the ion used to estimate ξ.

Characterizing Quasar Outflows II: The Incidence of the Highest Velocity Outflows

NASA Astrophysics Data System (ADS)

Stark, Michele A.; Ganguly, R.; Christenson, D. H.; Richmond, J. M.; Derseweh, J. A.; Robbins, J. M.; Townsend, S. L.

2012-05-01

Galaxy evolution models have shown that quasars are a crucial ingredient in the evolution of massive galaxies. Outflows play a key role in the story of quasars and their host galaxies, by helping regulate the accretion process, the star-formation rate and mass of the host galaxy (i.e., feedback). The prescription for modeling outflows as a contributor to feedback requires knowledge of the outflow velocity, geometry, and column density. In particular, we need to understand how these depend on physical parameters and how much is determined stochastically (and with what distribution). For this purpose, we are examining a sample of 11000 z=1.7-2.0 quasars from the Sloan Digital Sky Survey. This redshift range permits the following from the SDSS spectra: (1) separation of objects that do and do not exhibit outflows; (2) classification/measurement of outflow properties (ionization, velocity, velocity width); and (3) measurements of UV emission line and continuum parameters. In an accompanying poster, we subjectively divide these quasars into four categories (broad absorption-line quasars, associated absorption-line quasars, reddened quasars, and unabsorbed/unreddened quasars). This subjective scheme is limited with regard to classifying narrow absorption-line systems (NALs). With single epoch, low dispersion SDSS spectra, we cannot distinguish between cosmologically intervening NALs, and intrinsic NALs that appear at large velocity offsets. In this poster, we tackle this uncertainty statistically by considering the incidence of both CIV and MgII NALs as a function of velocity, and how this distribution changes with quasar properties. We expect that absorption by intervening structures should not vary with quasar property. Other accompanying posters add photometry from rest-frame X-ray through the infrared (WISE) to complete the SED, which we utilize in these efforts. This material is based upon work supported by the National Aeronautics and Space Administration under Grant No. 09-ADP09-0016 issued through the Astrophysics Data Analysis Program.

ROSSI X-RAY TIMING EXPLORER OBSERVATIONS OF THE LOW-MASS X-RAY BINARY 4U 1608-522 IN THE UPPER-BANANA STATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Hiromitsu; Sakurai, Soki; Makishima, Kazuo, E-mail: hirotaka@hep01.hepl.hiroshima-u.ac.jp

To investigate the physics of mass accretion onto weakly magnetized neutron stars (NSs), 95 archival Rossi X-Ray Timing Explorer data sets of an atoll source 4U 1608-522, acquired over 1996-2004 in the so-called upper-banana state, were analyzed. The object meantime exhibited 3-30 keV luminosity in the range of {approx}< 10{sup 35}-4 x 10{sup 37} erg s{sup -1}, assuming a distance of 3.6 kpc. The 3-30 keV Proportional Counter Array spectra, produced one from each data set, were represented successfully with a combination of a soft and a hard component, the presence of which was revealed in a model-independent manner bymore » studying spectral variations among the observations. The soft component is expressed by the so-called multi-color disk model with a temperature of {approx}1.8 keV, and is attributed to the emission from an optically thick standard accretion disk. The hard component is a blackbody (BB) emission with a temperature of {approx}2.7 keV, thought to be emitted from the NS surface. As the total luminosity increases, a continuous decrease is observed in the ratio of the BB luminosity to that of the disk component. This property suggests that it gradually becomes difficult for the matter flowing through the accretion disk to reach the NS surface, presumably forming outflows driven by the increased radiation pressure. On timescales of hours to days, the overall source variability was found to be controlled by two independent variables: the mass accretion rate and the innermost disk radius, which changes both physically and artificially.« less

The Multi-Dimensional Structure of Radiative Shocks: Suppressed Thermal X-rays and Relativistic Ion Acceleration

NASA Astrophysics Data System (ADS)

Steinberg, Elad; Metzger, Brian D.

2018-06-01

Radiative shocks, behind which gas cools faster than the dynamical time, play a key role in many astrophysical transients, including classical novae and young supernovae interacting with circumstellar material. The dense layer behind high Mach number M ≫ 1 radiative shocks is susceptible to thin-shell instabilities, creating a "corrugated" shock interface. We present two and three-dimensional hydrodynamical simulations of optically-thin radiative shocks to study their thermal radiation and acceleration of non-thermal relativistic ions. We employ a moving-mesh code and a specialized numerical technique to eliminate artificial heat conduction across grid cells. The fraction of the shock's luminosity Ltot radiated at X-ray temperatures kT_sh ≈ (3/16)μ m_p v_sh2 expected from a one-dimensional analysis is suppressed by a factor L(>T_sh/3)/L_tot ≈ 4.5/M^{4/3} for M ≈ 4-36. This suppression results in part from weak shocks driven into under-pressured cold filaments by hot shocked gas, which sap thermal energy from the latter faster than it is radiated. Combining particle-in-cell simulation results for diffusive shock acceleration with the inclination angle distribution across the shock (relative to an upstream magnetic field in the shock plane-the expected geometry for transient outflows), we predict the efficiency and energy spectrum of ion acceleration. Though negligible acceleration is predicted for adiabatic shocks, the corrugated shock front enables local regions to satisfy the quasi-parallel magnetic field geometry required for efficient acceleration, resulting in an average acceleration efficiency of ɛnth ˜ 0.005 - 0.02 for M ≈ 12-36, in agreement with modeling of the gamma-ray nova ASASSN-16ma.

Jet or Shock Breakout? The Low-Luminosity GRB 060218

NASA Astrophysics Data System (ADS)

Irwin, Christopher; Chevalier, Roger

2016-01-01

We consider a model for the long-duration, low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The components of our model are: (1) a long-lived (tj ~ 3000 s) central engine and accompanying low-luminosity (Lj ~ 1045 erg s-1), mildly relativistic jet; (2) a low-mass (~ 10-2 Msun) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ~ 0.1) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the prompt nonthermal X-rays and γ-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ~ 1013 cm can explain the early optical peak. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ~ 30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that ultra-long bursts such as GRB 060218 and GRB 100316D may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt high-energy emission from the supernova.

Jet or shock breakout? The low-luminosity GRB 060218

NASA Astrophysics Data System (ADS)

Irwin, Christopher M.; Chevalier, Roger A.

2016-08-01

We consider a model for the low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The model components are: (1) a long-lived (tj ˜ 3000 s) central engine and accompanying low-luminosity (Lj ˜ 1047 erg s-1), mildly relativistic (γ ˜ 10) jet; (2) a low-mass (˜4 × 10-3 M⊙) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ˜ 0.1 mag) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the non-thermal X-rays and gamma-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ˜1013 cm can explain the early optical emission. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ˜30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that bursts such as GRB 060218 may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt emission from the supernova.

Chandra High Resolution Spectroscopy of the Circumnuclear Matter in the Broad Line Radio Galaxy, 3C 445

NASA Technical Reports Server (NTRS)

Reeves, J. N.; Gofford, J.; Braito, V.; Sambruna, R.

2010-01-01

We present evidence for X-ray line emitting and absorbing gas in the nucleus of the Broad-Line Radio Galaxy (BLRG), 3C445. A 200 ks Chandra LETG observation of 3C 445 reveals the presence of several highly ionized emission lines in the soft X-ray spectrum, primarily from the He and H-like ions of O, Ne, Mg and Si. Radiative recombination emission is detected from O VII and O VIII, indicating that the emitting gas is photoionized. The He-like emission appears to be resolved into forbidden and intercombination line components, which implies a high density of greater than 10(sup 10) cm(sup -3), while the lines are velocity broadened with a mean width of 2600 km s(sup -1). The density and widths of the ionized lines indicate an origin of the gas on sub-parsec scales in the Broad Line Region (BLR). The X-ray continuum of 3C 445 is heavily obscured by a photoionized absorber of column density N(sub H) = 2 x 10(sup 23) cm(sup -2) and ionization parameter log xi = 1.4 erg cm s(sup -1). However the view of the X-ray line emission is unobscured, which requires the absorber to be located at radii well within any parsec scale molecular torus. Instead we suggest that the X-ray absorber in 3C 445 may be associated with an outflowing, but clumpy accretion disk wind, with an observed outflow velocity of approximately 10000 km s(sup -1).

Jets in Hydrogen-poor Superluminous Supernovae: Constraints from a Comprehensive Analysis of Radio Observations

NASA Astrophysics Data System (ADS)

Coppejans, D. L.; Margutti, R.; Guidorzi, C.; Chomiuk, L.; Alexander, K. D.; Berger, E.; Bietenholz, M. F.; Blanchard, P. K.; Challis, P.; Chornock, R.; Drout, M.; Fong, W.; MacFadyen, A.; Migliori, G.; Milisavljevic, D.; Nicholl, M.; Parrent, J. T.; Terreran, G.; Zauderer, B. A.

2018-03-01

The energy source powering the extreme optical luminosity of hydrogen-stripped superluminous supernovae (SLSNe-I) is not known, but recent studies have highlighted the case for a central engine. Radio and/or X-ray observations are best placed to track the fastest ejecta and probe the presence of outflows from a central engine. We compile all the published radio observations of SLSNe-I to date and present three new observations of two new SLSNe-I. None were detected. Through modeling the radio emission, we constrain the subparsec environments and possible outflows in SLSNe-I. In this sample, we rule out on-axis collimated relativistic jets of the kind detected in gamma-ray bursts (GRBs). We constrain off-axis jets with opening angles of 5° (30°) to energies of {E}{{k}}< 4× {10}50 {erg} ({E}{{k}}< {10}50 {erg}) in environments shaped by progenitors with mass-loss rates of \\dot{M}< {10}-4 {M}ȯ {yr}}-1 (\\dot{M}< {10}-5 {M}ȯ {yr}}-1) for all off-axis angles, assuming fiducial values {ε }e=0.1 and {ε }B=0.01. The deepest limits rule out emission of the kind seen in faint uncollimated GRBs (with the exception of GRB 060218) and from relativistic SNe. Finally, for the closest SLSN-I, SN 2017egm, we constrain the energy of an uncollimated nonrelativistic outflow like those observed in normal SNe to {E}{{k}}≲ {10}48 erg.

The kinematics and morphology of cool galactic winds and halo gas from galaxies at 0.3 < z < 1.4

NASA Astrophysics Data System (ADS)

Rubin, Kate H. R.

Large-scale redshift surveys tracing the evolution of the luminous components of galaxies have revealed both an increase in the number density of "red and dead" galaxies and a concomitant decline in the star formation rates (SFRs) of blue galaxies since z ˜ 1. The latter is predicted to be due to a decreasing cool gas supply over time; whereas the former may be explained by the theory of merger-driven galaxy evolution, which suggests that the merging of blue galaxies expels the interstellar medium (ISM), thereby quenching star formation in the remnant. While these theoretical explanations provide robust predictions for the evolution of the gaseous components of distant galaxies, we have few direct measurements of the location and kinematics of cool gas around galaxies beyond the local universe. This thesis uses three complementary observational techniques to provide new constraints on the kinematics and morphology of cool gas in galaxies at 0.3 < z < 1.4. First, we use spectra of ˜470 galaxies at 0.7 < z < 1.5 drawn from the Team Keck Treasury Redshift Survey to study absorption line profiles for the Mg II lambdalambda2796, 2803 and Fe II lambdalambda2586, 2600 transitions, which probe cool, photoionized gas with temperature T ˜ 10 4 K. By coadding several sub-samples of galaxy spectra, we identify gaseous outflows via the Doppler shift of the absorption lines, and find that outflows are ubiquitous in galaxies having SFR > 10 M⊙ yr-1 and stellar masses ≳1010.5M⊙ . By comparing these results to those of Weiner et al. (2009), who present a similar study of outflows in star-forming galaxies at z ˜ 1.4, we find that these outflows persist in high-mass galaxies as they age between z ˜ 1.4 and z ˜ 1. Using HST/ACS imaging of our galaxy sample, we present evidence for a weak trend of increasing outflow absorption strength with increasing galaxy SFR surface density (SigmaSFR). Theoretical studies suggest that a minimum SigmaSFR must be exceeded in the host galaxy for outflows to be driven by either radiation pressure or thermalized energy from supernovae. To test this directly, we use a similar technique to probe cool gas kinematics in the individual Keck/LRIS spectra of a sample of ˜120 galaxies at 0.3 < z < 1.4. These data permit modeling of Mg II and Fe II absorption lines to obtain, e.g., the cool gas outflow velocity and covering fraction. Using Spitzer/MIPS and GALEX imaging to determine SFRs in concert with HST/ACS imaging which enables measurements of the size of star-forming regions, we compare outflow velocity to SigmaSFR. We find that while we detect outflows over a range 0.005 M⊙ yr-1 kpc-2 < Sigma SFR < 1 M⊙ yr-1 kpc-2, outflows occur more frequently with increasing SigmaSFR. The absorption line studies described above provide strong constraints on, e.g., the cool gas velocities. However, they provide only weak constraints on the radial extent and morphology of the gas. Knowledge of the spatial extent of the outflow is essential for accurately estimating its mass and energy; measurements of these rates are in turn crucial to understanding the role of outflows in driving galaxy evolution. Next, we show that emission in Mg II and Fe II* fine-structure lines can provide novel constraints on the spatial extent of an outflow. We identify a starburst galaxy at z = 0.69 which exhibits emission and absorption in Mg II, yielding a P Cygni-like line profile. We demonstrate that this emission is spatially broader than the continuum emission and the emission from H II regions, and associate the Mg II and Fe II* emission with resonance-line scattering and fluorescence in the outflow. These features are common at z ˜ 1, and in principle yield the first direct constraint on the radial extent of the outflow in many distant galaxies. Finally, we present a study of the cool gas around a single galaxy at z = 0.47 using spectroscopy of a bright background galaxy at z = 0.7 at a transverse distance of 16.5 h-170 kpc. While cool halo gas is typically studied along sightlines to background QSOs, the use of background galaxies offers several advantages over more traditional techniques. Because the background galaxy is spatially extended, we probe absorption over a large (> 4 h-170 kpc) area in the foreground halo, and find that the gas exhibits a large velocity dispersion and high covering fraction over this area. Spectroscopy of the foreground host galaxy reveals that it experienced a burst of star formation ˜1 Gyr ago, and we suggest that the absorbing gas in the halo was most likely ejected or tidally stripped during this past violent event. As such, these results again place a novel constraint on the radial extent of cool gas originating in the ISM of a distant galaxy.

IMPLICATIONS OF THE TENTATIVE ASSOCIATION BETWEEN GW150914 AND A FERMI -GBM TRANSIENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xiang; Yuan, Qiang; Jin, Zhi-Ping

2016-08-10

The merger-driven gamma-ray bursts (GRBs) and their associated gravitational-wave (GW) radiation, if both are successfully detected, have some far-reaching implications, including, for instance: (i) the statistical comparison of the physical properties of the short/long-short GRBs with and without GW detection can test the general origin model; (ii) revealing the physical processes taking place at the central engine; (iii) measuring the velocity of the gravitational wave directly/accurately. In this work, we discuss these implications in the case of a possible association of GW150914/Gamma-ray Burst Monitor (GBM) transient 150914. We compared GBM transient 150914 with other SGRBs and found that such anmore » event may be a distinct outlier in some statistical diagrams, possibly due to its specific binary black hole merger origin. However, the presence of a “new” group of SGRBs with “unusual” physical parameters is also possible. If the outflow of GBM transient 150914 was launched by the accretion onto the nascent black hole, the magnetic activity rather than the neutrino process is likely responsible for the energy extraction, and the accretion disk mass is estimated to be ∼10{sup −5} M {sub ⊙}. The GW150914/GBM transient 150914 association, if confirmed, would provide the first opportunity to directly measure the GW velocity, and its departure from the speed of the light should be within a factor of ∼10{sup −17}.« less

Discovery of an X-ray Violently Variable Broad Absorption Line Quasar

NASA Technical Reports Server (NTRS)

Ghosh, Kajal K.; Gutierrez, Carlos M.; Punsly, Brian; Chevallier, Loic; Goncalves, Anabela C.

2006-01-01

In this letter, we report on a quasar that is violently variable in the X-rays, XVV. It is also a broad absorption line quasar (BALQSO) that exhibits both high ionization and low ionization UV absorption lines (LoBALQSO). It is very luminous in the X-rays (approximately 10(exp 46) ergs s(sup -l) over the entire X-ray band). Surprisingly, this does not over ionize the LoBAL outflow. The X-rays vary by a factor of two within minutes in the quasar rest frame, which is shorter than 1/30 of the light travel time across a scale length equal to the black hole radius. We concluded that the X-rays are produced in a relativistic jet beamed toward earth in which variations in the Doppler enhancement produce the XVV behavior.

Photospheric Emission from Stratified Jets

NASA Astrophysics Data System (ADS)

Ito, Hirotaka; Nagataki, Shigehiro; Ono, Masaomi; Lee, Shiu-Hang; Mao, Jirong; Yamada, Shoichi; Pe'er, Asaf; Mizuta, Akira; Harikae, Seiji

2013-11-01

We explore photospheric emissions from stratified two-component jets, wherein a highly relativistic spine outflow is surrounded by a wider and less relativistic sheath outflow. Thermal photons are injected in regions of high optical depth and propagated until the photons escape at the photosphere. Because of the presence of shear in velocity (Lorentz factor) at the boundary of the spine and sheath region, a fraction of the injected photons are accelerated using a Fermi-like acceleration mechanism such that a high-energy power-law tail is formed in the resultant spectrum. We show, in particular, that if a velocity shear with a considerable variance in the bulk Lorentz factor is present, the high-energy part of observed gamma-ray bursts (GRBs) photon spectrum can be explained by this photon acceleration mechanism. We also show that the accelerated photons might also account for the origin of the extra-hard power-law component above the bump of the thermal-like peak seen in some peculiar bursts (e.g., GRB 090510, 090902B, 090926A). We demonstrate that time-integrated spectra can also reproduce the low-energy spectrum of GRBs consistently using a multi-temperature effect when time evolution of the outflow is considered. Last, we show that the empirical E p-L p relation can be explained by differences in the outflow properties of individual sources.

The nature of ULX source M101 X-1: optically thick outflow from a stellar mass black hole

NASA Astrophysics Data System (ADS)

Shen, Rong-Feng; Barniol Duran, Rodolfo; Nakar, Ehud; Piran, Tsvi

2015-02-01

The nature of ultraluminous X-ray sources (ULXs) has long been plagued by an ambiguity about whether the central compact objects are intermediate-mass (IMBH, ≳103 M⊙) or stellar-mass (a few tens M⊙) black holes (BHs). The high-luminosity (≃1039 erg s-1) and supersoft spectrum (T ≃ 0.1 keV) during the high state of the ULX source X-1 in the galaxy M101 suggest a large emission radius (≳109 cm), consistent with being an IMBH accreting at a sub-Eddington rate. However, recent kinematic measurement of the binary orbit of this source and identification of the secondary as a Wolf-Rayet star suggest a stellar-mass BH primary with a super-Eddington accretion. If that is the case, a hot, optically thick outflow from the BH can account for the large emission radius and the soft spectrum. By considering the interplay of photons' absorption and scattering opacities, we determine the radius and mass density of the emission region of the outflow and constrain the outflow mass-loss rate. The analysis presented here can be potentially applied to other ULXs with thermally dominated spectra, and to other super-Eddington accreting sources.

Kinematic GPS Analysis Gives New Insights on the Origin of the Very-Long-Period Seismic Signals at Miyake-Jima Volcano during the Caldera Formation

NASA Astrophysics Data System (ADS)

Munekane, H.; Oikawa, J.; Kobayashi, T.

2014-12-01

Miyake-jima is an active basaltic stratovolcano that is located 200km south of Tokyo, Japan. Its eruption event in 2000 was remarkable in that the large caldera was formed at the summit in approximately one month. During the caldera forming stage, very-long-period (VLP) seismic pulse waves with a duration of about 50-s that were accompanied by the step-like inflation were repeatedly recorded. Based on the broadband seismometer data, the piston model is proposed in which a vertical piston of solid materials in the conduit is intermittently sucked into the magma chamber located 3-5 km beneath the edific. In this study, we used the kinematic displacements from the continuous GPS observation to obtain additonal insights on the source mechanism of the pulse waves. 　We calculated the kinematic displacements of 15 GPS stations on Miyake-jima that were in operation at that time at 30 sec interval. Then we extracted the displacements associated with each event using 20-hour time window centered at the occurrence of the event, and stacked the whole time series to obtain mean displacement time series. The obtained time series contain: 1) step-like displacements associated with the pulse waves, 2) exponential decay following the events with time constant of approximately half-day, and 3) steady linear displacements indicating continuous contraction of the edifice. The type one displacements can be attributed to the simultaneous inflation of an mogi-type spherical pressure source located at the depth of 3.6 km under the edifice, and the opening of the nearby vertical dike whose top is at the depth of 2.3 km. The type two displacements can be interpreted as the pressure adjustment at the type one source by the outflow of the magma driven by the pressure difference between the type one source and surrounding area. The type three displacements can be interpreted as the steady outflow of the magma from the type one source. The above results support the ``piston model'' for the source of the pulse waves. However, it seems that the pressure increases by the collapse of the piston are not adjusted by the steady magma outflow as the ``piston model'' suggests but by the pressure-driven magma outflow. The steady magma outflow instead seems to be responsible for the long-term shrinkage of the edifice observed at that period.

N uSTAR Hard X-Ray Data and Gemini 3D Spectra Reveal Powerful AGN and Outflow Histories in Two Low-redshift Lyα Blobs

NASA Astrophysics Data System (ADS)

Kawamuro, Taiki; Schirmer, Mischa; Turner, James E. H.; Davies, Rebecca L.; Ichikawa, Kohei

2017-10-01

We have shown that Lyα blobs (LABs) may still exist even at z˜ 0.3, about seven billion years later than most other LABs known (Shirmer et al.). Their luminous Lyα and [O III] emitters at z˜ 0.3 offer new insights into the ionization mechanism. This paper focuses on the two X-ray brightest LABs at z˜ 0.3, SDSS J0113+0106 (J0113) and SDSS J1155-0147 (J1155), comparable in size and luminosity to “B1,” one of the best-studied LABs at z≳ 2. Our NuSTAR hard X-ray (3-30 keV) observations reveal powerful active galactic nuclei (AGN) with {L}2{--10{keV}}=(0.5{--}3)× {10}44 erg s-1. J0113 also faded by a factor of ˜5 between 2014 and 2016, emphasizing that variable AGN may cause apparent ionization deficits in LABs. Joint spectral analyses including Chandra data constrain column densities of {N}{{H}}={5.1}-3.3+3.1× {10}23 cm-2 (J0113) and {N}{{H}}={6.0}-1.1+1.4× {10}22 cm-2 (J1155). J0113 is likely buried in a torus with a narrow ionization cone, but ionizing radiation is also leaking in other directions, as revealed by our Gemini/GMOS 3D spectroscopy. The latter shows a bipolar outflow over 10 kpc, with a peculiar velocity profile that is best explained by AGN flickering. X-ray analysis of J1155 reveals a weakly absorbed AGN that may ionize over a wide solid angle, consistent with our 3D spectra. Extinction-corrected [O III] log-luminosities are high, ˜43.6. The velocity dispersions are low, ˜100-150 km s-1, even at the AGN positions. We argue that this is a combination of high extinction hiding the turbulent gas and previous outflows that have cleared the escape paths for their successors.

An Axisymmetric, Hydrodynamical Model for the Torus Wind in Active Galactic Nuclei

NASA Technical Reports Server (NTRS)

Dorodnitsyn, A.; Kallman, T.; Proga, D.

2008-01-01

We report on time-dependent axisymmetric simulations of an X-ray-excited flow from a parsec-scale, rotating, cold torus around an active galactic nucleus. Our simulations account for radiative heating and cooling and radiation pressure force. The simulations follow the development of a broad biconical outflow induced mainly by X-ray heating. We compute synthetic spectra predicted by our simulations. The wind characteristics and the spectra support the hypothesis that a rotationally supported torus can serve as the source of a wind which is responsible for the warm absorber gas observed in the X-ray spectra of many Seyfert galaxies.

Off-axis emission of short γ-ray bursts and the detectability of electromagnetic counterparts of gravitational-wave-detected binary mergers

NASA Astrophysics Data System (ADS)

Lazzati, Davide; Deich, Alex; Morsony, Brian J.; Workman, Jared C.

2017-10-01

We present calculations of the wide angle emission of short-duration gamma-ray bursts from compact binary merger progenitors. Such events are expected to be localized by their gravitational wave emission, fairly irrespective of the orientation of the angular momentum vector of the system, along which the gamma-ray burst outflow is expected to propagate. We show that both the prompt and afterglow emission are dim and challenging to detect for observers lying outside the cone within which the relativistic outflow is propagating. If the jet initially propagates through a baryon contaminated region surrounding the merger site, however, a hot cocoon forms around it. The cocoon subsequently expands quasi-isotropically producing its own prompt emission and external shock powered afterglow. We show that the cocoon prompt emission is detectable by Swift BAT and Fermi GBM. We also show that the cocoon afterglow peaks a few hours to a few days after the burst and is detectable for up to a few weeks at all wavelengths. The timing and brightness of the transient are however uncertain due to their dependence on unknown quantities such as the density of the ambient medium surrounding the merger site, the cocoon energy and the cocoon Lorentz factor. For a significant fraction of the gravitationally detected neutron-star-binary mergers, the cocoon afterglow could possibly be the only identifiable electromagnetic counterpart, at least at radio and X-ray frequencies.

Novel Analysis of the Multiwavelength Structure of the Relativistic Jet in Quasar 3C 273

NASA Astrophysics Data System (ADS)

Marchenko, Volodymyr; Harris, D. E.; Ostrowski, Michał; Stawarz, Łukasz; Bohdan, Artem; Jamrozy, Marek; Hnatyk, Bohdan

2017-07-01

We present a detailed analysis of the best-quality multiwavelength data gathered for the large-scale jet in the core-dominated quasar 3C 273. We analyze all the archival observations of the target with the Chandra X-ray Observatory, the far-ultraviolet observations with the Hubble Space Telescope, and the 8.4 GHz map obtained with the Very Large Array. In our study, we focus on investigating the morphology of the outflow at different frequencies, and therefore we apply various techniques for the image deconvolution, paying particular attention to a precise modeling of the Chandra and Hubble point-spread functions. We find that the prominent brightness enhancements in the X-ray and far-ultraviolet jet of 3C 273—the “knots”—are not point-like, and can be resolved transversely as extended features with sizes of about ≃ 0.5 {kpc}. Also, the radio outflow is wider than the deconvolved X-ray/ultraviolet jet. We have also found circumstantial evidence that the intensity peaks of the X-ray knots are located systematically upstream of the corresponding radio intensity peaks, with the projected spatial offsets along the jet ranging from ≲ 0.2 {kpc} up to ≃ 1 {kpc}. We discuss our findings in the wider context of multi-component models for the emission and structure of large-scale quasar jets, and speculate on the physical processes enabling an efficient acceleration of the emitting ultrarelativistic electrons along the entire jet length that exceeds 100 kpc.

Signs of magnetic acceleration and multizone emission in GRB 080825C

DOE PAGES

Moretti, Elena; Axelsson, Magnus

2016-03-03

One of the major results from the study of gamma-ray bursts with the Fermi Gamma-ray Space Telescope has been the confirmation that several emission components can be present in the energy spectrum. In this paper, we reanalyse the spectrum of GRB 080825C using data from the Fermi-Large Area Telescope (LAT) and Gamma-ray Burst Monitor instruments. Although fairly weak, it is the first gamma-ray burst detected by the Fermi-LAT. We improve on the original analysis by using the LAT Low Energy events covering the 30–100 MeV band. We find evidence of an additional component above the main emission peak (modelled usingmore » a Band function) with a significance of 3.5σ in two out of the four time bins. The component is well fitted by a Planck function, but shows unusual behaviour: the peak energy increases in the prompt emission phase, reaching energies of several MeV. This is the first time such a trend has been seen, and implies that the origin of this component is different from those previously detected. We suggest that the two spectral components likely arise in different regions of the outflow, and that strong constraints can be achieved by assuming one of them originates from the photosphere. Finally, the most promising model appears to be that the high-energy peak is the result of photospheric emission in a Poynting flux dominated outflow where the magnetization increases with time.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moretti, Elena; Axelsson, Magnus

One of the major results from the study of gamma-ray bursts with the Fermi Gamma-ray Space Telescope has been the confirmation that several emission components can be present in the energy spectrum. In this paper, we reanalyse the spectrum of GRB 080825C using data from the Fermi-Large Area Telescope (LAT) and Gamma-ray Burst Monitor instruments. Although fairly weak, it is the first gamma-ray burst detected by the Fermi-LAT. We improve on the original analysis by using the LAT Low Energy events covering the 30–100 MeV band. We find evidence of an additional component above the main emission peak (modelled usingmore » a Band function) with a significance of 3.5σ in two out of the four time bins. The component is well fitted by a Planck function, but shows unusual behaviour: the peak energy increases in the prompt emission phase, reaching energies of several MeV. This is the first time such a trend has been seen, and implies that the origin of this component is different from those previously detected. We suggest that the two spectral components likely arise in different regions of the outflow, and that strong constraints can be achieved by assuming one of them originates from the photosphere. Finally, the most promising model appears to be that the high-energy peak is the result of photospheric emission in a Poynting flux dominated outflow where the magnetization increases with time.« less

Proposed Laser-driven, Dielectric Microstructure Few-cm Long Undulator for Attosecond Coherent X-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plettner, T; Byer, R.L.; /Stanford U., Ginzton Lab.

This article presents the concept of an all-dielectric laser-driven undulator for the generation of coherent X-rays. The proposed laser-driven undulator is expected to produce internal deflection forces equivalent to a several-Tesla magnetic field acting on a speed-of-light particle. The key idea for this laser-driven undulator is its ability to provide phase synchronicity between the deflection force and the electron beam for a distance that is much greater than the laser wavelength. The potential advantage of this undulator is illustrated with a possible design example that assumes a small laser accelerator which delivers a 2 GeV, 1 pC, 1 kHz electronmore » bunch train to a 10 cm long, 1/2 mm period laser-driven undulator. Such an undulator could produce coherent X-ray pulses with {approx}10{sup 9} photons of 64 keV energy. The numerical modeling for the expected X-ray pulse shape was performed with GENESIS, which predicts X-ray pulse durations in the few-attosecond range. Possible applications for nonlinear electromagnetic effects from these X-ray pulses are briefly discussed.« less

X-ray insights into star and planet formation.

PubMed

Feigelson, Eric D

2010-04-20

Although stars and planets form in cold environments, X-rays are produced in abundance by young stars. This review examines the implications of stellar X-rays for star and planet formation studies, highlighting the contributions of NASA's (National Aeronautics and Space Administration) Chandra X-ray Observatory. Seven topics are covered: X-rays from protostellar outflow shocks, X-rays from the youngest protostars, the stellar initial mass function, the structure of young stellar clusters, the fate of massive stellar winds, X-ray irradiation of protoplanetary disks, and X-ray flare effects on ancient meteorites. Chandra observations of star-forming regions often show dramatic star clusters, powerful magnetic reconnection flares, and parsec-scale diffuse plasma. X-ray selected samples of premain sequence stars significantly advance studies of star cluster formation, the stellar initial mass function, triggered star-formation processes, and protoplanetary disk evolution. Although X-rays themselves may not play a critical role in the physics of star formation, they likely have important effects on protoplanetary disks by heating and ionizing disk gases.

X-ray insights into star and planet formation

PubMed Central

Feigelson, Eric D.

2010-01-01

Although stars and planets form in cold environments, X-rays are produced in abundance by young stars. This review examines the implications of stellar X-rays for star and planet formation studies, highlighting the contributions of NASA’s (National Aeronautics and Space Administration) Chandra X-ray Observatory. Seven topics are covered: X-rays from protostellar outflow shocks, X-rays from the youngest protostars, the stellar initial mass function, the structure of young stellar clusters, the fate of massive stellar winds, X-ray irradiation of protoplanetary disks, and X-ray flare effects on ancient meteorites. Chandra observations of star-forming regions often show dramatic star clusters, powerful magnetic reconnection flares, and parsec-scale diffuse plasma. X-ray selected samples of premain sequence stars significantly advance studies of star cluster formation, the stellar initial mass function, triggered star-formation processes, and protoplanetary disk evolution. Although X-rays themselves may not play a critical role in the physics of star formation, they likely have important effects on protoplanetary disks by heating and ionizing disk gases. PMID:20404197

Ultrafast Outflows: Galaxy-scale Active Galactic Nucleus Feedback

NASA Astrophysics Data System (ADS)

Wagner, A. Y.; Umemura, M.; Bicknell, G. V.

2013-01-01

We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagner, A. Y.; Umemura, M.; Bicknell, G. V., E-mail: ayw@ccs.tsukuba.ac.jp

We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves inmore » the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.« less

Fermi observations of high-energy gamma-ray emission from GRB 080916C.

PubMed

Abdo, A A; Ackermann, M; Arimoto, M; Asano, K; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Band, D L; Barbiellini, G; Baring, M G; Bastieri, D; Battelino, M; Baughman, B M; Bechtol, K; Bellardi, F; Bellazzini, R; Berenji, B; Bhat, P N; Bissaldi, E; Blandford, R D; Bloom, E D; Bogaert, G; Bogart, J R; Bonamente, E; Bonnell, J; Borgland, A W; Bouvier, A; Bregeon, J; Brez, A; Briggs, M S; Brigida, M; Bruel, P; Burnett, T H; Burrows, D; Busetto, G; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Ceccanti, M; Cecchi, C; Celotti, A; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Cominsky, L R; Connaughton, V; Conrad, J; Costamante, L; Cutini, S; Deklotz, M; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; Dingus, B L; do Couto E Silva, E; Drell, P S; Dubois, R; Dumora, D; Edmonds, Y; Evans, P A; Fabiani, D; Farnier, C; Favuzzi, C; Finke, J; Fishman, G; Focke, W B; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giebels, B; Giglietto, N; Giommi, P; Giordano, F; Glanzman, T; Godfrey, G; Goldstein, A; Granot, J; Greiner, J; Grenier, I A; Grondin, M-H; Grove, J E; Guillemot, L; Guiriec, S; Haller, G; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hernando Morat, J A; Hoover, A; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kavelaars, A; Kawai, N; Kelly, H; Kennea, J; Kerr, M; Kippen, R M; Knödlseder, J; Kocevski, D; Kocian, M L; Komin, N; Kouveliotou, C; Kuehn, F; Kuss, M; Lande, J; Landriu, D; Larsson, S; Latronico, L; Lavalley, C; Lee, B; Lee, S-H; Lemoine-Goumard, M; Lichti, G G; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Marangelli, B; Mazziotta, M N; McBreen, S; McEnery, J E; McGlynn, S; Meegan, C; Mészáros, P; Meurer, C; Michelson, P F; Minuti, M; Mirizzi, N; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Moretti, E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Nelson, D; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paciesas, W S; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Perri, M; Pesce-Rollins, M; Petrosian, V; Pinchera, M; Piron, F; Porter, T A; Preece, R; Rainò, S; Ramirez-Ruiz, E; Rando, R; Rapposelli, E; Razzano, M; Razzaque, S; Rea, N; Reimer, A; Reimer, O; Reposeur, T; Reyes, L C; Ritz, S; Rochester, L S; Rodriguez, A Y; Roth, M; Ryde, F; Sadrozinski, H F-W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Segal, K N; Sgrò, C; Shimokawabe, T; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Stamatikos, M; Starck, J-L; Stecker, F W; Steinle, H; Stephens, T E; Strickman, M S; Suson, D J; Tagliaferri, G; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Tenze, A; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Turri, M; Tuvi, S; Usher, T L; van der Horst, A J; Vigiani, L; Vilchez, N; Vitale, V; von Kienlin, A; Waite, A P; Williams, D A; Wilson-Hodge, C; Winer, B L; Wood, K S; Wu, X F; Yamazaki, R; Ylinen, T; Ziegler, M

2009-03-27

Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.

THE ANATOMY OF A LONG GAMMA-RAY BURST: A SIMPLE CLASSIFICATION SCHEME FOR THE EMISSION MECHANISM(S)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bégué, D.; Burgess, J. Michael, E-mail: jamesb@kth.se, E-mail: damienb@kth.se

2016-03-20

Ultra-relativistic motion and efficient conversion of kinetic energy to radiation are required by gamma-ray burst (GRB) observations, yet they are difficult to simultaneously achieve. Three leading mechanisms have been proposed to explain the observed emission emanating from GRB outflows: radiation from either relativistic internal or external shocks, or thermal emission from a photosphere. Previous works were dedicated to independently treating these three mechanisms and arguing for a sole, unique origin of the prompt emission of GRBs. In contrast, herein, we first explain why all three models are valid mechanisms and that a contribution from each of them is expected inmore » the prompt phase. Additionally, we show that a single parameter, the dimensionless entropy of the GRB outflow, determines which mechanism contributes the most to the emission. More specifically, internal shocks dominate for low values of the dimensionless entropy, external shocks for intermediate values, and finally, photospheric emission for large values. We present a unified framework for the emission mechanisms of GRBs with easily testable predictions for each process.« less

The active nucleus of the ULIRG IRAS F00183-7111 viewed by NuSTAR

NASA Astrophysics Data System (ADS)

Iwasawa, K.; Spoon, H. W. W.; Comastri, A.; Gilli, R.; Lanzuisi, G.; Piconcelli, E.; Vignali, C.; Brusa, M.; Puccetti, S.

2017-10-01

We present an X-ray study of the ultra-luminous infrared galaxy IRAS F00183-7111 (z = 0.327), using data obtained from NuSTAR, Chandra X-ray Observatory, Suzaku and XMM-Newton. The Chandra imaging shows that a point-like X-ray source is located at the nucleus of the galaxy at energies above 2 keV. However, the point source resolves into diffuse emission at lower energies, extending to the east, where the extranuclear [Oiii]λ5007 emission, presumably induced by a galactic-scale outflow, is present. The nuclear source is detected by NuSTAR up to the rest-frame 30 keV. The strong, high-ionization Fe K line, first seen by XMM-Newton, and subsequently by Suzaku and Chandra, is not detected in the NuSTAR data. The line flux appears to have been declining continuously between 2003 and 2016, while the continuum emission remained stable to within 30%. Further observations are needed to confirm this. The X-ray continuum below 10 keV is characterised by a hard spectrum caused by cold absorption of NH 1 × 1023 cm-2, compatible to that of the silicate absorption at 9.7 μm, and a broad absorption feature around 8 keV which we attribute to a high-ionization Fe K absorption edge. The latter is best described by a blueshifted, high-ionization (log ξ 3) absorber with a column density of NH 1 × 1024 cm-2, similar to the X-ray high-velocity outflows observed in a number of active nuclei. No extra hard component, which would arise from a strongly absorbed (I.e. Compton-thick) source, is seen in the NuSTAR data. While a pure reflection scenario (with a totally hidden central source) is viable, direct emission from the central source of L2-10 keV ≃ 2 × 1044 erg s-1, behind layers of cold and hot absorbing gas may be an alternative explanation. In this case, the relative X-ray quietness (Lx/Lbol,AGN ≤ 6 × 10-3), the high-ionization Fe line, strong outflows inferred from various observations, and other similarities to the well-studied ULIRG/QSO Mrk 231 point that the central source in this ULIRG might be accreting close to the Eddington limit. This research has also made use of data obtained from ESO telescopes at the La Silla Paranal Observatory. The ESO VLT data are under programme IDs 386.B-0346, 088.B-0405, and 090.B-0098.

Particle-in-cell simulations of magnetically driven reconnection using laser-powered capacitor coils

NASA Astrophysics Data System (ADS)

Huang, Kai; Lu, Quanming; Gao, Lan; Ji, Hantao; Wang, Xueyi; Fan, Feibin

2018-05-01

In this paper, we propose an experimental scheme to fulfill magnetically driven reconnections. Here, two laser beams are focused on a capacitor-coil target and then strong currents are wired in two parallel circular coils. Magnetic reconnection occurs between the two magnetic bubbles created by the currents in the two parallel circular coils. A two-dimensional particle-in-cell simulation model in the cylindrical coordinate is used to investigate such a process, and the simulations are performed in the (r ,z ) plane. The results show that with the increase of the currents in the two coils, the associated magnetic bubbles expand and a current sheet is formed between the two bubbles. Magnetic reconnection occurs when the current sheet is sufficiently thin. A quadrupole structure of the magnetic field in the θ direction ( Bθ ) is generated in the diffusion region and a strong electron current along the r direction ( Je r ) is also formed due to the existence of the high-speed electron flow away from the X line in the center of the outflow region. Because the X line is a circle along the θ direction, the convergence of the plasma flow around r =0 will lead to the asymmetry of Je r and Bθ between the two outflow regions of magnetic reconnection.

Transitioning from a single-phase fluid to a porous medium: a boundary layer approach

NASA Astrophysics Data System (ADS)

Dalwadi, Mohit P.; Chapman, S. Jon; Oliver, James M.; Waters, Sarah L.

2014-11-01

Pressure-driven laminar channel flow is a classic problem in fluid mechanics, and the resultant Poiseuille flow is one of the few exact solutions to the Navier-Stokes equations. If the channel interior is a porous medium (governed by Darcy's law) rather than a single-phase fluid, the resultant behaviour is plug flow. But what happens when these two flow regions are coupled, as is the case for industrial membrane filtration systems or biological tissue engineering problems? How does one flow transition to the other? We use asymptotic methods to investigate pressure-driven flow through a long channel completely blocked by a finite-length porous obstacle. We analytically solve for the flow at both small and large Reynolds number (whilst remaining within the laminar regime). The boundary layer structure is surprisingly intricate for large Reynolds number. In that limit, the structure is markedly different depending on whether there is inflow or outflow through the porous medium, there being six asymptotic regions for inflow and three for outflow. We have extended this result to a wide class of 3D porous obstacles within a Hele-Shaw cell. We obtain general boundary conditions to couple the outer flows, and find that these conditions are far from obvious at higher order.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balman, Şölen; Godon, Patrick; Sion, Edward M., E-mail: solen@astroa.physics.metu.edu.tr, E-mail: patrick.godon@villanova.edu, E-mail: edward.sion@villanova.edu

We present a total of ∼45 ks (3 × 15 ks) of Swift X-Ray Telescope (XRT) observations for three nonmagnetic nova-like (NL) cataclysmic variables (CVs; MV Lyr, BZ Cam, V592 Cas) in order to study characteristics of boundary layers (BLs) in CVs. The nonmagnetic NLs are found mostly in a state of high mass accretion rate (≥1 × 10{sup –9} M {sub ☉} yr{sup –1}), and some show occasional low states. Using the XRT data, we find optically thin multiple-temperature cooling flow type emission spectra with X-ray temperatures (kT {sub max}) of 21-50 keV. These hard X-ray-emitting BLs diverge frommore » simple isobaric cooling flows, indicating X-ray temperatures that are of virial values in the disk. In addition, we detect power-law emission components from MV Lyr and BZ Cam and plausibly from V592 Cas, which may be a result of the Compton scattering of the optically thin emission from the fast wind outflows in these systems and/or Compton upscattering of the soft disk photons. The X-ray luminosities of the (multitemperature) thermal plasma emission in the 0.1-50.0 keV range are (0.9-5.0) × 10{sup 32} erg s{sup –1}. The ratio of the X-ray and disk luminosities (calculated from the UV-optical wavelengths) yields an efficiency (L{sub x} /L {sub disk}) ∼ 0.01-0.001. Given this non-radiative ratio for the X-ray-emitting BLs with no significant optically thick blackbody emission in the soft X-rays (consistent with ROSAT observations), together with the high/virial X-ray temperatures, we suggest that high-state NL systems may have optically thin BLs merged with ADAF-like flows and/or X-ray coronae. In addition, we note that the axisymmetric bipolar and/or rotation-dominated fast-wind outflows detected in these three NLs (particularly BZ Cam and V592 Cas) or some other NL may also be explained in the context of ADAF-like BL regions.« less

Forcing, variability, and pathway of a freshwater-driven current in the Eurasian Arctic

NASA Astrophysics Data System (ADS)

Janout, Markus; Aksenov, Yevgeny; Hölemann, Jens; Rabe, Benjamin; Schauer, Ursula; Polyakov, Igor; Bacon, Sheldon; Coward, Andrew; Karcher, Michael; Lenn, Yueng-Djern; Kassens, Heidi; Timokhov, Leo

2015-04-01

Siberian river water is a first-order contribution to the Arctic freshwater budget, with the Ob, Yenisey, and Lena supplying nearly half of the total surface freshwater flux. However, few details are known regarding where, when and how the freshwater transverses the vast Siberian shelf seas. This paper investigates the mechanism, variability and pathways of the fresh Kara Sea outflow through Vilkitsky Strait towards the Laptev Sea. We utilize a high-resolution ocean model and recent shipboard observations to characterize the freshwater-laden Vilkitsky Strait Current (VSC), and shed new light on the little-studied region between the Kara and Laptev Seas, characterized by harsh ice conditions, contrasting water masses, straits and a large submarine canyon. The VSC is 10-20 km wide, surface-intensified, and varies seasonally (maximum from August-March) and interannually. Average freshwater (volume) transport is 500 ± 120 km3 a-1 (0.53 ± 0.08 Sv), with a baroclinic flow contribution of 50-90%. Interannual transport variability is explained by a storage-release mechanism, where blocking-favorable summer winds hamper the outflow and cause accumulation of freshwater in the Kara Sea. The year following a blocking event is characterized by enhanced transports driven by a baroclinic flow along the coast that is set up by increased freshwater volumes. Eventually, the VSC merges with a slope current and provides a major pathway for Eurasian river water towards the Western Arctic along the Eurasian continental slope. Kara (and Laptev) Sea freshwater transport is not correlated with the Arctic Oscillation, but rather driven by regional summer pressure patterns.

Two-Dimensional Study of Mass Outflow from Central Gravitational Astrophysical Object. Analytical 2-D solutions for thermo-radiatively driven stellar winds.

NASA Astrophysics Data System (ADS)

Kakouris, A.

The present PhD Thesis deals with the two-dimensional description of the plasma outflow from central astrophysical objects. The concept of stellar winds was originated by Eugene Parker 1958, and has become a very hot area of research the last decade. Mass outflow from all types of stars, as well as AGNs, quasars or planetary nebulae are observed in all astrophysical scales indicating at least two-dimensional (2-D) features (e.g. Hughes (editor), 1991, Beams and jets in astrophysics, Cambridge University Press). In a first stage, the flows are modeled empirically but their origin has to be in accordance with the fluid mechanics and the conservation laws. So, self-consistent 2-D models are needed (i.e. full solutions of the total set of equations which conserve mass, momentum and energy). The main mechanisms of ejecting plasma from an astrophysical object are the thermal (similar to solar wind), the radiative and the magnetic. Self consistent analytical 2-D steady hydrodynamic (HD) solutions for stellar winds have been presented by Tsinganos & Vlastou 1988, Tsinganos & Trussoni 1990, Tsinganos & Sauty 1992 and Lima & Priest 1993. Following their description we derive a new set of solutions in the present work. Our main assumptions are steady state (\\partial/\\partial t = 0), axisymmetry to the rotational axis (\\partial/\\partial \\phi = 0) and helicoidal geometry for the streamlines (meridional velocity {\\vec u}_{\\theta} = {\\vec 0} ). Besides, the fluid is assumed to be a nonmagnetized fully ionized hydrogen. The model could be named as non polytropic since we do not follow the polytropic assumption with a constant polytropic exponent but we evaluate the total external energy needed by the 1st law of Thermodynamics. Also, the solutions are \\theta-self similar since the dependence to the colatitude is given from the beginning. The generalized differential rotation of the fluid is taken into account considering a dependence of the rotational velocity of (V\\phi \\propto \\sin\\mu \\theta / R ) where \\mu is a parameter and R the radial distance. Using these assumptions we derive fully analytical (only a Simpson integration is needed) 2-D solutions of four types (with velocity maximum either along the equator or the polar axis of the central astrophysical object). One of them (named as solution in Range I) exhibits suitable features for stellar wind interpretation with velocity maximum along the equator because the outflow starts subsonic at the stellar surface and terminates supersonic at infinity. The other solutions are subsonic (breeze) or they could be examined only as inflows. The Range I solution is applied to real astrophysical objects. Moreover, the thermally driven 2 - D solutions are extended including the radiative force due to the absorption of the stellar light in the fluid. So, the 2-D solutions represent thermally and radiatively driven flows. The assumptions for the radiative force inclusion are that the radiative acceleration is radial and it is a function of radial distance solely (i.e. it is independent of the velocity). The first radiatively driven wind model was presented in 1975 by Castor, Abbott & Klein and was applied to O5f main sequence stars. In order to describe the radiative origin of the massive winds from early and late spectral type stars, the radiative force is separated into its continuum, thick lines and thin lines parts. The mechanism of the continuous absorption is the Thomson scattering of the photons by the free plasma electrons and it is always present. If the line contribution corresponds to the thick absorption spectral lines the model is named as 'thick line driven' otherwise the atmosphere is thought 'optically thin'. In this Thesis we consider an optically thin atmosphere and in this case the radiative force is written as a power law of distance (Chen & Marlborough 1994, Lamers 1986). Moreover, we examine the exponential dependence of the radiative acceleration upon the radial distance and exponential deviations from power laws. We apply to supergiant B stars and we obtain results in agreement with observations (Underhill & i oazan 1982). In the first chapter of the Thesis, the reader is introduced in the concept of the astrophysical flows. I show some observational data for outflows and the basic mechanisms of the outflows are reported. In chapter 2, the basic hydrodynamic equations are presented. In chapter 3, some 1-D or 2-D models (relevant to this Thesis) are reported. The new results appear in chapters 4, 5, 6 which posses the 3/4 of the Thesis. In chapter 4, the basic assumptions are presented and the full mathematical derivation and deduction of the solutions are given. The inclusion of the radiative force is also given. In chapter 5, the thermally driven solution is applied to astrophysical objects. We first apply to Sun and to young T Tauri stars and to late type supergiant stars. The 2-D nature of the solutions is presented. We note that the model fails to describe the outflow at the stellar surface because it needs relatively high initial velocities. In that area the magnetic field plays probably an important role. I deduce the role of the centrifugal force in the solutions comparing it with the thermal pressure force, the radiative force and gravity. The result is that the influence of the centrifugal force is negligible. Moreover, I apply the thermally and radiatively driven solution in Range I to B type supergiants. The problem of the high initial velocity at the stellar surface is waved when the radiative force is important. The results coincide with observations. In chapter 6, the haracteristics of the model are summarized and compared with previous models.

Coulomb explosion of the hot spot of micropinches

NASA Astrophysics Data System (ADS)

Oreshkin, V. I.; Oreshkin, E. V.

2017-01-01

It has been shown that the generation of hard X-ray radiation, electron beam, and high energy ions that have been detected in experiments on compressing pinches can be related to the Coulomb explosion of a micropinch hot spot, which is formed due to the outflow of the material. In the outflow process, the plasma temperature in the hot spot increases and conditions appear for the transition of electrons to the regime of continuous acceleration. The exit of runaway electrons from the hot spot region leads to the creation of a positive bulk charge, then to a Coulomb explosion. Conditions under which electrons pass to the continuous acceleration regime have been determined and estimates of the ion kinetic energy upon a Coulomb explosion have been obtained.

Outflow from the outer Lagrangian point - Observations and models of 4U 2127 + 12 in M15

NASA Technical Reports Server (NTRS)

Bailyn, Charles D.; Garcia, Michael R.; Grindlay, Jonathan

1989-01-01

MMT observations of AC 211, the optical counterpart of the high-luminosity X-ray source in globular cluster M15, are presented. The observation of Naylor et al. (1988) that the He I absorption is blueshifted by more than 100 km/s with respect to the mean velocity of the cluster is confirmed. It is shown that if the absorption occurs in a stream of gas outflowing from the L2 point of a binary system, as might be expected for a common envelope binary, both the blueshift and the unexpectedly low velocity variations of the He I lines can be understood. The model predicts that the He I velocity curve is not sinusoidal.

Yet another UFO in the X-ray spectrum of a high-z lensed QSO

NASA Astrophysics Data System (ADS)

Dadina, M.; Vignali, C.; Cappi, M.; Lanzuisi, G.; Ponti, G.; Torresi, E.; De Marco, B.; Chartas, G.; Giustini, M.

2018-02-01

Aim. Ultra-fast outflows (UFO) appear to be common in local active galactic nuclei (AGN) and may be powerful enough (Ėkin ≥ 1% of Lbol) to effectively quench the star formation in their host galaxies. To test feedback models based on AGN outflows, it is mandatory to investigate UFOs near the peak of AGN activity, that is, at high-z where only a few studies are available to date. Methods: UFOs produce Fe resonant absorption lines measured above ≈7 keV. The most critical problem in detecting such features in distant objects is the difficulty in obtaining X-ray data with sufficient signal-to-noise. We therefore selected a distant QSO that gravitational lensing made bright enough for these purposes, the z = 2.64 QSO MG J0414+0534, and observed it with XMM-Newton for ≈78 ks. Results: The X-ray spectrum of MG J0414+0534 is complex and shows signatures of cold absorption (NH ≈ 4 × 1022 cm-2) and of the presence of an iron emission line (E ≈ 6.4 keV, EW = 95 ± 53 eV) consistent with it originating in the cold absorber. Our main result, however, is the robust detection (more than 5σ) of an absorption line at Eint ≈ 9.2 keV (Eobs ≈ 2.5 keV observer frame). If interpreted as due to FeXXVI, it implies gas outflowing at vout ≈ 0.3c. To our knowledge, this is the first detection of an UFO in a radio-loud quasar at z ≥ 1.5. We estimated that the UFO mechanical output is Ėkin ≈ 2.5Lbol with ṗout/ṗrad ≈ 17 indicating that it is capable of installing significant feedback between the super-massive black hole and the bulge of the host galaxy. We argue that this also suggests a magnetic driving origin of the UFO.

Similar Hydrodynamic and Morphological Changes in the Aqueous Humor Outflow Pathway after Washout and Y27632 Treatment in Monkey Eyes

PubMed Central

Lu, Zhaozeng; Zhang, Yuyan; Freddo, Thomas F.; Gong, Haiyan

2011-01-01

Our previous studies in bovine eyes demonstrated that the structural correlate to the increase in outflow facility after either Rho-kinase inhibitor Y-27632 (Y27) treatment or washout appeared to be separation between the juxtacanalicular tissue (JCT) and inner wall (IW) of the aqueous plexus, the bovine equivalent of Schlemm's canal (SC). While these findings suggest that Y27 and washout may increase outflow facility through a similar mechanism, the anatomy of bovine outflow pathway differs considerably from both the human and monkey outflow pathway; however, only the human eye does not exhibit washout. In light of this, we compared the effects of Y27 and washout on outflow facility, hydrodynamic patterns of outflow, and the morphology of the IW and JCT in monkey eyes, given that their anatomy is closer to human eyes. Twelve freshly enucleated monkey eyes were used in this study. Eyes were perfused with Dulbecco's PBS containing 5.5 mM glucose (GPBS) to establish a baseline facility at 15 mmHg. Four eyes were perfused for a short-duration (30 min) as a control, 4 eyes for a long-duration (180 min) to induce washout, and 4 eyes with GPBS+50 μM Y27 for 30 min. All eyes were then perfused with fluorescent microspheres (0.5μm; 0.002%) to label the hydrodynamic patterns of outflow and then perfusion-fixed. Confocal images of frontal sections were taken along the IW of SC. The total length (TL) and the tracer decorated length (FL) of the IW were measured to calculate the average percent effective filtration length (PEFL=FL/TL). Sections with SC were examined by light and electron microscopy. The TL of the IW and the length exhibiting separation (SL) in the JCT were measured to calculate the average percent separation length (PSL= SL/TL). Outflow facility increased 149.2% (p<0.01) from baseline after washout during long-duration perfusion, and 114.9% (p=0.004) after Y27 treatment, but did not change significantly after short-duration perfusion in control eyes (p=0.46). Distribution of the tracer labeling appeared punctate along the IW of control eyes, while a more uniform pattern was observed after washout and Y27 treatment. PEFL in washout (83.4±2.1%) and Y27 treated eyes (82.5±1.6%) was 3.4-fold larger compared to controls (24.2±4.2%, P<0.001). The JCT appeared distended with loss of connections between JCT cells and between JCT cells and their extracelluar matrix in eyes with washout or after Y-27 treatment. PSL in the JCT was 2.3-fold larger in washout eyes (77.4±3.3%) and 2.2-fold larger in Y27 treated eyes (75.2±5.3%) versus controls (33.5±5.3%, p=0.001). Significant positive correlations were found between outflow facility and PEFL, facility and PSL and between PEFL and PSL. Our data demonstrated that similar hydrodynamic and morphological changes occurred in the aqueous humor outflow pathway of monkey eyes after induction of washout and Y27 treatment. Both Y27 and washout increase outflow facility by redistributing aqueous outflow through a larger area in the JCT. These hydrodynamic changes are likely driven by morphologic changes associated with a decrease in cell-cell and cell-matrix connections in the JCT. PMID:21669200

Relativistic Outflows from Advection-dominated Accretion Disks around Black Holes

NASA Astrophysics Data System (ADS)

Becker, Peter A.; Subramanian, Prasad; Kazanas, Demosthenes

2001-05-01

Advection-dominated accretion flows (ADAFs) have a positive Bernoulli parameter and are therefore gravitationally unbound. The Newtonian ADAF model has been generalized recently to obtain the ADIOS model that includes outflows of energy and angular momentum, thereby allowing accretion to proceed self-consistently. However, the utilization of a Newtonian gravitational potential limits the ability of this model to describe the inner region of the disk, where any relativistic outflows are likely to originate. In this paper we modify the ADIOS scenario to incorporate a pseudo-Newtonian potential, which approximates the effects of general relativity. The analysis yields a unique, self-similar solution for the structure of the coupled disk/wind system. Interesting features of the new solution include the relativistic character of the outflow in the vicinity of the radius of marginal stability, which represents the inner edge of the quasi-Keplerian disk in our model. Hence, our self-similar solution may help to explain the origin of relativistic jets in active galaxies. At large distances the radial dependence of the accretion rate approaches the unique form M~r1/2, with an associated density variation given by ρ~r-1. This density variation agrees with that implied by the dependence of the hard X-ray time lags on the Fourier frequency for a number of accreting galactic black hole candidates. While intriguing, the predictions made using our self-similar solution need to be confirmed in the future using a detailed model that includes a physical description of the energization mechanism that drives the outflow, which is likely to be powered by the shear of the underlying accretion disk.

Relativistic Outflows from ADAFs

NASA Astrophysics Data System (ADS)

Becker, Peter; Subramanian, Prasad; Kazanas, Demosthenes

2001-04-01

Advection-dominated accretion flows (ADAFs) have a positive Bernoulli parameter, and are therefore gravitationally bound. The Newtonian ADAF model has been generalized recently to obtain the ADIOS model that includes outflows of energy and angular momentum, thereby allowing accretion to proceed self-consistently. However, the utilization of a Newtonian gravitational potential limits the ability of this model to describe the inner region of the disk, where any relativistic outflows are likely to originate. In this paper we modify the ADIOS scenario to incorporate a seudo - Newtonian potential, which approximates the effects of general relativity. The analysis yields a unique, self - similar solution for the structure of the coupled disk/wind system. Interesting features of the new solution include the relativistic character of the outflow in the vicinity of the radius of marginal stability, which represents the inner edge of the quasi-Keplerian disk in our model. Our self - similar model may therefore help to explain the origin of relativistic jets in active galaxies. At large distances the radial dependence of the accretion rate approachs the unique form dot M ∝ r^1/2, with an associated density variation given by ρ ∝ r-1. This density variation agrees with that implied by the dependence of the X-ray hard time lags on the Fourier frequency for a number of accreting galactic black hole candidates. While intriguing, the results of our self-similar model need to be confirmed in the future by incorporating a detailed physical description of the energization mechanism that drives the outflow, which is likely to be powered by the shear of the underlying accretion disk.

Simulating Sources of Superstorm Plasmas

NASA Technical Reports Server (NTRS)

Fok, Mei-Ching

2008-01-01

We evaluated the contributions to magnetospheric pressure (ring current) of the solar wind, polar wind, auroral wind, and plasmaspheric wind, with the surprising result that the main phase pressure is dominated by plasmaspheric protons. We used global simulation fields from the LFM single fluid ideal MHD model. We embedded the Comprehensive Ring Current Model within it, driven by the LFM transpolar potential, and supplied with plasmas at its boundary including solar wind protons, polar wind protons, auroral wind O+, and plasmaspheric protons. We included auroral outflows and acceleration driven by the LFM ionospheric boundary condition, including parallel ion acceleration driven by upward currents. Our plasmasphere model runs within the CRCM and is driven by it. Ionospheric sources were treated using our Global Ion Kinetics code based on full equations of motion. This treatment neglects inertial loading and pressure exerted by the ionospheric plasmas, and will be superceded by multifluid simulations that include those effects. However, these simulations provide new insights into the respective role of ionospheric sources in storm-time magnetospheric dynamics.

Systematic Comparison of Photoionized Plasma Codes with Application to Spectroscopic Studies of AGN in X-Rays

NASA Technical Reports Server (NTRS)

Mehdipour, M.; Kaastra, J. S.; Kallman, T.

2016-01-01

Atomic data and plasma models play a crucial role in the diagnosis and interpretation of astrophysical spectra, thus influencing our understanding of the Universe. In this investigation we present a systematic comparison of the leading photoionization codes to determine how much their intrinsic differences impact X-ray spectroscopic studies of hot plasmas in photoionization equilibrium. We carry out our computations using the Cloudy, SPEX, and XSTAR photoionization codes, and compare their derived thermal and ionization states for various ionizing spectral energy distributions. We examine the resulting absorption-line spectra from these codes for the case of ionized outflows in active galactic nuclei. By comparing the ionic abundances as a function of ionization parameter, we find that on average there is about 30 deviation between the codes in where ionic abundances peak. For H-like to B-like sequence ions alone, this deviation in is smaller at about 10 on average. The comparison of the absorption-line spectra in the X-ray band shows that there is on average about 30 deviation between the codes in the optical depth of the lines produced at log 1 to 2, reducing to about 20 deviation at log 3. We also simulate spectra of the ionized outflows with the current and upcoming high-resolution X-ray spectrometers, on board XMM-Newton, Chandra, Hitomi, and Athena. From these simulations we obtain the deviation on the best-fit model parameters, arising from the use of different photoionization codes, which is about 10 to40. We compare the modeling uncertainties with the observational uncertainties from the simulations. The results highlight the importance of continuous development and enhancement of photoionization codes for the upcoming era of X-ray astronomy with Athena.

X-ray Thomson scattering measurements from hohlraum-driven spheres on the OMEGA laser [X-ray Thomson scattering measurements from hohlraum targets on the OMEGA laser

DOE PAGES

Saunders, A. M.; Jenei, A.; Doppner, T.; ...

2016-08-30

X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH 2 targets on the OMEGA laser. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule, but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Here, knowledge gained in this experiment show a promising future for further XRTS measurements on indirectly driven OMEGA targets.

X-ray Thomson scattering measurements from hohlraum-driven spheres on the OMEGA laser [X-ray Thomson scattering measurements from hohlraum targets on the OMEGA laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saunders, A. M.; Jenei, A.; Doppner, T.

X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH 2 targets on the OMEGA laser. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule, but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Here, knowledge gained in this experiment show a promising future for further XRTS measurements on indirectly driven OMEGA targets.

Interrelation of soft and hard X-ray emissions during solar flares. I - Observations

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Kiplinger, A. L.; Zarro, D. M.; Dulk, G. A.; Lemen, J. R.

1991-01-01

The interrelation between the acceleration and heating of electrons and ions during impulsive solar flares is determined on the basis of simulataneous observations of hard and soft X-ray emission from the Solar Maximum Mission at high time resolution (6 s). For all the flares, the hard X-rays are found to have a power-law spectrum which breaks down during the rise phase and beginning of the decay phase. After that, the spectrum changes to either a single power law or a power law that breaks up at high energies. The characteristics of the soft X-ray are found to depend on the flare position. It is suggested that small-scale quasi-static electric fields are important for determining the acceleration of the X-ray-producing electrons and the outflowing chromospheric ions.

Waiting in the Wings: Reflected X-ray Emission from the Homunculus Nebula

NASA Technical Reports Server (NTRS)

Corcoran, M. F.; Hamaguchi, K.; Gull, T.; Davidson, K.; Petre, R.; Hillier, D. J.; Smith, N.; Damineli, A.; Morse, J. A.; Walborn, N. R.

2004-01-01

We report the first detection of X-ray emission associated with the Homunculus Nebula which surrounds the supermassive star eta Carinae. The emission is characterized by a temperature in excess of 100 MK, and is consistent with scattering of the time-delayed X-ray flux associated with the star. The nebular emission is bright in the northwestern lobe and near the central regions of the Homunculus, and fainter in the southeastern lobe. We also report the detection of an unusually broad Fe K fluorescent line, which may indicate fluorescent scattering off the wind of a companion star or some other high velocity outflow. The X-ray Homunculus is the nearest member of the small class of Galactic X-ray reflection nebulae, and the only one in which both the emitting and reflecting sources are distinguishable.

An explanation of the formation of the peculiar periphery of Tycho's supernova remnant

NASA Astrophysics Data System (ADS)

Fang, Jun; Yu, Huan; Zhang, Li

2018-02-01

Tycho's supernova remnant (SNR) has a periphery that clearly deviates from a spherical shape, based on X-ray and radio observations. The forward shock from the south-east to the north of the remnant has a deformed outline with a depression in the east, although in the west it is generally round and smooth. Moreover, at some locations in the shell, the supernova ejecta is located close to the forward shock, resulting in protrusions. Using 3D hydrodynamical simulations, we studied the dynamical evolution of the supernova ejecta in an inhomogeneous medium and the formation process of the profile of the forward shock. In order to reproduce the peculiar periphery of the remnant, we propose a model in which the supernova ejecta has evolved in a cavity blown by a latitude-dependent outflow. The results indicate that the depression to the east and the protrusion to the south-east on the observed periphery of the remnant can be generally reproduced if we assume a wind bubble driven by an anisotropic wind with a mass-loss rate of ˜10-7 M⊙ yr-1, a pole velocity of ˜100 km s-1, a duration of ˜105 yr prior to the supernova explosion, and a spatial velocity of ˜30 km s-1 of the progenitor with respect to the circumstellar medium. In conclusion, an explanation of the peculiar shape of the periphery of Tycho's SNR is that the supernova ejecta evolved in the cavity driven by a latitude-dependent wind.

Wind diagnostics and correlations with the near-infrared excess in Herbig Ae/Be stars

NASA Astrophysics Data System (ADS)

Corcoran, M.; Ray, T. P.

1998-03-01

Intermediate dispersion spectroscopic observations of 37 Herbig Ae/Be stars reveal that the equivalent widths of their [OI]lambda 6300 and Hα emission lines, are related to their near-infrared colours in the same fashion as the T-Tauri stars. Such a correlation strongly supports the idea that the winds from Herbig Ae/Be stars arise in the same manner as those from T-Tauri stars, i.e. through accretion driven mass-loss. We also find that the [OI]lambda 6300 line luminosity correlates better with excess infrared luminosity than with stellar luminosities, again supporting the idea that Herbig Ae/Be winds are accretion driven. If one includes the lower mass analogues of the Herbig Ae/Be stars with forbidden line emission, i.e. the classical T-Tauri stars, the correlation between mass-loss rate and infrared excess spans 5 orders of magnitude in luminosity and a range of masses from 0.5Msun to approximately 10Msun. Our observations therefore extend the findings of Cohen et al. (1989) and Cabrit et al. (1990) for low mass young stars and, taken in conjunction with other evidence (Corcoran & Ray 1997), strongly support the presence of circumstellar disks around intermediate mass stars with forbidden line emission. An implication of our findings is that the same outflow model must be applicable to these Herbig Ae/Be stars and the classical T Tauri stars. Based on observations made at the La Palma Observatory, the Caltech Submillimeter Observatory, and the European Southern Observatory/Max Planck Institute 2.2m Telescope.

Absorbed radiation dose in adults from iodine-131 and iodine-123 orthoiodohippurate and technetium-99m DTPA renography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlsen, O.

1988-03-01

A mathematic model for evaluation of absorbed dose in radionuclide renography has been developed and programmed for automatic calculation in the computer. Input data to the model are readily available from the results of the renography and, hence, the method described is suitable for individual dose determinations in adults. Apart from the situation with very considerable outflow obstructions (/sup 131/I)OIH single probe renography involves a 15-20 times smaller dose to radiation sensitive organs than (/sup 123/I)OIH gamma camera renography. Further, the latter examination results in a 2-10 times smaller dose than (/sup 99m/Tc)DTPA gamma camera renography under normal outflow conditions.more » Absorbed renal dose is large, approximately 70 mGy, in the three renographies in the borderline case with total outflow obstructions. For comparison, i.v. pyelography, which is the x-ray examination often used instead of radionuclide renography, involves an absorbed dose to ovaries 10-1000 times larger than in radionuclide renography« less

Advection-dominated Inflow/Outflows from Evaporating Accretion Disks.

PubMed

Turolla; Dullemond

2000-03-01

In this Letter we investigate the properties of advection-dominated accretion flows (ADAFs) fed by the evaporation of a Shakura-Sunyaev accretion disk (SSD). In our picture, the ADAF fills the central cavity evacuated by the SSD and extends beyond the transition radius into a coronal region. We find that, because of global angular momentum conservation, a significant fraction of the hot gas flows away from the black hole, forming a transsonic wind, unless the injection rate depends only weakly on radius (if r2sigma&d2;~r-xi, xi<1&solm0;2). The Bernoulli number of the inflowing gas is negative if the transition radius is less, similar100 Schwarzschild radii, so matter falling into the hole is gravitationally bound. The ratio of inflowing to outflowing mass is approximately 1/2, so in these solutions the accretion rate is of the same order as in standard ADAFs and much larger than in advection-dominated inflow/outflow models. The possible relevance of evaporation-fed solutions to accretion flows in black hole X-ray binaries is briefly discussed.

Ultrafast outflows in Super-Eddington Tidal Disruption Events

NASA Astrophysics Data System (ADS)

Kara, Erin

2017-08-01

The disruption of a star from the strong tidal forces of a supermassive black hole can cause the stellar debris to fall back towards the black hole at super Eddington rates. Efficient circularization of the debris can lead to the formation of an accretion disc with luminosities close to or potentially exceeding Eddington limit. Most super-Eddington accretion flow models (including recent magnetohydrodynamic simulations) predict large scale height, optically thick equatorial winds at relativistic velocities. In this talk, we will present observational results from two of the most well-observed X-ray emitting Tidal Disruption Events, Swift J1644+57 and ASASSN-14li. Both of these objects show evidence for massive outflows at tens of percent of the speed of light. The outflow in Swift J1644+57 was detected via blue shifted emission and reverberation of the iron K alpha line, and ASASSN-14li shows a potential P Cygni profile of the OVIII line. We will discuss the constraints that these observations put on the geometry of the super-Eddington accretion flows in tidal disruption events.

Differentiated norepinephrine spillover in human skeletal muscle.

PubMed

Karlsson, A K; Elam, M; Lönnroth, P; Sullivan, L; Friberg, P

1997-07-01

Most neurophysiological studies have shown similar sympathetic outflow to arm and leg. However, some direct microneurographic recordings indicate differentiated sympathetic outflow to limbs both at rest and during mental stress. Hence, differentiated levels of norepinephrine (NE) spillover could prevail. By steady-state infusion of [3H]NE and body composition determination by dual-energy X-ray absorptiometry-scan, we simultaneously assessed arm and leg NE spillover related to 100 g tissue and total limb weight. NE spillover was lower in leg than arm (0.26 vs. 1.51 pmol.min-1.100 g-1, P < 0.05), and the difference remained when expressed as a function of total limb weight (66 vs. 137 pmol/min, P < 0.05). Fractional extraction of [3H]NE was similar in arm and leg. Neuronal uptake blockade by desipramine was more effective in leg than arm; fractional extraction in leg decreased by 32% (P < 0.05) but was unaltered in arm. Thus a lower NE spillover was observed from leg than arm, possibly reflecting a lower sympathetic outflow and a more neuronally dependent reuptake.

Joint fit of Warm Absorbers in COS and HETG spectra of NGC 3783

NASA Astrophysics Data System (ADS)

Fu, Xiao-Dan; Zhang, Shui-Nai; Sun, Wei; Niu, Shu; Ji, Li

2017-09-01

Warm Absorbers (WAs), as an important form of AGN outflows, show absorption in both the UV and X-ray bands. Using XSTAR generated photoionization models, for the first time we present a joint fit to the simultaneous observations of HST/COS and Chandra/HETG on NGC 3783. A total of five WAs explain well all absorption features from the AGN outflows, which are spread over a wide range of parameters: ionization parameter logξ from 0.6 to 3.8, column density log {N}{{H}} from 19.5 to 22.3 cm-2, velocity v from 380 to 1060 km s-1, and covering factor from 0.33 to 0.75. Not all the five WAs are consistent in pressure. Two of them are likely different parts of the same absorbing gas, and two of the other WAs may be smaller discrete clouds that are blown out from the inner region of the torus at different periods. The five WAs suggest a total mass outflowing rate within the range of 0.22-4.1 solar mass per year.

Constraining physical parameters of ultra-fast outflows in PDS 456 with Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Hagino, K.; Odaka, H.; Done, C.; Gandhi, P.; Takahashi, T.

2014-07-01

Deep absorption lines with extremely high velocity of ˜0.3c observed in PDS 456 spectra strongly indicate the existence of ultra-fast outflows (UFOs). However, the launching and acceleration mechanisms of UFOs are still uncertain. One possible way to solve this is to constrain physical parameters as a function of distance from the source. In order to study the spatial dependence of parameters, it is essential to adopt 3-dimensional Monte Carlo simulations that treat radiation transfer in arbitrary geometry. We have developed a new simulation code of X-ray radiation reprocessed in AGN outflow. Our code implements radiative transfer in 3-dimensional biconical disk wind geometry, based on Monte Carlo simulation framework called MONACO (Watanabe et al. 2006, Odaka et al. 2011). Our simulations reproduce FeXXV and FeXXVI absorption features seen in the spectra. Also, broad Fe emission lines, which reflects the geometry and viewing angle, is successfully reproduced. By comparing the simulated spectra with Suzaku data, we obtained constraints on physical parameters. We discuss launching and acceleration mechanisms of UFOs in PDS 456 based on our analysis.

Storm Enhanced Density (SED) plumes as possible suppliers of dayside cleft ion fountain

NASA Astrophysics Data System (ADS)

Horwitz, James

Foster et al. [2002] have observed elevated ionospheric density regions being convected from the subauroral plasmaspheric region toward noon, in association with convection of plasmaspheric tails in the dayside magnetosphere. These so-called Storm Enhanced Density (SED) regions could serve as ionospheric plasma source populations for cleft ion fountain outflows. Here we examine this scenario and employ our fluid-kinetic ionospheric plasma transport code to simulate the entry of a high-density "plasmasphere-like" flux tube entering the cleft region and subjected to an episode of wave-driven transverse ion heating. We find that such pronounced intervals of SED at F-region and topside altitudes passing through regions of CIF processes indeed appear capable of supporting episodes of strong CIF outflows. Foster, J. C., P. J. Erickson, A. J. Coster, J. Goldstein, and F. J. Rich, Ionospheric signatures of plasmaspheric tails, Geophys. Res. Lett., 29(13), 1623, doi:10.1029/2002GL015067, 2002.

Ancient drainage basin of the Tharsis region, Mars: Potential source for outflow channel systems and putative oceans or paleolakes

USGS Publications Warehouse

Dohm, J.M.; Ferris, J.C.; Baker, V.R.; Anderson, R.C.; Hare, T.M.; Strom, R.G.; Barlow, N.G.; Tanaka, K.L.; Klemaszewski, J.E.; Scott, D.H.

2001-01-01

Paleotopographic reconstructions based on a synthesis of published geologic information and high-resolution topography, including topographic profiles, reveal the potential existence of an enormous drainage basin/aquifer system in the eastern part of the Tharsis region during the Noachian Period. Large topographic highs formed the margin of the gigantic drainage basin. Subsequently, lavas, sediments, and volatiles partly infilled the basin, resulting in an enormous and productive regional aquifer. The stacked sequences of water-bearing strata were then deformed locally and, in places, exposed by magmatic-driven uplifts, tectonic deformation, and erosion. This basin model provides a potential source of water necessary to carve the large outflow channel systems of the Tharsis and surrounding regions and to contribute to the formation of putative northern-plains ocean(s) and/or paleolakes. Copyright 2001 by the American Geophysical Union.

A Robust Response of the Hadley Circulation to Global Warming

NASA Technical Reports Server (NTRS)

Lau, William K M.; Kim, Kyu-Myong

2014-01-01

Tropical rainfall is expected to increase in a warmer climate. Yet, recent studies have inferred that the Hadley Circulation (HC), which is primarily driven by latent heating from tropical rainfall, is weakened under global warming. Here, we show evidence of a robust intensification of the HC from analyses of 33 CMIP5 model projections under a scenario of 1 per year CO2 emission increase. The intensification is manifested in a deep-tropics squeeze, characterized by a pronounced increase in the zonal mean ascending motion in the mid and upper troposphere, a deepening and narrowing of the convective zone and enhanced rainfall in the deep tropics. These changes occur in conjunction with a rise in the region of maximum outflow of the HC, with accelerated meridional mass outflow in the uppermost branch of the HC away from the equator, coupled to a weakened inflow in the return branches of the HC in the lower troposphere.

C-arm technique using distance driven method for nephrolithiasis and kidney stones detection

NASA Astrophysics Data System (ADS)

Malalla, Nuhad; Sun, Pengfei; Chen, Ying; Lipkin, Michael E.; Preminger, Glenn M.; Qin, Jun

2016-04-01

Distance driven represents a state of art method that used for reconstruction for x-ray techniques. C-arm tomography is an x-ray imaging technique that provides three dimensional information of the object by moving the C-shaped gantry around the patient. With limited view angle, C-arm system was investigated to generate volumetric data of the object with low radiation dosage and examination time. This paper is a new simulation study with two reconstruction methods based on distance driven including: simultaneous algebraic reconstruction technique (SART) and Maximum Likelihood expectation maximization (MLEM). Distance driven is an efficient method that has low computation cost and free artifacts compared with other methods such as ray driven and pixel driven methods. Projection images of spherical objects were simulated with a virtual C-arm system with a total view angle of 40 degrees. Results show the ability of limited angle C-arm technique to generate three dimensional images with distance driven reconstruction.

The Resolved Outflow from 3C 48

NASA Astrophysics Data System (ADS)

Shih, Hsin-Yi; Stockton, Alan

2014-10-01

We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 103-104 cm-3, the mass is ~6 × 106 M ⊙, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow that shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-11574. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some of the observations included were obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Pulsations, Shocks, and Mass Loss

NASA Technical Reports Server (NTRS)

Bally, John

1998-01-01

This grant provided long-term support for my investigation of the outflows powered by young stars. Several major research results emerged during the course of this research, including: (1) The discovery of giant Herbig-Haro outflows from young stars that can extend for many parsecs from their sources. The first parsec-scale outflow to be recognized led to the realization that Herbig-Haro outflows, even those produced by low mass young stellar objects, can extend orders of magnitude farther from their sources than previously thought. Our preconceptions were to a large extent driven by the narrow fields-of-view then provided by CCD detectors. With the recent advent of large format CCDs and CCD mosaics, we have come to realize that most outflows attain parsec-scale dimensions. Even at the distance of the Orion star forming clouds, such flows can subtend a degree on the sky. Our work has led to the recognition of over two dozen giant. (2) The discovery that outflows are highly clustered. Even regions of relatively isolated star formation such as those in Taurus frequently produce multiple outflows. (3) The discovery of a new family of externally irradiated jets. During the last year of support from this grant, we made the startling discovery that there is a class of jets from young stars that are illuminated by the ionizing radiation field of nearby massive stars. The first four examples were discovered in the vicinity of the a Orionis sub-group of the Orion OB Association which is believed to be at least 2 million years old. Since the jets are photo-ionized, their densities can be reliably estimated. Most HH jets are shock excited, and are therefore notoriously difficult to characterize since their visibility and observed properties depend on the complex and highly non-linear processes associated with shocks. Furthermore, many irradiated jets are one sided rather than bipolar. Thus, irradiated jets may for the first time be used to accurately diagnose jet densities and mass loss rates, and to probe the physics of jet collimation, and may indicate that the jet production phase of certain young stars may last more than a million years. These three discoveries provide us with fundamental new insights into the star formation process, into the physical conditions inside and near star forming clouds, and into new ways to probe the physics and chemistry of such clouds.

Multi-wavelength investigations on feedback of massive star formation

NASA Astrophysics Data System (ADS)

Yuan, Jinghua

2014-05-01

In the course of massive star formation, outflows, ionizing radiation and intense stellar winds could heavily affect their adjacent environs and natal clouds. There are several outstanding open questions related to these processes: i) whether they can drive turbulence in molecular clouds; ii) whether they are able to trigger star formation; iii) whether they can destroy natal clouds to terminate star formation at low efficiencies. This thesis investigates feedback in different stages of massive star formation. Influence of such feedback to the ambient medium has been revealed. A new type of millimeter methanol maser is detected for the first time. An uncommon bipolar outflow prominent in the mid-infrared is discovered. And features of triggered star formation are found on the border of an infrared bubble and in the surroundings of a Herbig Be star. Extended green objects (EGOs) are massive outflow candidates showing prominent shocked features in the mid-infrared. We have carried out a high resolution study of the EGO G22.04+0.22 (hereafter, G22) based on archived SMA data. Continuum and molecular lines at 1.3 mm reveal that G22 is still at a hot molecular core stage. A very young multi-polar outflow system is detected, which is interacting with the adjacent dense gas. Anomalous emission features from CH3OH (8,-1,8 - 7,0,7) and CH3OH (4,2,2 - 3,1,2) are proven to be millimeter masers. It is the first time that maser emission of CH3OH (8,-1,8 - 7,0,7) at 218.440 GHz is detected in a massive star-forming region. Bipolar outflows have been revealed and investigated almost always in the microwave or radio domain. It's sort of rare that hourglass-shaped morphology be discovered in the mid-infrared. Based on GLIMPSE data, we have discovered a bipolar object resembling an hourglass at 8.0 um. It is found to be associated with IRAS 18114-1825. Analysis based on fitted SED, optical spectroscopy, and infrared color indices suggests IRAS 18114-1825 is an uncommon bipolar outflow driven by a massive protostar. Multi-wavelength observations based on classical tracers of outflows are highly necessary. Extensive investigations of IRAS 18114-1825 may contribute to our understanding of massive star formation in early stage.

C IV absorption-line variability in X-ray-bright broad absorption-line quasi-stellar objects

NASA Astrophysics Data System (ADS)

Joshi, Ravi; Chand, Hum; Srianand, Raghunathan; Majumdar, Jhilik

2014-07-01

We report the kinematic shift and strength variability of the C IV broad absorption-line (BAL) trough in two high-ionization X-ray-bright quasi-stellar objects (QSOs): SDSS J085551+375752 (at zem ˜ 1.936) and SDSS J091127+055054 (at zem ˜ 2.793). Both these QSOs have shown a combination of profile shifts and the appearance and disappearance of absorption components belonging to a single BAL trough. The observed average kinematic shift of the whole BAL profile resulted in an average deceleration of ˜-0.7 ± 0.1, -2.0 ± 0.1 cm s-2 over rest-frame time-spans of 3.11 and 2.34 yr for SDSS J085551+375752 and SDSS J091127+055054, respectively. To our knowledge, these are the largest kinematic shifts known, exceeding by factors of about 2.8 and 7.8 the highest deceleration reported in the literature; this makes both objects potential candidates to investigate outflows using multiwavelength monitoring of their line and continuum variability. We explore various possible mechanisms to understand the observed profile variations. Outflow models involving many small self-shielded clouds, probably moving in a curved path, provide the simplest explanation for the C IV BAL strength and velocity variations, along with the X-ray-bright nature of these sources.

A Unified Model for Tidal Disruption Events

NASA Astrophysics Data System (ADS)

Dai, Lixin; McKinney, Jonathan C.; Roth, Nathaniel; Ramirez-Ruiz, Enrico; Miller, M. Coleman

2018-06-01

In the past few years wide-field optical and UV transient surveys and X-ray telescopes have allowed us to identify a few dozen candidate tidal disruption events (TDEs). While in theory the physical processes in TDEs are ubiquitous, a few distinct classes of TDEs have been observed. Some TDEs radiate mainly in NUV/optical, while others produce prominent X-rays. Moreover, relativistic jets have been observed in only a handful of TDEs. This diversity might be related to the details of the super-Eddington accretion and emission physics relevant to TDE disks. In this Letter, we utilize novel three-dimensional general relativistic radiation magnetohydrodynamics simulations to study the super-Eddington compact disk phase expected in TDEs. Consistent with previous studies, geometrically thick disks, wide-angle optically thick fast outflows, and relativistic jets are produced. The outflow density and velocity depend sensitively on the inclination angle, and hence so does the reprocessing of emission produced from the inner disk. We then use Monte Carlo radiative transfer to calculate the reprocessed spectra and find that that the observed ratio of optical to X-ray fluxes increases with increasing inclination angle. This naturally leads to a unified model for different classes of TDEs in which the spectral properties of the TDE depend mainly on the viewing angle of the observer with respect to the orientation of the disk.

Discovery of an Outflow from Radio Observations of the Tidal Disruption Event ASASSN-14li

NASA Astrophysics Data System (ADS)

Alexander, K. D.; Berger, E.; Guillochon, J.; Zauderer, B. A.; Williams, P. K. G.

2016-03-01

We report the discovery of transient radio emission from the nearby optically discovered tidal disruption event (TDE) ASASSN-14li (distance of 90 Mpc), making it the first typical TDE detected in the radio, and unambiguously pointing to the formation of a non-relativistic outflow with a kinetic energy of ≈(4-10) × 1047 erg, a velocity of ≈12,000-36,000 km s-1, and a mass of ≈3 × 10-5-7 × 10-4 M⊙. We show that the outflow was ejected on 2014 August 11-25, in agreement with an independent estimate of the timing of super-Eddington accretion based on the optical, ultraviolet, and X-ray observations, and that the ejected mass corresponds to about 1%-10% of the mass accreted in the super-Eddington phase. The temporal evolution of the radio emission also uncovers the circumnuclear density profile, ρ (R)\\propto {R}-2.5 on a scale of about 0.01 pc, a scale that cannot be probed via direct measurements even in the nearest supermassive black holes. Our discovery of radio emission from the nearest well-studied TDE to date, with a radio luminosity lower than all previous limits, indicates that non-relativistic outflows are ubiquitous in TDEs, and that future, more sensitive, radio surveys will uncover similar events.

A TWO-PHASE LOW-VELOCITY OUTFLOW IN THE SEYFERT 1 GALAXY Ark 564

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, A.; Mathur, S.; Krongold, Y.

2013-05-10

The Seyfert 1 galaxy Ark 564 was observed with Chandra high-energy transmission gratings for 250 ks. We present the high-resolution X-ray spectrum that shows several associated absorption lines. The photoionization model requires two warm absorbers (WAs) with two different ionization states (log U = 0.39 {+-} 0.03 and log U = -0.99 {+-} 0.13), both with moderate outflow velocities ({approx}100 km s{sup -1}) and relatively low line of sight column densities (log N{sub H} = 20.94 and 20.11 cm{sup -2}). The high-ionization phase produces absorption lines of O VII, O VIII, Ne IX, Ne X, Mg XI, Fe XVII, andmore » Fe XVIII, while the low-ionization phase produces lines at lower energies (O VIand O VII). The pressure-temperature equilibrium curve for the Ark 564 absorber does not have the typical ''S'' shape, even if the metallicity is super-solar; as a result, the two WA phases do not appear to be in pressure balance. This suggests that the continuum incident on the absorbing gas is perhaps different from the observed continuum. We also estimated the mass outflow rate and the associated kinetic energy and find it to be at most 0.009% of the bolometric luminosity of Ark 564. Thus, it is highly unlikely that these outflows provide significant feedback required by the galaxy formation models.« less

Regulation of black-hole accretion by a disk wind during a violent outburst of V404 Cygni

NASA Astrophysics Data System (ADS)

Muñoz-Darias, T.; Casares, J.; Mata Sánchez, D.; Fender, R. P.; Armas Padilla, M.; Linares, M.; Ponti, G.; Charles, P. A.; Mooley, K. P.; Rodriguez, J.

2016-06-01

Accretion of matter onto black holes is universally associated with strong radiative feedback and powerful outflows. In particular, black-hole transients have outflows whose properties are strongly coupled to those of the accretion flow. This includes X-ray winds of ionized material, expelled from the accretion disk encircling the black hole, and collimated radio jets. Very recently, a distinct optical variability pattern has been reported in the transient stellar-mass black hole V404 Cygni, and interpreted as disrupted mass flow into the inner regions of its large accretion disk. Here we report observations of a sustained outer accretion disk wind in V404 Cyg, which is unlike any seen hitherto. We find that the outflowing wind is neutral, has a large covering factor, expands at one per cent of the speed of light and triggers a nebular phase once accretion drops sharply and the ejecta become optically thin. The large expelled mass (>10-8 solar masses) indicates that the outburst was prematurely ended when a sizeable fraction of the outer disk was depleted by the wind, detaching the inner regions from the rest of the disk. The luminous, but brief, accretion phases shown by transients with large accretion disks imply that this outflow is probably a fundamental ingredient in regulating mass accretion onto black holes.

Regulation of black-hole accretion by a disk wind during a violent outburst of V404 Cygni.

PubMed

Muñoz-Darias, T; Casares, J; Mata Sánchez, D; Fender, R P; Armas Padilla, M; Linares, M; Ponti, G; Charles, P A; Mooley, K P; Rodriguez, J

2016-06-02

Accretion of matter onto black holes is universally associated with strong radiative feedback and powerful outflows. In particular, black-hole transients have outflows whose properties are strongly coupled to those of the accretion flow. This includes X-ray winds of ionized material, expelled from the accretion disk encircling the black hole, and collimated radio jets. Very recently, a distinct optical variability pattern has been reported in the transient stellar-mass black hole V404 Cygni, and interpreted as disrupted mass flow into the inner regions of its large accretion disk. Here we report observations of a sustained outer accretion disk wind in V404 Cyg, which is unlike any seen hitherto. We find that the outflowing wind is neutral, has a large covering factor, expands at one per cent of the speed of light and triggers a nebular phase once accretion drops sharply and the ejecta become optically thin. The large expelled mass (>10(-8) solar masses) indicates that the outburst was prematurely ended when a sizeable fraction of the outer disk was depleted by the wind, detaching the inner regions from the rest of the disk. The luminous, but brief, accretion phases shown by transients with large accretion disks imply that this outflow is probably a fundamental ingredient in regulating mass accretion onto black holes.

Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C

DOE PAGES

Abdo, A. A.; Ackermann, M.; Arimoto, M.; ...

2009-02-19

Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. Finally, the known distance of the burstmore » enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.« less

Radio Observations as a Tool to Investigate Shocks and Asymmetries in Accreting White Dwarf Binaries

NASA Astrophysics Data System (ADS)

Weston, Jennifer H. S.

2016-07-01

This dissertation uses radio observations with the Karl G. Jansky Very Large Array (VLA) to investigate the mechanisms that power and shape accreting white dwarfs (WD) and their ejecta. We test the predictions of both simple spherical and steady-state radio emission models by examining nova V1723 Aql, nova V5589 Sgr, symbiotic CH Cyg, and two small surveys of symbiotic binaries. First, we highlight classical nova V1723 Aql with three years of radio observations alongside optical and X-ray observations. We use these observations to show that multiple outflows from the system collided to create early non-thermal shocks with a brightness temperature of ≥106 K. While the late-time radio light curve is roughly consistent an expanding thermal shell of mass 2x10-4 M⊙ solar masses, resolved images of V1723 Aql show elongated material that apparently rotates its major axis over the course of 15 months, much like what is seen in gamma-ray producing nova V959 Mon, suggesting similar structures in the two systems. Next, we examine nova V5589 Sgr, where we find that the early radio emission is dominated by a shock-powered non-thermal flare that produces strong (kTx > 33 keV) X-rays. We additionally find roughly 10-5 M⊙ solar masses of thermal bremsstrahlung emitting material, all at a distance of ~4 kpc. The similarities in the evolution of both V1723 Aql and V5589 Sgr to that of nova V959 Mon suggest that these systems may all have dense equatorial tori shaping faster flows at their poles. Turning our focus to symbiotic binaries, we first use our radio observations of CH Cyg to link the ejection of a collimated jet to a change of state in the accretion disk. We additionally estimate the amount of mass ejected during this period (10-7 M⊙ masses), and improve measurements of the period of jet precession (P=12013 ± 74 days). We then use our survey of eleven accretion-driven symbiotic systems to determine that the radio brightness of a symbiotic system could potentially be used as an indicator of w hether a symbiotic is powered predominantly by shell burning on the surface of the WD or by accretion. We additionally make the first ever radio detections of seven of the targets in our survey. Our survey of seventeen radio bright symbiotics, comparing observations before and after the upgrades to the VLA, shows the technological feasibility to resolve the nebulae of nearby symbiotic binaries, opening the door for new lines of research. We spatially resolve extended structure in several symbiotic systems in radio for the first time. Additionally, our observations reveal extreme radio variability in symbiotic BF Cyg before and after the production of a jet from the system. Our results from our surveys of symbiotics provide some support for the model of radio emission where the red giant wind is photoionized by the WD, and suggests that there may be a greater population of radio faint, accretion driven symbiotic systems. This work emphasizes the powerful nature of radio observations as a tool for understanding eruptive WD binaries and their outflows.

Physics from Time Variability of the VHE Blazar PKS 2155-304

NASA Astrophysics Data System (ADS)

Barres de Almeida, Ulisses

2010-10-01

Blazars are the principal extragalactic sources of very high energy gamma-ray emission in the Universe. These objects constitute a sub-class of Active Galactic Nuclei whose emission is dominated by Doppler boosted non-thermal radiation from plasma outflow- ing at relativistic speeds from the central engine. This plasma outflow happens in the form of large-scale collimated structures called jets, which can extend for Mpc in length and transport energy from the central engine of the galaxy to the larger scale intergalac- tic medium. Over thirty such sources have been discovered to date by ground-based gamma-ray telescopes such as H.E.S.S., and PKS 2155-304 is the prototypical southern- hemisphere representative of this population of objects. In this thesis we have studied in detail some aspects of the temporal variability of the jet emission from PKS 2155-304, combining coordinated observations across the electro- magnetic spectrum, from optical polarimetric measurements to X-ray and ground-based gamma-ray data. The temporal properties of the dataset allowed us to derive important physical information about the structure and emission mechanisms of the source and put constraints to the location of the sites of VHE emission and particle acceleration within the jet. We have also derived a sensitive statistical measure, called Kolmogorov distance, which we applied to the large outburst observed from PKS 2155-304 in July 2006, to de- rive the most stringent constraints to date on limits for the violation of Lorentz invariance induced by quantum-gravity effects from AGN measurements.

High-resolution X-Ray Spectroscopy of the Seyfert 1 Galaxy Mrk 1040. Revealing the Failed Nuclear Wind with Chandra

NASA Astrophysics Data System (ADS)

Reeves, J. N.; Braito, V.; Behar, E.; Fischer, T. C.; Kraemer, S. B.; Lobban, A.; Nardini, E.; Porquet, D.; Turner, T. J.

2017-03-01

High-resolution X-ray spectroscopy of the warm absorber in the nearby X-ray bright Seyfert 1 galaxy Mrk 1040 is presented. The observations were carried out in the 2013-2014 timeframe using the Chandra High Energy Transmission Grating with a total exposure of 200 ks. A multitude of absorption lines from Ne, Mg, and Si are detected from a wide variety of ionization states. In particular, the detection of inner K-shell absorption lines from Ne, Mg, and Si, from charge states ranging from F-like to Li-like ions, suggests the presence of a substantial amount of low-ionization absorbing gas, illuminated by a steep soft X-ray continuum. The observations reveal at least three warm absorbing components ranging in ionization parameter from {log}(ξ /{erg} {cm} {{{s}}}-1)=0{--}2 and with column densities of {N}{{H}}=1.5{--}4.0× {10}21 cm-2. The velocity profiles imply that the outflow velocities of the absorbing gas are low and within ±100 km s-1 of the systemic velocity of Mrk 1040, which suggests that any outflowing gas may have stalled in this AGN on large enough scales. The warm absorber is likely located far from the black hole, within 300 pc of the nucleus, and is spatially coincident with emission from an extended narrow-line region as seen in the Hubble Space Telescope images. The iron K-band spectrum reveals only narrow emission lines, with Fe Kα at 6.4 keV consistent with originating from reflection off Compton-thick pc-scale reprocessing gas.

Testing Models of the Black-Hole X-ray Source in the NGC4472 Globular Cluster RZ2109 with COS UV Spectroscopy

NASA Astrophysics Data System (ADS)

Zepf, Stephen

2014-10-01

We propose to obtain COS ultraviolet spectroscopy of the black-hole X-ray source in the NGC 4472 globular cluster RZ2109. This object was the first unambiguous black hole X-ray source in a globular cluster. It is clearly identified as a black hole through its high X-ray luminosity and short-term variability. The optical spectrum of RZ2109 shows strong and extraordinarily broad [OIII]4959, 5007 emission, and our recent STIS spectrum demonstrates that this comes from an outflow extended across most of the globular cluster. The optical spectrum also remarkably shows no emission lines other than [OIII] to sensitive limits, indicating that the material is very hydrogen-poor. One way to account for these observations is if RZ2109 hosts a CO white dwarf accreting onto a stellar mass black hole. In this case, CIV 1549 emission is expected and no nitrogren lines will be seen. However, if nitrogen lines such as NIV 1486 and NV 1239, 1243 are observed, then a different source for the accreting material such as a nova shell or a horizontal branch star would be required, and a re-evaluation of all aspects of our understanding of the dynamics and accretion in RZ2109 would be needed. Determining which of these is the case is a major step for understanding how accreting black holes form and grow in dense stellar systems, whether they make intermediate mass black holes, and what accretion and feedback processes lead to strong outflows rich in elements such as oxygen.

Black Hole Hyperaccretion Inflow–Outflow Model. I. Long and Ultra-long Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Liu, Tong; Song, Cui-Ying; Zhang, Bing; Gu, Wei-Min; Heger, Alexander

2018-01-01

Long-duration gamma-ray bursts (LGRBs) and ultra-LGRBs (ULGRBs) originate from collapsars, in the center of which a newborn rotating stellar-mass black hole (BH) surrounded by a massive accretion disk may form. In the scenario of the BH hyperaccretion inflow–outflow model and Blandford–Znajek (BZ) mechanism to trigger gamma-ray bursts (GRBs), the real accretion rate to power a BZ jet is far lower than the mass supply rate from the progenitor star. The characteristics of the progenitor stars can be constrained by GRB luminosity observations, and the results exceed usual expectations. LGRBs lasting from several seconds to tens of seconds in the rest frame may originate from solar-metallicity (Z∼ 1 {Z}ȯ , where Z and {Z}ȯ are the metallicities of progenitor stars and the Sun), massive (M≳ 34 {M}ȯ , where M and {M}ȯ are the masses of progenitor stars and the Sun) stars or some zero-metallicity (Z∼ 0) stars. A fraction of low-metallicity (Z≲ {10}-2 {Z}ȯ ) stars, including Population III stars, can produce ULGRBs such as GRB 111209A. The fraction of LGRBs lasting less than tens of seconds in the rest frame is more than 40%, which cannot conform to the fraction of the demanded type of progenitor star. It possibly implies that the activity timescale of the central engine may be much longer than the observed timescale of prompt emission phase, as indicated by X-ray late-time activities. Alternatively, LGRBs and ULGRBs may be powered by a millisecond magnetar central engine.

Seasonal changes and driving forces of inflow and outflow through the Bohai Strait

NASA Astrophysics Data System (ADS)

Zhang, Zhixin; Qiao, Fangli; Guo, Jingsong; Guo, Binghuo

2018-02-01

This work focuses on analyzing seasonal variation of inflow and outflow through the Bohai Strait that greatly affect the marine environment in the Bohai Sea, using observational data including sea bed mounted acoustic Doppler current profiler currents, CTD salinity data on deck, sea level anomalies of coastal tide gauge stations, and climatological monthly sea level anomalies from Archiving, Validation and Interpretation of Satellite Oceanographic data. Our results show three patterns of outflow and inflow through the Bohai Strait. The first is such that outflow and inflow occur respectively in the southern and northern parts of the strait, as in the traditional understanding. Our results suggest that this pattern occurs only in autumn and winter. Beginning in late September, Ekman currents driven by the northwesterly monsoon carry Bohai Sea water that piles up in the southern part of that sea and then exits eastward to the Yellow Sea. In this process, the pressure and current fields are continuously adjusted, until a quasi balance state between wind stress, Coriolis force and pressure gradient force is reached in winter. Inflow with a compensating property through the northern channel is close to the outflow through the southern channel in winter. The second pattern is a single inflow in spring, and the current and pressure fields are in adjustment. In early spring, the northwesterly monsoon ceases, Yellow Sea water enters the Bohai Sea under the pressure gradient force. With southeasterly monsoon establishment and strengthening, northern Yellow Sea water continually flows into the Bohai Sea and causes sea level rise northward. In the third pattern, outflow is much greater than inflow in summer. The currents run eastward in the central Bohai Sea and then enter the northern Yellow Sea through the northern channel and upper layer of the southern channel, while a westward current with a compensating property enters via the lower layer of the southern channel. Larger net transport is through the Bohai Strait to the northern Yellow Sea, which is related to strong precipitation and runoff into the Bohai Sea.

Outflow structure and velocity field of Orion source. I. ALMA imaging of SiO isotopologue maser and thermal emission

NASA Astrophysics Data System (ADS)

Niederhofer, F.; Humphreys, E. M. L.; Goddi, C.

2012-12-01

Using Science Verification data from the Atacama Large Millimeter/Submillimeter Array (ALMA), we have identified and imaged five rotational transitions (J = 5-4 and J = 6-5) of the three silicon monoxide isotopologues 28SiO v = 0, 1, 2 and 29SiO v = 0 and 28Si18O v = 0 in the frequency range from 214 to 246 GHz towards the Orion BN/KL region. The emission of the ground-state 28SiO, 29SiO and 28Si18O shows an extended bipolar shape in the northeast-southwest direction at the position of Radio Source I, indicating that these isotopologues trace an outflow ( 18 km s-1, PA 50°, 5000 AU in diameter) that is driven by this embedded high-mass young stellar object (YSO). Whereas on small scales (10-1000 AU) the outflow from Source I has a well-ordered spatial and velocity structure, as probed by Very Long Baseline Interferometry (VLBI) imaging of SiO masers, the large scales (500-5000 AU) probed by thermal SiO with ALMA reveal a complex structure and velocity field, most likely related to the effects of the environment of the BN/KL region on the outflow emanating from Source I. The emission of the vibrationally-excited species peaks at the position of Source I. This emission is compact and not resolved at an angular resolution of 1farcs5 ( 600 AU at a distance of 420 pc). 2D Gaussian fitting to individual velocity channels locates emission peaks within radii of 100 AU, i.e. they trace the innermost part of the outflow. A narrow spectral profile and spatial distribution of the v = 1 J = 5-4 line similar to the masing v = 1 J = 1-0 transition, provide evidence for the most highly rotationally excited (frequency > 200 GHz) SiO maser emission associated with Source I known to date. The maser emission will enable studies of the Source I disk-outflow interface with future ALMA longest baselines.

Microbial communities of the Lemon Creek Glacier show subtle structural variation yet stable phylogenetic composition over space and time

PubMed Central

Sheik, Cody S.; Stevenson, Emily I.; Den Uyl, Paul A.; Arendt, Carli A.; Aciego, Sarah M.; Dick, Gregory J.

2015-01-01

Glaciers are geologically important yet transient ecosystems that support diverse, biogeochemically significant microbial communities. During the melt season glaciers undergo dramatic physical, geochemical, and biological changes that exert great influence on downstream biogeochemical cycles. Thus, we sought to understand the temporal melt-season dynamics of microbial communities and associated geochemistry at the terminus of Lemon Creek Glacier (LCG) in coastal southern Alaska. Due to late season snowfall, sampling of LCG occurred in three interconnected areas: proglacial Lake Thomas, the lower glacial outflow stream, and the glacier’s terminus. LCG associated microbial communities were phylogenetically diverse and varied by sampling location. However, Betaproteobacteria, Alphaproteobacteria, and Bacteroidetes dominated communities at all sampling locations. Strict anaerobic groups such as methanogens, SR1, and OP11 were also recovered from glacier outflows, indicating anoxic conditions in at least some portions of the LCG subglacial environment. Microbial community structure was significantly correlated with sampling location and sodium concentrations. Microbial communities sampled from terminus outflow waters exhibited day-to-day fluctuation in taxonomy and phylogenetic similarity. However, these communities were not significantly different from randomly constructed communities from all three sites. These results indicate that glacial outflows share a large proportion of phylogenetic overlap with downstream environments and that the observed significant shifts in community structure are driven by changes in relative abundance of different taxa, and not complete restructuring of communities. We conclude that LCG glacial discharge hosts a diverse and relatively stable microbiome that shifts at fine taxonomic scales in response to geochemistry and likely water residence time. PMID:26042114

SDSS-IV MaNGA: modelling the metallicity gradients of gas and stars - radially dependent metal outflow versus IMF

NASA Astrophysics Data System (ADS)

Lian, Jianhui; Thomas, Daniel; Maraston, Claudia; Goddard, Daniel; Parikh, Taniya; Fernández-Trincado, J. G.; Roman-Lopes, Alexandre; Rong, Yu; Tang, Baitian; Yan, Renbin

2018-05-01

In our previous work, we found that only two scenarios are capable of reproducing the observed integrated mass-metallicity relations for the gas and stellar components of local star-forming galaxies simultaneously. One scenario invokes a time-dependent metal outflow loading factor with stronger outflows at early times. The other scenario uses a time-dependent initial mass function (IMF) slope with a steeper IMF at early times. In this work, we extend our study to investigate the radial profile of gas and stellar metallicity in local star-forming galaxies using spatially resolved spectroscopic data from the SDSS-IV MaNGA survey. We find that most galaxies show negative gradients in both gas and stellar metallicity with steeper gradients in stellar metallicity. The stellar metallicity gradients tend to be mass dependent with steeper gradients in more massive galaxies while no clear mass dependence is found for the gas metallicity gradient. Then we compare the observations with the predictions from a chemical evolution model of the radial profiles of gas and stellar metallicities. We confirm that the two scenarios proposed in our previous work are also required to explain the metallicity gradients. Based on these two scenarios, we successfully reproduce the radial profiles of gas metallicity, stellar metallicity, stellar mass surface density, and star formation rate surface density simultaneously. The origin of the negative gradient in stellar metallicity turns out to be driven by either radially dependent metal outflow or IMF slope. In contrast, the radial dependence of the gas metallicity is less constrained because of the degeneracy in model parameters.