Science.gov

Sample records for mini-bal quasar outflows

  1. Physical Properties of Quasar Outflows: From BALs to mini-BALs

    NASA Astrophysics Data System (ADS)

    Hamann, Frederick

    2009-07-01

    Accretion disk outflows are important components of quasar environments. They might play a major role in facilitating accretion, regulating star formation in the host galaxies and distributing metals to the surrounding gas. They reveal themselves most conspicuously via broad absorption lines {BALs}, but they appear even more frequently in other guises such as the weaker and narrower ``mini-BALs.'' How are these diverse outflow features related? Are mini-BALs really just ``mini'' versions of the BALs, or do they represent a fundamentally different type of outflow, with different degrees of ionization, column densities, mass loss rates, physical origins, etc.? We propose HST-COS spectroscopy to make the first quantitative assessment of the outflow physical conditions across the full range of weak/narrow mini-BALs to strong/broad BALs. Our strategy is to measure key diagnostic lines {SVI, OVI, CIII, SIV, PV, etc.} at 930A - 1130A {rest-frame} in a sample of 7 outflow quasars with known mini-BALs through weak BALs. We will then 1} combine the COS data with ground-based spectra of the same quasars to include more lines {CIV, SiIV} at longer wavelengths, and 2} include in our analysis a nearly identical UV/optical dataset obtained previously for a sample of quasars with strong BALs. Our study of this combined dataset will be an essential next step toward a more global understanding of quasar outflows.

  2. Optical variability properties of mini-BAL and NAL quasars

    NASA Astrophysics Data System (ADS)

    Horiuchi, Takashi; Misawa, Toru; Morokuma, Tomoki; Koyamada, Suzuka; Takahashi, Kazuma; Wada, Hisashi

    2016-05-01

    While narrow absorption lines (NALs) are relatively stable, broad absorption lines (BALs) and mini-BAL systems usually show violent time variability within a few years via a mechanism that is not yet understood. In this study, we examine the variable ionization state (VIS) scenario as a plausible mechanism, as previously suspected. Over three years, we performed photometric monitoring observations of four mini-BAL and five NAL quasars at zem ˜ 2.0-3.1 using the 105 cm Kiso Schmidt Telescope in u, g, and i bands. We also performed spectroscopic monitoring observation of one of our mini-BAL quasars (HS 1603+3820) using the 188 cm Okayama Telescope over the same period as the photometric observations. Our main results are as follows: (1) Structure function (SF) analysis revealed that the quasar UV flux variability over three years was not large enough to support the VIS scenario, unless the ionization condition of outflow gas is very low. (2) There was no crucial difference between the SFs of mini-BAL and NAL quasars. (3) The variability of the mini-BAL and quasar light curves was weakly synchronized with a small time delay for HS 1603+3820. These results suggest that the VIS scenario may need additional mechanisms such as variable shielding by X-ray warm absorbers.

  3. Optical variability properties of mini-BAL and NAL quasars

    NASA Astrophysics Data System (ADS)

    Horiuchi, Takashi; Misawa, Toru; Morokuma, Tomoki; Koyamada, Suzuka; Takahashi, Kazuma; Wada, Hisashi

    2016-08-01

    While narrow absorption lines (NALs) are relatively stable, broad absorption lines (BALs) and mini-BAL systems usually show violent time variability within a few years via a mechanism that is not yet understood. In this study, we examine the variable ionization state (VIS) scenario as a plausible mechanism, as previously suspected. Over three years, we performed photometric monitoring observations of four mini-BAL and five NAL quasars at zem ˜ 2.0-3.1 using the 105 cm Kiso Schmidt Telescope in u, g, and i bands. We also performed spectroscopic monitoring observation of one of our mini-BAL quasars (HS 1603+3820) using the 188 cm Okayama Telescope over the same period as the photometric observations. Our main results are as follows: (1) Structure function (SF) analysis revealed that the quasar UV flux variability over three years was not large enough to support the VIS scenario, unless the ionization condition of outflow gas is very low. (2) There was no crucial difference between the SFs of mini-BAL and NAL quasars. (3) The variability of the mini-BAL and quasar light curves was weakly synchronized with a small time delay for HS 1603+3820. These results suggest that the VIS scenario may need additional mechanisms such as variable shielding by X-ray warm absorbers.

  4. THE X-RAY PROPERTIES OF THE OPTICALLY BRIGHTEST MINI-BAL QUASARS FROM THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Wu Jianfeng; Brandt, W. N.; Comins, M. L.; Garmire, Gordon P.; Schneider, Donald P.; Gibson, Robert R.; Shemmer, Ohad

    2010-11-20

    We have compiled a sample of 14 of the optically brightest radio-quiet quasars (m{sub i} {<=} 17.5 and z {>=} 1.9) in the Sloan Digital Sky Survey Data Release 5 quasar catalog that have C IV mini-broad absorption lines (mini-BALs) present in their spectra. X-ray data for 12 of the objects were obtained via a Chandra snapshot survey using ACIS-S, while data for the other two quasars were obtained from archival XMM-Newton observations. Joint X-ray spectral analysis shows that the mini-BAL quasars have a similar average power-law photon index ({Gamma} {approx} 1.9) and level of intrinsic absorption (N{sub H} {approx}< 8 x 10{sup 21} cm{sup -2}) as non-BMB (neither BAL nor mini-BAL) quasars. Mini-BAL quasars are more similar to non-BMB quasars than to BAL quasars in their distribution of relative X-ray brightness (assessed with {Delta}{alpha}{sub ox}). Relative colors indicate mild dust reddening in the optical spectra of mini-BAL quasars. Significant correlations between {Delta}{alpha}{sub ox} and UV absorption properties are confirmed for a sample of 56 sources combining mini-BAL and BAL quasars with high signal-to-noise ratio rest-frame UV spectra, which generally supports models in which X-ray absorption is important in enabling driving of the UV absorption-line wind. We also propose alternative parameterizations of the UV absorption properties of mini-BAL and BAL quasars, which may better describe the broad absorption troughs in some respects.

  5. On the covering fraction variability in an EUV mini-BAL outflow from PG 1206+459

    NASA Astrophysics Data System (ADS)

    Muzahid, S.; Srianand, R.; Charlton, J.; Eracleous, M.

    2016-04-01

    We report on the first detection of extreme-ultraviolet (EUV) absorption variability in the Ne VIII λλ770, 780 mini-broad absorption line (mini-BAL) in the spectrum of the quasar (QSO) PG 1206+459. The observed equivalent width (EW) of the Ne VIII doublet shows a ˜4σ variation over a time-scale of 2.8 months in the QSO's rest frame. Both members of the Ne VIII doublet exhibit non-black saturation, indicating partial coverage of the continuum source. An increase in the Ne VIII covering fraction from fc = 0.59 ± 0.05 to 0.72 ± 0.03 is observed over the same period. The Ne VIII profiles are too highly saturated to be susceptible to changes in the ionization state of the absorbing gas. In fact, we do not observe any significant variation in the EW and/or column density after correcting the spectra for partial coverage. We, thus, propose transverse motions of the absorbing gas as the cause of the observed variability. Using a simple model of a transiting cloud we estimate a transverse speed of ˜1800 km s-1. For Keplerian motion, this corresponds to a distance between the absorber and the central engine of ˜1.3 pc, which places the absorber just outside the broad-line region. We further estimate a density of ˜5 × 106 cm-3 and a kinetic luminosity of ˜1043-1044 erg s-1. Such large kinetic powers suggest that outflows detected via EUV lines are potentially major contributors to active galactic nuclei feedback.

  6. Extreme-velocity quasar outflows and the role of X-ray shielding

    NASA Astrophysics Data System (ADS)

    Hamann, F.; Chartas, G.; McGraw, S.; Rodriguez Hidalgo, P.; Shields, J.; Capellupo, D.; Charlton, J.; Eracleous, M.

    2013-10-01

    Quasar accretion disc winds observed via broad absorption lines (BALs) in the UV produce strong continuous absorption in X-rays. The X-ray absorber is believed to serve critically as a radiative shield to keep the outflow ionizations low enough for radiative driving. However, previous studies have shown that `mini-BAL' and narrow absorption line (NAL) outflows have dramatically less X-ray absorption than BALs. Here, we examine X-ray and rest-frame UV spectra of eight mini-BAL quasars with outflow speeds in the range 0.1-0.2c to test the hypothesis that these extreme speeds require a strong shield. We find that the X-ray absorption is weak or moderate, with neutral-equivalent column densities NH < few × 1022 cm-2, consistent with mini-BALs at lower speeds. We use photoionization models to show that the amount of shielding consistent with our data is too weak to control the outflow ionizations and, therefore, it is not important for the acceleration. Shielding in complex geometries also seems unlikely because the alleged shield would need to extinguish the ionizing far-UV flux while avoiding detection in X-rays and the near-UV. We argue that the outflow ionizations are kept moderate, instead, by high gas densities in small clouds. If the mini-BALs form at radial distances of the order of R ˜ 2 pc from the central quasar (broadly consistent with theoretical models and with the mini-BAL variabilities observed here and in previous work), and the total column densities in the mini-BAL gas are NH ≲ 1021 cm-2, then the total radial extent of outflow clouds is only ΔRclouds ≲ 3 × 1013 cm in cases of no/weak shielding or ΔRclouds ≲ 3 × 1014 cm behind the maximum shield allowed by our data. This implies radial filling factors ΔRclouds/R ≲ 5 × 10- 6 or ≲ 5 × 10- 5 for the unshielded or maximally shielded cases, respectively. Compared to the transverse sizes ≳ 8 × 1015 cm (based on measured line depths), the outflows have shapes like thin `pancakes' viewed

  7. 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.

  8. Metallicity and Quasar Outflows

    NASA Astrophysics Data System (ADS)

    Wang, Huiyuan; Zhou, Hongyan; Yuan, Weimin; Wang, Tinggui

    2012-06-01

    Correlations of the outflow strength of quasars, as measured by the blueshift and asymmetry index (BAI) of the C IV line, with intensities and ratios of broad emission lines, based on composite quasar spectra built from the Sloan Digital Sky Survey, are investigated. We find that most of the line ratios of other ions to C IV increase prominently with BAI. These behaviors can be well understood in the context of increasing metallicity with BAI. The strength of the dominant coolant, C IV line, decreases, and weak collisionally excited lines increase with gas metallicity as a result of the competition between different line coolants. Using Si IV+O IV]/C IV as an indicator of gas metallicity, we present, for the first time, a strong correlation between the metallicity and the outflow strength of quasars over a wide range of 1.7-6.9 times solar abundance. Our result implies that metallicity plays an important role in the formation of quasar outflows, likely by affecting outflow acceleration. This effect may have a profound impact on galaxy evolution via momentum feedback and chemical enrichment.

  9. METALLICITY AND QUASAR OUTFLOWS

    SciTech Connect

    Wang, Huiyuan; Zhou, Hongyan; Wang, Tinggui; Yuan, Weimin

    2012-06-01

    Correlations of the outflow strength of quasars, as measured by the blueshift and asymmetry index (BAI) of the C IV line, with intensities and ratios of broad emission lines, based on composite quasar spectra built from the Sloan Digital Sky Survey, are investigated. We find that most of the line ratios of other ions to C IV increase prominently with BAI. These behaviors can be well understood in the context of increasing metallicity with BAI. The strength of the dominant coolant, C IV line, decreases, and weak collisionally excited lines increase with gas metallicity as a result of the competition between different line coolants. Using Si IV+O IV]/C IV as an indicator of gas metallicity, we present, for the first time, a strong correlation between the metallicity and the outflow strength of quasars over a wide range of 1.7-6.9 times solar abundance. Our result implies that metallicity plays an important role in the formation of quasar outflows, likely by affecting outflow acceleration. This effect may have a profound impact on galaxy evolution via momentum feedback and chemical enrichment.

  10. Studies of Quasar Outflows

    NASA Technical Reports Server (NTRS)

    Arav, Nahum

    2002-01-01

    The main aim of this research program is to determine the ionization equilibrium and abundances in quasar outflows. Especially in the broad absorption line QSO PG 0946+301. We find that the outflow's metalicity is consistent with being solar, while the abundance ratio of phosphorus to other metals is at least ten times solar. These findings are based on diagnostics that are not sensitive to saturation and partial covering effects in the BALs (Broad Adsorption Lines), which considerably weakened previous claims for enhanced metalicity. Ample evidence for these effects is seen in the spectrum.

  11. The Geometry of Quasar Outflows

    NASA Astrophysics Data System (ADS)

    Ganguly, Rajib

    2012-10-01

    Quasar outflows are important for understanding the accretion and growth processes of the central black hole, but also potentially play a role in feedback to the galaxy, halting star formation and infall of gas. A big uncertainty lies in the geometry and density of these outflows, especially as a function of ionization and velocity. We aim to tackle this using the archival COS M grating spectra of 266 quasars. We separate the geometry of outflows into two parts: the solid angle subtended around the black hole, and the distance of the outflow from the central engine. Large numbers of quasars with high resolution spectra are required for each aspect of this statistical investigation. First, we will determine which/how many absorption-line systems are intrinsic through both partial covering methods and statistical assessments. Second, we will consider the incidence of intrinsic absorbers as a function of quasar property {e.g., radio-loudness, SED shape, black hole mass, bolometric luminosity}. This will reveal what determines the solid angle. This can only be done at moderate redshifts where quasars with a larger range of properties are observable, and hence requires HST/COS. Third, we will use the wide range of diagnostic lines to constrain the physical conditions of the absorbers. We will target the CIII*1175 complex and apply photoionization models to constrain the densities and ionization parameters. This will provide the largest set yet of intrinsic absorbers with systematic distance constraints. In tandem with the solid angles, this work will inform models regarding the geometry of quasar outflows.

  12. 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

  13. 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.

  14. 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.

  15. A SPECTACULAR OUTFLOW IN AN OBSCURED QUASAR

    SciTech Connect

    Greene, Jenny E.; Zakamska, Nadia L.; Smith, Paul S.

    2012-02-10

    SDSS J1356+1026 is a pair of interacting galaxies at redshift z = 0.123 that hosts a luminous obscured quasar in its northern nucleus. Here we present two long-slit Magellan LDSS-3 spectra that reveal a pair of symmetric {approx}10 kpc size outflows emerging from this nucleus, with observed expansion velocities of {approx}250 km s{sup -1} in projection. We present a kinematic model of these outflows and argue that the deprojected physical velocities of expansion are likely {approx}1000 km s{sup -1} and that the kinetic energy of the expanding shells is likely 10{sup 44-45} erg s{sup -1}, with an absolute minimum of >10{sup 42} erg s{sup -1}. Although a radio counterpart is detected at 1.4 GHz, it is faint enough that the quasar is considered to be radio quiet by all standard criteria, and there is no evidence of extended emission due to radio lobes, whether aged or continuously powered by an ongoing jet. We argue that the likely level of star formation is insufficient to power the observed energetic outflow and that SDSS J1356+1026 is a good case for radio-quiet quasar feedback. In further support of this hypothesis, polarimetric observations show that the direction of quasar illumination is coincident with the direction of the outflow.

  16. 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

  17. Properties of quasar broad absorption line outflows

    NASA Astrophysics Data System (ADS)

    Capellupo, Daniel Moshin

    2012-06-01

    Broad absorption lines (BALs) in quasar spectra identify high velocity outflows that likely exist in all quasars and could play a major role in feedback to galaxy evolution. In this dissertation, I use two methods to illuminate important properties of these outflows with the goal of a better understanding of these outflow systems and ultimately of the connection between quasars and their host galaxies. The variability of BALs can help us understand the structure, evolution, and basic physical properties of the outflows. I report here on a BAL monitoring programme of a sample of 24 luminous quasars at redshifts 1.2quasar rest-frame. I find that 39% (7/18) of the quasars varied in the short-term, whereas 65% (15/23) varied in the long-term, with a larger typical change in strength in the long-term data. The variability occurs typically in only portions of the BAL troughs. The components at higher outflow velocities are more likely to vary than those at lower velocities, and weaker BALs are more likely to vary than stronger BALs. I then directly compare the variabilities in the C IV and Si IV lambda1400 absorption to try to ascertain the cause(s) of the variability. I find that Si IV BALs are more likely to vary than C IV BALs. When both C IV and Si IV varied, those changes always occurred in the same sense (either getting weaker or stronger). The multi-epoch data, including up to 10 epochs of data per quasar, show that the BAL changes were not generally monotonic across the full ˜5 to ˜8 yr time span of our observations, suggesting that the characteristic time-scale for significant line variations, and (perhaps) for structural changes in the outflows, is less than a few years. The evidence presented here indicates that the cause of variability is likely a complex mixture of changing ionization in the outflowing

  18. Outflows of stars due to quasar feedback

    NASA Astrophysics Data System (ADS)

    Zubovas, Kastytis; Nayakshin, Sergei; Sazonov, Sergey; Sunyaev, Rashid

    2013-05-01

    Quasar feedback outflows are commonly invoked to drive gas out of galaxies in the early gas-rich epoch to terminate growth of galaxies. Here we present simulations that show that AGN feedback may drive not only gas but also stars out of their host galaxies under certain conditions. The mechanics of this process is as follows: (1) AGN-driven outflows accelerate and compress gas filling the host galaxy; (2) the accelerated dense shells become gravitationally unstable and form stars on radial trajectories. For the spherically symmetric initial conditions explored here, the black hole needs to exceed the host's Mσ mass by a factor of a few to accelerate the shells and the new stars to escape velocities. We discuss potential implications of these effects for the host galaxies: (i) radial mixing of bulge stars with the rest of the host; (ii) contribution of quasar outflows to galactic fountains as sources of high-velocity clouds; (iii) wholesale ejection of hypervelocity stars out of their hosts, giving rise to Type II supernovae on galactic outskirts, and contributing to reionization and metal enrichment of the Universe; (iv) bulge erosion and even complete destruction in extreme cases resulting in overweight or bulgeless SMBHs.

  19. Quasar Outflows and Black Hole Masses

    NASA Astrophysics Data System (ADS)

    Coatman, Liam; Hewett, Paul; Banerji, Manda; Richards, Gordon; Hennawi, Joseph; Prochaska, Jason X.

    2016-08-01

    Black-hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z > 2, black hole masses are normally derived using the velocity-width of the CIV broad emission line, based on the assumption that the observed velocity-widths arise from virial-induced motions. In many quasars, the CIV-emission line exhibits significant blue asymmetries ('blueshifts') with the line centroid displaced by up to thousands of km/s to the blue. These blueshifts almost certainly signal the presence of strong outflows, most likely originating in a disc wind. Using both archival data and new observations, we have obtained near-infrared spectra, including the Ha and/or Hb emission lines, for ~400 luminous (L_Bol = 45.5-48.5 erg/s) SDSS quasars, at redshifts 1.5 < z < 4, with CIV emission lines spanning the full-range of blueshifts present in the population. A strong correlation between CIV-velocity width and blueshift is found and, at large blueshifts, >2000 km/s, the velocity-widths appear to be dominated by non-virial motions. Using the Ha/Hb emission to provide black hole masses free from non-virial contributions, we are able to derive a quantitative correction to the CIV-based black-hole masses as a function of blueshift. This correction reduces the scatter between Ha/Hb and CIV velocity widths to just ~0.1 dex. Without the correction, black hole masses would be overestimated by a factor of nine at the largest blueshifts. With a suitable systemic redshift-estimation algorithm, this correction can be straightforwardly applied based only on information contained in the rest-frame UV spectra.

  20. 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.

  1. Outflow and hot dust emission in broad absorption line quasars

    SciTech Connect

    Zhang, Shaohua; Zhou, Hongyan; Wang, Huiyuan; Wang, Tinggui; Xing, Feijun; Jiang, Peng; Zhang, Kai E-mail: whywang@mail.ustc.edu.cn

    2014-05-01

    We have investigated a sample of 2099 broad absorption line (BAL) quasars with z = 1.7-2.2 built from the Sloan Digital Sky Survey Data Release Seven and the Wide-field Infrared Survey. This sample is collected from two BAL quasar samples in the literature and is refined by our new algorithm. Correlations of outflow velocity and strength with a hot dust indicator (β{sub NIR}) and other quasar physical parameters—such as an Eddington ratio, luminosity, and a UV continuum slope—are explored in order to figure out which parameters drive outflows. Here β{sub NIR} is the near-infrared continuum slope, which is a good indicator of the amount of hot dust emission relative to the accretion disk emission. We confirm previous findings that outflow properties moderately or weakly depend on the Eddington ratio, UV slope, and luminosity. For the first time, we report moderate and significant correlations of outflow strength and velocity with β{sub NIR} in BAL quasars. It is consistent with the behavior of blueshifted broad emission lines in non-BAL quasars. The statistical analysis and composite spectra study both reveal that outflow strength and velocity are more strongly correlated with β{sub NIR} than the Eddington ratio, luminosity, and UV slope. In particular, the composites show that the entire C IV absorption profile shifts blueward and broadens as β{sub NIR} increases, while the Eddington ratio and UV slope only affect the high and low velocity part of outflows, respectively. We discuss several potential processes and suggest that the dusty outflow scenario, i.e., that dust is intrinsic to outflows and may contribute to the outflow acceleration, is most likely.

  2. OUTFLOW AND HOT DUST EMISSION IN HIGH-REDSHIFT QUASARS

    SciTech Connect

    Wang, Huiyuan; Xing, Feijun; Wang, Tinggui; Zhou, Hongyan; Zhang, Kai; Zhang, Shaohua

    2013-10-10

    Correlations of hot dust emission with outflow properties are investigated, based on a large z ∼ 2 non-broad absorption line quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near-infrared slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from the accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of C IV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, C IV regions are dominated by outflows so the BAI and FWHM (C IV) can reliably reflect the general properties and velocity of outflows, respectively. In low Eddington ratio quasars, on the other hand, C IV lines are primarily emitted by virialized gas so the BAI and FWHM (C IV) become less sensitive to outflows. Therefore, the correlations for the highest Eddington ratio quasars are more likely to represent the true dependence of hot dust emission on outflows and the correlations for the entire sample are significantly diluted by the low Eddington ratio quasars. Our results show that an outflow with a large BAI or velocity can double the hot dust emission on average. We suggest that outflows either contain hot dust in themselves or interact with the dusty interstellar medium or torus.

  3. 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

  4. Characterizing Quasar Outflows III: SEDs, and Bolometric Luminosity Estimates

    NASA Astrophysics Data System (ADS)

    Richmond, Joseph; Robbins, J. M.; Ganguly, R.; Stark, M. A.; Christenson, D. H.; Derseweh, J. A.; 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 this poster, we add photometry from both the Two Micron All-Sky Survey (2MASS) and from the Wide-Field Infrared Survey Explorer (WISE). 2MASS photometry covers the rest-frame optical regime of these qusars, while the WISE W1, W2, and W3 bands cover the rest-frame wavelength ranges 0.9-1.27 micron, 1.35-1.75 micron, and 2.52-5.51 micron, respectively. The preliminary release of WISE data cover 3800 of our quasars. In an accompnying poster, we have subjectively divided 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). Here, we present average SEDs for these subsamples, estimates of bolometric luminosity, and explore changes in SED based on 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

  5. Analytical Investigation of Mass Outflow Rate in Quasars

    NASA Astrophysics Data System (ADS)

    Das, Santabrata; Chakrabarti, Sandip K.

    Centrifugal force of rapidly infalling matter onto a quasar brakes the flow and forms a centrifugal pressure dominated boundary layer (CENBOL) around the central engine. The thermal and magnetic pressure pushes matter along the axis to form observed radio jets. We present analytical work showing how the inflow influences the nature of CENBOL and dictates the outflow rate from the accretion disks. We show that the outflow rate directly depends on the temperature of CENBOL.

  6. Characterizing Quasar Outflows IV: Regulating Outflows Through X-ray and EUV Absorption

    NASA Astrophysics Data System (ADS)

    Derseweh, Jeffrey; Ganguly, R.; Richmond, J. M.; Stark, M. A.; Christenson, D. H.; 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 this poster, we add photometry from the GALEX All-sky imaging survey, as well as the Chandra and ROSAT archives. These provide coverage of the rest-frame extreme ultraviolet, and soft X-ray bands. In an accompanying poster, we have subjectively divided 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 are interested in testing the radiative-driving hypothesis that requires a suppression of X-ray flux in order to transfer momentum efficiently to the UV-absorbing gas. Hence, we explore how absorption in both the extreme ultraviolet and the soft X-ray bands correlate with properties of the UV outflows, quasar property, and changes in SED shape. 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 and by Chandra

  7. LOW-IONIZATION OUTFLOWS IN HIGH EDDINGTON RATIO QUASARS

    SciTech Connect

    Marziani, Paola; Sulentic, Jack W.; Plauchu-Frayn, Ilse; Del Olmo, Ascension

    2013-02-20

    The broad Mg II {lambda}2800 doublet has been frequently studied in connection with its potentially important role as a virial estimator of black hole mass in high-redshift quasars. An important task, therefore, is the identification of any line components that are likely related to broadening by non-virial motions. High signal-to-noise median composite spectra (binned in the {sup f}our-dimensional eigenvector 1'' context of Sulentic et al.) were constructed for the brightest 680 Sloan Digital Sky Survey Data Release 7 quasars in the 0.4 {<=} z {<=} 0.75 range where both Mg II {lambda}2800 and H{beta} are recorded in the same spectra. Composite spectra representing 90% of the quasars confirm previous findings that FWHM(Mg II {lambda}2800) is about 20% narrower than FWHM(H{beta}). The situation is clearly different for the most extreme (Population A) sources, which are the highest Eddington radiators in the sample. In the median spectra of these sources, FWHM Mg II {lambda}2800 is equal to or greater than FWHM(H{beta}) and shows a significant blueshift relative to H{beta}. We interpret the Mg II {lambda}2800 blueshift as the signature of a radiation-driven wind or outflow in the highest accreting quasars. In this interpretation, the Mg II {lambda}2800 line width-affected by blueshifted emission-is unsuitable for virial mass estimation in Almost-Equal-To 10% of quasars.

  8. Low-ionization Outflows in High Eddington Ratio Quasars

    NASA Astrophysics Data System (ADS)

    Marziani, Paola; Sulentic, Jack W.; Plauchu-Frayn, Ilse; del Olmo, Ascensión

    2013-02-01

    The broad Mg II λ2800 doublet has been frequently studied in connection with its potentially important role as a virial estimator of black hole mass in high-redshift quasars. An important task, therefore, is the identification of any line components that are likely related to broadening by non-virial motions. High signal-to-noise median composite spectra (binned in the "four-dimensional eigenvector 1" context of Sulentic et al.) were constructed for the brightest 680 Sloan Digital Sky Survey Data Release 7 quasars in the 0.4 <= z <= 0.75 range where both Mg II λ2800 and Hβ are recorded in the same spectra. Composite spectra representing 90% of the quasars confirm previous findings that FWHM(Mg II λ2800) is about 20% narrower than FWHM(Hβ). The situation is clearly different for the most extreme (Population A) sources, which are the highest Eddington radiators in the sample. In the median spectra of these sources, FWHM Mg II λ2800 is equal to or greater than FWHM(Hβ) and shows a significant blueshift relative to Hβ. We interpret the Mg II λ2800 blueshift as the signature of a radiation-driven wind or outflow in the highest accreting quasars. In this interpretation, the Mg II λ2800 line width—affected by blueshifted emission—is unsuitable for virial mass estimation in ≈10% of quasars.

  9. Testing the Radiative-Driving Hypothesis of Quasar Outflows

    NASA Astrophysics Data System (ADS)

    Stark, Michele A.; Ganguly, R.; Gallagher, S. C.; Gibson, R.; Brotherton, M. S.

    2011-01-01

    Outflows are seen prominently in the UV spectra of Broad Absorption Line (BAL) QSOs. Models of radiatively-driven outflows predict that the velocity should scale with UV luminosity. Observations show that the UV luminosity only provides a cap to the velocity. One explanation is that the X-ray absorbing gas in an individual quasar provides a shield that improves its radiative-driving efficiency. That is, quasars with thick shields can accelerate gas to higher velocity. X-ray observations of BALQSOs support this in the sense that BALQSOs with more soft X-ray absorption tend to have higher velocity outflows. But there is much scatter in this trend, making the underlying physics difficult to extract. To combat this, we conducted an experiment using exploratory Chandra-ACIS observations of 12 carefully-selected z=1.7-2.0 BALQSOs. These BALQSOs were chosen to have very narrow ranges in (1) UV luminosity, (2) UV spectral shape, and (3) absorption velocity width. Within this otherwise uniform sample, the outflow velocities range from 4500km/s to 18000km/s, a factor of four. All objects are detected in the full band (0.5-8keV), with count rates in the range (0.5-5)e-3 cps, and have hardness ratios in the range -0.6 to 0.3. We compare the X-ray brightnesses and spectral shapes of our sample with those of more diverse samples of BALQSOs. We gratefully acknowledge support through Chandra grant GO9-0120X.

  10. Fast outflows and star formation quenching in 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.

    2016-06-01

    Negative feedback from active galactic nuclei (AGN) is considered a key mechanism in shaping galaxy evolution. Fast, extended outflows are frequently detected in the AGN host galaxies at all redshifts and luminosities, both in ionised and molecular gas. However, these outflows are only potentially able to quench star formation, and we are still lacking decisive evidence of negative feedback in action. Here we present observations obtained with the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) H- and K-band integral-field of two quasars at z ~ 2.4 that are characterised by fast, extended outflows detected through the [Oiii]λ5007 line. The high signal-to-noise ratio of our observations allows us to identify faint narrow (FWHM< 500 km s-1) and spatially extended components in [Oiii]λ5007 and Hα emission associated with star formation in the host galaxy. This star formation powered emission is spatially anti-correlated with the fast outflows. The ionised outflows therefore appear to be able to suppress star formation in the region where the outflow is expanding. However, the detection of narrow spatially extended Hα emission indicates star formation rates of at least ~50-90 M⊙ yr-1, suggesting either that AGN feedback does not affect the whole galaxy or that many feedback episodes are required before star formation is completely quenched. On the other hand, the narrow Hα emission extending along the edges of the outflow cone may also lead also to a positive feedback interpretation. Our results highlight the possible double role of galaxy-wide outflows in host galaxy evolution. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, P.ID: 086.B-0579(A) and 091.A-0261(A).The reduced data cubes 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/591/A28

  11. Unusual high-redshift radio broad absorption-line quasar 1624+3758

    NASA Astrophysics Data System (ADS)

    Benn, C. R.; Carballo, R.; Holt, J.; Vigotti, M.; González-Serrano, J. I.; Mack, K.-H.; Perley, R. A.

    2005-07-01

    We present observations of the most radio-luminous broad absorption-line (BAL) quasar known, 1624+3758, at redshift z= 3.377. The quasar has several unusual properties. (1) The FeII UV191 1787-Åemission line is very prominent. (2) The BAL trough (BALnicity index 2990 km s-1) is detached by 21000 km s-1 and extends to velocity v=-29000 km s-1. There are additional intrinsic absorbers at -1900 and -2800 km s-1. (3) The radio rotation measure of the quasar, 18350 rad m-2, is the second highest known. The radio luminosity is P1.4GHz= 4.3 × 1027 W Hz-1 (H0= 50 km s-1 Mpc-1, q0= 0.5) and the radio loudness is R*= 260. The radio source is compact and the radio spectrum is GHz-peaked, consistent with it being relatively young. The width of the CIV emission line, in conjunction with the total optical luminosity, implies a black hole mass MBH~ 109Msolar, L/LEddington~ 2. The high Eddington ratio and the radio-loudness place this quasar in one corner of Boroson's two-component scheme for the classification of active galactic nuclei, implying a very high accretion rate, and this may account for some of the unusual observed properties. The v=-1900km s-1 absorber is a possible Lyman-limit system, with N(HI) = 4 × 1018 cm-2, and a covering factor of 0.7. A complex mini-BAL absorber at v=-2200 to -3400 km s-1 is detected in each of CIV, NV and OVI. The blue and red components of the CIV doublet happen to be unblended, allowing both the covering factor and optical depth to be determined as a function of velocity. Variation of the covering factor with velocity dominates the form of the mini-BAL, with the absorption being saturated (e-τ~ 0) over most of the velocity range. The velocity dependence of the covering factor and the large velocity width imply that the mini-BAL is intrinsic to the quasar. There is some evidence of line-locking between velocity components in the CIV mini-BAL, suggesting that radiation pressure plays a role in accelerating the outflow.

  12. Monitoring the variability of intrinsic absorption lines in quasar spectra , ,

    SciTech Connect

    Misawa, Toru; Charlton, Jane C.; Eracleous, Michael

    2014-09-01

    We have monitored 12 intrinsic narrow absorption lines (NALs) in five quasars and seven mini-broad absorption lines (mini-BALs) in six quasars for a period of 4-12 yr (1-3.5 yr in the quasar rest-frame). We present the observational data and the conclusions that follow immediately from them, as a prelude to a more detailed analysis. We found clear variability in the equivalent widths (EWs) of the mini-BAL systems but no easily discernible changes in their profiles. We did not detect any variability in the NAL systems or in narrow components that are often located at the center of mini-BAL profiles. Variations in mini-BAL EWs are larger at longer time intervals, reminiscent of the trend seen in variable BALs. If we assume that the observed variations result from changes in the ionization state of the mini-BAL gas, we infer lower limits to the gas density ∼10{sup 3}-10{sup 5} cm{sup –3} and upper limits on the distance of the absorbers from the central engine of the order of a few kiloparsecs. Motivated by the observed variability properties, we suggest that mini-BALs can vary because of fluctuations of the ionizing continuum or changes in partial coverage while NALs can vary primarily because of changes in partial coverage.

  13. The most powerful quasar outflows as revealed by the Civ λ1549 resonance line

    NASA Astrophysics Data System (ADS)

    Marziani, P.; Martínez Carballo, M. A.; Sulentic, J. W.; Del Olmo, A.; Stirpe, G. M.; Dultzin, D.

    2016-01-01

    Outflows from quasars may be almost ubiquitous, but there are significant differences on a source- by-source basis. These differences can be organized along the 4D Eigenvector 1 sequence: at low z, only the Population A sources radiating at relatively high Eddington ratio show evidences of prominent high- velocity outflows from the Civλ1549 line profiles. Here we discuss, starting from recent observations of high-luminosity sample of Hamburg-ESO quasars, the Civλ1549 emission line profiles and how they are affected by outflow motion as a function of the quasar luminosity. Our high-luminosity sample has the notable advantage that the rest frame has been set by previous Hβ observations in the J, H, and K band, therefore making measurements of inter-line shift accurate and free of systemic biases. As the redshift increases and the luminosity of the brightest quasars grows, powerful, high-velocity outflows may become more frequent. We then discuss the outflow contextualisation following the 4DE1 approach as a tool for unveiling the nature of the so-called Weak Lined Quasars (WLQs) that have emerged in recent years as a new, poorly understood class of quasars. We estimate the kinetic power associated with the Civλ1549 emitting gas in outflow, and we suggest that the host galaxies of the most luminous sources may experience a significant feedback effect.

  14. A variable P v broad absorption line and quasar outflow energetics

    NASA Astrophysics Data System (ADS)

    Capellupo, D. M.; Hamann, F.; Barlow, T. A.

    2014-10-01

    Broad absorption lines (BALs) in quasar spectra identify high-velocity outflows that might exist in all quasars and could play a major role in feedback to galaxy evolution. The viability of BAL outflows as a feedback mechanism depends on their kinetic energies, as derived from the outflow velocities, column densities, and distances from the central quasar. We estimate these quantities for the quasar, Q1413+1143 (redshift ze = 2.56), aided by the first detection of P V λλ1118, 1128 BAL variability in a quasar. In particular, P V absorption at velocities where the C IV trough does not reach zero intensity implies that the C IV BAL is saturated and the absorber only partially covers the background continuum source (with characteristic size <0.01 pc). With the assumption of solar abundances, we estimate that the total column density in the BAL outflow is log NH ≳ 22.3 cm-2. Variability in the P V and saturated C IV BALs strongly disfavours changes in the ionization as the cause of the BAL variability, but supports models with high column density BAL clouds moving across our lines of sight. The observed variability time of 1.6 yr in the quasar rest frame indicates crossing speeds >750 km s-1 and a radial distance from the central black hole of ≲ 3.5 pc, if the crossing speeds are Keplerian. The total outflow mass is ˜4100 M⊙, the kinetic energy ˜4 × 1054 erg, and the ratio of the outflow kinetic energy luminosity to the quasar bolometric luminosity is ˜0.02 (at the minimum column density and maximum distance), which might be sufficient for important feedback to the quasar's host galaxy.

  15. Evidence for Fluorescent Fe II Emission from Extended Low Ionization Outflows in Obscured Quasars

    NASA Astrophysics Data System (ADS)

    Wang, Tinggui; Ferland, Gary J.; Yang, Chenwei; Wang, Huiyuan; Zhang, Shaohua

    2016-06-01

    Recent studies have shown that outflows in at least some broad absorption line (BAL) quasars are extended well beyond the putative dusty torus. Such outflows should be detectable in obscured quasars. We present four WISE selected infrared red quasars with very strong and peculiar ultraviolet Fe ii emission lines: strong UV Fe ii UV arising from transitions to ground/low excitation levels, and very weak Fe ii at wavelengths longer than 2800 Å. The spectra of these quasars display strong resonant emission lines, such as C iv, Al iii and Mg ii but sometimes, a lack of non-resonant lines such as C iii], S iii and He ii. We interpret the Fe ii lines as resonantly scattered light from the extended outflows that are viewed nearly edge-on, so that the accretion disk and broad line region are obscured by the dusty torus, while the extended outflows are not. We show that dust free gas exposed to strong radiation longward of 912 Å produces Fe ii emission very similar to that observed. The gas is too cool to collisionally excite Fe ii lines, accounting for the lack of optical emission. The spectral energy distribution from the UV to the mid-infrared can be modeled as emission from a clumpy dusty torus, with UV emission being reflected/scattered light either by the dusty torus or the outflow. Within this scenario, we estimate a minimum covering factor of the outflows from a few to 20% for the Fe ii scattering region, suggesting that Fe ii BAL quasars are at a special stage of quasar evolution.

  16. Powerful quasar outflow in a massive disc galaxy at z ˜ 5

    NASA Astrophysics Data System (ADS)

    Curtis, Michael; Sijacki, Debora

    2016-03-01

    There is growing observational evidence of high-redshift quasars launching energetic, fast outflows, but the effects that these have on their host galaxies is poorly understood. We employ the moving-mesh code AREPO to study the feedback from a quasar that has grown to ˜109 M⊙ by z ˜ 5 and the impact that this has on its host galaxy. Our simulations use a super-Lagrangian refinement technique to increase the accuracy with which the interface of the quasar-driven wind and the surrounding gas is resolved. We find that the feedback injected in these simulations is less efficient at removing gas from the galaxy than in an identical simulation with no super-Lagrangian refinement. This leads to the growth of a massive, rotationally supported, star-forming disc, co-existing with a powerful quasar-driven outflow. The properties of our host galaxy, including the kinematical structure of the gaseous disc and of the outflow, are in good agreement with current observations. Upcoming ALMA and JWST observations will be an excellent test of our model and will provide further clues as to the variance in properties of high-redshift quasar hosts.

  17. 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.

  18. 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.

  19. Studying AGN Feedback with Galactic Outflows in Luminous Obscured Quasar

    NASA Astrophysics Data System (ADS)

    Sun, Ai-Lei

    2016-01-01

    Feedback from Active galactic nuclei (AGN) has been proposed as an important quenching mechanism to suppress star formation in massive galaxies. We investigate the most direct form of AGN feedback - galactic outflows - in the most luminous obscured AGN (L>10^45 erg/s) from the SDSS sample in the nearby universe (z<0.2). Using ALMA and Magellan observations to target molecular and ionized outflows, we find that luminous AGN can impact the dynamics and phase of the galactic medium, and confirm the complex multi-phase and multi-scaled nature of the feedback phenomenon. In particular, we found that most of these luminous AGN hosts ionized outflows. The outflow size, velocity, and energetics correlate with the AGN luminosity, and can be very extended (r > 10 kpc) and fast (v > 1000 km/s) for the most luminous ones. I end with presenting a new technique to find extended ionized outflows using broadband imaging surveys, and to characterize their occurrence rate, morphology, size distribution, and their dependence on the AGN luminosity. This technique will open a new window for feedback studies in the era of large-scale optical imaging surveys, e.g., HSC and then LSST.

  20. Large-scale outflow in quasar LBQS J1206+1052: HST/COS observations

    NASA Astrophysics Data System (ADS)

    Chamberlain, Carter; Arav, Nahum

    2015-11-01

    Using two orbits of HST/COS archival observations, we measure the location and energetics of a quasar outflow from LBQS J1206+1052. From separate collisional excitation models of observed N III/N III* and S III/S III* troughs, we measure the electron number density n_e of the outflow. Both independent determinations are in full agreement and yield n_e =10^{3.0} cm^{-3}. Combining this value of n_e with photoionization simulations, we determine that the outflow is located 840 pc from the central source. The outflow has a velocity of 1400 km s-1, a mass flux of 9 M⊙ yr-1 and a kinetic luminosity of 1042.8 erg s-1. The distance finding is much larger than predicted from radiative acceleration models, but is consistent with recent empirical distance determinations.

  1. Fast Molecular Outflows in Luminous Galaxy Mergers: Evidence for Quasar Feedback from Herschel

    NASA Technical Reports Server (NTRS)

    Veilleux, S.; Melendez, M.; Sturm, E.; Garcia-Carpio, J.; Fischer, J.; Gonzalez-Alfonso, E.; Contursi, A.; Lutz, D.; Poglitsch, A.; Davies, R.; Genzel, R.; Tacconi, L.; deJong, J. A.; Sternberg, A.; Netzer, H.; Hailey-Dunsheath, S.; Verma, A.; Rupke, D. S. N.; Maiolino, R.; Teng, S. H.; Polisensky, E.

    2013-01-01

    We report the results from a systematic search for molecular (OH 119 micron) outflows with Herschel/PACS in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7 micron silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than-50 km/s, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (approx. 145 deg.) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km/s is seen in only four objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of approx. -1000 km/s are measured in several objects, but median outflow velocities are typically approx.-200 km/s-1. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large active galactic nucleus (AGN) fractions and luminosities [log (L(sub AGN)/L(sub solar)) => 11.8 +/- 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. However, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

  2. FAST MOLECULAR OUTFLOWS IN LUMINOUS GALAXY MERGERS: EVIDENCE FOR QUASAR FEEDBACK FROM HERSCHEL

    SciTech Connect

    Veilleux, S.; Meléndez, M.; Sturm, E.; Gracia-Carpio, J.; Contursi, A.; Lutz, D.; Poglitsch, A.; Davies, R.; Genzel, R.; Tacconi, L.; De Jong, J. A.; Fischer, J.; González-Alfonso, E.; Sternberg, A.; Netzer, H.; Hailey-Dunsheath, S.; Verma, A.; Rupke, D. S. N.; Maiolino, R.; Teng, S. H. E-mail: marcio@astro.umd.edu; and others

    2013-10-10

    We report the results from a systematic search for molecular (OH 119 μm) outflows with Herschel/PACS in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7 μm silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than –50 km s{sup –1}, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (∼145°) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km s{sup –1}, is seen in only four objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of ∼–1000 km s{sup –1} are measured in several objects, but median outflow velocities are typically ∼–200 km s{sup –1}. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large active galactic nucleus (AGN) fractions and luminosities [log (L{sub AGN}/L{sub ☉}) ≥ 11.8 ± 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. However, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

  3. Monitoring the Variability of Intrinsic Absorption Lines in Quasar Spectra

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Charlton, Jane C.; Eracleous, Michael

    2014-09-01

    We have monitored 12 intrinsic narrow absorption lines (NALs) in five quasars and seven mini-broad absorption lines (mini-BALs) in six quasars for a period of 4-12 yr (1-3.5 yr in the quasar rest-frame). We present the observational data and the conclusions that follow immediately from them, as a prelude to a more detailed analysis. We found clear variability in the equivalent widths (EWs) of the mini-BAL systems but no easily discernible changes in their profiles. We did not detect any variability in the NAL systems or in narrow components that are often located at the center of mini-BAL profiles. Variations in mini-BAL EWs are larger at longer time intervals, reminiscent of the trend seen in variable BALs. If we assume that the observed variations result from changes in the ionization state of the mini-BAL gas, we infer lower limits to the gas density ~103-105 cm-3 and upper limits on the distance of the absorbers from the central engine of the order of a few kiloparsecs. Motivated by the observed variability properties, we suggest that mini-BALs can vary because of fluctuations of the ionizing continuum or changes in partial coverage while NALs can vary primarily because of changes in partial coverage. Based on data collected at Subaru telescope, which is operated by the National Astronomical Observatory of Japan. Based on observations obtained at the European Southern Observatory at La Silla, Chile in programs 65.O-0063(B), 65.O-0474(A), 67.A-0078(A), 68.A-0461(A), 69.A-0204(A), 70.B-0522(A), 072.A-0346(A), 076.A-0860(A), 079.B-0469(A), and 166.A-0106(A).

  4. Discovery of extreme [O III] λ5007 Å outflows in high-redshift red quasars

    NASA Astrophysics Data System (ADS)

    Zakamska, Nadia L.; Hamann, Fred; Pâris, Isabelle; Brandt, W. N.; Greene, Jenny E.; Strauss, Michael A.; Villforth, Carolin; Wylezalek, Dominika; Alexandroff, Rachael M.; Ross, Nicholas P.

    2016-07-01

    Black hole feedback is now a standard component of galaxy formation models. These models predict that the impact of black hole activity on its host galaxy likely peaked at z = 2-3, the epoch of strongest star formation activity and black hole accretion activity in the Universe. We used XSHOOTER on the Very Large Telescope to measure rest-frame optical spectra of four z ˜ 2.5 extremely red quasars with infrared luminosities ˜1047 erg s-1. We present the discovery of very broad (full width at half max = 2600-5000 km s-1), strongly blueshifted (by up to 1500 km s-1) [O III] λ5007 Å emission lines in these objects. In a large sample of type 2 and red quasars, [O III] kinematics are positively correlated with infrared luminosity, and the four objects in our sample are on the extreme end in both [O III] kinematics and infrared luminosity. We estimate that at least 3 per cent of the bolometric luminosity in these objects is being converted into the kinetic power of the observed wind. Photo-ionization estimates suggest that the [O III] emission might be extended on a few kpc scales, which would suggest that the extreme outflow is affecting the entire host galaxy of the quasar. These sources may be the signposts of the most extreme form of quasar feedback at the peak epoch of galaxy formation, and may represent an active `blow-out' phase of quasar evolution.

  5. Variability of the high-velocity outflow in the quasar PDS 456

    SciTech Connect

    Reeves, J. N.; Gofford, J.; Costa, M.; Matzeu, G.; Braito, V.; Sim, S. A.; Behar, E.; Kaspi, S.; Miller, L.; O'Brien, P.; Turner, T. J.; Ward, M.

    2014-01-01

    We present a comparison of two Suzaku X-ray observations of the nearby (z = 0.184), luminous (L {sub bol} ∼ 10{sup 47} erg s{sup –1}) type I quasar, PDS 456. A new 125 ks Suzaku observation in 2011 caught the quasar during a period of low X-ray flux and with a hard X-ray spectrum, in contrast with a previous 190 ks Suzaku observation in 2007 when the quasar appeared brighter and had a steep (Γ > 2) X-ray spectrum. The 2011 X-ray spectrum contains a pronounced trough near 9 keV in the quasar rest frame, which can be modeled with blueshifted iron K-shell absorption, most likely from the He- and H-like transitions of iron. The absorption trough is observed at a similar rest-frame energy as in the earlier 2007 observation, which appears to confirm the existence of a persistent high-velocity wind in PDS 456, at an outflow velocity of 0.25-0.30c. The spectral variability between 2007 and 2011 can be accounted for by variations in a partial covering absorber, increasing in covering fraction from the brighter 2007 observation to the hard and faint 2011 observation. Overall, the low-flux 2011 observation can be explained if PDS 456 is observed at relatively low inclination angles through a Compton-thick wind, originating from the accretion disk, which significantly attenuates the X-ray flux from the quasar.

  6. The triggering mechanism and properties of ionized outflows in the nearest obscured quasars

    NASA Astrophysics Data System (ADS)

    Villar Martín, M.; Emonts, B.; Humphrey, A.; Cabrera Lavers, A.; Binette, L.

    2014-06-01

    We have identified ionized outflows in the narrow-line region of all but one Sloan Digital Sky Survey type 2 quasars (QSO2) at z≲0.1 (20/21, detection rate 95 per cent), implying that this is a ubiquitous phenomenon in this object class also at the lowest z. The outflowing gas has high densities (ne≳1000 cm-3) and covers a region the size of a few kpc. This implies ionized outflow masses Moutf ˜ (0.3-2.4) × 106 M⊙ and mass outflow rates Ṁ< few M⊙ yr-1. The triggering mechanism of the outflows is related to the nuclear activity. The QSO2 can be classified into two groups according to the behaviour and properties of the outflowing gas. QSO2 in Group 1 (5/20 objects) show the most extreme turbulence; they have on average higher radio luminosities and higher excess of radio emission. QSO2 in Group 2 (15/20 objects) show less extreme turbulence; they have lower radio luminosities and, on average, lower or no radio excess. We propose that two competing outflow mechanisms are at work: radio jets and accretion disc winds. Radio jet induced outflows are dominant in Group 1, while disc winds dominate in Group 2. We find that the radio jet mode is capable of producing more extreme outflows. To test this interpretation, we predict that (1) high resolution radio imaging will reveal the presence of jets in Group 1 QSO2; (2) the morphology of their extended ionized nebulae must be more highly collimated and kinematically perturbed.

  7. SPECTROSCOPY ALONG MULTIPLE, LENSED SIGHT LINES THROUGH OUTFLOWING WINDS IN THE QUASAR SDSS J1029+2623

    SciTech Connect

    Misawa, Toru; Inada, Naohisa; Ohsuga, Ken; Gandhi, Poshak; Takahashi, Rohta; Oguri, Masamune

    2013-02-01

    We study the origin of absorption features on the blue side of the C IV broad emission line of the large-separation lensed quasar SDSS J1029+2623 at z{sub em} {approx} 2.197. The quasar images, produced by a foreground cluster of galaxies, have a maximum separation angle of {theta} {approx} 22.''5. The large angular separation suggests that the sight lines to the quasar central source can go through different regions of outflowing winds from the accretion disk of the quasar, providing a unique opportunity to study the structure of outflows from the accretion disk, a key ingredient for the evolution of quasars as well as for galaxy formation and evolution. Based on medium- and high-resolution spectroscopy of the two brightest images conducted at the Subaru telescope, we find that each image has different intrinsic levels of absorptions, which can be attributed either to variability of absorption features over the time delay between the lensed images, {Delta}t {approx} 744 days, or to the fine structure of quasar outflows probed by the multiple sight lines toward the quasar. While both these scenarios are consistent with the current data, we argue that they can be distinguished with additional spectroscopic monitoring observations.

  8. Outflows Driven by Quasars in High-Redshift Galaxies with Radiation Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Bieri, Rebekka; Dubois, Yohan; Rosdahl, Joakim; Wagner, Alexander; Silk, Joseph; Mamon, Gary A.

    2016-09-01

    The quasar mode of Active Galactic Nuclei (AGN) in the high-redshift Universe is routinely observed in gas-rich galaxies together with large-scale AGN-driven winds. It is crucial to understand how photons emitted by the central AGN source couple to the ambient interstellar-medium to trigger large-scale outflows. By means of radiation-hydrodynamical simulations of idealised galactic discs, we study the coupling of photons with the multiphase galactic gas, and how it varies with gas cloud sizes, and the radiation bands included in the simulations, which are ultraviolet (UV), optical, and infrared (IR). We show how a quasar with a luminosity of 146 erg s-1 can drive large-scale winds with velocities of 102 - 103 km s-1 and mass outflow rates around 10^3 M_⊙ yr^{-1} for times of order a few million years. Infrared radiation is necessary to efficiently transfer momentum to the gas via multi-scattering on dust in dense clouds. However, IR multi-scattering, despite being extremely important at early times, quickly declines as the central gas cloud expands and breaks up, allowing the radiation to escape through low gas density channels. The typical number of multi-scattering events for an IR photon is only about a quarter of the mean optical depth from the center of the cloud. Our models account for the observed outflow rates of ˜ 500-1000 M_{⊙} {yr}^{-1} and high velocities of ˜ 10^3 km s^{-1}, favouring winds that are energy-driven via extremely fast nuclear outflows, interpreted here as being IR-radiatively-driven winds.

  9. THE QUASAR OUTFLOW CONTRIBUTION TO AGN FEEDBACK: VLT MEASUREMENTS OF SDSS J0318-0600

    SciTech Connect

    Dunn, Jay P.; Bautista, Manuel; Arav, Nahum; Edmonds, Doug; Moe, Max; Korista, Kirk; Costantini, Elisa; Benn, Chris; Ellison, Sara E-mail: arav@vt.ed E-mail: kirk.korista@wmich.ed E-mail: mmoe@cfa.harvard.ed

    2010-02-01

    We present high spectral resolution Very Large Telescope observations of the broad absorption line quasar SDSS J0318 - 0600. This high-quality data set allows us to extract accurate ionic column densities and determine an electron number density of n{sub e} = 10{sup 3.3+}-{sup 0.2} cm{sup -3} for the main outflow absorption component. The heavily reddened spectrum of SDSS J0318-0600 requires purely silicate dust with a reddening curve characteristic of predominately large grains, from which we estimate the bolometric luminosity. We carry out photoionization modeling to determine the total column density, ionization parameter, and distance of the gas and find that the photoionization models suggest abundances greater than solar. Due to the uncertainty in the location of the dust extinction, we arrive at two viable distances for the main ouflow component from the central source, 6 and 17 kpc, where we consider the 6 kpc location as somewhat more physically plausible. Assuming the canonical global covering of 20% for the outflow and a distance of 6 kpc, our analysis yields a mass flux of 120 M{sub sun} yr{sup -1} and a kinetic luminosity that is approx0.1% of the bolometric luminosity of the object. Should the dust be part of the outflow, then these values are approx4x larger. The large mass flux and kinetic luminosity make this outflow a significant contributor to active galactic nucleus feedback processes.

  10. Fast outflows in broad absorption line quasars and their connection with CSS/GPS sources

    NASA Astrophysics Data System (ADS)

    Bruni , G.; Mack, K.-H.; Montenegro-Montes, F. M.; Brienza, M.; González-Serrano, J. I.

    2016-02-01

    Broad absorption line quasars are among the objects presenting the fastest outflows. The launching mechanism itself is not completely understood. Models in which they could be launched from the accretion disk, and then curved and accelerated by the effect of the radiation pressure, have been presented. We conducted an extensive observational campaign, from radio to optical band, to collect information about their nature and test the models present in the literature, the main dichotomy being between a young scenario and an orientation one. We found a variety of possible orientations, morphologies, and radio ages, not converging to a particular explanation for the BAL phenomenon. From our latest observations in the m- and mm-band, we obtained an indication of a lower dust abundance with respect to normal quasars, thus suggesting a possible feedback process on the host galaxy. Also, in the low-frequency regime we confirmed the presence of CSS components, sometime in conjunction with a GPS one already detected at higher frequencies. Following this, about 70 % of our sample turns out to be in a GPS or CSS+GPS phase. We conclude that fast outflows, responsible for the BAL features, can be more easily present among objects going through a restarting or just-started radio phase, where radiation pressure can substantially contribute to their acceleration.

  11. ALMA observations of a candidate molecular outflow in an obscured quasar

    SciTech Connect

    Sun, Ai-Lei; Greene, Jenny E.; Zakamska, Nadia L.; Nesvadba, Nicole P. H.

    2014-08-01

    We present Atacama Large Millimeter/Submillimeter Array CO (1-0) and CO (3-2) observations of SDSS J135646.10+102609.0, an obscured quasar and ultra-luminous infrared galaxy with two merging nuclei and a known 20 kpc scale ionized outflow. The total molecular gas mass is M{sub mol}≈9{sub −6}{sup +19}×10{sup 8} M{sub ☉}, mostly distributed in a compact rotating disk at the primary nucleus (M{sub mol} ≈ 3 × 10{sup 8} M{sub ☉}) and an extended tidal arm (M{sub mol} ≈ 5 × 10{sup 8} M{sub ☉}). The tidal arm is one of the most massive molecular tidal features known; we suggest that it is due to the lower chance of shock dissociation in this elliptical/disk galaxy merger. In the spatially resolved CO (3-2) data, we find a compact (r ≈ 0.3 kpc) high-velocity (v ≈ 500 km s{sup –1}) redshifted feature in addition to the rotation at the N nucleus. We propose a molecular outflow as the most likely explanation for the high-velocity gas. The outflowing mass of M{sub mol} ≈ 7 × 10{sup 7} M{sub ☉} and the short dynamical time of t{sub dyn} ≈ 0.6 Myr yield a very high outflow rate of M-dot{sub mol}≈350 M{sub ☉} yr{sup –1} and can deplete the gas in a million years. We find a low star formation rate (<16 M{sub ☉} yr{sup –1} from the molecular content and <21 M{sub ☉} yr{sup –1} from the far-infrared spectral energy distribution decomposition) that is inadequate to supply the kinetic luminosity of the outflow ( E-dot ≈3×10{sup 43} erg s{sup –1}). Therefore, the active galactic nucleus (AGN), with a bolometric luminosity of 10{sup 46} erg s{sup –1}, likely powers the outflow. The momentum boost rate of the outflow ( p-dot /(L{sub bol}/c)≈3) is lower than typical molecular outflows associated with AGNs, which may be related to its compactness. The molecular and ionized outflows are likely two distinct bursts induced by episodic AGN activity which varies on a timescale of 10{sup 7} yr.

  12. 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.

  13. 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.

  14. GREEN BANK TELESCOPE DETECTION OF POLARIZATION-DEPENDENT H I ABSORPTION AND H I OUTFLOWS IN LOCAL ULIRGs AND QUASARS

    SciTech Connect

    Teng, Stacy H.; Veilleux, Sylvain; Baker, Andrew J.

    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%) 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.

  15. EVIDENCE FOR ACTIVE GALACTIC NUCLEUS DRIVEN OUTFLOWS IN YOUNG RADIO QUASARS

    SciTech Connect

    Kim, Minjin; Ho, Luis C.; Lonsdale, Carol J.; Lacy, Mark; Kimball, Amy E.; Blain, Andrew W.

    2013-05-01

    We present near-infrared spectra of young radio quasars (P{sub 1.4GHz} Almost-Equal-To 26-27 W Hz{sup -1}) selected from the Wide-Field Infrared Survey Explorer. The detected objects have typical redshifts of z Almost-Equal-To 1.6-2.5 and bolometric luminosities {approx}10{sup 47} erg s{sup -1}. Based on the intensity ratios of narrow emission lines, we find that these objects are mainly powered by active galactic nuclei (AGNs), although star formation contribution cannot be completely ruled out. The host galaxies experience moderate levels of extinction, A{sub V} Almost-Equal-To 0-1.3 mag. The observed [O III] {lambda}5007 luminosities and rest-frame J-band magnitudes constrain the black hole masses to lie in the range {approx}10{sup 8.9}-10{sup 9.7} M{sub Sun }. From the empirical correlation between black hole mass and host galaxy mass, we infer stellar masses of {approx}10{sup 11.3}-10{sup 12.2} M{sub Sun }. The [O III] line is exceptionally broad, with FWHM {approx}1300-2100 km s{sup -1}, significantly larger than that of ordinary distant quasars. We argue that these large line widths can be explained by jet-induced outflows, as predicted by theoretical models of AGN feedback.

  16. Constraining the Dynamical Importance of Hot Gas and Radiation Pressure in Quasar Outflows Using Emission Line Ratios

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Faucher-Giguère, Claude-André; Zakamska, Nadia L.; Hennawi, Joseph F.

    2016-03-01

    Quasar feedback models often predict an expanding hot gas bubble that drives a galaxy-scale outflow. In many circumstances this hot gas radiates inefficiently and is therefore difficult to observe directly. We present an indirect method to detect the presence of a hot bubble using hydrostatic photoionization calculations of the cold (∼ {10}4 {{K}}) line-emitting gas. We compare our calculations with observations of the broad line region, the inner face of the torus, the narrow line region (NLR), and the extended NLR, and thus constrain the hot gas pressure at distances 0.1 {{pc}}{--}10 {{kpc}} from the center. We find that emission line ratios observed in the average quasar spectrum are consistent with radiation-pressure-dominated models on all scales. On scales \\lt 40 {{pc}} a dynamically significant hot gas pressure is ruled out, while on larger scales the hot gas pressure cannot exceed six times the local radiation pressure. In individual quasars, ≈25% of quasars exhibit NLR ratios that are inconsistent with radiation-pressure-dominated models, although in these objects the hot gas pressure is also unlikely to exceed the radiation pressure by an order of magnitude or more. The derived upper limits on the hot gas pressure imply that the instantaneous gas pressure force acting on galaxy-scale outflows falls short of the time-averaged force needed to explain the large momentum fluxes \\dot{p}\\gg {L}{{AGN}}/c inferred for galaxy-scale outflows. This apparent discrepancy can be reconciled if optical quasars previously experienced a buried, fully obscured phase during which the hot gas bubble was more effectively confined and during which galactic wind acceleration occurred.

  17. A high-redshift quasar absorber without C IV. A galactic outflow caught in the act?

    NASA Astrophysics Data System (ADS)

    Fox, Anne; Richter, Philipp

    2016-04-01

    We present a detailed analysis of a very unusual sub-damped Lyman α (sub-DLA) system at redshift z = 2.304 towards the quasar Q 0453-423, based on high signal-to-noise (S/N), high-resolution spectral data obtained with VLT/UVES. With a neutral hydrogen column density of log N(H i) = 19.23 and a metallicity of -1.61 as indicated by [O i/H i] the sub-DLA mimics the properties of many other optically thick absorbers at this redshift. A very unusual feature of this system is, however, the lack of any C iv absorption at the redshift of the neutral hydrogen absorption, although the relevant spectral region is free of line blends and has very high S/N. Instead, we find high-ion absorption from C iv and O vi in another metal absorber at a velocity more than 220 km s-1 redwards of the neutral gas component. We explore the physical conditions in the two different absorption systems using Cloudy photoionisation models. We find that the weakly ionised absorber is dense and metal-poor while the highly ionised system is thin and more metal-rich. The absorber pair towards Q 0453-423 mimics the expected features of a galactic outflow with highly ionised material that moves away with high radial velocities from a (proto)galactic gas disk in which star-formation takes place. We discuss our findings in the context of C iv absorption line statistics at high redshift and compare our results to recent galactic-wind and outflow models.

  18. BAL PHOSPHORUS ABUNDANCE AND EVIDENCE FOR IMMENSE IONIC COLUMN DENSITIES IN QUASAR OUTFLOWS: VLT/X-SHOOTER OBSERVATIONS OF QUASAR SDSS J1512+1119

    SciTech Connect

    Borguet, Benoit C. J.; Edmonds, Doug; Arav, Nahum; Chamberlain, Carter; Benn, Chris

    2012-10-10

    We present spectroscopic analysis of the broad absorption line (BAL) outflow in quasar SDSS J1512+1119. In particular, we focus our attention on a kinematic component in which we identify P V and S IV/S IV* absorption troughs. The shape of the unblended phosphorus doublet troughs and the three S IV/S IV* troughs allow us to obtain reliable column density measurements for these two ions. Photoionization modeling using these column densities and those of He I* constrain the abundance of phosphorus to the range of 0.5-4 times the solar value. The total column density, ionization parameter, and metallicity inferred from the P V and S IV column densities lead to large optical depth values for the common transition observed in BAL outflows. We show that the true C IV optical depth is {approx}1000 times greater in the core of the absorption profile than the value deduced from its apparent optical depth.

  19. 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.

  20. RESOLVING THE CLUMPY STRUCTURE OF THE OUTFLOW WINDS IN THE GRAVITATIONALLY LENSED QUASAR SDSS J1029+2623

    SciTech Connect

    Misawa, Toru; Inada, Naohisa; Oguri, Masamune; Gandhi, Poshak; Horiuchi, Takashi; Koyamada, Suzuka; Okamoto, Rina

    2014-10-20

    We study the geometry and the internal structure of the outflowing wind from the accretion disk of a quasar by observing multiple sightlines with the aid of strong gravitational lensing. Using Subaru/High Dispersion Spectrograph, we performed high-resolution (R ∼ 36,000) spectroscopic observations of images A and B of the gravitationally lensed quasar SDSS J1029+2623 (at z {sub em} ∼ 2.197) whose image separation angle, θ ∼ 22.''5, is the largest among those discovered so far. We confirm that the difference in absorption profiles in images A and B discovered by Misawa et al. has remained unchanged since 2010, implying the difference is not due to time variability of the absorption profiles over the delay between the images, Δt ∼ 744 days, but rather due to differences along the sightlines. We also discovered a time variation of C IV absorption strength in both images A and B due to a change in the ionization condition. If a typical absorber's size is smaller than its distance from the flux source by more than five orders of magnitude, it should be possible to detect sightline variations among images of other smaller separation, galaxy-scale gravitationally lensed quasars.

  1. Quasars.

    PubMed

    Smith, H J

    1966-11-01

    A short historical outline of the discovery and a description of observed properties of quasars introduces questions as to their nature. Some of the principal arguments concerning their reality, distance, intrinsic properties and age lead to the conclusion that, while there is room for other points of view; a strong case can be made for the interpretation, on which quasars are the most distant observable objects in the known universe. To produce such luminosities over times of thousands to millions of years requires the presence of millions of solar masses. For each quasar this enormous mass may be concentrated into a single object, in which case novel physics comes into play. Whatever the final interpretation, quasars seem certain to illuminate such questions as the origin and evolution of galaxies, perhaps also the structure and origin of the universe.

  2. A Spectropolarimetric Test of the Structure of the Intrinsic Absorbers in the Quasar HS 1603+3820

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Kawabata, Koji S.; Eracleous, Michael; Charlton, Jane C.; Kashikawa, Nobunari

    2010-08-01

    We report the results of a spectropolarimetric observation of the C VI "mini-broad" absorption line (mini-BAL) in the quasar HS 1603+3820 (z em = 2.542). The observations were carried out with the FOCAS instrument on the Subaru Telescope and yielded an extremely high polarization sensitivity of δp~ 0.1%, at a resolving power of R ~ 1500. HS 1603+3820 has been the target of a high-resolution spectroscopic monitoring campaign for more than four years, aimed at studying its highly variable C VI mini-BAL profile. Using the monitoring observations in an earlier paper, we were able to narrow down the causes of the variability to the following two scenarios: (1) scattering material of variable optical depth redirecting photons around the absorber and (2) a variable, highly ionized screen between the continuum source and the absorber which modulates the UV continuum incident on the absorber. The observations presented here provide a crucial test of the scattering scenario and lead us to disfavor it because (1) the polarization level is very small (p ~ 0.6%) throughout the spectrum and (2) the polarization level does not increase across the mini-BAL trough. Thus, the variable screen scenario emerges as our favored explanation of the C VI mini-BAL variability. Our conclusion is bolstered by recent X-ray observations of nearby mini-BAL quasars, which show a rapidly variable soft X-ray continuum that appears to be the result of transmission through an ionized absorber of variable ionization parameter and optical depth. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  3. A SPECTROPOLARIMETRIC TEST OF THE STRUCTURE OF THE INTRINSIC ABSORBERS IN THE QUASAR HS 1603+3820

    SciTech Connect

    Misawa, Toru; Kawabata, Koji S.; Eracleous, Michael; Charlton, Jane C.; Kashikawa, Nobunari E-mail: mce@astro.psu.ed E-mail: kawabtkj@hiroshima-u.ac.j

    2010-08-20

    We report the results of a spectropolarimetric observation of the C VI 'mini-broad' absorption line (mini-BAL) in the quasar HS 1603+3820 (z {sub em} = 2.542). The observations were carried out with the FOCAS instrument on the Subaru Telescope and yielded an extremely high polarization sensitivity of {delta}p{approx} 0.1%, at a resolving power of R {approx} 1500. HS 1603+3820 has been the target of a high-resolution spectroscopic monitoring campaign for more than four years, aimed at studying its highly variable C VI mini-BAL profile. Using the monitoring observations in an earlier paper, we were able to narrow down the causes of the variability to the following two scenarios: (1) scattering material of variable optical depth redirecting photons around the absorber and (2) a variable, highly ionized screen between the continuum source and the absorber which modulates the UV continuum incident on the absorber. The observations presented here provide a crucial test of the scattering scenario and lead us to disfavor it because (1) the polarization level is very small (p {approx} 0.6%) throughout the spectrum and (2) the polarization level does not increase across the mini-BAL trough. Thus, the variable screen scenario emerges as our favored explanation of the C VI mini-BAL variability. Our conclusion is bolstered by recent X-ray observations of nearby mini-BAL quasars, which show a rapidly variable soft X-ray continuum that appears to be the result of transmission through an ionized absorber of variable ionization parameter and optical depth.

  4. Very extended cold gas, star formation and outflows in the halo of a bright quasar at z > 6

    NASA Astrophysics Data System (ADS)

    Cicone, C.; Maiolino, R.; Gallerani, S.; Neri, R.; Ferrara, A.; Sturm, E.; Fiore, F.; Piconcelli, E.; Feruglio, C.

    2015-02-01

    Past observations of quasar host galaxies at z> 6 have found cold gas and star formation on compact scales of a few kiloparsecs. We present new high sensitivity IRAM Plateau de Bure Interferometer follow-up observations of the [C ii] 158 μm emission line and far-infrared (FIR) continuum in the host galaxy of SDSS J1148+5251, a luminous quasar at redshift 6.4189. We find that a large portion of the gas traced by [C ii] is at high velocities, up to ~1400 km s-1relative to the systemic velocity, confirming the presence of a major outflow as indicated by previous observations. The outflow has a complex morphology and reaches a maximum projected radius of ≃30 kpc. The extreme spatial extent of the outflow allows us, for the first time in an external galaxy, to estimate mass-loss rate, kinetic power, and momentum rate of the outflow as a function of the projected distance from the nucleus and the dynamical time scale. These trends reveal multiple outflow events during the past 100 Myr, although the bulk of the mass, energy, and momentum appear to have been released more recently within the past ~20 Myr. Surprisingly, we discover that the quiescent gas at systemic velocity is also extremely extended. More specifically, we find that, while 30% of the [C ii] within v ∈(-200, 200) km s-1 traces a compact component that is not resolved by our observations, 70% of the [C ii] emission in this velocity range is extended with a projected full width at half maximum (FWHM) size of 17.4 ± 1.4 kpc. We detect FIR continuum emission associated with both the compact and the extended [C ii] components, although the extended FIR emission has a FWHM of 11 ± 3 kpc, thus smaller than the extended [C ii] source. Overall, our results indicate that the cold gas traced by [C ii] is distributed up to r ~ 30 kpc in the host galaxy of SDSS J1148+5251. A large amount of extended [C ii] is likely to be associated with star formation occurring on large scales, but the [C ii] source extends well

  5. Multiple Views of the Accretion Disk and Outflow of the Cloverleaf Quasar.

    NASA Astrophysics Data System (ADS)

    Chartas, George; Eracleous, M.; Gallagher, S.; Agol, E.; Dai, X.

    2006-09-01

    We present results from Chandra and XMM-Newton observations of the low-ionization broad absorption line (LoBAL) quasar H 1413+117 (Cloverleaf quasar). Our spatial and spectral analysis confirm a microlensing event in one of the images. Based on the microlensing interpretation we estimate that the size-scale of the Fe emission region in this quasar is of the order of 10 rg. Our analysis of the combined Chandra spectrum of the images indicates the presence of two Fe emission lines at rest-frame energies of 5.4 keV and 6.3 keV and detected at the >97% and >99% confidence levels, respectively. The Fe Ka emission in the Cloverleaf quasar is fit well with an accretion disk-line model. Another possible interpretation of the Fe emission is fluorescent Fe emission from the back-side of the wind. The deep Chandra observation of H 1413+117 has also revealed several remarkable absorption features.The spectra of images C and D show significant high-energy broad absorption lines that extend up to rest-frame energies of 9 keV and 15 keV, respectively. We investigate several plausible scenarios to explain the spectral differences between the images.

  6. NuSTAR REVEALS RELATIVISTIC REFLECTION BUT NO ULTRA-FAST OUTFLOW IN THE QUASAR PG 1211+143

    SciTech Connect

    Zoghbi, A.; Miller, J. M.; Walton, D. J.; Stern, D.; Harrison, F. A.; Fabian, A. C.; Reynolds, C. S.; Boggs, S. E.; Craig, W.; Christensen, F. E.; Hailey, C. J.; Zhang, W. W.

    2015-02-01

    We report on four epochs of observations of the quasar PG 1211+143 using NuSTAR. The net exposure time is 300 ks. Prior work on this source found suggestive evidence of an ultra-fast outflow (UFO) in the Fe K band with a velocity of approximately 0.1c. The putative flow would carry away a high-mass flux and kinetic power, with broad implications for feedback and black hole--galaxy co-evolution. NuSTAR detects PG 1211+143 out to 30 keV, meaning that the continuum is well-defined both through and above the Fe K band. A characteristic relativistic disk reflection spectrum is clearly revealed via a broad Fe K emission line and Compton back-scattering curvature. The data offer only weak constraints on the spin of the black hole. A careful search for UFOs shows no significant absorption feature above 90% confidence. The limits are particularly tight when relativistic reflection is included. We discuss the statistics and the implications of these results in terms of connections between accretion onto quasars, Seyferts, and stellar-mass black holes, and feedback into their host environments.

  7. NuSTAR Reveals Relativistic Reflection But No Ultra-Fast Outflow in the Quasar Pg∼1211+143

    NASA Astrophysics Data System (ADS)

    Zoghbi, A.; Miller, J. M.; Walton, D. J.; Harrison, F. A.; Fabian, A. C.; Reynolds, C. S.; Boggs, S. E.; Christensen, F. E.; Craig, W.; Hailey, C. J.; Stern, D.; Zhang, W. W.

    2015-01-01

    We report on four epochs of observations of the quasar PG 1211+143 using NuSTAR. The net exposure time is 300 ks. Prior work on this source found suggestive evidence of an ultra-fast outflow (UFO) in the Fe K band with a velocity of approximately 0.1c. The putative flow would carry away a high-mass flux and kinetic power, with broad implications for feedback and black hole--galaxy co-evolution. NuSTAR detects PG 1211+143 out to 30 keV, meaning that the continuum is well-defined both through and above the Fe K band. A characteristic relativistic disk reflection spectrum is clearly revealed via a broad Fe K emission line and Compton back-scattering curvature. The data offer only weak constraints on the spin of the black hole. A careful search for UFOs shows no significant absorption feature above 90% confidence. The limits are particularly tight when relativistic reflection is included. We discuss the statistics and the implications of these results in terms of connections between accretion onto quasars, Seyferts, and stellar-mass black holes, and feedback into their host environments.

  8. The Evolution of Quasar C IV and Si IV Broad Absorption Lines over Multi-year Timescales

    NASA Astrophysics Data System (ADS)

    Gibson, Robert R.; Brandt, W. N.; Gallagher, S. C.; Hewett, Paul C.; Schneider, Donald P.

    2010-04-01

    We investigate the variability of C IV λ1549 broad absorption line (BAL) troughs over rest-frame timescales of up to ≈7 yr in 14 quasars at redshifts z >~ 2.1. For nine sources at sufficiently high redshift, we also compare the C IV and Si IV λ1400 absorption variation. We compare shorter and longer term variability using spectra from up to four different epochs per source and find complex patterns of variation in the sample overall. The scatter in the change of absorption equivalent width (EW), ΔEW, increases with the time between observations. BALs do not, in general, strengthen or weaken monotonically, and variation observed over shorter (lsimmonths) timescales is not predictive of multi-year variation. We find no evidence for asymmetry in the distribution of ΔEW that would indicate that BALs form and decay on different timescales, and we constrain the typical BAL lifetime to be gsim30 yr. The BAL absorption for one source, LBQS 0022+0150, has weakened and may now be classified as a mini-BAL. Another source, 1235+1453, shows evidence of variable, blue continuum emission that is relatively unabsorbed by the BAL outflow. C IV and Si IV BAL shape changes are related in at least some sources. Given their high velocities, BAL outflows apparently traverse large spatial regions and may interact with parsec-scale structures such as an obscuring torus. Assuming BAL outflows are launched from a rotating accretion disk, notable azimuthal symmetry is required in the outflow to explain the relatively small changes observed in velocity structure over times up to 7 yr.

  9. Physical Conditions in Quasar Outflows: Very Large Telescope Observations of QSO 2359-1241

    NASA Astrophysics Data System (ADS)

    Korista, Kirk T.; Bautista, Manuel A.; Arav, Nahum; Moe, Maxwell; Costantini, Elisa; Benn, Chris

    2008-11-01

    We analyze the physical conditions of the outflow seen in QSO 2359-1241 (NVSS J235953-124148), based on high-resolution spectroscopic VLT observations. This object was previously studied using Keck HIRES data. The main improvement over the HIRES results is our ability to accurately determine the number density of the outflow. For the major absorption component, the populations from five different Fe II excited levels yield a gas density nH = 104.4 cm-3 with less than 20% scatter. We find that the Fe II absorption arises from a region with roughly constant conditions and temperature greater than 9000 K, before the ionization front where temperature and electron density drop. Further, we model the observed spectra and investigate the effects of varying gas metallicities and the spectral energy distribution of the incident ionizing radiation field. The accurately measured column densities allow us to determine the ionization parameter (log UH ≈ - 2.4) and total column density of the outflow [log NH(cm -2) ≈ 20.6]. Combined with the number density finding, these are stepping stones toward determining the mass flux and kinetic luminosity of the outflow, and therefore its importance to AGN feedback processes. Based on observations made with ESO Telescopes at the Paranal Observatories under program 078.B-0433(A).

  10. Evidence for powerful AGN winds at high redshift: dynamics of galactic outflows in radio galaxies during the ``Quasar Era''

    NASA Astrophysics Data System (ADS)

    Nesvadba, N. P. H.; Lehnert, M. D.; De Breuck, C.; Gilbert, A. M.; van Breugel, W.

    2008-11-01

    AGN feedback now appears as an attractive mechanism to resolve some of the outstanding problems with the “standard” cosmological models, in particular those related to massive galaxies. At low redshift, evidence is growing that gas cooling and star formation may be efficiently suppressed by mechanical energy input from radio sources. To directly constrain how this may influence the formation of massive galaxies near the peak in the redshift distribution of powerful quasars, z˜ 2, we present an analysis of the emission-line kinematics of 3 powerful radio galaxies at z˜ 2-3 (HzRGs) based on rest-frame optical integral-field spectroscopy obtained with SINFONI on the VLT. The host galaxies of powerful radio-loud AGN are among the most massive galaxies, and thus AGN feedback may have a particularly clear signature in these galaxies. We find evidence for bipolar outflows in all HzRGs, with kinetic energies that are equivalent to 0.2% of the rest-mass of the supermassive black hole. Observed total velocity offsets in the outflows are ~800-1000 km s-1 between the blueshifted and redshifted line emission, and FWHMs ~ 1000 km s-1 suggest strong turbulence. Line ratios allow to measure electron temperatures, ~104 K from [OIII]λλλ4363, 4959, 5007 at z˜ 2, electron densities (~500 cm-3) and extinction (A_V˜ 1-4 mag). Ionized gas masses estimated from the Hα luminosity are of order 1010~M⊙, similar to the molecular gas content of HzRGs, underlining that these outflows may indicate a significant phase in the evolution of the host galaxy. The total energy release of ~1060 erg during a dynamical time of ~107 yrs corresponds to about the binding energy of a massive galaxy, similar to the prescriptions adopted in galaxy evolution models. Geometry, timescales and energy injection rates of order 10% of the kinetic energy flux of the jet suggest that the outflows are most likely driven by the radio source. The global energy density release of ~1057 erg s-1 Mpc-3 may also

  11. Stellar and quasar feedback in concert: effects on AGN accretion, obscuration, and outflows

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Torrey, Paul; Faucher-Giguère, Claude-André; Quataert, Eliot; Murray, Norman

    2016-05-01

    We study the interaction of feedback from active galactic nuclei (AGN) and a multiphase interstellar medium (ISM), in simulations including explicit stellar feedback, multiphase cooling, accretion-disc winds, and Compton heating. We examine radii ˜0.1-100 pc around a black hole (BH), where the accretion rate on to the BH is determined and where AGN-powered winds and radiation couple to the ISM. We conclude: (1) the BH accretion rate is determined by exchange of angular momentum between gas and stars in gravitational instabilities. This produces accretion rates ˜0.03-1 M⊙ yr-1, sufficient to power luminous AGN. (2) The gas disc in the galactic nucleus undergoes an initial burst of star formation followed by several million years where stellar feedback suppresses the star formation rate (SFR). (3) AGN winds injected at small radii with momentum fluxes ˜LAGN/c couple efficiently to the ISM and have dramatic effects on ISM properties within ˜100 pc. AGN winds suppress the nuclear SFR by factors ˜10-30 and BH accretion rate by factors ˜3-30. They increase the outflow rate from the nucleus by factors ˜10, consistent with observational evidence for galaxy-scale AGN-driven outflows. (4) With AGN feedback, the predicted column density distribution to the BH is consistent with observations. Absent AGN feedback, the BH is isotropically obscured and there are not enough optically thin sightlines to explain type-I AGN. A `torus-like' geometry arises self-consistently as AGN feedback evacuates gas in polar regions.

  12. Results of Monitoring the Dramatically Variable C IV Mini-Broad Absorption Line System in the Quasar HS 1603+3820

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Eracleous, Michael; Charlton, Jane C.; Kashikawa, Nobunari

    2007-05-01

    We present six new and two previously published high-resolution spectra of the quasar HS 1603+3820 (zem=2.542) taken over an interval of 4.2 yr (1.2 yr in the quasar rest frame). The observations were made with the High Dispersion Spectrograph on the Subaru telescope and the Medium Resolution Spectrograph on the Hobby-Eberly Telescope. The purpose was to study the narrow absorption lines (NALs). We use time variability and coverage fraction analysis to separate intrinsic absorption lines, which are physically related to the quasar, from intervening absorption lines. By fitting models to the line profiles, we derive the parameters of the respective absorbers as a function of time. Only the mini-BAL system at zabs~2.43 (vshift~9500 km s-1) shows both partial coverage and time variability, although two NAL systems possibly show evidence of partial coverage. We find that all the troughs of the mini-BAL system vary in concert and its total equivalent width variations resemble those of the coverage fraction. However, no other correlations are seen between the variations of different model parameters. Thus, the observed variations cannot be reproduced by a simple change of ionization state or by motion of a homogeneous parcel of gas across the cylinder of sight. We propose that the observed variations are a result of rapid continuum fluctuations, coupled with coverage fraction fluctuations caused by a clumpy screen of variable optical depth located between the continuum source and the mini-BAL gas. An alternative explanation is that the observed partial coverage signature is the result of scattering of continuum photons around the absorber, thus the equivalent width of the mini-BAL can vary as the intensity of the scattered continuum changes. Based on data collected at the Subaru telescope, which is operated by the National Astronomical Observatory of Japan.

  13. GALACTIC-SCALE ABSORPTION OUTFLOW IN THE LOW-LUMINOSITY QUASAR IRAS F04250-5718: HUBBLE SPACE TELESCOPE/COSMIC ORIGINS SPECTROGRAPH OBSERVATIONS

    SciTech Connect

    Edmonds, Doug; Borguet, Benoit; Arav, Nahum; Dunn, Jay P.; Penton, Steve; Kriss, Gerard A.; Korista, Kirk; Bautista, Manuel; Costantini, Elisa; Kaastra, Jelle; Steenbrugge, Katrien; Ignacio Gonzalez-Serrano, J.; Benn, Chris; Aoki, Kentaro; Behar, Ehud; Micheal Crenshaw, D.; Everett, John; Gabel, Jack; Moe, Maxwell; Scott, Jennifer

    2011-09-20

    We present absorption line analysis of the outflow in the quasar IRAS F04250-5718. Far-ultraviolet data from the Cosmic Origins Spectrograph on board the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization ions (e.g., C IV, N V, and O VI) as well as low ionization ions (e.g., C II and Si III). We identify three kinematic components with central velocities ranging from {approx}-50 to {approx}-230 km s{sup -1}. Velocity-dependent, non-black saturation is evident from the line profiles of the high ionization ions. From the non-detection of absorption from a metastable level of C II, we are able to determine that the electron number density in the main component of the outflow is {approx}<30 cm{sup -3}. Photoionization analysis yields an ionization parameter log U{sub H} {approx} -1.6 {+-} 0.2, which accounts for changes in the metallicity of the outflow and the shape of the incident spectrum. We also consider solutions with two ionization parameters. If the ionization structure of the outflow is due to photoionization by the active galactic nucleus, we determine that the distance to this component from the central source is {approx}>3 kpc. Due to the large distance determined for the main kinematic component, we discuss the possibility that this outflow is part of a galactic wind.

  14. SDSS J163459.82+204936.0: A Ringed Infrared-luminous Quasar with Outflows in Both Absorption and Emission Lines

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Juan; Zhou, Hong-Yan; Jiang, Ning; Wu, Xufen; Lyu, Jianwei; Shi, Xiheng; Shu, Xinwen; Jiang, Peng; Ji, Tuo; Wang, Jian-Guo; Wang, Shu-Fen; Sun, Luming

    2016-05-01

    SDSS J163459.82+204936.0 is a local (z = 0.1293) infrared-luminous quasar with L IR = 1011.91 {L}ȯ . We present a detailed multiwavelength study of both the host galaxy and the nucleus. The host galaxy, appearing as an early-type galaxy in the optical images and spectra, demonstrates violent, obscured star formation activities with SFR ≈ 140 {M}ȯ yr‑1, estimated from either the polycyclic aromatic hydrocarbon emission or IR luminosity. The optical to NIR spectra exhibit a blueshifted narrow cuspy component in Hβ, He i λλ5876, 10830, and other emission lines consistently with an offset velocity of ≈900 {km} {{{s}}}-1, as well as additional blueshifting phenomena in high-ionization lines (e.g., a blueshifted broad component of He i λ10830 and the bulk blueshifting of [O iii]λ5007), while there exist blueshifted broad absorption lines (BALs) in Na i D and He i λλ3889, 10830, indicative of the active galactic nucleus outflows producing BALs and emission lines. Constrained mutually by the several BALs in the photoionization simulations with Cloudy, the physical properties of the absorption line outflow are derived as follows: density 104 < n H ≲ 105 cm‑3, ionization parameter 10‑1.3 ≲ U ≲ 10‑0.7 , and column density 1022.5 ≲ N H ≲ 1022.9 cm‑2, which are similar to those derived for the emission line outflows. This similarity suggests a common origin. Taking advantages of both the absorption lines and outflowing emission lines, we find that the outflow gas is located at a distance of ˜48–65 pc from the nucleus and that the kinetic luminosity of the outflow is 1044–1046 {erg} {{{s}}}-1. J1634+2049 has a off-centered galactic ring on the scale of ˜30 kpc that is proved to be formed by a recent head-on collision by a nearby galaxy for which we spectroscopically measure the redshift. Thus, this quasar is a valuable object in the transitional phase emerging out of dust enshrouding as depicted by the co-evolution scenario invoking galaxy

  15. SDSS J163459.82+204936.0: A Ringed Infrared-luminous Quasar with Outflows in Both Absorption and Emission Lines

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Juan; Zhou, Hong-Yan; Jiang, Ning; Wu, Xufen; Lyu, Jianwei; Shi, Xiheng; Shu, Xinwen; Jiang, Peng; Ji, Tuo; Wang, Jian-Guo; Wang, Shu-Fen; Sun, Luming

    2016-05-01

    SDSS J163459.82+204936.0 is a local (z = 0.1293) infrared-luminous quasar with L IR = 1011.91 {L}⊙ . We present a detailed multiwavelength study of both the host galaxy and the nucleus. The host galaxy, appearing as an early-type galaxy in the optical images and spectra, demonstrates violent, obscured star formation activities with SFR ≈ 140 {M}⊙ yr-1, estimated from either the polycyclic aromatic hydrocarbon emission or IR luminosity. The optical to NIR spectra exhibit a blueshifted narrow cuspy component in Hβ, He i λλ5876, 10830, and other emission lines consistently with an offset velocity of ≈900 {km} {{{s}}}-1, as well as additional blueshifting phenomena in high-ionization lines (e.g., a blueshifted broad component of He i λ10830 and the bulk blueshifting of [O iii]λ5007), while there exist blueshifted broad absorption lines (BALs) in Na i D and He i λλ3889, 10830, indicative of the active galactic nucleus outflows producing BALs and emission lines. Constrained mutually by the several BALs in the photoionization simulations with Cloudy, the physical properties of the absorption line outflow are derived as follows: density 104 < n H ≲ 105 cm-3, ionization parameter 10-1.3 ≲ U ≲ 10-0.7 , and column density 1022.5 ≲ N H ≲ 1022.9 cm-2, which are similar to those derived for the emission line outflows. This similarity suggests a common origin. Taking advantages of both the absorption lines and outflowing emission lines, we find that the outflow gas is located at a distance of ˜48-65 pc from the nucleus and that the kinetic luminosity of the outflow is 1044-1046 {erg} {{{s}}}-1. J1634+2049 has a off-centered galactic ring on the scale of ˜30 kpc that is proved to be formed by a recent head-on collision by a nearby galaxy for which we spectroscopically measure the redshift. Thus, this quasar is a valuable object in the transitional phase emerging out of dust enshrouding as depicted by the co-evolution scenario invoking galaxy merger (or

  16. The XMM deep survey in the CDF-S. IX. An X-ray outflow in a luminous obscured quasar at z ≈ 1.6

    NASA Astrophysics Data System (ADS)

    Vignali, C.; Iwasawa, K.; Comastri, A.; Gilli, R.; Lanzuisi, G.; Ranalli, P.; Cappelluti, N.; Mainieri, V.; Georgantopoulos, I.; Carrera, F. J.; Fritz, J.; Brusa, M.; Brandt, W. N.; Bauer, F. E.; Fiore, F.; Tombesi, F.

    2015-11-01

    In active galactic nuclei (AGN)-galaxy co-evolution models, AGN winds and outflows are often invoked to explain why super-massive black holes and galaxies stop growing efficiently at a certain phase of their lives. They are commonly referred to as the leading actors of feedback processes. Evidence of ultra-fast (v ≳ 0.05c) outflows in the innermost regions of AGN has been collected in the past decade by sensitive X-ray observations for sizable samples of AGN, mostly at low redshift. Here we present ultra-deep XMM-Newton and Chandra spectral data of an obscured (NH≈ 2 × 1023 cm-2), intrinsically luminous (L2-10 keV≈ 4 × 1044 erg s-1) quasar (named PID352) at z ≈ 1.6 (derived from the X-ray spectral analysis) in the Chandra Deep Field-South. The source is characterized by an iron emission and absorption line complex at observed energies of E ≈ 2-3 keV. While the emission line is interpreted as being due to neutral iron (consistent with the presence of cold absorption), the absorption feature is due to highly ionized iron transitions (FeXXV, FeXXVI) with an outflowing velocity of , as derived from photoionization models. The mass outflow rate - ~2 M⊙ yr-1 - is similar to the source accretion rate, and the derived mechanical energy rate is ~9.5 × 1044 erg s-1, corresponding to 9% of the source bolometric luminosity. PID352 represents one of the few cases where indications of X-ray outflowing gas have been observed at high redshift thus far. This wind is powerful enough to provide feedback on the host galaxy.

  17. The Complete Ultraviolet Spectrum of the Archetypal "Wind-dominated" Quasar Mrk 231: Absorption and Emission from a High-speed Dusty Nuclear Outflow

    NASA Astrophysics Data System (ADS)

    Veilleux, S.; Meléndez, M.; Tripp, T. M.; Hamann, F.; Rupke, D. S. N.

    2016-07-01

    New near- and far-ultraviolet (NUV and FUV) Hubble Space Telescope spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ˜7000 km s-1), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na i D, He i, and Ca ii H and K lines, exhibiting broad blueshifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ˜90% of the observed continuum source at a distance ≲2-20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ˜22 (3) years and are unresolved on scales ˜40 (170) pc. These results favor an active galactic nucleus origin for the NUV-FUV line and continuum emission. The observed FUV line emission is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad line region seen through the dusty BAL screen. Our data are inconsistent with the recently proposed binary black hole model. We argue instead that Mrk 231 is the nearest example of weak-lined “wind-dominated” quasars with high Eddington ratios and geometrically thick (“slim”) accretion disks; these quasars are likely more common in the early universe.

  18. X-RAYS FROM A RADIO-LOUD COMPACT BROAD ABSORPTION LINE QUASAR 1045+352 AND THE NATURE OF OUTFLOWS IN RADIO-LOUD BROAD ABSORPTION LINE QUASARS

    SciTech Connect

    Kunert-Bajraszewska, Magdalena; Katarzynski, Krzysztof; Siemiginowska, Aneta; Janiuk, Agnieszka

    2009-11-10

    We present new results on X-ray properties of radio-loud broad absorption line (BAL) quasars and focus on broadband spectral properties of a high-ionization BAL (HiBAL) compact steep spectrum (CSS) radio-loud quasar 1045+352. This HiBAL quasar has a very complex radio morphology indicating either strong interactions between a radio jet and the surrounding interstellar medium or a possible re-start of the jet activity. We detected 1045+352 quasar in a short 5 ksec Chandra ACIS-S observation. We applied theoretical models to explain spectral energy distribution of 1045+352 and argue that non-thermal, inverse-Compton (IC) emission from the innermost parts of the radio jet can account for a large fraction of the observed X-ray emission. In our analysis, we also consider a scenario in which the observed X-ray emission from radio-loud BAL quasars can be a sum of IC jet X-ray emission and optically thin corona X-ray emission. We compiled a sample of radio-loud BAL quasars that were observed in X-rays to date and report no correlation between their X-ray and radio luminosity. However, the radio-loud BAL quasars show a large range of X-ray luminosities and absorption columns. This is consistent with the results obtained earlier for radio-quiet BAL quasars and may indicate an orientation effect in BAL quasars or more complex dependence between X-ray emission, radio emission, and an orientation based on the radio morphology.

  19. The X-ray spectrum and spectral energy distribution of FIRST J155633.8+351758: a LoBAL quasar with a probable polar outflow

    NASA Astrophysics Data System (ADS)

    Berrington, Robert C.; Brotherton, Michael S.; Gallagher, Sarah C.; Ganguly, Rajib; Shang, Zhaohui; DiPompeo, Michael; Chatterjee, Ritaban; Lacy, Mark; Gregg, Michael D.; Hall, Patrick B.; Laurent-Muehleisen, S. A.

    2013-12-01

    We report the results of a new 60 ks Chandra X-ray Observatory Advanced CCD Imaging Spectrometer S-array (ACIS-S) observation of the reddened, radio-selected, highly polarized `FeLoBAL' quasar FIRST J1556+3517. We investigated a number of models of varied sophistication to fit the 531-photon spectrum. These models ranged from simple power laws to power laws absorbed by hydrogen gas in differing ionization states and degrees of partial covering. Preferred fits indicate that the intrinsic X-ray flux is consistent with that expected for quasars of similarly high luminosity, i.e. an intrinsic, dereddened and unabsorbed optical to X-ray spectral index of -1.7. We cannot tightly constrain the intrinsic X-ray power-law slope, but find indications that it is flat (photon index Γ = 1.7 or flatter at a >99 per cent confidence for a neutral hydrogen absorber model). Absorption is present, with a column density a few times 1023 cm-2, with both partially ionized models and partially covering neutral hydrogen models providing good fits. We present several lines of argument that suggest the fraction of X-ray emissions associated with the radio jet is not large. We combine our Chandra data with observations from the literature to construct the spectral energy distribution of FIRST J1556+3517 from radio to X-ray energies. We make corrections for Doppler beaming for the pole-on radio jet, optical dust reddening and X-ray absorption, in order to recover a probable intrinsic spectrum. The quasar FIRST J1556+3517 seems to be an intrinsically normal radio-quiet quasar with a reddened optical/UV spectrum, a Doppler-boosted but intrinsically weak radio jet and an X-ray absorber not dissimilar from that of other broad absorption line quasars.

  20. The X-ray Spectrum and Spectral Energy Distribution of FIRST J155633.8+351758: A Beamed Radio-Quiet Quasar with a Polar Outflow

    NASA Astrophysics Data System (ADS)

    Berrington, Robert C.; Brotherton, M. S.; Gallagher, S. C.; Ganguly, R.; Shang, Z.; Lacy, M.; Gregg, M. D.; Hall, P. B.; Laurent-Muehleisen, S. A.

    2007-12-01

    We report the results of a 60 ks Chandra X-ray Observatory ACIS-S observation of the reddened, radio-selected, highly polarized "FeLoBAL" quasar FIRST J155633.8+351758. Our analyses of the 531 photon spectrum indicate that the intrinsic X-ray flux is consistent with that expected for quasars of similarly high luminosity. We cannot tightly constrain the intrinsic X-ray power-law slope, but find indications that it is flat (photon index Γ = 1.7 or flatter). No iron K-α line is detected, and the X-rays appear to be down by only an order of magnitude below their intrinsic unabsorbed levels. Absorption is present with both partially ionized models and neutral hydrogen models with partial covering providing good fits. The level of partial covering in the latter model is consistent with the rest-frame ultraviolet maximum polarization of 13%, in the sense that light scattered by electrons around the X-ray absorber could account for both results. We present the spectral energy distribution (SED) of FIRST J155633.8+351758 from radio through X-ray energies, and make corrections for Doppler beaming for the pole-on radio-quiet jet, optical dust reddening, and X-ray absorption. The corrected SED appears to be that of a luminous radio-quiet quasar deficient in the mid and far-infrared, suggesting that the dust covering fraction of the quasar is not large and that star formation is not excessive. FIRST J155633.8+351758 seems to be an intrinsically normal radio-quiet quasar with an X-ray absorber not dissimilar from that of other broad absorption line quasars studied in detail at X-ray wavelengths. We acknowledge support from Chandra Award No. GO6-7105X, from the US NSF (grant AST 05-07781), from NASA under the grant NNG05GD03G, and from the National Natural Science Foundation of China (grant 10643001). This work was performed under the auspices of the US DOE by the University of California, LLNL (Contract No. W-7405-Eng-48).

  1. Quasar Dust Factories.

    NASA Astrophysics Data System (ADS)

    Marengo, Massimo; Elvis, Martin; Karovska, Margarita

    We show that quasars are naturally copious producers of dust, assuming only that the quasar broad emission lines (BELs) are produced by gas clouds that are part of an outflowing wind. These BEL clouds have large initial densities (ne ˜109 - 1011 cm-3) so that as they expand quasi-adiabatically they cool from an initial T = 104 K to a dust-capable T = 103 K, and reduce their pressures from ˜0.1 dyn cm-2 to ˜ 10-3 -10-5 dyn cm-2.. This places the expanded BEL clouds in the (T,P) dust forming regime of late-type giants extended atmospheres, both static and pulsing. The result applies whether the clouds have C/O abundance ratio greater or lower than 1. Photo-destruction of the grains by the quasar UV/X-ray continuum is not important, as the BEL clouds reach these conditions several parsecs from the quasar nucleus, well below the dust evaporation temperature. This result offers a new insight for the strong link between quasars and dust, and for the heavy obscuration around many quasars. It also introduces a new means of forming dust at early cosmological times, and a direct mechanism for the injection of such dust in the intergalactic medium. Since dust at high z is found only by observing quasars, our result allows far less dust to be present at early epochs, since dust only need be present where a quasar is, rather than the quasar illuminating pre-existing dust which would then need to be present in all galaxies at high z. See astro-ph/0202002 or ApJ 576, L107 (2002).

  2. X-ray absorption and high redshift quasars

    NASA Technical Reports Server (NTRS)

    Elvis, Martin

    1996-01-01

    The low energy cut-offs toward radio-loud quasars with z greater than 2, red quasars, and broad absorption line quasars are discussed. The X-ray absorption seems to be common among different types of red shift quasar. The Rosat position sensitive proportional counter (PSPC) spectra of z = 3 quasars and of a red quasar are presented. Broad absorption lines show outflow velocities of up to 0.1 c to 0.2 c. The advantages and the disadvantages of high red shift observations are underlined.

  3. Quasar microlensing

    NASA Astrophysics Data System (ADS)

    Schmidt, R. W.; Wambsganss, J.

    2010-09-01

    Quasar microlensing deals with the effect of compact objects along the line of sight on the apparent brightness of the background quasars. Due to the relative motion between quasar, lenses and observer, the microlensing magnification changes with time which results in uncorrelated brightness variations in the various images of multiple quasar systems. The amplitudes of the signal can be more than a magnitude with time scales of weeks to months to years. The effect is due to the “granular” nature of the gravitational microlenses—stars or other compact objects in the stellar mass range. Quasar microlensing allows to study the quasar accretion disk with a resolution of tens of microarcseconds, hence quasar microlensing can be used to explore an astrophysical field that is hardly accessible by any other means. Quasar microlensing can also be used to study the lensing objects in a statistical sense, their nature (compact or smoothly distributed, normal stars or dark matter) as well as transverse velocities. Quasar microlensing light curves are now being obtained from monitoring programs across the electromagnetic spectrum from the radio through the infrared and optical range to the X-ray regime. Recently, spectroscopic microlensing was successfully applied, it provides quantitative comparisons with quasar/accretion disk models. There are now more than a handful of systems with several-year long light curves and significant microlensing signal, lending to detailed analysis. This review summarizes the current state of the art of quasar microlensing and shows that at this point in time, observational monitoring programs and complementary intense simulations provide a scenario where some of the early promises of quasar microlensing can be quantitatively applied. It has been shown, e.g., that smaller sources display more violent microlensing variability, first quantitative comparison with accretion disk models has been achieved, and quasar microlensing has been used to

  4. Quasar feedback and the origin of radio emission in radio-quiet quasars

    NASA Astrophysics Data System (ADS)

    Zakamska, Nadia L.; Greene, Jenny E.

    2014-07-01

    We analyse Sloan Digital Sky Survey spectra of 568 obscured luminous quasars. The [O III] λ5007 Å emission line shows blueshifts and blue excess, indicating that some of the narrow-line gas is undergoing an organized outflow. The velocity width containing 90 per cent of line power ranges from 370 to 4780 km s-1, suggesting outflow velocities up to ˜2000 km s-1, and is strongly correlated with the radio luminosity among the radio-quiet quasars. We propose that radio emission in radio-quiet quasars is due to relativistic particles accelerated in the shocks within the quasar-driven outflows; star formation in quasar hosts is insufficient to explain the observed radio emission. The median radio luminosity of the sample of νLν[1.4 GHz] = 1040 erg s-1 suggests a median kinetic luminosity of the quasar-driven wind of Lwind = 3 × 1044 erg s-1, or about 4 per cent of the estimated median bolometric luminosity Lbol = 8 × 1045 erg s-1. Furthermore, the velocity width of [O III] is positively correlated with mid-infrared luminosity, which suggests that outflows are ultimately driven by the radiative output of the quasar. Emission lines characteristic of shocks in quasi-neutral medium increase with the velocity of the outflow, which we take as evidence of quasar-driven winds propagating into the interstellar medium of the host galaxy. Quasar feedback appears to operate above the threshold luminosity of Lbol ˜ 3 × 1045 erg s-1.

  5. HST images of FeLoBAL quasars: Testing quasar-galaxy evolution models

    NASA Astrophysics Data System (ADS)

    Herbst, Hanna; Hamann, Fred; Villforth, Carolin; Caselli, Paola; Koekemoer, Anton M.; Veilleux, Sylvain

    2016-01-01

    We present preliminary results from an HST imaging study of FeLoBAL quasars, which have extremely low-ionization Broad Absorption Line (BAL) outflows and might be a young quasar population based on their red colors, large far-IR luminosities (suggesting high star formation rates), and powerful outflows. Some models of quasar - host galaxy evolution propose a triggering event, such as a merger, to fuel both a burst of star formation and the quasar/AGN activity. These models suggest young quasars are initially obscured inside the dusty starburst until a "blowout" phase, driven by the starburst or quasar outflows like FeLoBALs, ends the star formation and reveals the visibly luminous quasar. Despite the popularity of this evolution scheme, there is little observational evidence to support the role of mergers in triggering AGN or the youth of dust-reddened quasars (such as FeLoBALs) compared to normal blue quasars.Our Cycle 22 HST program is designed to test the youth of FeLoBAL quasars and the connection of FeLoBALs to mergers. We obtain WFC3/IR F160W images of 10 FeLoBAL quasars at redshift z~0.9 (covering ~8500A in the quasar rest frame). We will compare the host galaxy morphologies and merger signatures of FeLoBALs with normal blue quasars (which are older according to the evolution model) and non-AGN galaxies matched in redshift and stellar mass. If FeLoBAL quasars are indeed in a young evolutionary state, close in time to the initial merging event, they should have stronger merger features compared to blue quasars and non-AGN galaxies. Preliminary results suggest that this is not the case - FeLoBAL quasars appear to reside in faint, compact hosts with weak or absent merger signatures. We discuss the implications of these results for galaxy evolution models and other studies of dust-reddened quasar populations.

  6. Extreme Red Quasars in SDSS-BOSS

    NASA Astrophysics Data System (ADS)

    Hamann, Fred; Zakamska, Nadia; Paris, Isabelle; Herbst, Hanna; Villforth, Carolin; Alexandroff, Rachael; Ross, Nicholas; Greene, Jenny; Strauss, Michael

    2015-08-01

    Red quasars are believed to mark a critical transition stage of massive galaxy evolution when a blowout of gas and dust truncates the initial starburst and provides our first visible views of a luminous central AGN. Red quasars could therefore have unusual properties associated with a young evolution stage, such as higher accretion rates, higher rates of mergers and interactions, and more common or more powerful outflows capable of driving a galaxy-wide blowout (e.g., compared to normal blue quasars in presumably more evolved galaxy hosts). The recently completed Baryon Oscillation Spectroscopy Survey (BOSS) of SDSS-III has discovered many more faint quasars with higher redshifts and redder colors than any previous large survey. We combine BOSS spectra with SDSS and Wide-Field Infrared Survey Explorer (WISE) photometry of nearly 100,000 quasars to identify and characterize the red quasar population at redshifts >2. We find a number of strong trends with the amount of reddening/obscuration. For example, red quasars are 5 to 8 times more likely to have broad absorption lines and other "intrinsic" absorption lines that identify quasar-driven outflows. Perhaps most interesting is that extreme red quasars (ERQs), selected via rest-frame UV to near-IR colors similar to Dust Obscured Galaxies (DOGs), have uniquely exotic emission line properties that include extreme velocity shifts between lines and the broadest and most blueshifted [OIII] lines yet discovered (with FWHMs reaching >3000 km/s). We will discuss the implications of these results for models of the structure and evolution of quasars and their host galaxy environments.

  7. Protostellar Outflows

    NASA Astrophysics Data System (ADS)

    Bally, John

    2016-09-01

    Outflows from accreting, rotating, and magnetized systems are ubiquitous. Protostellar outflows can be observed from radio to X-ray wavelengths in the continuum and a multitude of spectral lines that probe a wide range of physical conditions, chemical phases, radial velocities, and proper motions. Wide-field visual and near-IR data, mid-IR observations from space, and aperture synthesis with centimeter- and millimeterwave interferometers are revolutionizing outflow studies. Many outflows originate in multiple systems and clusters. Although most flows are bipolar and some contain highly collimated jets, others are wide-angle winds, and a few are nearly isotropic and exhibit explosive behavior. Morphologies and velocity fields indicate variations in ejection velocity, mass-loss rate, and in some cases, flow orientation and degree of collimation. These trends indicate that stellar accretion is episodic and often occurs in a complex dynamical environment. Outflow power increases with source luminosity but decreases with evolutionary stage. The youngest outflows are small and best traced by molecules such as CO, SiO, H2O, and H2. Older outflows can grow to parsec scales and are best traced by shock-excited atoms and ions such as hydrogen-recombination lines, [Sii], and [Oii]. Outflows inject momentum and energy into their surroundings and provide an important mechanism in the self-regulation of star formation. However, momentum injection rates remain uncertain with estimates providing lower bounds.

  8. Powerful Winds in Extreme RBS quasars (POWER)

    NASA Astrophysics Data System (ADS)

    Piconcelli, Enrico

    2013-10-01

    This proposal aims at studying powerful outflows in ultra-luminous (log Lx >45) Radio-Quiet Quasars (RQQ). We propose to observe four objects extracted from a luminosity limited sample in the ROSAT Bright Survey for a full orbit (130 ks) each. Both models and observations suggest that the efficiency of driving energetic outflows increases with the AGN luminosity. Therefore, our targets are potentially the best objects to hunt for very powerful outflows expected in the AGN/galaxy feedback scenario. Our observations represent the first attempt ever to obtain deep, high-resolution-driven spectroscopy of a representative sample of RQQ in this high-luminosity regime.

  9. Absorbing Outflows in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  10. Spectrophotometry of Michigan-Tololo quasars

    NASA Technical Reports Server (NTRS)

    Lewis, D. W.; Macalpine, G. M.; Weedman, D. W.

    1979-01-01

    Emission-line quasar characteristics are confirmed for 80% of the objects observed, including at least four new quasars with spectral features indicative of supernova-like outflow. Approximately 73% of the redshifts predicted from the discovery plates are found accurate with a mean error in z of 0.03, and a large range of z (from about 0.1 to 3.16) is represented in the sample. The observed redshift distribution for quasars is marginally consistent with a constant co-moving quasar density above z approximately 2.0. The shape of the redshift distribution may be used as an isotropy probe with a cosmic time resolution of a few times one-hundred million years in the early universe; therefore, continued surveys of this sort are important even if accurate magnitudes are not determined.

  11. Through BAL Quasars Brightly

    NASA Technical Reports Server (NTRS)

    Chartas, George

    2003-01-01

    We report on an observation of the broad absorption line (BAL) quasar PG 1115+080 performed with the XMM-Newton observatory. Spectral analysis reveals the second case of a relativistic X-ray-absorbing outflow in a BAL quasar. The first case was revealed in a recent observation of APM 08279+5255 with the Chandra X-Ray Observatory. As in the case of APM 08279+5255, the observed flux of PG 1115+080 is greatly magnified by gravitational lensing. The relatively high redshift (z=1.72) of the quasar places the redshifted energies of resonant absorption features in a sensitive portion of the XMM- Newton spectral response. The spectrum indicates the presence of complex low-energy absorption in the 0.2-0.6 keV observed energy band and high-energy absorption in the 2-5 keV observed energy band. The high-energy absorption is best modeled by two Gaussian absorption lines with rest-frame energies of 7.4 and 9.5 keV. Assuming that these two lines axe produced by resonant absorption due to Fe XXV, we infer that the X-ray absorbers are outflowing with velocities of approx. 0.10c and approx. 0.34c respectively. We have detected significant variability of the energies and widths of the X-ray BALs in PG 1115+080 and APM 08279+5255 over timescales of 19 and 1.8 weeks (proper time), respectively. The BAL variability observed from APM 08279+5255 supports our earlier conclusion that these absorbers are most likely launched at relatively small radii of less than 10(exp 16)(Mbh/M8)(sup 1/2) cm. A comparison of the ionization properties and column densities of the low-energy and high-energy absorbers indicates that these absorbers are likely distinct; however, higher spectral resolution is needed to confirm this result. Finally, we comment on prospects for constraining the kinematic and ionization properties of these X-ray BALs with the next generation of X-ray observatories.

  12. Blue outliers among intermediate redshift quasars

    NASA Astrophysics Data System (ADS)

    Marziani, P.; Sulentic, J. W.; Stirpe, G. M.; Dultzin, D.; Del Olmo, A.; Martínez-Carballo, M. A.

    2016-01-01

    [OIII]λ 5007 "blue outliers"—that are suggestive of outflows in the narrow line region of quasars—appear to be much more common at intermediate z (high luminosity) than at low z. About 40~% of quasars in a Hamburg ESO intermediate z sample of 52 sources qualify as "blue outliers" (i.e., quasars with [OIII]λλ 4959,5007 lines showing large systematic blueshifts with respect to rest frame). We discuss major findings on what has become an intriguing field in active galactic nuclei research and stress the relevance of "blue outliers" to feedback and host galaxy evolution.

  13. Powerful Molecular Outflows in Nearby Active Galaxies

    NASA Astrophysics Data System (ADS)

    Veilleux, Sylvain; Meléndez, Marcio

    2014-07-01

    We report the results from a systematic search for molecular (OH 119 μm) outflows with Herschel-PACS† in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7-μm silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than -50 km s-1, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (~ 145°) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km s-1, is seen in only 4 objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of ~ -1000 km s-1 are measured in several objects, but median outflow velocities are typically ~ -200 km s-1. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large AGN fractions and luminosities [log (L AGN/L ⊙) >= 11.8 +/- 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. In contrast, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

  14. Ultra-fast outflows (aka UFOs) from AGNs and QSOs

    NASA Astrophysics Data System (ADS)

    Cappi, M.; Tombesi, F.; Giustini, M.

    During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of the most recent developments in this field and discuss the relevance of UFOs for both understanding the physics of accretion disk winds in AGNs, and for quantifying the global amount of AGN feedback on the surrounding medium.

  15. Monitoring Emergent Absorption Troughs in Quasars

    NASA Astrophysics Data System (ADS)

    Hall, Patrick; Rodriguez Hidalgo, Paola; Brandt, W. Niel; Rogerson, Jesse; Filiz Ak, Nur; Chajet, Laura

    2014-02-01

    Outflows from luminous AGN are important ingredients in galaxy formation. These outflows manifest as broad absorption line (BAL) troughs in quasar spectra. Trough variability can be used to constrain the physical parameters of these absorbing structures through comparison to models and simulations of accretion disk winds. Monitoring appearing/disappearing BAL troughs can constrain the distribution of BAL trough lifetimes along our line of sight. By comparing spectra from the SDSS Data Release (DR) 7 and DR 9, we identified 68 quasars in whose spectra new absorption troughs have appeared over 300-1200 restframe days, including one trough outflowing at v=60,000 km/s. We propose to complete our third-epoch GMOS spectroscopy of the brightest of those quasars (48 in 2013AB and 9 proposed here) to measure the absorption strength in newly appeared troughs <=365 restframe days after their previous measurement. Preliminary 2013AB results indicate that troughs are not on average still strengthening between SDSS and Gemini epochs; we therefore propose observations of 40 targets to probe shorter rest-frame time separations. We also target 8 objects showing simultaneous absorption variations in multiple ionization states, to help develop methods to distinguish absorption variations from cloud motion vs. those from ionization changes within clouds.

  16. Unveiling the X-ray/UV properties of disk winds in active galactic nuclei using broad and mini-broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    Giustini, M.

    2016-05-01

    We present the results of the uniform analysis of 46 XMM-Newton observations of six BAL and seven mini-BAL QSOs belonging to the Palomar-Green Quasar catalogue. Moderate-quality X-ray spectroscopy was performed with the EPIC-pn, and allowed to characterise the general source spectral shape to be complex, significantly deviating from a power law emission. A simple power law analysis in different energy bands strongly suggests absorption to be more significant than reflection in shaping the spectra. If allowing for the absorbing gas to be either partially covering the continuum emission source or to be ionised, large column densities of the order of 1022-1024 cm-2 are inferred. When the statistics was high enough, virtually every source was found to vary in spectral shape on various time scales, from years to hours. All in all these observational results are compatible with radiation driven accretion disk winds shaping the spectra of these intriguing cosmic sources.

  17. Relativistic redshifts in quasar broad lines

    SciTech Connect

    Tremaine, Scott; Shen, Yue; Liu, Xin; Loeb, Abraham E-mail: yshen@obs.carnegiescience.edu E-mail: aloeb@cfa.harvard.edu

    2014-10-10

    The broad emission lines commonly seen in quasar spectra have velocity widths of a few percent of the speed of light, so special- and general-relativistic effects have a significant influence on the line profile. We have determined the redshift of the broad Hβ line in the quasar rest frame (determined from the core component of the [O III] line) for over 20,000 quasars from the Sloan Digital Sky Survey Data Release 7 quasar catalog. The mean redshift as a function of line width is approximately consistent with the relativistic redshift that is expected if the line originates in a randomly oriented Keplerian disk that is obscured when the inclination of the disk to the line of sight exceeds ∼30°-45°, consistent with simple active galactic nucleus unification schemes. This result also implies that the net line-of-sight inflow/outflow velocities in the broad-line region are much less than the Keplerian velocity when averaged over a large sample of quasars with a given line width.

  18. BAL OUTFLOW CONTRIBUTION TO AGN FEEDBACK: FREQUENCY OF S IV OUTFLOWS IN THE SDSS

    SciTech Connect

    Dunn, Jay P.; Arav, Nahum; Laughlin, Courtney; Edmonds, Doug; Aoki, Kentaro; Wilkins, Ashlee; Bautista, Manuel E-mail: arav@vt.edu E-mail: kentaro.aoki@hawaiiantel.net E-mail: manuel.bautista@wmich.edu

    2012-05-10

    We present a study of broad absorption line (BAL) quasar outflows that show S IV {lambda}1063 and S IV* {lambda}1073 troughs. The fractional abundances of S IV and C IV peak at similar value of the ionization parameter, implying that they arise from the same physical component of the outflow. Detection of the S IV* troughs will allow us to determine the distance to this gas with higher resolution and higher signal-to-noise spectra, therefore providing the distance and energetics of the ubiquitous C IV BAL outflows. In our bright sample of 156 SDSS quasars, 14% show C IV and 1.9% S IV troughs, which are consistent with a fainter magnitude sample with twice as many objects. One object in the fainter sample shows evidence of a broad S IV trough without any significant trough present from the excited state line, which implies that this outflow could be at a distance of several kpc. Given the fractions of C IV and S IV, we establish firm limits on the global covering factor on S IV that ranges from 2.8% to 21% (allowing for the k-correction). Comparison of the expected optical depth for these ions with their detected percentage suggests that these species arise from common outflows with a covering factor closer to the latter.

  19. Unveiling the X-ray/UV properties of AGN winds using Broad and mini-Broad Absorption Line Quasars

    NASA Astrophysics Data System (ADS)

    Giustini, M.

    2015-07-01

    BAL/mini-BALs are observed in the UV spectra of ˜ 20-30% of optically selected AGN as broad absorption troughs blueshifted by several thousands km/s, indicative of powerful nuclear winds. They could be representative of the average AGN if their winds cover only 20-30% of the continuum source, and/or represent an evolutionary state analogous to the high-soft state of BHB, when the jet emission is quenched and strong X-ray absorbing equatorial disk winds are virtually ubiquitous. High-quality, possibly time-resolved X-ray/UV studies are crucial to assess the global amount and 'character' of absorption in BAL/mini-BAL QSOs and to constrain the physical mechanism responsible for the launch and acceleration of their winds, therefore placing them in the broader context of AGN geometry and evolution. I will review here the known X-ray properties of BAL/mini-BAL QSOs, and present new results from a comprehensive X-ray spectral analysis of all the Palomar-Green BAL/mini-BAL QSOs with available XMM-Newton observations, for a total of 51 pointings of 14 different sources. These will include the most recent results from a high-quality simultaneous XMM/HST observational campaign on the mini-BAL QSO PG 1126-041, that unveiled with stunning details the X-ray/UV connection in action in an AGN disk wind through correlated X-ray/UV absorption variability.

  20. SPITZER OBSERVATIONS OF YOUNG RED QUASARS

    SciTech Connect

    Urrutia, Tanya; Lacy, Mark; Spoon, Henrik; Glikman, Eilat; Petric, Andreea; Schulz, Bernhard E-mail: mlacy@nrao.edu E-mail: eilat.glikman@yale.edu E-mail: bschulz@ipac.caltech.edu

    2012-10-01

    We present mid-infrared spectra and photometry of 13 redshift 0.4 < z < 1 dust reddened quasars obtained with Spitzer IRS and MIPS. We compare properties derived from their infrared spectral energy distributions (intrinsic active galactic nucleus (AGN) luminosity and far-infrared luminosity from star formation) to the host luminosities and morphologies from Hubble Space Telescope imaging, and black hole masses estimated from optical and/or near-infrared spectroscopy. Our results are broadly consistent with models in which most dust reddened quasars are an intermediate phase between a merger-driven starburst triggering a completely obscured AGN, and a normal, unreddened quasar. We find that many of our objects have high accretion rates, close to the Eddington limit. These objects tend to fall below the black hole mass-bulge luminosity relation as defined by local galaxies, whereas most of our low accretion rate objects are slightly above the local relation, as typical for normal quasars at these redshifts. Our observations are therefore most readily interpreted in a scenario in which galaxy stellar mass growth occurs first by about a factor of three in each merger/starburst event, followed sometime later by black hole growth by a similar amount. We do not, however, see any direct evidence for quasar feedback affecting star formation in our objects, for example, in the form of a relationship between accretion rate and star formation. Five of our objects, however, do show evidence for outflows in the [O III]5007 A emission line profile, suggesting that the quasar activity is driving thermal winds in at least some members of our sample.

  1. Quasar feedback at the peak of the galaxy formation epoch

    NASA Astrophysics Data System (ADS)

    Alexandroff, Rachael; Zakamska, Nadia; Liu, Guilin; Greene, Jenny; Strauss, Michael

    2014-08-01

    Feedback from accreting supermassive black holes is now a standard ingredient in galaxy formation models. It is seen as necessary for limiting the maximal masses of galaxies and for establishing the black- hole / bulge correlations. Using Gemini GMOS, we demonstrated that powerful ionized gas winds are a ubiquitous feature in luminous obscured z=0.5 quasars. We now propose to extend this discovery to the epoch of peak galaxy formation and quasar activity - to the era at which feedback was most prominent and the galaxy / black hole correlations were established. We request 4.5 hours of Gemini-NIFS LGS adaptive- optics observations of an extremely luminous moderately obscured quasar at z=2.3 to map the morphology and kinematics of the ionized gas and to determine whether it exhibits the signs of black hole feedback in the form of an unbound ionized gas outflow. We will observe H(beta) and [OIII](lambda)5007Ain the H-band and H(alpha) and [NII](lambda)(lambda)6548,6583Ain the K-band on sub-galactic and galaxy-wide scales (spatial resolution 0.8 kpc, field of view 24 kpc). Obscured quasars likely constitute the majority of the quasar population and may represent the relatively early enshrouded phase of the black hole growth; thus, luminous obscured quasars are the most likely sites of quasar feedback, in agreement with our findings at low redshift.

  2. Quasars, blazars, and gamma rays.

    PubMed

    Dermer, C D; Schlickeiser, R

    1992-09-18

    Before the launch of the Compton Gamma Ray Observatory (CGRO), the only source of >100-megaelectron volt (MeV) gamma radiation known outside our galaxy was the quasar 3C 273. After less than a year of observing, 13 other extragalactic sources have been discovered with the Energetic Gamma Ray Experiment Telescope (EGRET) on CGRO, and it is expected that many more will be found before the full sky survey is complete. All 14 sources show evidence of blazar properties at other wavelengths; these properties include high optical polarization, extreme optical variability, flat-spectrum radio emission associated with a compact core, and apparent superluminal motion. Such properties are thought to be produced by those few, rare extragalactic radio galaxies and quasars that are favorably aligned to permit us to look almost directly down a relativistically outflowing jet of matter expelled from a supermassive black hole. Although the origin of the gamma rays from radio jets is a subject of much controversy, the gamma-ray window probed by CGRO is providing a wealth of knowledge about the central engines of active galactic nuclei and the most energetic processes occurring in nature.

  3. Quasars, blazars, and gamma rays.

    PubMed

    Dermer, C D; Schlickeiser, R

    1992-09-18

    Before the launch of the Compton Gamma Ray Observatory (CGRO), the only source of >100-megaelectron volt (MeV) gamma radiation known outside our galaxy was the quasar 3C 273. After less than a year of observing, 13 other extragalactic sources have been discovered with the Energetic Gamma Ray Experiment Telescope (EGRET) on CGRO, and it is expected that many more will be found before the full sky survey is complete. All 14 sources show evidence of blazar properties at other wavelengths; these properties include high optical polarization, extreme optical variability, flat-spectrum radio emission associated with a compact core, and apparent superluminal motion. Such properties are thought to be produced by those few, rare extragalactic radio galaxies and quasars that are favorably aligned to permit us to look almost directly down a relativistically outflowing jet of matter expelled from a supermassive black hole. Although the origin of the gamma rays from radio jets is a subject of much controversy, the gamma-ray window probed by CGRO is providing a wealth of knowledge about the central engines of active galactic nuclei and the most energetic processes occurring in nature. PMID:17841159

  4. Study of quasar variability

    NASA Astrophysics Data System (ADS)

    Jerke, Jonathan Lee

    The Palomar-QUEST Variability Survey has been completed. This thesis has analyzed the data set with the goal of determining the variability of a large sample of quasars. We construct light curves for each individual quasar. We interpret the light curves in terms of a structure function analysis. A slope is extracted from the scaling of the structure function to measure the power law of the quasar optical variability, taking the power spectral density to behave as a power law of the frequency of variation, f-alpha. Monte carlo simulations are used to estimate the errors on the model and the final data quality. With these estimates, individual quasars are assigned a chi2 value and nearly every event has a reduced chi 2 less than 10. The first 100 light curves and structure functions with errors are shown in the Appendix. We have shown that the final distribution of power law coefficients alpha of 1944 quasars is inconsistent with a model with a simple value of alpha. Several models with different alpha are required to explain the behavior of the sample. We find that quasars are less variable on all time scales for increasing luminosity. We also find that the quasars with black hole masses below 10 8 show a lower power law then the average. This means less massive quasars are less variable at long time scales.

  5. Measuring Black Hole Masses in Quasars: The Hows and Whys

    NASA Astrophysics Data System (ADS)

    Denney, Kelly D.

    2015-08-01

    The co-evolution of galaxies and the supermassive black holes that reside in their centers, combined with the overwhelming success of cosmological models to describe the observed universe through hierarchical growth of structure, suggests that these black holes are necessary building blocks of galaxies. Studying the demographics and growth rates of black holes and the impact of black hole accretion and feedback on the host galaxy and circumgalactic medium are imperative for our understanding of galaxy evolution. The only way to probe these properties at high redshift, where the bulk of stellar-mass assembly and black hole growth takes place, is through studies of quasars - galaxies containing supermassive black holes that are actively accreting. I will discuss recent work to improve the reliability of high redshift quasar black hole mass measurements, and thereby growth rates, and the current best practices for making these measurements. In addition, I will discuss how the intrinsic structure of the quasar itself, including the presence of AGN winds and outflows, is correlated with the data quality of quasar spectra to impact the reliability of quasar black hole masses. Finally, I will briefly discuss international efforts, of both collaborations and resources, toward making direct black hole mass measurements in high redshift quasars.

  6. Quasars: A Progress Report.

    ERIC Educational Resources Information Center

    Weedman, Daniel

    1988-01-01

    Reports on some of the discoveries over the last quarter century regarding quasars including spectra and energy sources, formation and evolution, and cosmological probes. Describes some of the fundamental mysteries that remain. (CW)

  7. High Redshift Quasars

    NASA Technical Reports Server (NTRS)

    Elvis, Martin S.

    1996-01-01

    The report for this period includes three papers: 'Associated Absorption at Low and High Redshift'; 'Strong X-ray Absorption in a Broad Absorption Line Quasar: PHL5200'; and 'ASCA and ROSAT X-ray Spectra of High-Redshift Radio-Loud Quasars'. The first gives examples from both low and high redshift for combining information on absorbing material in active galactic nuclei from both x-ray and the UV. The second presents ASCA observations of the z = 1.98 prototype broad absorption line quasar (BALQSO): PHL 5200, detected with both the solid-state imaging spectrometers and the gas imaging spectometers. The third paper presents results on the x-ray properties of 9 high-redshift radio-loud quasars observed by ASCA and ROSAT, including ASCA observations of S5 0014+81 (z = 3.38) and S5 0836+71 (z = 2.17) and ROSAT observations of PKS 2126-158.

  8. Quasars and gravitational lenses.

    PubMed

    Turner, E L

    1984-03-23

    Despite the expenditure of large amounts of telescope time and other resources, most of the fundamental questions concerning quasi-stellar objects (quasars) remain unanswered. A complex phenomenology of radio, infrared, optical, and x-ray properties has accumulated but has not yielded even a satisfactory classification system. The large red shifts (distances) of quasars make them very valuable tools for studying cosmology and the properties of intervening matter in the Universe through observations of absorption lines and gravitational lenses.

  9. The Growth of Central Black Hole and the Ionization Instability of Quasar Disk

    NASA Technical Reports Server (NTRS)

    Lu, Ye; Cheng, K. S.; Zhang, S. N.

    2003-01-01

    A possible accretion model associated with the ionization instability of quasar disks is proposed to address the growth of the central black hole harbored in the host galaxy. The evolution of quasars in cosmic time is assumed to change from a highly active state to a quiescent state triggered by the S-shaped ionization instability of the quasar accretion disk. For a given external mass transfer rate supplied by the quasar host galaxy, ionization instability can modify accretion rate in the disk and separates the accretion flows of the disk into three different phases, like a S-shape. We suggest that the bright quasars observed today are those quasars with disks in the upper branch of S-shaped instability, and the faint or 'dormant' quasars are simply the system in the lower branch. The middle branch is the transition state which is unstable. We assume the quasar disk evolves according to the advection-dominated inflow-outflow solutions (ADIOS) configuration in the stable lower branch of S-shaped instability, and Eddington accretion rate is used to constrain the accretion rate in each phase. The mass ratio between black hole and its host galactic bulge is a nature consequence of ADIOS. Our model also demonstrates that a seed black hole (BH) similar to those found in spiral galaxies today is needed to produce a BH with a final mass 2 x 10(exp 8) solar mases.

  10. Testing quasar unification: radiative transfer in clumpy winds

    NASA Astrophysics Data System (ADS)

    Matthews, J. H.; Knigge, C.; Long, K. S.; Sim, S. A.; Higginbottom, N.; Mangham, S. W.

    2016-05-01

    Various unification schemes interpret the complex phenomenology of quasars and luminous active galactic nuclei (AGN) in terms of a simple picture involving a central black hole, an accretion disc and an associated outflow. Here, we continue our tests of this paradigm by comparing quasar spectra to synthetic spectra of biconical disc wind models, produced with our state-of-the-art Monte Carlo radiative transfer code. Previously, we have shown that we could produce synthetic spectra resembling those of observed broad absorption line (BAL) quasars, but only if the X-ray luminosity was limited to 1043 erg s-1. Here, we introduce a simple treatment of clumping, and find that a filling factor of ˜0.01 moderates the ionization state sufficiently for BAL features to form in the rest-frame UV at more realistic X-ray luminosities. Our fiducial model shows good agreement with AGN X-ray properties and the wind produces strong line emission in, e.g., Lyα and C IV 1550 Å at low inclinations. At high inclinations, the spectra possess prominent LoBAL features. Despite these successes, we cannot reproduce all emission lines seen in quasar spectra with the correct equivalent-width ratios, and we find an angular dependence of emission line equivalent width despite the similarities in the observed emission line properties of BAL and non-BAL quasars. Overall, our work suggests that biconical winds can reproduce much of the qualitative behaviour expected from a unified model, but we cannot yet provide quantitative matches with quasar properties at all viewing angles. Whether disc winds can successfully unify quasars is therefore still an open question.

  11. Obscured quasars at high redshift in the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Strauss, Michael

    2016-08-01

    The SDSS has uncovered a substantial number of luminous quasars with weak continuum, strong narrow lines, and strong evidence for obscuration, at redshifts from 0.4 to 4. I will discuss the selection of such objects and their properties in the optical and infrared. Some of these objects show evidence for significant outflows, with substantial wings in their [OIII] profiles.

  12. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  13. Quasar Spectral Energy Distributions As A Function Of Physical Property

    NASA Astrophysics Data System (ADS)

    Townsend, Shonda; Ganguly, R.; Stark, M. A.; Derseweh, J. A.; Richmond, J. M.

    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). In turn, models of outflows have shown particular sensitivity to the shape of the spectral energy distribution (SED), depending on the UV luminosity to transfer momentum to the gas, the X-ray luminosity to regulate how efficiently that transfer can be, etc. To investigate how SED changes with physical properties, we follow up on Richards et al. (2006), who constructed SEDs with varying luminosity. Here, we construct SEDs as a function of redshift, and physical property (black hole mass, bolometric luminosity, Eddington ratio) for volume limited samples drawn from the Sloan Digital Sky Survey, with photometry supplemented from 2MASS, WISE, GALEX, ROSAT, and Chandra. To estimate black hole masses, we adopt the scaling relations from Greene & Ho (2005) based on the H-alpha emission line FWHM. This requires redshifts less than 0.4. To construct volume-limited subsamples, we begin by adopting g=19.8 as a nominal limiting magnitude over which we are guaranteed to detect z<0.4 quasars. At redshift 0.4, we are complete down to Mg=-21.8, which yields 3300 objects from Data Release 7. At z=0.1, we are complete down to Mg=-18.5. 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.

  14. THE COLOR VARIABILITY OF QUASARS

    SciTech Connect

    Schmidt, Kasper B.; Rix, Hans-Walter; Knecht, Matthias; Hogg, David W.; Shields, Joseph C.; Maoz, Dan; Bovy, Jo

    2012-01-10

    We quantify quasar color variability using an unprecedented variability database-ugriz photometry of 9093 quasars from Sloan Digital Sky Survey (SDSS) Stripe 82, observed over 8 years at {approx}60 epochs each. We confirm previous reports that quasars become bluer when brightening. We find a redshift dependence of this blueing in a given set of bands (e.g., g and r), but show that it is the result of the flux contribution from less-variable or delayed emission lines in the different SDSS bands at different redshifts. After correcting for this effect, quasar color variability is remarkably uniform, and independent not only of redshift, but also of quasar luminosity and black hole mass. The color variations of individual quasars, as they vary in brightness on year timescales, are much more pronounced than the ranges in color seen in samples of quasars across many orders of magnitude in luminosity. This indicates distinct physical mechanisms behind quasar variability and the observed range of quasar luminosities at a given black hole mass-quasar variations cannot be explained by changes in the mean accretion rate. We do find some dependence of the color variability on the characteristics of the flux variations themselves, with fast, low-amplitude, brightness variations producing more color variability. The observed behavior could arise if quasar variability results from flares or ephemeral hot spots in an accretion disk.

  15. Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Meléndez, M.; Veilleux, S.; Reeves, J. N.; González-Alfonso, E.; Reynolds, C. S.

    2015-03-01

    Powerful winds driven by active galactic nuclei are often thought to affect the evolution of both supermassive black holes and their host galaxies, quenching star formation and explaining the close relationship between black holes and galaxies. Recent observations of large-scale molecular outflows in ultraluminous infrared galaxies support this quasar-feedback idea, because they directly trace the gas from which stars form. Theoretical models suggest that these outflows originate as energy-conserving flows driven by fast accretion-disk winds. Proposed connections between large-scale molecular outflows and accretion-disk activity in ultraluminous galaxies were incomplete because no accretion-disk wind had been detected. Conversely, studies of powerful accretion-disk winds have until now focused only on X-ray observations of local Seyfert galaxies and a few higher-redshift quasars. Here we report observations of a powerful accretion-disk wind with a mildly relativistic velocity (a quarter that of light) in the X-ray spectrum of IRAS F11119+3257, a nearby (redshift 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow. The active galactic nucleus is responsible for about 80 per cent of the emission, with a quasar-like luminosity of 1.5 × 1046 ergs per second. The energetics of these two types of wide-angle outflows is consistent with the energy-conserving mechanism that is the basis of the quasar feedback in active galactic nuclei that lack powerful radio jets (such jets are an alternative way to drive molecular outflows).

  16. Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy.

    PubMed

    Tombesi, F; Meléndez, M; Veilleux, S; Reeves, J N; González-Alfonso, E; Reynolds, C S

    2015-03-26

    Powerful winds driven by active galactic nuclei are often thought to affect the evolution of both supermassive black holes and their host galaxies, quenching star formation and explaining the close relationship between black holes and galaxies. Recent observations of large-scale molecular outflows in ultraluminous infrared galaxies support this quasar-feedback idea, because they directly trace the gas from which stars form. Theoretical models suggest that these outflows originate as energy-conserving flows driven by fast accretion-disk winds. Proposed connections between large-scale molecular outflows and accretion-disk activity in ultraluminous galaxies were incomplete because no accretion-disk wind had been detected. Conversely, studies of powerful accretion-disk winds have until now focused only on X-ray observations of local Seyfert galaxies and a few higher-redshift quasars. Here we report observations of a powerful accretion-disk wind with a mildly relativistic velocity (a quarter that of light) in the X-ray spectrum of IRAS F11119+3257, a nearby (redshift 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow. The active galactic nucleus is responsible for about 80 per cent of the emission, with a quasar-like luminosity of 1.5 × 10(46) ergs per second. The energetics of these two types of wide-angle outflows is consistent with the energy-conserving mechanism that is the basis of the quasar feedback in active galactic nuclei that lack powerful radio jets (such jets are an alternative way to drive molecular outflows). PMID:25810204

  17. Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy.

    PubMed

    Tombesi, F; Meléndez, M; Veilleux, S; Reeves, J N; González-Alfonso, E; Reynolds, C S

    2015-03-26

    Powerful winds driven by active galactic nuclei are often thought to affect the evolution of both supermassive black holes and their host galaxies, quenching star formation and explaining the close relationship between black holes and galaxies. Recent observations of large-scale molecular outflows in ultraluminous infrared galaxies support this quasar-feedback idea, because they directly trace the gas from which stars form. Theoretical models suggest that these outflows originate as energy-conserving flows driven by fast accretion-disk winds. Proposed connections between large-scale molecular outflows and accretion-disk activity in ultraluminous galaxies were incomplete because no accretion-disk wind had been detected. Conversely, studies of powerful accretion-disk winds have until now focused only on X-ray observations of local Seyfert galaxies and a few higher-redshift quasars. Here we report observations of a powerful accretion-disk wind with a mildly relativistic velocity (a quarter that of light) in the X-ray spectrum of IRAS F11119+3257, a nearby (redshift 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow. The active galactic nucleus is responsible for about 80 per cent of the emission, with a quasar-like luminosity of 1.5 × 10(46) ergs per second. The energetics of these two types of wide-angle outflows is consistent with the energy-conserving mechanism that is the basis of the quasar feedback in active galactic nuclei that lack powerful radio jets (such jets are an alternative way to drive molecular outflows).

  18. Fifty Years of Quasars

    NASA Astrophysics Data System (ADS)

    Kellermann, Kenneth I.

    2013-01-01

    Although the extragalactic nature of quasars was discussed as early as 1960, it was dismissed largely because of preconceived ideas about what appeared to be an unrealistically high luminosity. Following the 1962 occultations of the strong radio source 3C 273 at Parkes, and the subsequent identification with an apparent stellar object, Maartin Schmidt recognized that the relatively simple hydrogen line Balmer series spectrum implied a redshift of 0.16 leading to the general acceptance of the quasars as being extragalactic origin and the most luminous objects in the Universe. Subsequent radio and optical measurements quickly led to the identification of other quasars with increasingly large redshifts. However, claims for a more local population continued for at least several decades confused perhaps by the recognition of the much larger class of radio quiet quasars and active galactic nuclei (AGN), and the uncertain connection with Seyfert galaxies and Zwicky’s compact galaxies. Curiously, 3C 273, which is one of the brightest extragalactic extragalactic sources in the sky, was first catalogued in 1959 and the mag 13 optical counterpart was known at least as early as 1887. Although, since 1960, much fainter optical counterparts were being routinely identified using accurate radio interferometer positions, 3C273 eluded identification until the series of lunar occultations by Cyril Hazard and others were used to determine the position and morphology of the radio source.

  19. Physical Evolution of Quasars

    NASA Astrophysics Data System (ADS)

    Kuhn, Olga Patricia

    1996-01-01

    The evolution of the quasar luminosity function is well described by pure luminosity evolution (PLE), in which the statistical luminosity, L^*(z), declines by a factor of ~100 from z = 3 to z sim 0.1 (Boyle et al. 1988a). If PLE is produced by the gradual dimming of a single generation of long-lived quasars, then the emitted continua of high redshift, younger, quasars are expected to differ from those of their low redshift, older, counterparts. This thesis aims to test this interpretation of PLE via a statistical comparison between the continua of sets of high and low redshift quasars which match in evolved luminosity, having similar L/L^ *(z).. Rest-frame ~ 1200A-5500A spectral energy distributions were constructed for 15 high redshift quasars and compared to those of 27 z sim 0.1 quasars (Elvis et al. 1994a). Optical/UV spectral indices, alpha (F_ nu ~nu^alpha), were determined by fitting single power laws through narrow (Deltalambda/lambda < 2%) continuum bands at 1285A, 1460A, 4200A, 4650A and 5100A. The mean spectral indices are -0.38 +/- 0.07 for the low and -0.32 +/- 0.07 for the high redshift samples. No significant evolution is found in the optical/UV continuum shapes. K-S tests give probabilities < 4% that the distributions of alpha for the high and low redshift samples differ. There is a significant range in continuum shapes within the low (alpha = -1.2 to +0.5) and high (alpha = { -}0.75 to +0.2) redshift samples. The spread is real, being about 20 times greater than the typical errors, sim 0.01 - 0.08. The distributions of spectral indices that result from fits using a power law plus SMC reddening model are not consistent with the hypothesis that the range is produced by intrinsic extinction. The predicted spectra from non-steady accretion disks, as would result from temperature redistribution due to irradiation or unstable mass accretion, can explain values of alpha from 1/3 down to at least - 1, and may account for the full range. The strengths of

  20. Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.; Alexander, D. M.; Mullaney, J. R.; Swinbank, A. M.

    2014-07-01

    We present integral field unit observations covering the [O III]λλ4959, 5007 and Hβ emission lines of 16 z < 0.2 type 2 active galactic nuclei (AGN). Our targets are selected from a well-constrained parent sample of ≈24 000 AGN so that we can place our observations into the context of the overall AGN population. Our targets are radio quiet with star formation rates (SFRs; ≲[10-100] M⊙ yr-1) that are consistent with normal star-forming galaxies. We decouple the kinematics of galaxy dynamics and mergers from outflows. We find high-velocity ionized gas (velocity widths ≈600-1500 km s-1; maximum velocities ≤1700 km s-1) with observed spatial extents of ≳(6-16) kpc in all targets and observe signatures of spherical outflows and bi-polar superbubbles. We show that our targets are representative of z < 0.2, luminous (i.e. L[O III] > 1041.7 erg s-1) type 2 AGN and that ionized outflows are not only common but also in ≥70 per cent (3σ confidence) of cases, they are extended over kiloparsec scales. Our study demonstrates that galaxy-wide energetic outflows are not confined to the most extreme star-forming galaxies or radio-luminous AGN; however, there may be a higher incidence of the most extreme outflow velocities in quasars hosted in ultraluminous infrared galaxies. Both star formation and AGN activity appear to be energetically viable to drive the outflows and we find no definitive evidence that favours one process over the other. Although highly uncertain, we derive mass outflow rates (typically ≈10 times the SFRs), kinetic energies (≈0.5-10 per cent of LAGN) and momentum rates (typically ≳10-20 × LAGN/c) consistent with theoretical models that predict AGN-driven outflows play a significant role in shaping the evolution of galaxies.

  1. The discovery of quasars

    NASA Astrophysics Data System (ADS)

    Kellermann, K. I.

    2013-03-01

    Although the extragalactic nature of quasars was discussed as early as 1960, it was rejected largely because of preconceived ideas about what appeared to be an unrealistically high radio and optical luminosity. Following the 1962 occultations of the strong radio source 3C 273 at Parkes, and the subsequent identification with an apparent stellar object, Maarten Schmidt recognized that the relatively simple hydrogen line Balmer series spectrum implied a redshift of 0.16. Successive radio and optical measurements quickly led to the identification of other quasars with increasingly large redshifts and the general, although for some decades not universal, acceptance of quasars as being by far the most distant and the most luminous objects in the Universe. Arguments for a more local population continued for at least several decades, fueled in part by a greater willingness to accept the unclear new physics needed to interpret the large observed redshifts rather than the extreme luminosities and energies implied by the cosmological interpretation of the redshifts. Curiously, 3C 273, which is one of the strongest extragalactic sources in the sky, was first catalogued in 1959 and the magnitude 13 optical counterpart was observed at least as early as 1887. Since 1960, much fainter optical counterparts were being routinely identified using accurate radio interferometer positions, measured primarily at the Caltech Owens Valley Radio Observatory. However, 3C 273 eluded identification until the series of lunar occultation observations led by Cyril Hazard. Subsequent attempts to classify quasars into numerous sub-categories based on their observed optical, radio, IR and high energy properties have perhaps led to more confusion than clarity. However, quasars and the broader class of AGN are now a fundamental part of astrophysics and cosmology. They were the basis for the recognition of supermassive black holes in galactic nuclei, which are intimately tied to the formation and

  2. The luminosity function of quasars

    NASA Technical Reports Server (NTRS)

    Pei, Yichuan C.

    1995-01-01

    We propose a new evolutionary model for the optical luminosity function of quasars. Our analytical model is derived from fits to the empirical luminosity function estimated by Hartwick and Schade and Warren, Hewett, and Osmer on the basis of more than 1200 quasars over the range of redshifts 0 approximately less than z approximately less than 4.5. We find that the evolution of quasars over this entire redshift range can be well fitted by a Gaussian distribution, while the shape of the luminosity function can be well fitted by either a double power law or an exponential L(exp 1/4) law. The predicted number counts of quasars, as a function of either apparent magnitude or redshift, are fully consistent with the observed ones. Our model indicates that the evolution of quasars reaches its maximum at z approximately = 2.8 and declines at higher redshifts. An extrapolation of the evolution to z approximately greater than 4.5 implies that quasars may have started their cosmic fireworks at z(sub f) approximately = 5.2-5.5. Forthcoming surveys of quasars at these redshifts will be critical to constrain the epoch of quasar formation. All the results we derived are based on observed quasars and are therefore subject to the bias of obscuration by dust in damped Ly alpha systems. Future surveys of these absorption systems at z approximately greater than 3 will also be important if the formation epoch of quasars is to be known unambiguously.

  3. 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.

  4. Quasar Winds Near the Peak in Galaxy Merger Rate

    NASA Astrophysics Data System (ADS)

    Chartas, George; Brandt, Niel; Saez, Cristian; Giustini, Margherita; Garmire, Gordon

    We present results from recent XMM-Newton, Chandra and Suzaku monitoring observations of the BAL quasar APM 08279+5255. We present constraints on the kinematic and photoion-ization properties of the wind in this z=3.91 quasar and find that it is capable of playing an important role in controlling the evolution of the host galaxy and central black hole close to the peak in galaxy merger rate. We place constraints of the X-ray emission region of APM08279 and find it to be comparable to its ISCO radius. The X-ray emission size of APM08279 is consistent with sizes derived from our analysis of microlensing lightcurves of several gravitationally lensed quasars. A possible trend found between the X-ray photon index and the maximum outflow veloc-ity points towards a plausible mechanism that may explain the acceleration of the wind in APM08279. We also present prospects for future advances in our understanding of the role of quasar winds in galaxy feedback with the International X-ray Observatory.

  5. Outflow Propagation in Collapsars: Collimated Jets And Expanding Outflows

    SciTech Connect

    Mizuta, A.; Yamasaki, T.; Nagataki, S.; Mineshige, S.; /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park

    2007-06-08

    We investigate the outflow propagation in the collapsar in the context of gamma-ray bursts (GRBs) with 2D relativistic hydrodynamic simulations. We vary the specific internal energy and bulk Lorentz factor of the injected outflow from non-relativistic regime to relativistic one, fixing the power of the outflow to be 10{sup 51}erg s{sup -1}. We observed the collimated outflow, when the Lorentz factor of the injected outflow is roughly greater than 2. To the contrary, when the velocity of the injected outflow is slower, the expanding outflow is observed. The transition from collimated jet to expanding outflow continuously occurs by decreasing the injected velocity. Different features of the dynamics of the outflows would cause the difference between the GRBs and similar phenomena, such as, X-ray flashes.

  6. Dusty Quasars at High Redshifts

    NASA Astrophysics Data System (ADS)

    Weedman, Daniel; Sargsyan, Lusine

    2016-09-01

    A population of quasars at z ˜ 2 is determined based on dust luminosities νL ν (7.8 μm) that includes unobscured, partially obscured, and obscured quasars. Quasars are classified by the ratio νL ν (0.25 μm)/νL ν (7.8 μm) = UV/IR, assumed to measure obscuration of UV luminosity by the dust that produces IR luminosity. Quasar counts at rest-frame 7.8 μm are determined for quasars in the Boötes field of the NOAO Deep Wide Field Survey using 24 μm sources with optical redshifts from the AGN and Galaxy Evolution Survey (AGES) or infrared redshifts from the Spitzer Infrared Spectrograph. Spectral energy distributions are extended to far-infrared wavelengths using observations from the Herschel Space Observatory Spectral and Photometric Imaging Receiver (SPIRE), and new SPIRE photometry is presented for 77 high-redshift quasars from the Sloan Digital Sky Survey. It is found that unobscured and obscured quasars have similar space densities at rest-frame 7.8 μm, but the ratio L ν (100 μm)/L ν (7.8 μm) is about three times higher for obscured quasars than for unobscured, so that far-infrared or submillimeter quasar detections are dominated by obscured quasars. We find that only ˜5% of high-redshift submillimeter sources are quasars and that existing 850 μm surveys or 2 mm surveys should already have detected sources at z ˜ 10 if quasar and starburst luminosity functions remain the same from z = 2 until z = 10.

  7. QUART: Quasar hosts Unveiled by high Angular Resolution Techniques

    NASA Astrophysics Data System (ADS)

    Vayner, Andrey; Wright, Shelley; Murray, Norman W.; Armus, Lee; Larkin, James E.

    2016-06-01

    We present results from the new QUART survey that aims to resolve high-redshift (z = 1.5 - 2.5) radio-quiet and radio-loud quasi stellar object (QSO) host galaxies using the integral field spectrograph (IFS) OSIRIS, and the Keck Adaptive Optics (AO) system. The combination of AO and IFS provides the necessary contrast to disentangle the bright-unresolved QSO from the underlying faint host galaxy with unprecedented sensitivity. We study the ionized gas in these systems to sub-kiloparsec scales, yielding essential constraints on the resolved host galaxies dynamics, morphologies, star formation rates, metallicities, and nebular emission diagnostics. We combine OSIRIS and AO observations with multi-wavelength data sets from Atacama Large Millimeter/submillimeter Array, Hubble Space Telescope, and Very Large Array to better understand the multiple phases of the ISM and stellar population properties of the hosts. Radio-quiet QSOs have shown little-to-no star formation and no evidence of extended QSO narrow line emission. In contrast, our latest OSIRIS results of radio-loud z~1.5-2 quasars have revealed evidence for both concurrent star formation and extended quasar narrow line emission with strong outflows. These outflows are co-spatial with structure observed in the radio data, typically with the path of the quasar jet and/or lobe structure. These winds are highly extended (8-12 kpc) and show broad emission line profiles (extending up to 2,500 km/s), indicating strong evidence of quasar “feedback” in their host galaxies.

  8. Quasars at 25.

    PubMed

    Trimble, V; Woltjer, L

    1986-10-10

    In the quarter century since the first optical identification of a "radio star" (3C 48), astronomers have come to general agreement that the underlying quasar energy source is accretion onto a massive black hole. There is much less agreement on the detailed physics of the processes by which this energy is converted to the forms observed, but this has not prevented the objects from serving as valuable probes of the universe at distant times and places.

  9. The road to quasars

    NASA Astrophysics Data System (ADS)

    Kellermann, K. I.

    2015-03-01

    Although the extragalactic nature of 3C 48 and other quasi stellar radio sources was discussed as early as 1960 by John Bolton and others, it was rejected largely because of preconceived ideas about what appeared to be unrealistically high radio and optical luminosities. Not until the 1962 occultations of the strong radio source 3C 273 at Parkes, which led Maarten Schmidt to identify 3C 273 with an apparent stellar object at a redshift of 0.16, was the true nature understood. Successive radio and optical measurements quickly led to the identification of other quasars with increasingly large redshifts and the general, although for some decades not universal, acceptance of quasars as the very luminous nuclei of galaxies. Curiously, 3C 273, which is one of the strongest extragalactic sources in the sky, was first cataloged in 1959 and the magnitude 13 optical counterpart was observed at least as early as 1887. Since 1960, much fainter optical counterparts were being routinely identified using accurate radio interferometer positions which were measured primarily at the Caltech Owens Valley Radio Observatory. However, 3C 273 eluded identification until the series of lunar occultation observations led by Cyril Hazard. Although an accurate radio position had been obtained earlier with the OVRO interferometer, inexplicably 3C 273 was initially misidentified with a faint galaxy located about an arc minute away from the true quasar position.

  10. An Accretion Model for the Growth of the Central Black Holes Associated with Ionization Instability in Quasars

    NASA Technical Reports Server (NTRS)

    Lu, Y.; Cheng, K. S.; Zhang, S. N.

    2003-01-01

    A possible accretion model associated with the ionization instability of quasar disks is proposed to address the growth of the central black hole (BH) harbored in the host galaxy. The evolution of quasars in cosmic time is assumed to change from a highly active state to a quiescent state triggered by the S-shaped ionization instability of the quasar accretion disk. For a given external mass transfer rate supplied by the quasar host galaxy, ionization instability can modify the accretion rate in the disk and separate the accretion flows of the disk into three different phases, like an S-shape. We suggest that the bright quasars observed today are those quasars with disks in the upper branch of the S-shaped instability, and the faint or 'dormant' quasars are simply these systems in the lower branch. The middle branch is the transition state, which is unstable. We assume the quasar disk evolves according to the advection-dominated inflow-outflow solution (ADIOS) configuration in the stable lower branch of the S-shaped instability, and the Eddington accretion rate is used to constrain the accretion rate in the highly active phase. The mass ratio between a BH and its host galactic bulge is a natural consequence of an ADIOS. Our model also demonstrates that a seed BH approx. 2 x 10(exp 6) solar masses similar to those found in spiral galaxies today is needed to produce a BH with a final mass of approx. 2 x 10(exp 8) solar masses.

  11. Observations of feedback from radio-quiet quasars - II. Kinematics of ionized gas nebulae

    NASA Astrophysics Data System (ADS)

    Liu, Guilin; Zakamska, Nadia L.; Greene, Jenny E.; Nesvadba, Nicole P. H.; Liu, Xin

    2013-12-01

    The prevalence and energetics of quasar feedback is a major unresolved problem in galaxy formation theory. In this paper, we present Gemini Integral Field Unit observations of ionized gas around 11 luminous, obscured, radio-quiet quasars at z ˜ 0.5 out to ˜15 kpc from the quasar; specifically, we measure the kinematics and morphology of [O III] λ5007 Å emission. The round morphologies of the nebulae and the large line-of-sight velocity widths (with velocities containing 80 per cent of the emission as high as 103 km s-1) combined with relatively small velocity difference across them (from 90 to 520 km s-1) point towards wide-angle quasi-spherical outflows. We use the observed velocity widths to estimate a median outflow velocity of 760 km s-1, similar to or above the escape velocities from the host galaxies. The line-of-sight velocity dispersion declines slightly towards outer parts of the nebulae (by 3 per cent kpc-1 on average). The majority of nebulae show blueshifted excesses in their line profiles across most of their extents, signifying gas outflows. For the median outflow velocity, we find dot{E}_kin between 4 × 1044 and 3 × 1045 erg s-1 and dot{M} between 2 × 103 and 2 × 104 M⊙ yr-1. These values are large enough for the observed quasar winds to have a significant impact on their host galaxies. The median rate of converting bolometric luminosity to kinetic energy of ionized gas clouds is ˜2 per cent. We report four new candidates for `superbubbles' - outflows that may have broken out of the denser regions of the host galaxy.

  12. IFU Observations of Feedback from Radio-Quiet Quasars at 0.5

    NASA Astrophysics Data System (ADS)

    Liu, Guilin; Zakamska, N. L.; Greene, J. E.; Nesvadba, N.; Liu, X.

    2014-01-01

    Feedback from black holes is now understood to be a key ingredient in galaxy formation modeling, but direct probes of this process in action are scarce and limited to small samples of active nuclei. Meanwhile, theories have long predicted an evolutionary scenario in which galaxy mergers induce both star formation and nuclear activity, triggering a violent transition from an obscured accretion stage to an unobscured phase as a Type 1 quasar, yet direct evidence is lacking. We present Gemini Integral Field Unit (IFU) observations of the distribution of warm ionized gas 104 K) around two luminous radio-quiet quasars: 11 obscured (Type 2) and 12 unobscured (Type 1) quasars with matched [O III]5007 luminosities (L[O III] > 1042.7-43.6 erg/s) and redshifts ( 0.5). For the Type 2 quasar sample, we have found that their gas nebulae are: (1) existent and extended on galactic scales in every case (15-39 kpc across); (2) nearly perfectly round, in striking contrast with lumpy and/or elongated nebulae around radio galaxies; (3) signifying wide-angle quasi-spherical outflows by their roundness and large velocity dispersion (FWHM˜1000 km/s); (4) likely escaping from the host galaxies (the derived median outflow velocity is 760 km/s); (5) showing slightly declining velocity dispersions toward their outer parts (˜3% per kpc); (6) blowing winds with high kinetic energy (1045 erg/s, ˜2% of Lbol) and mass (2×103-4 M⊙/yr) flows. (7) showing a universal radial profile of [O III]/Hβ (8) constructing a size-luminosity relation with a flat slope, implying clumpy nebulae that transition from being ionization-bounded at small radii to being matter-bounded in the outer parts. For the Type 1 quasar sample, we also detect extended nebulae surrounding all quasars with sizes, morphology and gas kinematics surprisingly similar to the Type 2 quasar nebulae. In conclusion, energetic quasi-spherical outflows are ubiquitous in luminous quasars of all types at 0.5. Such striking smooth and

  13. On the Radio and Optical Luminosity Evolution of Quasars

    SciTech Connect

    Singal, J.; Petrosian, V.; Lawrence, A.; Stawarz, L.; /JAXA, Sagamihara /Jagiellonian U., Astron. Observ.

    2011-05-20

    We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multivariate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolution with redshift from a data set truncated due to observational biases. It is found that as expected the population of quasars exhibits strong positive correlation between the radio and optical luminosities and that this correlation deviates from a simple linear relation in a way indicating that more luminous quasars are more radio loud. We also find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio loud (R > 10) and radio quiet (R < 10) populations introduces significant biases that skew the result considerably. We also construct the local radio and optical luminosity functions and the density evolution. Finally, we consider the distribution of the radio loudness parameter R obtained from careful treatment of the selection effects and luminosity evolutions with that obtained from the raw data without such considerations. We find a significant difference between the two distributions and no clear sign of bi-modality in the true distribution. Our results indicate therefore, somewhat surprisingly, that there is no critical switch in the efficiency of the production of disk outflows/jets between very radio quiet and very radio

  14. The Circumgalactic Medium of Quasars

    NASA Astrophysics Data System (ADS)

    Hennawi, Joe

    2014-07-01

    I will argue that observations of the diffuse gas in the outskirts of quasar host galaxies, or the so called circumgalactic medium, are essential for understanding how luminous quasars evolve in a cosmological context. Such observations also provide a fruitful comparison to theory, because hydrodynamics at moderate overdensities is much easier to simulate than the complicated processes which trigger quasar activity. A novel technique will be introduced, whereby a foreground quasar can be studied in absorption against a background quasar, resolving scales as small as 30 kpc. This experiment reveals a rich absorption spectrum which contains a wealth of information about the physical conditions of diffuse gas around quasars. Hydrodynamical simulations of the massive dark matter halos which host luminous quasars under predict the amount of cool gas observed in quasar environs by a large factor, challenging our understanding of how massive galaxies form. I will also discuss a very sensitive search for Ly-alpha emission from the same gas which we study in absorption.

  15. BROAD ABSORPTION LINE DISAPPEARANCE ON MULTI-YEAR TIMESCALES IN A LARGE QUASAR SAMPLE

    SciTech Connect

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P.; Hall, P. B.; Anderson, S. F.; Gibson, R. R.; Lundgren, B. F.; Myers, A. D.; Petitjean, P.; Ross, Nicholas P.; Shen Yue; York, D. G.; Bizyaev, D.; Brinkmann, J.; Malanushenko, E.; Oravetz, D. J.; Pan, K.; Simmons, A. E.; Weaver, B. A.

    2012-10-01

    We present 21 examples of C IV broad absorption line (BAL) trough disappearance in 19 quasars selected from systematic multi-epoch observations of 582 bright BAL quasars (1.9 < z < 4.5) by the Sloan Digital Sky Survey-I/II (SDSS-I/II) and SDSS-III. The observations span 1.1-3.9 yr rest-frame timescales, longer than have been sampled in many previous BAL variability studies. On these timescales, Almost-Equal-To 2.3% of C IV BAL troughs disappear and Almost-Equal-To 3.3% of BAL quasars show a disappearing trough. These observed frequencies suggest that many C IV BAL absorbers spend on average at most a century along our line of sight to their quasar. Ten of the 19 BAL quasars showing C IV BAL disappearance have apparently transformed from BAL to non-BAL quasars; these are the first reported examples of such transformations. The BAL troughs that disappear tend to be those with small-to-moderate equivalent widths, relatively shallow depths, and high outflow velocities. Other non-disappearing C IV BALs in those nine objects having multiple troughs tend to weaken when one of them disappears, indicating a connection between the disappearing and non-disappearing troughs, even for velocity separations as large as 10,000-15,000 km s{sup -1}. We discuss possible origins of this connection including disk-wind rotation and changes in shielding gas.

  16. ANOMALOUSLY STEEP REDDENING LAW IN QUASARS: AN EXCEPTIONAL EXAMPLE OBSERVED IN IRAS 14026+4341

    SciTech Connect

    Jiang Peng; Zhou Hongyan; Ji Tuo; Shu Xinwen; Liu Wenjuan; Dong Xiaobo; Wang Huiyuan; Wang Tinggui; Wang Jianguo

    2013-06-15

    A fraction of the heavily reddened quasars require a reddening curve that is even steeper than that of the Small Magellanic Cloud. In this paper, we thoroughly characterize the anomalously steep reddening law in quasars via an exceptional example observed in IRAS 14026+4341. By comparing the observed spectrum to the quasar composite spectrum, we derive a reddening curve in the rest-frame wavelength range of 1200-10000 A. It has a steep rise at wavelengths shorter than 3000 A, but no significant reddening at longer wavelengths. The absence of dust reddening in the optical continuum is confirmed by the normal broad-line Balmer decrement (the H{alpha}/H{beta} ratio) in IRAS 14026+4341. The anomalous reddening curve can be satisfactorily reproduced with a dust model containing silicate grains in a power-law size distribution, dn(a)/da{proportional_to}a {sup -1.4}, truncated at a maximum size of a{sub max} = 70 nm. The unusual size distribution may be caused by the destruction of large 'stardust' grains by quasar activities or a different dust formation mechanism (i.e., the in situ formation of dust grains in quasar outflows). It is also possible that the analogies of the dust grains observed near the Galactic center are responsible for the steep reddening curve. In addition, we find that IRAS 14026+4341 is a weak emission-line quasar (i.e., PHL 1811 analogies) with heavy dust reddening and blueshifted broad absorption lines.

  17. Anomalously Steep Reddening Law in Quasars: An Exceptional Example Observed in IRAS 14026+4341

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Zhou, Hongyan; Ji, Tuo; Shu, Xinwen; Liu, Wenjuan; Wang, Jianguo; Dong, Xiaobo; Bai, Jinming; Wang, Huiyuan; Wang, Tinggui

    2013-06-01

    A fraction of the heavily reddened quasars require a reddening curve that is even steeper than that of the Small Magellanic Cloud. In this paper, we thoroughly characterize the anomalously steep reddening law in quasars via an exceptional example observed in IRAS 14026+4341. By comparing the observed spectrum to the quasar composite spectrum, we derive a reddening curve in the rest-frame wavelength range of 1200-10000 Å. It has a steep rise at wavelengths shorter than 3000 Å, but no significant reddening at longer wavelengths. The absence of dust reddening in the optical continuum is confirmed by the normal broad-line Balmer decrement (the Hα/Hβ ratio) in IRAS 14026+4341. The anomalous reddening curve can be satisfactorily reproduced with a dust model containing silicate grains in a power-law size distribution, dn(a)/davpropa -1.4, truncated at a maximum size of a max = 70 nm. The unusual size distribution may be caused by the destruction of large "stardust" grains by quasar activities or a different dust formation mechanism (i.e., the in situ formation of dust grains in quasar outflows). It is also possible that the analogies of the dust grains observed near the Galactic center are responsible for the steep reddening curve. In addition, we find that IRAS 14026+4341 is a weak emission-line quasar (i.e., PHL 1811 analogies) with heavy dust reddening and blueshifted broad absorption lines.

  18. MAJOR CONTRIBUTOR TO AGN FEEDBACK: VLT X-SHOOTER OBSERVATIONS OF S IV BALQSO OUTFLOWS

    SciTech Connect

    Borguet, Benoit C. J.; Arav, Nahum; Edmonds, Doug; Chamberlain, Carter; Benn, Chris

    2013-01-01

    We present the most energetic BALQSO outflow measured to date, with a kinetic luminosity of at least 10{sup 46} erg s{sup -1}, which is 5% of the bolometric luminosity of this high Eddington ratio quasar. The associated mass-flow rate is 400 solar masses per year. Such kinetic luminosity and mass-flow rate should provide strong active galactic nucleus feedback effects. The outflow is located at about 300 pc from the quasar and has a velocity of roughly 8000 km s{sup -1}. Our distance and energetic measurements are based in large part on the identification and measurement of S IV and S IV* broad absorption lines (BALs). The use of this high-ionization species allows us to generalize the result to the majority of high-ionization BALQSOs that are identified by their C IV absorption. We also report the energetics of two other outflows seen in another object using the same technique. The distances of all three outflows from the central source (100-2000 pc) suggest that we observe BAL troughs much farther away from the central source than the assumed acceleration region of these outflows (0.01-0.1 pc).

  19. Ultra-fast outflows (aka UFOs) in AGNs and their relevance for feedback

    NASA Astrophysics Data System (ADS)

    Cappi, Massimo; Tombesi, F.; Giustini, M.; Dadina, M.; Braito, V.; Kaastra, J.; Reeves, J.; Chartas, G.; Gaspari, M.; Vignali, C.; Gofford, J.; Lanzuisi, G.

    2012-09-01

    During the last decade, several observational evidences have been accumulated for the existence of massive, high velocity winds/outflows (aka UFOs) in nearby AGNs and, possibly, distant quasars. I will review here such evidences, present some of the latest results in this field, and discuss the relevance of UFOs for both understanding the physics of accretion/ejection flows on supermassive black holes, and for quantifying the amount of AGN feedback.

  20. 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.

  1. PHL 1092: A narrow-line quasar emerging from the darkness

    NASA Astrophysics Data System (ADS)

    Gallo, Luigi

    2013-10-01

    The radio quiet, narrow line quasar, PHL1092 exhibits the extreme behaviour associated with 1H0707 and IRAS13224, but at a high redshift (z=0.396) and with high luminosity (~10^45 erg/s). From a short, bright state observation of PHL1092 we discovered a super soft excess, possible relativistically broadened FeL and K emission, high radiative efficiency, and possible high velocity outflow. Follow up observations between 2008-10 caught the quasar in a deep minimum that could be attributed to disruption of the corona. We will monitor PHL1092 with Swift to catch the quasar emerging from its current low-flux state so that we can study the bright state of the AGN with a triggered 130ks XMM observation.

  2. Vanishing absorption and blueshifted emission in FeLoBAL quasars

    NASA Astrophysics Data System (ADS)

    Rafiee, Alireza; Pirkola, Patrik; Hall, Patrick B.; Galati, Natalee; Rogerson, Jesse; Ameri, Abtin

    2016-07-01

    We study the dramatic decrease in iron absorption strength in the iron low-ionization broad absorption line quasar SDSS J084133.15+200525.8. We report on the continued weakening of absorption in the prototype of this class of variable broad absorption line quasar, FBQS J140806.2+305448. We also report a third example of this class, SDSS J123103.70+392903.6; unlike the other two examples, it has undergone an increase in observed continuum brightness (at 3000 Å rest frame) as well as a decrease in iron absorption strength. These changes could be caused by absorber transverse motion or by ionization variability. We note that the Mg II and UV Fe II lines in several FeLoBAL quasars are blueshifted by thousands of km s-1 relative to the H β emission line peak. We suggest that such emission arises in the outflowing winds normally seen only in absorption.

  3. What Quasars Really Look Like: Unification of the Emission and Absorption Line Regions

    NASA Technical Reports Server (NTRS)

    Elvis, Martin

    2000-01-01

    We propose a simple unifying structure for the inner regions of quasars and AGN. This empirically derived model links together the broad absorption line (BALS), the narrow UV/X-ray ionized absorbers, the BELR, and the 5 Compton scattering/fluorescing regions into a single structure. The model also suggests an alternative origin for the large-scale bi-conical outflows. Some other potential implications of this structure are discussed.

  4. Variations in active outflow along the trabecular outflow pathway.

    PubMed

    Cha, Elliott D K; Xu, Jia; Gong, Lihua; Gong, Haiyan

    2016-05-01

    Previous tracer studies have shown segmental outflow in the trabecular meshwork (TM) and along the inner wall (IW) of Schlemm's canal (SC). Whether segmental outflow is conserved distal to SC has not yet been investigated. This study aims to investigate whether the segmented pattern of outflow is conserved in distal outflow pathways by using a newly developed global imaging method and to evaluate variations of active outflow in three distinct regions along trabecular outflow pathway. Six normal whole globe human eyes were first perfused at 15 mmHg to establish a stable baseline outflow facility. The anterior chamber was then exchanged (5 mL) and perfused with fluorescent microspheres (0.002% v/v, 200 μL) to label areas of active outflow. All eyes were perfusion fixed and dissected into anterior segments. The TM and scleral surface were en face imaged globally. Effective filtration area (EFA) and fluorescent tracer distribution and intensity were analyzed in global images for both the TM and episcleral veins (EPVs). Anterior segments were further dissected into a minimum of 16 radial wedges, from which frontal sections were cut, stained, and imaged, using confocal microscopy. EFA from all three locations along the trabecular outflow pathway were measured and compared. Additionally, TM thickness, SC height, and total number of collector channels (CC) were analyzed and compared between active and inactive areas of outflow. Statistical analysis was performed using Student's t-tests and Wilcoxon signed-rank test with a required significance of p ≤ 0.05. All three locations showed a segmental outflow pattern. The TM had a significantly higher mean EFA (86.3 ± 3.5%) compared to both the IW (34.7 ± 2.9%; p ≤ 0.01) and EPVs (41.1 ± 3.8%; p ≤ 0.01). No significant difference in mean EFA was found between IW and EPVs. Preferential active outflow was observed in the nasal and inferior quadrants. TM thickness was significantly larger in areas of active

  5. Asteroids to Quasars

    NASA Astrophysics Data System (ADS)

    Lugger, Phyllis M.

    2004-12-01

    Asteroid dedication; William Liller: Biographical Sketch; William Liller: Autobiographical Meanderings; Preface; List of Participants; Conference Photo; Part I. 1. Solar System Astronomy: Asteroids Joseph Veverka; 2. Sixteen years of stellar occultations James Elliott; 3. Comets to Quasars: Surface photometry from standard stars and the morphology of the galaxy-quasar interface Peter Usher; 4. Observing Solar Eclipses Jay Pasachoff; Part II. 5. Planetary Nebulae: new insights and opportunities Lawrence Aller; 6. Studies of planetary nebulae at radio wavelengths Yervant Terzian; 7. Optical identifications of compact galactic X-ray sources: Liller Lore Jonathan Grindlay; 8. Ages of globular clusters derived from BVRI CCD photometry Gonzalo Alcaino; 9. Stellar spectrum synthesis Jun Jugaku; 10. Mass exchange and stellar abundance anomalies Benjamin Peery; Part III. Extragalactic Astronomy: 11. The M31 globular cluster system John Huchra; 12. Spiral structure and star formation in galaxies Debra Elmegreen; 13. The discovery of hot coronae around early type galaxies William Forman and Christine Jones; 14. The morphology of clusters of galaxies, the formation efficiency of galaxies and the origin of the intracluster medium Christine Jones and William Forman; 15. Testing models for the dynamical evolution of clusters of galaxies Phyllis Lugger; 16. What is in the X-ray sky? Rudolph Schild; 17. Einstein deep surveys Stephen Murray, Christine Jones and William Forman; Part IV. History, Lore and Archaeoastronomy: 18. Robert Wheeler Willson: His Life and Legacy Barbara Welther; 19. The great mnemonics contest Owen Gingerich; 20. Hetu'u Rapanui: The archaeoastronomy of Easter Island William Liller; Indexes; Names; Objects; Subjects.

  6. Quasar Unification Via Disk Winds: From Phenomenology to Physics

    NASA Astrophysics Data System (ADS)

    Knigge, C.

    2015-09-01

    I will give an overview of a collaborative project aimed at testing the viability of QSO unification via accretion disk winds. In this scenario, most of the characteristic spectral features of QSOs are formed in these outflows. More specifically, broad absorption lines (BALs) are produced for sight lines within the outflow, while broad emission lines (BELs) are observed for other viewing angles. In order to test these ideas, we use a state-of- the-art Monte Carlo radiative transfer and photoionization code to predict emergent spectra for a wide range of viewing angles and quasar properties (black hole mass, accretion rate, X-ray luminosity, etc). It turns out to be relatively straightforward to produce BALs, but harder to obtain sufficiently strong BELs. We also find that it is easy to overionize the wind with realistic X-ray luminosities. In addition, we are using our code to test and improve hydrodynamic disk wind models for quasars. So far, we have been able to demonstrate that the treatment of ionization in existing hydrodynamic models of line-driven disk winds is too simplistic to yield realistic results: the modelled outflows would be strongly overionized and hence would not feel the line-driving forces that are asssumed to produce them. We have therefore embarked on an effort to model line-driven disk winds self-consistently by linking a hydrodynamics code with our ionization and radiative transfer code. Finally, we can also predict the reverberation signatures produced by disk winds, which can be directly compared to the results of the latest reverberation mapping campaigns.

  7. The Environments of Obscured Quasars

    NASA Astrophysics Data System (ADS)

    Jones, Kristen M.; Lacy, Mark; Nielsen, Danielle

    2016-01-01

    Supermassive Black Hole (SMBH) feedback is prescribed for driving the high-end shape of the galaxy luminosity function, clearing the circumnuclear environment during the end stages of mergers, and eventually turning off its own accretion. Yet the dominant processes and characteristics of active galactic nuclei are indistinct. Chief among this confusion is how significant the role of dust is in each galaxy. Orientation of the dusty torus is attributed to causing the differences between Sy1 and Sy2, but whether obscured quasars are found in particularly dusty host galaxies, if they exist at a different stage in the merger process (early on, before the dust is blown out), or if they are merely oriented differently than optical quasars is not yet so well distinguished. With obscured quasars now observed to make up 50% or greater of the population of quasars, the question of what causes obscuration becomes vital to address. With this in mind, I study matched samples of obscured and unobscured quasars to characterize their environments, with the intent of addressing what contribution environment has to obscuration levels. I investigate the megaparsec-scale environments of SIRTF Wide-field Infra-Red Extragalactic Survey (SWIRE) quasars at z ˜ 1-3 by cross-correlating the sample with 3.8 million galaxies from the Spitzer Extragalactic Representative Volume Survey (SERVS). Optically obscured quasars are compared to a control sample of optically-bright quasars via selection in the mid-infrared. Environments were observed at 3.6 and 4.5 μm to a depth of ≈ 2 μJy (AB = 23.1). Recent work has found diverse results in such studies, with dependence of environmental richness on both redshift and level of obscuration. I find that, within reasonable error, on average there is no distinct difference between the level of clustering for obscured and normal quasars, and that there is no dependence on redshift of this result within the range of 1.3 < z < 2.5. I compare our results

  8. Spin properties of supermassive black holes with powerful outflows

    NASA Astrophysics Data System (ADS)

    Daly, Ruth. A.

    2016-05-01

    Relationships between beam power and accretion disc luminosity are studied for a sample of 55 high excitation radio galaxies (HERG), 13 low excitation radio galaxies (LERG), and 29 radio loud quasars (RLQ) with powerful outflows. The ratio of beam power to disc luminosity tends to be high for LERG, low for RLQ, and spans the full range of values for HERG. Writing general expressions for the disc luminosity and beam power and applying the empirically determined relationships allows a function that parametrizes the spins of the holes to be estimated. Interestingly, one of the solutions that is consistent with the data has a functional form that is remarkably similar to that expected in the generalized Blandford-Znajek model with a magnetic field that is similar in form to that expected in magnetically arrested disk (MAD) and advection-dominated accretion flow (ADAF) models. Values of the spin function, obtained independent of specific outflow models, suggest that spin and active galactic nucleus type are not related for these types of sources. The spin function can be used to solve for black hole spin in the context of particular outflow models, and one example is provided.

  9. Extreme star formation events in quasar hosts over 0.5 < z < 4

    NASA Astrophysics Data System (ADS)

    Pitchford, L. K.; Hatziminaoglou, E.; Feltre, A.; Farrah, D.; Clarke, C.; Harris, K. A.; Hurley, P.; Oliver, S.; Page, M.; Wang, L.

    2016-11-01

    We explore the relationship between active galactic nuclei (AGN) and star formation in a sample of 513 optically luminous type 1 quasars up to redshifts of ˜4 hosting extremely high star formation rates (SFRs). The quasars are selected to be individually detected by the Herschel SPIRE instrument at >3σ at 250 μm, leading to typical SFRs of order of 1000 M⊙ yr-1. We find the average SFRs to increase by almost a factor 10 from z ˜ 0.5 to z ˜ 3, mirroring the rise in the comoving SFR density over the same epoch. However, we find that the SFRs remain approximately constant with increasing accretion luminosity for accretion luminosities above 1012 L⊙. We also find that the SFRs do not correlate with black hole mass. Both of these results are most plausibly explained by the existence of a self-regulation process by the starburst at high SFRs, which controls SFRs on time-scales comparable to or shorter than the AGN or starburst duty cycles. We additionally find that SFRs do not depend on Eddington ratio at any redshift, consistent with no relation between SFR and black hole growth rate per unit black hole mass. Finally, we find that high-ionization broad absorption line (HiBAL) quasars have indistinguishable far-infrared properties to those of classical quasars, consistent with HiBAL quasars being normal quasars observed along a particular line of sight, with the outflows in HiBAL quasars not having any measurable effect on the star formation in their hosts.

  10. Spectroscopic identification of type 2 quasars at z < 1 in SDSS-III/BOSS

    NASA Astrophysics Data System (ADS)

    Yuan, Sihan; Strauss, Michael A.; Zakamska, Nadia L.

    2016-10-01

    The physics and demographics of type 2 quasars remain poorly understood, and new samples of such objects selected in a variety of ways can give insight into their physical properties, evolution, and relationship to their host galaxies. We present a sample of 2758 type 2 quasars at z ≲ 1 from the Sloan Digital Sky Survey-III (SDSS-III)/Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopic data base, selected on the basis of their emission-line properties. We probe the luminous end of the population by requiring the rest-frame equivalent width of [O III] to be >100 Å. We distinguish our objects from star-forming galaxies and type 1 quasars using line widths, standard emission line ratio diagnostic diagrams at z < 0.52 and detection of [Ne V]λ3426 Å at z > 0.52. The majority of our objects have [O III] luminosities in the range 1.2 × 1042-3.8 × 1043 erg s-1 and redshifts between 0.4 and 0.65. Our sample includes over 400 type 2 quasars with incorrectly measured redshifts in the BOSS data base; such objects often show kinematic substructure or outflows in the [O III] line. The majority of the sample has counterparts in the Wide-field Infrared Survey Explorer survey, with median infrared luminosity νLν[12 μm] = 4.2 × 1044 erg s- 1. Only 34 per cent of the newly identified type 2 quasars would be selected by infrared colour cuts designed to identify obscured active nuclei, highlighting the difficulty of identifying complete samples of type 2 quasars. We make public the multi-Gaussian decompositions of all [O III] profiles for the new sample and for 568 type 2 quasars from SDSS I/II, together with non-parametric measures of the [O III] line profile shapes. We also identify over 600 candidate double-peaked [O III] profiles.

  11. 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.

  12. Zephyria Outflow Features

    NASA Technical Reports Server (NTRS)

    2004-01-01

    1 October 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows streamlined islands and a small cataract in an outflow channel system in the Zephyria region of Mars, south of Cerberus. The fluids responsible for creating these landforms flowed from the lower left (southwest) toward upper right (northeast). The fluids may have been water and mud or, some Mars scientists have argued, extremely fluid lava. The presence of a small cataract probably argues more strongly for a water and mud origin. This image is located near 3.8oN, 204.7oW. The picture covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from upper left.

  13. Ion Outflow Observations

    NASA Technical Reports Server (NTRS)

    Mellot, Mary (Technical Monitor)

    2002-01-01

    The characteristics of out-flowing ions have been investigated under various circumstances. In particular the upwelling of ions from the cleft region has been studied to attempt to look at source characteristics (e.g., temperature, altitude). High altitude (6-8 Re) data tend to show ions species that have the same velocity and are adiabatically cooled. Such ions, while representative of their source, can not provide an accurate picture. Ion observations from the TIDE detector on the Polar spacecraft show an energy (or equivalently a velocity) spectrum of ions as they undo the geomagnetic mass spectrometer effect due to convection-gravity separation of the different species. Consolidation of this type of data into a complete representation of the source spectrum can be attempted by building a set of maximum-phase-space- density-velocity pairs and attributing the total to the source.

  14. Blowin' in the wind: feedback from QSO outflows at high-z

    NASA Astrophysics Data System (ADS)

    Cresci, G.

    2016-06-01

    Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, although direct observational evidences are still scarce, probably because radiatively driven winds are rare as they arise during a short-lived phase. I will present near-IR integral field observations of a sample of high-z QSOs, in which we clearly resolve fast (up to 1500 km/s) extended (up to 13 kpc from the black hole) outflows in the [OIII] lines, whose high velocity and high mass outflow rate are unlikely to be sustained by star formation only. Moreover, Star Formation tracers in some of these objects show that the outflow position is anti-correlated with the star forming regions in the host galaxy, representing the first direct evidences of powerful outflows removing the gas from the host galaxy (`negative feedback'). Evidences of gas depletion in these source are also provided by the direct measurement of molecular gas from PDBI and ALMA observations. However, in one of the objects we also have evidences of the opposite mechanism, star formation triggered at the edges of the outflow ('positive feedback').

  15. Quasar Structure from Microlensing in Gravitationally Lensed Quasars

    NASA Astrophysics Data System (ADS)

    Morgan, Christopher W.

    2007-12-01

    I investigate microlensing in gravitationally lensed quasars and discuss the use of its signal to probe quasar structure on small angular scales. I describe our lensed quasar optical monitoring program and RETROCAM, the optical camera I built for the 2.4m Hiltner telescope to monitor lensed quasars. I use the microlensing variability observed in 11 gravitationally lensed quasars to show that the accretion disk size at 2500Å is related to the black hole mass by log(R2500/cm) = (15.70±0.16) + (0.64±0.18)log(MBH/109M⊙). This scaling is consistent with the expectation from thin disk theory (R ∝ MBH2/3), but it implies that black holes radiate with relatively low efficiency, log(η) = -1.54±0.36 + log(L/LE) where η=L/(Mdotc2). With one exception, these sizes are larger by a factor of 4 than the size needed to produce the observed 0.8µm quasar flux by thermal radiation from a thin disk with the same T ∝ R-3/4 temperature profile. More sophisticated disk models are clearly required, particularly as our continuing observations improve the precision of the measurements and yield estimates of the scaling with wavelength and accretion rate. This research made extensive use of a Beowulf computer cluster obtained through the Cluster Ohio program of the Ohio Supercomputer Center. Support for program HST-GO-9744 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS-5-26666.

  16. A DISTANT QUASAR'S BRILLIANT LIGHT

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The arrow in this image, taken by a ground-based telescope, points to a distant quasar, the brilliant core of an active galaxy residing billions of light-years from Earth. As light from this faraway object travels across space, it picks up information on galaxies and the vast clouds of material between galaxies as it moves through them. The Space Telescope Imaging Spectrograph aboard NASA's Hubble Space Telescope decoded the quasar's light to find the spectral 'fingerprints' of highly ionized (energized) oxygen, which had mixed with invisible clouds of hydrogen in intergalactic space. The quasar's brilliant beam pierced at least four separate filaments of the invisible hydrogen laced with the telltale oxygen. The presence of oxygen between the galaxies implies there are huge quantities of hydrogen in the universe. Credits: WIYN Telescope at Kitt Peak National Observatory in Arizona. The telescope is owned and operated by the University of Wisconsin, Indiana University, Yale University, and the National Optical Astronomy Observatories.

  17. "Dead quasars" in nearby galaxies?

    PubMed

    Rees, M J

    1990-02-16

    The nuclei of some galaxies undergo violent activity, quasars being the most extreme instances of this phenomenon. Such activity is probably short-lived compared to galactic lifetimes, and was most prevalent when the universe was only about one-fifth of its present age. A massive black hole seems the inevitable end point of such activity, and dead quasars should greatly outnumber active ones. In recent years, studies of stellar motions in the cores of several nearby galaxies indicate the presence of central dark masses which could be black holes. This article discusses how such evidence might be corroborated, and the potential implications for our understanding of active galaxies and black holes.

  18. Cardiac outflow tract anomalies

    PubMed Central

    Neeb, Zachary; Lajiness, Jacquelyn D.; Bolanis, Esther; Conway, Simon J

    2014-01-01

    The mature outflow tract (OFT) is, in basic terms, a short conduit. It is a simple, although vital, connection situated between contracting muscular heart chambers and a vast embryonic vascular network. Unfortunately, it is also a focal point underlying many multifactorial congenital heart defects (CHDs). Through the use of various animal models combined with human genetic investigations, we are beginning to comprehend the molecular and cellular framework that controls OFT morphogenesis. Clear roles of neural crest cells (NCC) and second heart field (SHF) derivatives have been established during OFT formation and remodeling. The challenge now is to determine how the SHF and cardiac NCC interact, the complex reciprocal signaling that appears to be occurring at various stages of OFT morphogenesis, and finally how endocardial progenitors and primary heart field (PHF) communicate with both these colonizing extra-cardiac lineages. Although we are beginning to understand that this dance of progenitor populations is wonderfully intricate, the underlying pathogenesis and the spatiotemporal cell lineage interactions remain to be fully elucidated. What is now clear is that OFT alignment and septation are independent processes, invested via separate SHF and cardiac neural crest (CNC) lineages. This review will focus on our current understanding of the respective contributions of the SHF and CNC lineage during OFT development and pathogenesis. PMID:24014420

  19. The pattern of extreme star formation events in SDSS quasar hosts in Herschel fields

    NASA Astrophysics Data System (ADS)

    Pitchford, Lura Katherine; Hatziminaoglou, Evanthia; Feltre, Anna; Clarke, Charlotte; Farrah, Duncan; Harris, Kathryn Amy; Hurley, Peter; Oliver, Sebastian; Page, Mat; Wang, Lingyu

    2016-01-01

    Using a sample of ~500 quasars up to redshifts of ~4 detected by the Sloan Digital Sky Survey (SDSS) and the Spectral and Photometric Imaging Receiver (SPIRE) instrument of Herschel, we describe the behavior of intense starbursts in luminous quasars and how it correlates with the properties of the active galactic nuclei (AGN). We select our objects in the Herschel Stripe 82 Survey (HerS) and in the largest fields of the Herschel Multi-tiered Extragalactic Survey (HerMES), including the HerMES Large Mode Survey (HeLMS).The far-infrared (FIR) emission of our objects is quantified using a spectral energy distribution (SED) fitting technique. As our sources are individually detected in the SPIRE bands, they are bright in the FIR, exhibiting typical star formation rates (SFRs) of order of 1000 M⊙yr-1. We find the SFR to increase by a factor of nearly ten from z~0.5 to z~3, in line with the increasing comoving SFR density over a similar redshift range. The SFR, however, is shown to remain constant with increasing quasar luminosity for quasars with IR luminosities above 1012L⊙, indicating a self-regulating star formation process rather than a suppression effect due to the presence of powerful AGN. We find no further proof of a causal relation between star formation and accretion onto the central black hole, as the SFR and the Eddington ratio, λEdd, are found to be uncorrelated.We then compare the broad absorption line (BAL) quasars to the rest of the quasar population, as they are candidates for outflows in action from which shorter-term feedback effects could be sought. We find the accretion luminosities and λEdd values of BAL quasars to be drawn from the same population as those of the non-BAL quasars; further, the host SFRs are statistically similar among the two populations, all of which argue against feedback effects. These similarities also oppose an evolutionary scenario, as a different evolutionary stage would imply differences in either the accretion state

  20. C IV emission-line properties and systematic trends in quasar black hole mass estimates

    NASA Astrophysics Data System (ADS)

    Coatman, Liam; Hewett, Paul C.; Banerji, Manda; Richards, Gordon T.

    2016-09-01

    Black hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z ≳ 2.1, black hole masses are normally derived using the velocity width of the C IV λ λ1548, 1550 broad emission line, based on the assumption that the observed velocity widths arise from virial-induced motions. In many quasars, the C IV emission line exhibits significant blue asymmetries (`blueshifts') with the line centroid displaced by up to thousands of km s-1 to the blue. These blueshifts almost certainly signal the presence of strong outflows, most likely originating in a disc wind. We have obtained near-infrared spectra, including the Hα λ6565 emission line, for 19 luminous (LBol = 46.5-47.5 erg s-1) Sloan Digital Sky Survey quasars, at redshifts 2 < z < 2.7, with C IV emission lines spanning the full range of blueshifts present in the population. A strong correlation between C IV velocity width and blueshift is found and, at large blueshifts, >2000 km s-1, the velocity widths appear to be dominated by non-virial motions. Black hole masses, based on the full width at half-maximum of the C IV emission line, can be overestimated by a factor of 5 at large blueshifts. A larger sample of quasar spectra with both C IV and H β, or Hα, emission lines will allow quantitative corrections to C IV-based black hole masses as a function of blueshift to be derived. We find that quasars with large C IV blueshifts possess high Eddington luminosity ratios and that the fraction of high-blueshift quasars in a flux-limited sample is enhanced by a factor of approximately 4 relative to a sample limited by black hole mass.

  1. The three-dimensional properties and energetics of radio-jet-driven outflows

    SciTech Connect

    Shih, Hsin-Yi; Stockton, Alan E-mail: stockton@ifa.hawaii.edu

    2014-05-01

    Extended emission-line regions (EELRs), found around radio-loud sources, are likely outflows driven by one form of powerful active galactic nucleus (AGN) feedback mechanism. We seek to constrain the three-dimensional gas properties and the outflow energetics of the EELRs in this study. We used an integral field unit to observe EELRs around two samples of radio-loud AGNs with similar radio properties, but different orientations: a sample of quasars and a sample of radio galaxies. A morphological comparison suggests a scenario where the three-dimensional EELR gas distribution follows rough biconical shapes with wide opening angles. The average extent of the EELRs is ∼18.5 kpc. The estimated average mass of the EELRs, with reasonable assumptions for gas densities, is ∼3 × 10{sup 8} M {sub ☉}, and the average mass outflow rate is ∼30 M {sub ☉} yr{sup –1}. The EELRs around quasars and radio galaxies share similar kinematic properties. Both samples have velocity structures that display a range of complexities, they do not appear to correlate with the jet orientations, and both span a similar range of velocity dispersions. Around 30% of the detected EELRs show large-scale rotational motions, which may have originated from recent mergers involving gas-rich disk galaxies.

  2. Dust in the wind I: Spectropolarimetric signatures from disk-born outflows

    NASA Astrophysics Data System (ADS)

    Marin, F.; Goosmann, R. W.

    2013-11-01

    In this first research note of a series of two, we conduct optical/UV investigations of the spectropolarimetric signatures emerging from the structure of quasars Elvis et al. (2000) applied to a purely theoretical, dusty model. We aim to explore the similarities/differences between an absorbing, disk-born outflow and the usual dusty torus that is supposed to hide the internal regions of active galactic nuclei (AGN). Using radiative transfer Monte Carlo simulations, we compute the continuum polarization signatures emerging from the model setup of Elvis et al. (2000). We find that a dust-filled outflow produces very low amount of wavelength-depend polarization degrees, associated with a photon polarization angle perpendicular to the projected symmetry axis of the model. The polarization percentages are ten times lower than what can be produced by a toroidal model, with a maximal polarization degree found for intermediate viewing angle (i.e. when the observer's line-of-sight crosses the outflowing material). The structure for quasars unsuccessfully blocks the radiation from the central irradiating source and shows a spectropolarimetric behavior that cannot be conciliated with observations. Either a new set of morphological parameters or different optical thickness must be considered.

  3. A SIMPLE MODEL FOR QUASAR DEMOGRAPHICS

    SciTech Connect

    Conroy, Charlie; White, Martin

    2013-01-10

    We present a simple model for the relationship between quasars, galaxies, and dark matter halos from 0.5 < z < 6. In the model, black hole (BH) mass is linearly related to galaxy mass, and galaxies are connected to dark matter halos via empirically constrained relations. A simple 'scattered' light bulb model for quasars is adopted, wherein BHs shine at a fixed fraction of the Eddington luminosity during accretion episodes, and Eddington ratios are drawn from a lognormal distribution that is redshift independent. This model has two free, physically meaningful parameters at each redshift: the normalization of the M {sub BH}-M {sub gal} relation and the quasar duty cycle; these parameters are fit to the observed quasar luminosity function (LF) over the interval 0.5 < z < 6. This simple model provides an excellent fit to the LF at all epochs and also successfully predicts the observed projected two-point correlation of quasars from 0.5 < z < 2.5. It is significant that a single quasar duty cycle at each redshift is capable of reproducing the extant observations. The data are therefore consistent with a scenario wherein quasars are equally likely to exist in galaxies, and therefore dark matter halos, over a wide range in masses. The knee in the quasar LF is a reflection of the knee in the stellar-mass-halo-mass relation. Future constraints on the quasar LF and quasar clustering at high redshift will provide strong constraints on the model. In the model, the autocorrelation function of quasars becomes a strong function of luminosity only at the very highest luminosities and will be difficult to observe because such quasars are so rare. Cross-correlation techniques may provide useful constraints on the bias of such rare objects. The simplicity of the model allows for rapid generation of quasar mock catalogs from N-body simulations that match the observed LF and clustering to high redshift.

  4. A Ly{alpha} HALO AROUND A QUASAR AT REDSHIFT z = 6.4

    SciTech Connect

    Willott, Chris J.; Chet, Savironi; Hutchings, John B.; Bergeron, Jacqueline

    2011-12-15

    We present long-slit spectroscopic data that reveal extended Ly{alpha} emission around the z = 6.417 radio-quiet quasar CFHQS J2329-0301. The Ly{alpha} emission is extended over 15 kpc and has a luminosity of >8 Multiplication-Sign 10{sup 36} W, comparable to the most luminous Ly{alpha} halos known. The emission has complex kinematics, in part due to foreground absorption, which only partly covers the extended nebula. The velocity ranges from -500 km s{sup -1} to +500 km s{sup -1}, with a peak remarkably close to the systemic velocity identified by broad Mg II emission of the quasar. There is no evidence for infall or outflow of the halo gas. We speculate that the Ly{alpha} emission mechanism is recombination after quasar photoionization of gas sitting within a high-mass dark matter halo. The immense Ly{alpha} luminosity indicates a higher covering factor of cold gas compared with typical radio-quiet quasars at lower redshift.

  5. Morphology of the AGN Outflow from FBQS J0209-0438

    NASA Astrophysics Data System (ADS)

    Chamberlain, Carter; Arav, N.; Kriss, G. A.; Muzahid, S.

    2014-01-01

    Spectroscopic observations of quasar outflows at rest-frame 500Å-1000Å have immense diagnostic power. Wavelength coverage of this range includes absorption troughs from OIV and OIV*, which allow us to measure the hydrogen number density through collisional excitation modeling, leading to a measurement of the outflow's distance from the central source. In the object we present, FBQS J0209-0438, such absorption troughs separate into five kinematic components, allowing for velocity-dependent photoionization modeling, and a determination of the distance-velocity relation. Through this relation, our analysis shows that the outflow from FBQS J0209-0438 has a lesser outward radial velocity at larger distances than it exhibits closer to the AGN (i.e. it is decelerating either as an outflow or infall). Absorption troughs from very highly ionized species such as NeVIII, ArVIII and MgX also appear in this spectral range and confirm the presence of 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. These two results create a detailed schematic of the structure of this typical AGN outflow.

  6. The SDSS-III BOSS quasar lens survey: discovery of 13 gravitationally lensed quasars

    NASA Astrophysics Data System (ADS)

    More, Anupreeta; Oguri, Masamune; Kayo, Issha; Zinn, Joel; Strauss, Michael A.; Santiago, Basilio X.; Mosquera, Ana M.; Inada, Naohisa; Kochanek, Christopher S.; Rusu, Cristian E.; Brownstein, Joel R.; da Costa, Luiz N.; Kneib, Jean-Paul; Maia, Marcio A. G.; Quimby, Robert M.; Schneider, Donald P.; Streblyanska, Alina; York, Donald G.

    2016-02-01

    We report the discovery of 13 confirmed two-image quasar lenses from a systematic search for gravitationally lensed quasars in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). We adopted a methodology similar to that used in the SDSS Quasar Lens Search (SQLS). In addition to the confirmed lenses, we report 11 quasar pairs with small angular separations ( ≲ 2 arcsec) confirmed from our spectroscopy, which are either projected pairs, physical binaries, or possibly quasar lens systems whose lens galaxies have not yet been detected. The newly discovered quasar lens system, SDSS J1452+4224 at zs ≈ 4.8 is one of the highest redshift multiply imaged quasars found to date. Furthermore, we have over 50 good lens candidates yet to be followed up. Owing to the heterogeneous selection of BOSS quasars, the lens sample presented here does not have a well-defined selection function.

  7. Four Quasars above Redshift 6 Discovered by the Canada-France High-z Quasar Survey

    NASA Astrophysics Data System (ADS)

    Willott, Chris J.; Delorme, Philippe; Omont, Alain; Bergeron, Jacqueline; Delfosse, Xavier; Forveille, Thierry; Albert, Loic; Reylé, Céline; Hill, Gary J.; Gully-Santiago, Michael; Vinten, Phillip; Crampton, David; Hutchings, John B.; Schade, David; Simard, Luc; Sawicki, Marcin; Beelen, Alexandre; Cox, Pierre

    2007-12-01

    The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars at redshifts greater than 6, including the most distant known quasar, CFHQS J2329-0301 at z = 6.43. We describe the observational method used to identify the quasars and present optical, infrared, and millimeter photometry and optical and near-infrared spectroscopy. We investigate the dust properties of these quasars, finding an unusual dust extinction curve for one quasar and a high far-infrared luminosity due to dust emission for another. The mean millimeter continuum flux for CFHQS quasars is substantially lower than that for SDSS quasars at the same redshift, likely due to a correlation with quasar UV luminosity. For two quasars with sufficiently high signal-to-noise ratio optical spectra, we use the spectra to investigate the ionization state of hydrogen at z > 5. For CFHQS J1509-1749 at z = 6.12 we find significant evolution (beyond a simple extrapolation of lower redshift data) in the Gunn-Peterson optical depth at z > 5.4. The line of sight to this quasar has one of the highest known optical depths at z approx 5.8. An analysis of the sizes of the highly ionized near-zones in the spectra of two quasars at z = 6.12 and 6.43 suggest that the intergalactic medium surrounding these quasars was substantially ionized before these quasars turned on. Together, these observations point toward an extended reionization process, but we caution that cosmic variance is still a major limitation in z > 6 quasar observations.

  8. Giant magnetized outflows from the centre of the Milky Way.

    PubMed

    Carretti, Ettore; Crocker, Roland M; Staveley-Smith, Lister; Haverkorn, Marijke; Purcell, Cormac; Gaensler, B M; Bernardi, Gianni; Kesteven, Michael J; Poppi, Sergio

    2013-01-01

    The nucleus of the Milky Way is known to harbour regions of intense star formation activity as well as a supermassive black hole. Recent observations have revealed regions of γ-ray emission reaching far above and below the Galactic Centre (relative to the Galactic plane), the so-called 'Fermi bubbles'. It is uncertain whether these were generated by nuclear star formation or by quasar-like outbursts of the central black hole and no information on the structures' magnetic field has been reported. Here we report observations of two giant, linearly polarized radio lobes, containing three ridge-like substructures, emanating from the Galactic Centre. The lobes each extend about 60 degrees in the Galactic bulge, closely corresponding to the Fermi bubbles, and are permeated by strong magnetic fields of up to 15 microgauss. We conclude that the radio lobes originate in a biconical, star-formation-driven (rather than black-hole-driven) outflow from the Galaxy's central 200 parsecs that transports a huge amount of magnetic energy, about 10(55) ergs, into the Galactic halo. The ridges wind around this outflow and, we suggest, constitute a 'phonographic' record of nuclear star formation activity over at least ten million years.

  9. Giant magnetized outflows from the centre of the Milky Way.

    PubMed

    Carretti, Ettore; Crocker, Roland M; Staveley-Smith, Lister; Haverkorn, Marijke; Purcell, Cormac; Gaensler, B M; Bernardi, Gianni; Kesteven, Michael J; Poppi, Sergio

    2013-01-01

    The nucleus of the Milky Way is known to harbour regions of intense star formation activity as well as a supermassive black hole. Recent observations have revealed regions of γ-ray emission reaching far above and below the Galactic Centre (relative to the Galactic plane), the so-called 'Fermi bubbles'. It is uncertain whether these were generated by nuclear star formation or by quasar-like outbursts of the central black hole and no information on the structures' magnetic field has been reported. Here we report observations of two giant, linearly polarized radio lobes, containing three ridge-like substructures, emanating from the Galactic Centre. The lobes each extend about 60 degrees in the Galactic bulge, closely corresponding to the Fermi bubbles, and are permeated by strong magnetic fields of up to 15 microgauss. We conclude that the radio lobes originate in a biconical, star-formation-driven (rather than black-hole-driven) outflow from the Galaxy's central 200 parsecs that transports a huge amount of magnetic energy, about 10(55) ergs, into the Galactic halo. The ridges wind around this outflow and, we suggest, constitute a 'phonographic' record of nuclear star formation activity over at least ten million years. PMID:23282363

  10. 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. PMID:25700515

  11. Extended X-ray emission from a quasar-driven superbubble

    SciTech Connect

    Greene, Jenny E.; Sun, Ai-Lei; Pooley, David; Zakamska, Nadia L.; Comerford, Julia M.

    2014-06-10

    We present observations of extended, 20 kpc scale soft X-ray gas around a luminous obscured quasar hosted by an ultraluminous infrared galaxy caught in the midst of a major merger. The extended X-ray emission is well fit as a thermal gas with a temperature of kT ≈280 eV and a luminosity of L {sub X} ≈ 10{sup 42} erg s{sup –1} and is spatially coincident with a known ionized gas outflow. Based on the X-ray luminosity, a factor of ∼10 fainter than the [O III] emission, we conclude that the X-ray emission is either dominated by photoionization, or by shocked emission from cloud surfaces in a hot quasar-driven wind.

  12. 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.

  13. Discovery of a narrow line quasar

    NASA Technical Reports Server (NTRS)

    Stocke, J.; Liebert, J.; Maccacaro, T.; Griffiths, R. E.; Steiner, J. E.

    1982-01-01

    A stellar object is reported which, while having X-ray and optical luminosities typical of quasars, has narrow permitted and forbidden emission lines over the observed spectral range. The narrow-line spectrum is high-excitation, the Balmer lines seem to be recombinational, and a redder optical spectrum than that of most quasars is exhibited, despite detection as a weak radio source. The object does not conform to the relationships between H-beta parameters and X-ray flux previously claimed for a large sample of the active galactic nuclei. Because reddish quasars with narrow lines, such as the object identified, may not be found by the standard techniques for the discovery of quasars, the object may be a prototype of a new class of quasars analogous to high-luminosity Seyfert type 2 galaxies. It is suggested that these objects cannot comprise more than 10% of all quasars.

  14. A Hubble Diagram for Quasars

    NASA Astrophysics Data System (ADS)

    Risaliti, G.; Lusso, E.

    2015-12-01

    We present a new method to test the ΛCDM cosmological model and to estimate cosmological parameters based on the nonlinear relation between the ultraviolet and X-ray luminosities of quasars. We built a data set of 1138 quasars by merging several samples from the literature with X-ray measurements at 2 keV and SDSS photometry, which was used to estimate the extinction-corrected 2500 Å flux. We obtained three main results: (1) we checked the nonlinear relation between X-ray and UV luminosities in small redshift bins up to z˜ 6, confirming that the relation holds at all redshifts with the same slope; (2) we built a Hubble diagram for quasars up to z˜ 6, which is well matched to that of supernovae in the common z = 0-1.4 redshift interval and extends the test of the cosmological model up to z˜ 6; and (3) we showed that this nonlinear relation is a powerful tool for estimating cosmological parameters. Using the present data and assuming a ΛCDM model, we obtain {{{Ω }}}M = 0.22{}-0.08+0.10 and {{{Ω }}}{{Λ }} = 0.92{}-0.30+0.18 ({{{Ω }}}M = 0.28 ± 0.04 and {{{Ω }}}{{Λ }} = 0.73 +/- 0.08 from a joint quasar-SNe fit). Much more precise measurements will be achieved with future surveys. A few thousand SDSS quasars already have serendipitous X-ray observations from Chandra or XMM-Newton, and at least 100,000 quasars with UV and X-ray data will be made available by the extended ROentgen Survey with an Imaging Telescope Array all-sky survey in a few years. The Euclid, Large Synoptic Survey Telescope, and Advanced Telescope for High ENergy Astrophysics surveys will further increase the sample size to at least several hundred thousand. Our simulations show that these samples will provide tight constraints on the cosmological parameters and will allow us to test for possible deviations from the standard model with higher precision than is possible today.

  15. Origin of outflows and winds

    NASA Technical Reports Server (NTRS)

    Koenigl, Arieh; Ruden, Steven P.

    1993-01-01

    Recent developments concerning the accretion-outflow connection and the role of magnetic fields are examined. It is argued that the weakly ionized wind most likely represents an MHD outflow driven centrifugally from the disk surfaces or from the boundary between the disk and the star. Specific wind models for each of these alternatives are presented, and it is contended that both provide a natural explanation of the observed correlation between accretion and outflow. The kinematic, thermal, and chemical wind properties predicted by these models are described and their observational implications are considered. It is suggested that the wind characteristics may be reflected in the observed forbidden line and IR continuum emission of T Tauri stars and in the measured abundances of various molecular species.

  16. The rotating wind of the quasar PG 1700+518.

    PubMed

    Young, S; Axon, D J; Robinson, A; Hough, J H; Smith, J E

    2007-11-01

    It is now widely accepted that most galaxies undergo an active phase, during which a central super-massive black hole generates vast radiant luminosities through the gravitational accretion of gas. Winds launched from a rotating accretion disk surrounding the black hole are thought to play a critical role, allowing the disk to shed angular momentum that would otherwise inhibit accretion. Such winds are capable of depositing large amounts of mechanical energy in the host galaxy and its environs, profoundly affecting its formation and evolution, and perhaps regulating the formation of large-scale cosmological structures in the early Universe. Although there are good theoretical grounds for believing that outflows from active galactic nuclei originate as disk winds, observational verification has proven elusive. Here we show that structures observed in polarized light across the broad Halpha emission line in the quasar PG 1700+518 originate close to the accretion disk in an electron scattering wind. The wind has large rotational motions (approximately 4,000 km s(-1)), providing direct observational evidence that outflows from active galactic nuclei are launched from the disks. Moreover, the wind rises nearly vertically from the disk, favouring launch mechanisms that impart an initial acceleration perpendicular to the disk plane.

  17. Half-megasecond Chandra spectral imaging of the hot circumgalactic nebula around quasar MRK 231

    SciTech Connect

    Veilleux, S.; Teng, S. H.; Rupke, D. S. N.; Maiolino, R.; Sturm, E.

    2014-08-01

    A deep 400 ks ACIS-S observation of the nearest quasar known, Mrk 231, is combined with archival 120 ks data to carry out the first ever spatially resolved spectral analysis of a hot X-ray-emitting circumgalactic nebula around a quasar. The 65 × 50 kpc X-ray nebula shares no resemblance with the tidal debris seen at optical wavelengths. One notable exception is the small tidal arc ∼3.5 kpc south of the nucleus where excess soft X-ray continuum emission and Si XIII 1.8 keV line emission are detected, consistent with star formation and its associated alpha-element enhancement, respectively. An X-ray shadow is also detected at the location of the 15 kpc northern tidal tail. The hard X-ray continuum emission within ∼6 kpc of the center is consistent with being due entirely to the bright central active galactic nucleus. The soft X-ray spectrum of the outer (≳6 kpc) portion of the nebula is best described as the sum of two thermal components with temperatures ∼3 and ∼8 million K and spatially uniform super-solar alpha-element abundances, relative to iron. This result implies enhanced star formation activity over ∼10{sup 8} yr, accompanied by redistribution of the metals on a large scale. The low-temperature thermal component is not present within ∼6 kpc of the nucleus, suggesting extra heating in this region from the circumnuclear starburst, the central quasar, or the optically identified ≳3 kpc quasar-driven outflow. The soft X-ray emission is weaker in the western quadrant, coincident with a deficit of Hα and some of the largest columns of neutral gas outflowing from the nucleus. Shocks may heat the gas to high temperatures at this location, consistent with the tentative ∼2σ detection of extended Fe XXV 6.7 keV line emission.

  18. Exploration of quasars with the Gaia mission

    NASA Astrophysics Data System (ADS)

    Proft, Svea; Wambsganss, Joachim

    2015-01-01

    We analyze the opportunities in and limits to investigating quasars with the Gaia satellite by studying Gaia's low- and high-resolution quasar spectra, with consideration of their signal-to-noise ratios. Furthermore, we explore bright quasars from the Sloan Digital Sky Survey with broad emission lines (BELs) redshifted into the spectral range of Gaia's Radial Velocity Spectrograph (RVS). We find that Gaia low-resolution spectra of quasars enable a determination of equivalent widths, continuum variability, and the Baldwin effect. Additionally, it will be feasible to analyze BEL reverberation mapping with Gaia data for a small sample of objects. These quasars should have a high cadence of measurements or higher time lags due to large redshifts, high quasar luminosities, or selected low-ionization lines. More than 500 known quasars will also get high-resolution spectra of individual BELs in the small wavelength range of the RVS. This allows an investigation of broad emission line shapes and their variabilities to get information on the spatial structure and kinematics of the broad line region. We identify six known variable SDSS quasars with BELs in the RVS that have interesting spectra for a potential intrinsic line variability investigation. However, the signal-to-noise ratio of the RVS is too small for studying narrow and broad absorption lines in quasar spectra.

  19. Quasars and Active Galaxies: A Reading List.

    ERIC Educational Resources Information Center

    Fraknoi, Andrew

    1988-01-01

    Contains the annotated bibliographies of introductory books and sections of books, recent introductory articles, more advanced articles, and more advanced books dealing with quasars and active galaxies. (CW)

  20. "Dead quasars" in nearby galaxies?

    PubMed

    Rees, M J

    1990-02-16

    The nuclei of some galaxies undergo violent activity, quasars being the most extreme instances of this phenomenon. Such activity is probably short-lived compared to galactic lifetimes, and was most prevalent when the universe was only about one-fifth of its present age. A massive black hole seems the inevitable end point of such activity, and dead quasars should greatly outnumber active ones. In recent years, studies of stellar motions in the cores of several nearby galaxies indicate the presence of central dark masses which could be black holes. This article discusses how such evidence might be corroborated, and the potential implications for our understanding of active galaxies and black holes. PMID:17746076

  1. OPTOPUS observations of quasar candidates.

    NASA Astrophysics Data System (ADS)

    Cristiani, S.

    1987-06-01

    OPTOPUS is a fiber-optic instrument for multiple-object spectroscopy with the Boiler & Chivens spectrograph and a CCD detector at the 3.6-m telescope. The system has been described in detail by the Optical Instrumentation Group (1985, The Messenger 41,25). Its application for observing Halley's comet has been reported by Lund and Surdej (1986, The Messenger 43, 1). Here another "classical" use of multiple-object spectroscopy is presented: followup observations of quasar candidates.

  2. Quasar redshifts: the intrinsic component

    NASA Astrophysics Data System (ADS)

    Hansen, Peter M.

    2016-09-01

    The large observed redshift of quasars has suggested large cosmological distances and a corresponding enormous energy output to explain the brightness or luminosity as seen at earth. Alternative or complementary sources of redshift have not been identified by the astronomical community. This study examines one possible source of additional redshift: an intrinsic component based on the plasma characteristics of high temperature and high electron density which are believed to be present.

  3. Broad absorption line variability on multi-year timescales in a large quasar sample

    NASA Astrophysics Data System (ADS)

    Filiz Ak, Nurten

    Outflows launched near the central supermassive black holes (SMBHs) are a common and important component of active galactic nuclei (AGNs). Outflows in luminous AGNs (i.e., quasars) play a key role in mass accretion onto SMBH as well as in the feedback into host galaxies. The most prominent signature of such outflows appears as broad absorption lines (BALs) that are blueshifted from the emission line with a few thousands km s--1 velocities. In this dissertation, I place further constrains upon the size scale, internal structure, dynamics, and evolution of the outflows investigating profiles, properties, and variation characteristics of BAL troughs. I present observational results on BAL troughs in a large quasar sample utilizing spectroscopic observations from the Sloan Digital Sky Survey spanning on multi-year timescales. The results presented here, for the first time, provide a large and well-defined variability data base capable of discriminating between time-dependent hydrodynamic wind calculations in a statistically powerful manner. In a study of 582 quasars, I present 21 examples of BAL trough disappearance. Approximately 3.3% of BAL quasars show disappearing C IV trough on rest-frame timescales of 1.1--3.9 yr. BAL disappearance appears to occur mainly for shallow and weak or moderate-strength absorption troughs but not the strongest ones. When one BAL trough in a quasar spectrum disappears, the other present troughs usually weaken. Possible causes of such coordinated variations could be disk-wind rotation or variations of shielding gas that lead to variations of ionizing-continuum radiation. I present a detailed study on the variability of 428 C IV and 235 Si IV BAL troughs using a systematically observed sample of 291 BAL quasars. BAL variation distributions indicate that BAL disappearance is an extreme type of general BAL variability, rather than a qualitatively distinct phenomenon. The high observed frequency of BAL variability on multi-year timescales is

  4. Quasar target selection fiber efficiency

    SciTech Connect

    Newberg, H.; Yanny, B.

    1996-05-01

    We present estimates of the efficiency for finding QSOs as a function of limiting magnitude and galactic latitude. From these estimates, we have formulated a target selection strategy that should net 80,000 QSOs in the north galactic cap with an average of 70 fibers per plate, not including fibers reserved for high-redshift quasars. With this plan, we expect 54% of the targets to be QSOs. The North Galactic Cap is divided into two zones of high and low stellar density. We use about five times as many fibers for QSO candidates in the half of the survey with the lower stellar density as we use in the half with higher stellar density. The current plan assigns 15% of the fibers to FIRST radio sources; if these are not available, those fibers would be allocated to lower probability QSO sources, dropping the total number of QSOs by a small factor (5%). We will find about 17,000 additional quasars in the southern strips, and maybe a few more at very high redshift. Use was made of two data sets: the star and quasar simulated test data generated by Don Schneider, and the data from UJFN plate surveys by Koo (1986) and Kron (1980). This data was compared to results from the Palomar-Green Survey and a recent survey by Pat Osmer and collaborators.

  5. NEW PERSPECTIVE ON GALAXY OUTFLOWS FROM THE FIRST DETECTION OF BOTH INTRINSIC AND TRAVERSE METAL-LINE ABSORPTION

    SciTech Connect

    Kacprzak, Glenn G.; Cooke, Jeff; Martin, Crystal L.; Ho, Stephanie H.; Bouché, Nicolas; LeReun, Audrey; Schroetter, Ilane; Churchill, Christopher W.; Klimek, Elizabeth

    2014-09-01

    We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V {sub dtb} = 45-255 km s{sup –1}. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V {sub outflow} = 40-80 km s{sup –1} to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V {sub dtb}. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = –0.21 ± 0.08, whereas the transverse absorption has [X/H] = –1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M {sub ☉} yr{sup –1} while the estimated outflow rate ranges between 1.6-4.2 M {sub ☉} yr{sup –1} and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ∼1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

  6. New Perspective on Galaxy Outflows from the First Detection of Both Intrinsic and Traverse Metal-line Absorption

    NASA Astrophysics Data System (ADS)

    Kacprzak, Glenn G.; Martin, Crystal L.; Bouché, Nicolas; Churchill, Christopher W.; Cooke, Jeff; LeReun, Audrey; Schroetter, Ilane; Ho, Stephanie H.; Klimek, Elizabeth

    2014-09-01

    We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V dtb = 45-255 km s-1. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V outflow = 40-80 km s-1 to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V dtb. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = -0.21 ± 0.08, whereas the transverse absorption has [X/H] = -1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M ⊙ yr-1 while the estimated outflow rate ranges between 1.6-4.2 M ⊙ yr-1 and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ~1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

  7. The Nature of Partial Covering in Broad Absorption Line Quasars

    NASA Astrophysics Data System (ADS)

    Leighly, Karen

    2012-10-01

    Ejected gas is seen as broad absorption lines in 20% of quasars. It has been known for 15 years that prominent lines such as CIV are usually saturated but not black because the absorbing gas only partially covers the continuum emission region. Therefore, column densities estimated from these lines are only lower limits. Accurate column densities can be obtained from rare ions that have two or more transitions from the same lower level, so that the optical depth and covering fraction can be solved for simultanously. Suitable lines are hard to find, so such measurements are rare. We have found that metastable helium is particularly useful for these measurements. Yet despite these advances, partial covering remains a just a parameter and its physical nature is not understood.We propose a unique experiment to constrain the physical nature of partial covering. We will compare the covering fraction measured from PV {a doublet in the far UV} with that measured from metastable HeI {optical and IR}. The ions creating these lines are relatively rare, and they present similar opacity over a wide range of gas parameters. But due to their wide wavelength separation, these lines probe dramatically different regions of the continuum source, the temperature-dependent accretion disk. So we expect different covering fraction behavior for different partial covering scenarios. This experiment is relevant for understanding the geometry and clumpiness of the outflow, and the results may impact our understanding of the global covering fraction, a parameter critical for determining the outflow kinetic luminosity, and thereby estimating feedback efficiency for broad absorption line outflows.

  8. The luminosity function of quasars and its evolution: A comparison of optically selected quasars and quasars found in radio catalogs

    NASA Technical Reports Server (NTRS)

    Petrosian, V.

    1973-01-01

    The luminosity function of quasars and its evolution are discussed, based on comparison of available data on optically selected quasars and quasars found in radio catalogs. It is assumed that the red shift of quasars is cosmological and the results are expressed in the framework of the Lambda = 0, Q sub Q = 1 cosmological model. The predictions of various density evolution laws are compared with observations of an optically selected sample of quasars and quasar samples from radio catalogs. The differences between the optical luminosity functions, the red shift distributions and the radio to optical luminosity ratios of optically selected quasars and radio quasars rule out luminosity functions where there is complete absence of correlation between radio and optical luminosities. These differences also imply that Schmidt's (1970) luminosity function, where there exists a statistical correlation between radio and optical luminosities, although may be correct for high red shift objects, disagrees with observation at low red shifts. These differences can be accounted for by postulating existence of two classes (1 and 2) of objects.

  9. Water in Shocks and Outflows

    NASA Astrophysics Data System (ADS)

    Neufeld, D. A.; Melnick, G. J.; Stauffer, J. R.; Ashby, M. L. N.; Bergin, E. A.; Kleiner, S. C.; Patten, B. M.; Plume, R.; Tolls, V.; Wang, Z.; Zhang, Y. F.; Goldsmith, P. F.; Harwit, M.; Erickson, N. R.; Howe, J. E.; Snell, R. L.; Koch, D. G.; Schieder, R.; Winnewisser, G.; Chin, G.

    1999-12-01

    We have observed water vapor emission from several protostellar outflow regions with SWAS, including the sources Orion-KL, NGC 2071, NGC 1333 IRAS 4, L1157, RCrA, and L1689N. Observations of the 110}-1{01 water transition toward each of these sources have revealed the presence of broad line emission accompanied by narrow absorption in quiescent foreground gas or -- in the case of Orion-KL, by a narrow emission line component. In each case, the width of the broad emission line component, typically 20 - 40 km s-1 (FWHM), suggests an origin in the outflowing gas. From the observed line fluxes, we estimate water abundances ranging from 10-6 in low mass outflow regions to several x 10-4 in the Orion-KL region. These values are all significantly larger than the water abundance estimates of few x 10-9 - 10-7 derived from SWAS observations of quiescent regions, implying that the water abundances are enhanced in outflow regions. Such enhancements are indeed expected to result from the effects of shocks in (1) vaporizing icy grain mantles and/or (2) producing water in the gas-phase (by means of neutral-neutral reactions that are negligibly slow at the low temperatures of quiescent clouds but rapid at the elevated temperatures present behind a shock.)

  10. Molecular outflows in starburst nuclei

    NASA Astrophysics Data System (ADS)

    Roy, Arpita; Nath, Biman B.; Sharma, Prateek; Shchekinov, Yuri

    2016-08-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with NOB ≥ 105 (corresponding to a star formation rate (SFR)≥1 M⊙ yr-1 in the nuclear region), in a stratified disk with mid-plane density n0 ˜ 200-1000 cm-3 and scale height z0 ≥ 200(n0/102 cm-3)-3/5 pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is ≥107 M⊙ at a distance of a few hundred pc, with a speed of several tens of km s-1. We show that a SFR surface density of 10 ≤ ΣSFR ≤ 50 M⊙ yr-1 kpc-2 favours the production of molecular outflows, consistent with observed values.

  11. Ionized Absorbers in Active Galactic Nuclei and Very Steap Soft X-Ray Quasars

    NASA Technical Reports Server (NTRS)

    Fiore, Fabrizio; White, Nicholas (Technical Monitor)

    2000-01-01

    Steep soft X-ray (0.1-2 keV) quasars share several unusual properties: narrow Balmer lines, strong Fe II emission, large and fast X-ray variability, and a rather steep 2-10 keV spectrum. These intriguing objects have been suggested to be the analogues of Galactic black hole candidates in the high, soft state. We present here results from ASCA observations for two of these quasars: NAB 0205 + 024 and PG 1244 + 026. Both objects show similar variations (factor of approximately 2 in 10 ks), despite a factor of approximately 10 difference in the 0.5-10 keV luminosity (7.3 x 10(exp 43) erg/s for PG 1244 + 026 and 6.4 x 10(exp 44) erg/s for NAB 0205 + 024, assuming isotropic emission, H(sub 0) = 50.0 and q(sub 0) = 0.0). The X-ray continuum of the two quasars flattens by 0.5-1 going from the 0.1-2 keV band towards higher energies, strengthening recent results on another half-dozen steep soft X-ray active galactic nuclei. PG 1244 + 026 shows a significant feature in the '1-keV' region, which can be described either as a broad emission line centered at 0.95 keV (quasar frame) or as edge or line absorption at 1.17 (1.22) keV. The line emission could be a result of reflection from a highly ionized accretion disc, in line with the view that steep soft X-ray quasars are emitting close to the Eddington luminosity. Photoelectric edge absorption or resonant line absorption could be produced by gas outflowing at a large velocity (0.3-0.6 c).

  12. Hot outflows in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, C. C.; McNamara, B. R.

    2015-10-01

    The gas-phase metallicity distribution has been analysed for the hot atmospheres of 29 galaxy clusters using Chandra X-ray Observatory observations. All host brightest cluster galaxies (BCGs) with X-ray cavity systems produced by radio AGN. We find high elemental abundances projected preferentially along the cavities of 16 clusters. The metal-rich plasma was apparently lifted out of the BCGs with the rising X-ray cavities (bubbles) to altitudes between twenty and several hundred kiloparsecs. A relationship between the maximum projected altitude of the uplifted gas (the `iron radius') and jet power is found with the form R_Fe ∝ P_jet^{0.45}. The estimated outflow rates are typically tens of solar masses per year but exceed 100 M⊙ yr- 1 in the most powerful AGN. The outflow rates are 10-20 per cent of the cooling rates, and thus alone are unable to offset a cooling inflow. Nevertheless, hot outflows effectively redistribute the cooling gas and may play a significant role at regulating star formation and AGN activity in BCGs and presumably in giant elliptical galaxies. The metallicity distribution overall can be complex, perhaps due to metal-rich gas returning in circulation flows or being blown around in the hot atmospheres. Roughly 15 per cent of the work done by the cavities is expended lifting the metal-enriched gas, implying their nuclear black holes have increased in mass by at least ˜107-109 M⊙. Finally, we show that hot outflows can account for the broad, gas-phase metallicity distribution compared to the stellar light profiles of BCGs, and we consider a possible connection between hot outflows and cold molecular gas flows discovered in recent Atacama Large Millimeter Array observations.

  13. Quasars: Active nuclei of young galaxies

    NASA Technical Reports Server (NTRS)

    Komberg, B. V.

    1980-01-01

    The hypothetical properties of 'young' galaxies and possible methods of observing them are discussed. It is proposed that star formation first takes place in the central regions of protogalaxies which may appear as quasar-like objects. An evolutionary scheme is outlined in which the radio quasars are transformed in time into the nuclei of radio galaxies.

  14. Quasars - powerhouses at the edge of time

    NASA Astrophysics Data System (ADS)

    Gavin, M.

    2000-06-01

    1999 was the 70th anniversary of Edwin Hubble's seminal publication1 showing a cosmological redshift in galaxies. More recent discoveries of quasars have extended the universe's boundaries back in time nearer to the Big Bang. Some amateur spectrograms of quasars are presented showing a cosmological redshift.

  15. HST Imaging of Quasar Host Galaxies

    NASA Astrophysics Data System (ADS)

    Hooper, E. J.; Impey, C. D.; Foltz, C. B.

    1996-12-01

    A sample of 16 quasars from the Large Bright Quasar Survey (LBQS) has been imaged with WFPC2 on the Hubble Space Telescope. The sample was selected to cover a range of radio luminosity typical of optically selected quasars in narrow intervals of redshift (0.4 <= z >= 0.5) and absolute magnitude (-25 < MB < -23). Two-dimensional cross-correlation techniques were used to determine the magnitudes of the host galaxies and quasar nuclear components, as well as the axial ratios of the hosts. The derived host galaxy magnitudes are near or below L(*) and are correlated with the quasar nuclear magnitude, similar to the trend in near-infrared host galaxy luminosity found by McLeod & Rieke (1995, ApJ, 454, L77). There is no discernable difference in host galaxy luminosity between radio-loud and radio-quiet quasars in the sample. Preliminary analysis of the host galaxy morphologies indicates that many, including several of the radio-quiet quasars, are probably in early type galaxies, consistent with other high-resolution imaging studies of quasar hosts. However, the distribution of axial ratios is not consistent with a population of early type galaxies. The hosts in the LBQS sample are rather flattened, with half having axial ratios <= 0.5. It is possible that these are inclined disk systems or galaxies with substantial bar components.

  16. Quasars as very-accurate clock synchronizers

    NASA Technical Reports Server (NTRS)

    Hurd, W. J.; Goldstein, R. M.

    1975-01-01

    Quasars can be employed to synchronize global data communications, geophysical measurements, and atomic clocks. It is potentially two to three orders of magnitude better than presently-used Moon-bounce system. Comparisons between quasar and clock pulses are used to develop correction or synchronization factors for station clocks.

  17. A HIGH RESOLUTION VIEW OF THE WARM ABSORBER IN THE QUASAR MR 2251-178

    SciTech Connect

    Reeves, J. N.; Gofford, J.; Nardini, E.; Porquet, D.; Braito, V.; Turner, T. J.; Crenshaw, D. M.; Kraemer, S. B.

    2013-10-20

    High resolution X-ray spectroscopy of the warm absorber in a nearby quasar, MR 2251-178 (z = 0.06398), is presented. The observations were carried out in 2011 using the Chandra High Energy Transmission Grating (HETG) and the XMM-Newton Reflection Grating Spectrometer, with net exposure times of approximately 400 ks each. A multitude of absorption lines from C to Fe are detected, revealing at least three warm absorbing components ranging in ionization parameter from log (ξ/erg cm s{sup –1}) = 1-3 with outflow velocities ∼< 500 km s{sup –1}. The lowest ionization absorber appears to vary between the Chandra and XMM-Newton observations, which implies a radial distance of between 9 and 17 pc from the black hole. Several broad soft X-ray emission lines are strongly detected, most notably from He-like oxygen, with FWHM velocity widths of up to 10,000 km s{sup –1}, consistent with an origin from broad-line region (BLR) clouds. In addition to the warm absorber, gas partially covering the line of sight to the quasar appears to be present, with a typical column density of N{sub H} = 10{sup 23} cm{sup –2}. We suggest that the partial covering absorber may arise from the same BLR clouds responsible for the broad soft X-ray emission lines. Finally, the presence of a highly ionized outflow in the iron K band from both the 2002 and 2011 Chandra HETG observations appears to be confirmed, which has an outflow velocity of –15600 ± 2400 km s{sup –1}. However, a partial covering origin for the iron K absorption cannot be excluded, resulting from low ionization material with little or no outflow velocity.

  18. The warm absorber in the radio-loud quasar 4C +74.26

    NASA Astrophysics Data System (ADS)

    Di Gesu, L.; Costantini, E.

    2016-10-01

    Outflows of photoionized gas are commonly detected in the X-ray spectra of Seyfert 1 galaxies. However, the evidence for this phenomenon in broad line radio galaxies, which are analogous to Seyfert 1 galaxies in the radio-loud regime, has so far been scarce. Here, we present the analysis of the X-ray absorption in the radio-loud quasar 4C +74.26. With the aim of characterizing the kinetic and the ionization conditions of the absorbing material, we fitted jointly the XMM-Newton Reflection Grating Spectrometer (RGS) and the Chandra High Energy Transmission Grating Spectrometer (HETGS) spectra, which were taken 4 months apart. The intrinsic continuum flux did not vary significantly during this time lapse. The spectrum shows the absorption signatures (e.g., Fe-UTA, O vii, and Ne vii-Ne x) of a photoionized gas outflow (NH ~ 3.5 × 1021 cm-2, log ξ ~ 2.6, vout ~ 3600 km s-1) located at the redshift of source. We estimate that the gas is located outside the broad line region but within the boundaries of the putative torus. This ionized absorber is consistent with the X-ray counterpart of a polar scattering outflow reported in the optical band for this source. The kinetic luminosity carried by the outflow is insufficient to produce a significant feedback is this quasar. Finally, we show that the heavy soft X-ray absorption that was noticed in the past for this source arises mostly in the Galactic interstellar medium.

  19. 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.

  20. The Wide-angle Outflow of the Lensed z = 1.51 AGN HS 0810+2554

    NASA Astrophysics Data System (ADS)

    Chartas, G.; Cappi, M.; Hamann, F.; Eracleous, M.; Strickland, S.; Giustini, M.; Misawa, T.

    2016-06-01

    We present results from X-ray observations of the gravitationally lensed z = 1.51 active galactic nucleus (AGN) HS 0810+2554 performed with the Chandra X-ray Observatory and XMM-Newton. Blueshifted absorption lines are detected in both observations at rest-frame energies ranging between ˜1 and 12 keV at ≳99% confidence. The inferred velocities of the outflowing components range between ˜0.1c and ˜0.4c. A strong emission line at ˜6.8 keV that is accompanied by a significant absorption line at ˜7.8 keV is also detected in the Chandra observation. The presence of these lines is a characteristic feature of a P-Cygni profile supporting the presence of an expanding, outflowing, highly ionized iron absorber in this quasar. Modeling of the P-Cygni profile constrains the covering factor of the wind to be ≳0.6, assuming disk shielding. A disk-reflection component is detected in the XMM-Newton observation accompanied by blueshifted absorption lines. The XMM-Newton observation constrains the inclination angle to be <45° at 90% confidence, assuming that the hard excess is due to blurred reflection from the accretion disk. The detection of an ultrafast and wide-angle wind in an AGN with intrinsic narrow absorption lines (NALs) would suggest that quasar winds may couple efficiently with the intergalactic medium and provide significant feedback if ubiquitous in all NAL and broad absorption line (BAL) quasars. We estimate the mass-outflow rate of the absorbers to lie in the range of 1.5-3.4 M ⊙ yr-1 for the two observations. We find that the fraction of kinetic to electromagnetic luminosity released by HS 0810+2554 is large (ɛ k = 9{}-6+8), which suggests that magnetic driving is likely a significant contributor to the acceleration of this outflow.

  1. Evidence for the alignment of quasar radio polarizations with large quasar group axes

    NASA Astrophysics Data System (ADS)

    Pelgrims, V.; Hutsemékers, D.

    2016-05-01

    Recently, evidence has been presented for the polarization vectors from quasars to preferentially align with the axes of the large quasar groups (LQG) to which they belong. This report was based on observations made at optical wavelengths for two LQGs at redshift ~1.3. The correlation suggests that the spin axes of quasars preferentially align with their surrounding large-scale structure that is assumed to be traced by the LQGs. Here, we consider a large sample of LQGs built from the Sloan Digital Sky Survey DR7 quasar catalogue in the redshift range 1.0-1.8. For quasars embedded in this sample, we collected radio polarization measurements with the goal to study possible correlations between quasar polarization vectors and the major axis of their host LQGs. Assuming the radio polarization vector is perpendicular to the quasar spin axis, we found that the quasar spin axis is preferentially parallel to the LQG major axis inside LQGs that have at least 20 members. This result independently supports the observations at optical wavelengths. We additionally found that when the richness of an LQG decreases, the quasar spin axis becomes preferentially perpendicular to the LQG major axis and that no correlation is detected for quasar groups with fewer than 10 members.

  2. The VLT SINFONI Mg II Program for Line Emitters (SIMPLE). II. Background Quasars Probing Z ~ 1 Galactic Winds

    NASA Astrophysics Data System (ADS)

    Schroetter, Ilane; Bouché, Nicolas; Péroux, Céline; Murphy, Michael T.; Contini, Thierry; Finley, Hayley

    2015-05-01

    The physical properties of galactic winds are of paramount importance for our understanding of galaxy formation. Fortunately, they can be constrained using background quasars passing near star-forming galaxies (SFGs). From the 14 quasar-galaxy pairs in our Very Large Telescope (VLT)/SINFONI Mg ii Program for Line Emitters sample, we reobserved the 10 brightest galaxies in Hα with the VLT/SINFONI with 0.″ 7 seeing and the corresponding quasar with the VLT/UVES spectrograph. Applying geometrical arguments to these 10 pairs, we find that four are likely probing galactic outflows, three are likely probing extended gaseous disks, and the remaining three are not classifiable because they are viewed face-on. In this paper we present a detailed comparison between the line-of-sight kinematics and the host galaxy emission kinematics for the pairs suitable for wind studies. We find that the kinematic profile shapes (asymmetries) can be well reproduced by a purely geometrical wind model with a constant wind speed, except for one pair (toward J2357-2736) that has the smallest impact parameter b = 6 kpc and requires an accelerated wind flow. Globally, the outflow speeds are ˜100 km s-1 and the mass ejection rates (or {{\\dot{M}}out}) in the gas traced by the low-ionization species are similar to the star formation rate (SFR), meaning that the mass loading factor, η ={{\\dot{M}}out}/SFR, is ≈1.0. The outflow speeds are also smaller than the local escape velocity, which implies that the outflows do not escape the galaxy halo and are likely to fall back into the interstellar medium. Based on observations made at the ESO telescopes under program 080.A-0364(A) 080.A-0364(B) and 079.A-0600(B).

  3. 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.

  4. BLOWIN' IN THE WIND: BOTH ''NEGATIVE'' AND ''POSITIVE'' FEEDBACK IN AN OBSCURED HIGH-z QUASAR

    SciTech Connect

    Cresci, G.; Mannucci, F.; Mainieri, V.; Brusa, M.; Perna, M.; Lanzuisi, G.; Piconcelli, E.; Feruglio, C.; Fiore, F.; Bongiorno, A.; Maiolino, R.; Merloni, A; Schramm, M.; Silverman, J. D.; Civano, F.

    2015-01-20

    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{sup –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.

  5. HUBBLE CAPTURES MERGER BETWEEN QUASAR AND GALAXY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This NASA Hubble Space Telescope image shows evidence fo r a merger between a quasar and a companion galaxy. This surprising result might require theorists to rethink their explanations for the nature of quasars, the most energetic objects in the universe. The bright central object is the quasar itself, located several billion light-years away. The two wisps on the (left) of the bright central object are remnants of a bright galaxy that have been disrupted by the mutual gravitational attraction between the quasar and the companion galaxy. This provides clear evidence for a merger between the two objects. Since their discovery in 1963, quasars (quasi-stellar objects) have been enigmatic because they emit prodigious amounts of energy from a very compact source. The most widely accepted model is that a quasar is powered by a supermassive black hole in the core of a galaxy. These new observations proved a challenge for theorists as no current models predict the complex quasar interactions unveiled by Hubble. The image was taken with the Wide Field Planetary Camera-2. Credit: John Bahcall, Institute for Advanced Study, NASA.

  6. The FIRST-2MASS Red Quasar Survey

    SciTech Connect

    Glikman, E; Helfand, D J; White, R L; Becker, R H; Gregg, M D; Lacy, M

    2007-06-28

    Combining radio observations with optical and infrared color selection--demonstrated in our pilot study to be an efficient selection algorithm for finding red quasars--we have obtained optical and infrared spectroscopy for 120 objects in a complete sample of 156 candidates from a sky area of 2716 square degrees. Consistent with our initial results, we find our selection criteria--J-K > 1.7,R-K > 4.0--yield a {approx} 50% success rate for discovering quasars substantially redder than those found in optical surveys. Comparison with UVX- and optical color-selected samples shows that {approx}> 10% of the quasars are missed in a magnitude-limited survey. Simultaneous two-frequency radio observations for part of the sample indicate that a synchrotron continuum component is ruled out as a significant contributor to reddening the quasars spectra. We go on to estimate extinctions for our objects assuming their red colors are caused by dust. Continuum fits and Balmer decrements suggest E(B-V) values ranging from near zero to 2.5 magnitudes. Correcting the K-band magnitudes for these extinctions, we find that for K {le} 14.0, red quasars make up between 25% and 60% of the underlying quasar population; owing to the incompleteness of the 2MASS survey at fainter K-band magnitudes, we can only set a lower limit to the radio-detected red quasar population of > 20-30%.

  7. Quasar Classification Using Color and Variability

    NASA Astrophysics Data System (ADS)

    Peters, Christina M.; Richards, Gordon

    2015-08-01

    We use the Non-parametric Bayesian Classification Kernel Density Estimation (NBC KDE) quasar selection algorithm (Richards et al. 2004) to identify 36,569 type 1 quasar candidates in the Sloan Digital Sky Survey (SDSS) Stripe 82 field using the combination of optical photometry and variability. 5-band coadded optical photometry is taken from the SDSS-I/II to a depth of r ~ 22.4; from these data variability parameters are calculated by fitting the structure function of each object in each band with a power law using 10 to >100 observations for timescales from ~1 day to ~8 years. Selection was based on a training sample of 13,221 spectroscopically-confirmed type 1 quasars from SDSS-I/II and the Baryon Oscillation Spectroscopic Survey (BOSS). Using variability alone, colors alone, and combining variability and colors we achieve 91%, 93%, and 97% quasar completeness and 98%, 98%, and 97% efficiency respectively, with particular improvement in the selection of quasars at 2.7 < z < 3.5 where quasars and stars have similar optical colors. The 23,043 quasar candidates that are not spectroscopically confirmed reach a depth of coadd i ~ 22: 0 and 21,380 (92.8%) are dimmer than coadded i -band magnitude of 20.2, the cut off for spectroscopic follow-up for SDSSDR7.

  8. Understanding post-starburst quasars

    NASA Astrophysics Data System (ADS)

    Cales, Sabrina L.

    Post-starburst quasars (PSQs) are an interesting type of hybrid galaxy that harbor both a post-starburst stellar population and luminous AGN. The starburst is hundreds of millions of years old with a mass on the order of 10 billion solar masses. This type of hybrid galaxy provides a natural breading ground for studying the role active galactic nuclei (AGN) play in galaxy evolution (i.e., the black hole mass-galaxy bulge mass relation). My thesis work has centered on testing the idea that, at z ˜ 0.3, PSQs are a phase in the life of galaxies triggered by external events (e.g., mergers, tidal interactions) or whether they are a more heterogeneous population in which multiple mechanisms can contribute to the class (i.e., external events and internal processes). This project is devoted to understanding the properties of PSQs and is comprised of three sub-projects: (i) two-dimensional image analysis with HST imaging and characterization of PSQ morphologies, (ii) determination of stellar population ages and masses and quasar black hole masses and accretion rates via spectral modeling of Keck and KPNO spectroscopy, (iii) comparisons of PSQ properties with other galaxy types and models. Finally, I briefly outline my conclusions in the context of AGN/galaxy evolution.

  9. OPTIMAL TIME-SERIES SELECTION OF QUASARS

    SciTech Connect

    Butler, Nathaniel R.; Bloom, Joshua S.

    2011-03-15

    We present a novel method for the optimal selection of quasars using time-series observations in a single photometric bandpass. Utilizing the damped random walk model of Kelly et al., we parameterize the ensemble quasar structure function in Sloan Stripe 82 as a function of observed brightness. The ensemble model fit can then be evaluated rigorously for and calibrated with individual light curves with no parameter fitting. This yields a classification in two statistics-one describing the fit confidence and the other describing the probability of a false alarm-which can be tuned, a priori, to achieve high quasar detection fractions (99% completeness with default cuts), given an acceptable rate of false alarms. We establish the typical rate of false alarms due to known variable stars as {approx}<3% (high purity). Applying the classification, we increase the sample of potential quasars relative to those known in Stripe 82 by as much as 29%, and by nearly a factor of two in the redshift range 2.5 < z < 3, where selection by color is extremely inefficient. This represents 1875 new quasars in a 290 deg{sup 2} field. The observed rates of both quasars and stars agree well with the model predictions, with >99% of quasars exhibiting the expected variability profile. We discuss the utility of the method at high redshift and in the regime of noisy and sparse data. Our time-series selection complements well-independent selection based on quasar colors and has strong potential for identifying high-redshift quasars for Baryon Acoustic Oscillations and other cosmology studies in the LSST era.

  10. Moderate resolution spectrophotometry of high redshift quasars

    NASA Technical Reports Server (NTRS)

    Schneider, Donald P.; Schmidt, Maarten; Gunn, James E.

    1991-01-01

    A uniform set of photometry and high signal-to-noise moderate resolution spectroscopy of 33 quasars with redshifts larger than 3.1 is presented. The sample consists of 17 newly discovered quasars (two with redshifts in excess of 4.4) and 16 sources drawn from the literature. The objects in this sample have r magnitudes between 17.4 and 21.4; their luminosities range from -28.8 to -24.9. Three of the 33 objects are broad absorption line quasars. A number of possible high redshift damped Ly-alpha systems were found.

  11. Merging Galaxies Create a Binary Quasar

    NASA Astrophysics Data System (ADS)

    2010-02-01

    Astronomers have found the first clear evidence of a binary quasar within a pair of actively merging galaxies. Quasars are the extremely bright centers of galaxies surrounding super-massive black holes, and binary quasars are pairs of quasars bound together by gravity. Binary quasars, like other quasars, are thought to be the product of galaxy mergers. Until now, however, binary quasars have not been seen in galaxies that are unambiguously in the act of merging. But images of a new binary quasar from the Carnegie Institution's Magellan telescope in Chile show two distinct galaxies with "tails" produced by tidal forces from their mutual gravitational attraction. "This is really the first case in which you see two separate galaxies, both with quasars, that are clearly interacting," says Carnegie astronomer John Mulchaey who made observations crucial to understanding the galaxy merger. Most, if not all, large galaxies, such as our galaxy the Milky Way, host super-massive black holes at their centers. Because galaxies regularly interact and merge, astronomers have assumed that binary super-massive black holes have been common in the Universe, especially during its early history. Black holes can only be detected as quasars when they are actively accreting matter, a process that releases vast amounts of energy. A leading theory is that galaxy mergers trigger accretion, creating quasars in both galaxies. Because most such mergers would have happened in the distant past, binary quasars and their associated galaxies are very far away and therefore difficult for most telescopes to resolve. The binary quasar, labeled SDSS J1254+0846, was initially detected by the Sloan Digital Sky Survey, a large scale astronomical survey of galaxies and over 120,000 quasars. Further observations by Paul Green of the Harvard-Smithsonian Center for Astrophysics and colleagues* using NASA's Chandra's X-ray Observatory and telescopes at Kitt Peak National Observatory in Arizona and Palomar

  12. Aqueous outflow: Segmental and distal flow

    PubMed Central

    Swaminathan, Swarup S.; Oh, Dong-Jin; Kang, Min Hyung; Rhee, Douglas J.

    2014-01-01

    A prominent risk factor of primary open-angle glaucoma is ocular hypertension, a pathologic state caused by impaired outflow of aqueous humor through the trabecular meshwork within the iridocorneal angle. The juxtacanalicular region of the trabecular meshwork and the inner wall of Schlemm canal have been identified as the main contributors to aqueous outflow resistance, and both extracellular matrix within the trabecular meshwork and trabecular meshwork cell shape have been shown to affect outflow. Overexpression of multiple ECM proteins in perfused cadaveric human eyes has led to increased outflow resistance and elevated IOP. Pharmacologic agents targeting trabecular meshwork cytoskeletal arrangements have been developed after multiple studies demonstrated the importance of cell shape on outflow. Several groups have shown that aqueous outflow occurs only at certain segments of the trabecular meshwork circumferentially, a concept known as segmental flow. This is based on the theory that aqueous outflow is dependent on the presence of discrete pores within the Schlemm canal. Segmental flow has been described in the eyes of multiple species, including primate, bovine, mouse, and human samples. While the trabecular meshwork appears to be the major source of resistance, trabecular meshwork bypass procedures have been unable to achieve the degree of IOP reduction observed with trabeculectomy, reflecting the potential impact of distal flow, or flow through Schlemm canal and collector channels, on outflow. Multiple studies have demonstrated that outflow occurs preferentially near collector channels, suggesting that these distal structures may be more important to aqueous outflow than previously believed. PMID:25088623

  13. Microlensing of the broad line region in 17 lensed quasars

    NASA Astrophysics Data System (ADS)

    Sluse, D.; Hutsemékers, D.; Courbin, F.; Meylan, G.; Wambsganss, J.

    2012-08-01

    When an image of a strongly lensed quasar is microlensed, the different components of its spectrum are expected to be differentially magnified owing to the different sizes of the corresponding emitting region. Chromatic changes are expected to be observed in the continuum while the emission lines should be deformed as a function of the size, geometry and kinematics of the regions from which they originate. Microlensing of the emission lines has been reported only in a handful of systems so far. In this paper we search for microlensing deformations of the optical spectra of pairs of images in 17 lensed quasars with bolometric luminosities between 1044.7 - 47.4 erg/s and black hole masses 107.6 - 9.8 M⊙. This sample is composed of 13 pairs of previously unpublished spectra and four pairs of spectra from literature. Our analysis is based on a simple spectral decomposition technique which allows us to isolate the microlensed fraction of the flux independently of a detailed modeling of the quasar emission lines. Using this technique, we detect microlensing of the continuum in 85% of the systems. Among them, 80% show microlensing of the broad emission lines. Focusing on the most common emission lines in our spectra (C III] and Mg II) we detect microlensing of either the blue or the red wing, or of both wings with the same amplitude. This observation implies that the broad line region is not in general spherically symmetric. In addition, the frequent detection of microlensing of the blue and red wings independently but not simultaneously with a different amplitude, does not support existing microlensing simulations of a biconical outflow. Our analysis also provides the intrinsic flux ratio between the lensed images and the magnitude of the microlensing affecting the continuum. These two quantities are particularly relevant for the determination of the fraction of matter in clumpy form in galaxies and for the detection of dark matter substructures via the identification

  14. Ultrafast outflows in radio-loud active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Tazaki, F.; Mushotzky, R. F.; Ueda, Y.; Cappi, M.; Gofford, J.; Reeves, J. N.; Guainazzi, M.

    2014-09-01

    Recent X-ray observations show absorbing winds with velocities up to mildly relativistic values of the order of ˜0.1c in a limited sample of six broad-line radio galaxies. They are observed as blueshifted Fe XXV-XXVI K-shell absorption lines, similarly to the ultrafast outflows (UFOs) reported in Seyferts and quasars. In this work we extend the search for such Fe K absorption lines to a larger sample of 26 radio-loud active galactic nuclei (AGN) observed with XMM-Newton and Suzaku. The sample is drawn from the Swift Burst Alert Telescope 58-month catalogue and blazars are excluded. X-ray bright Fanaroff-Riley Class II radio galaxies constitute the majority of the sources. Combining the results of this analysis with those in the literature we find that UFOs are detected in >27 per cent of the sources. However, correcting for the number of spectra with insufficient signal-to-noise ratio, we can estimate that the incidence of UFOs is this sample of radio-loud AGN is likely in the range f ≃ (50 ± 20) per cent. A photoionization modelling of the absorption lines with XSTAR allows us to estimate the distribution of their main parameters. The observed outflow velocities are broadly distributed between vout ≲ 1000 km s-1 and vout ≃ 0.4c, with mean and median values of vout ≃ 0.133c and vout ≃ 0.117c, respectively. The material is highly ionized, with an average ionization parameter of logξ ≃ 4.5 erg s-1 cm, and the column densities are larger than NH > 1022 cm-2. Overall, these characteristics are consistent with the presence of complex accretion disc winds in a significant fraction of radio-loud AGN and demonstrate that the presence of relativistic jets does not preclude the existence of winds, in accordance with several theoretical models.

  15. Black-Hole Feedback in Quasars

    NASA Video Gallery

    This animation illustrates how black-hole feedback works in quasars. Dense gas and dust in the center simultaneously fuels the black hole and shrouds it from view. The black-hole wind propels large...

  16. Quasars, pulsars, black holes and HEAO's

    NASA Technical Reports Server (NTRS)

    Doolitte, R. F.; Moritz, K.; Whilden, R. D. C.

    1974-01-01

    Astronomical surveys are discussed by large X-ray, gamma ray, and cosmic ray instruments carried onboard high-energy astronomy observatories. Quasars, pulsars, black holes, and the ultimate benefits of the new astronomy are briefly discussed.

  17. Quasars as tracers of cosmic flows

    NASA Astrophysics Data System (ADS)

    Modzelewska, J.; Czerny, B.; Bilicki, M.; Hryniewicz, K.; Krupa, M.; Petrogalli, F.; Pych, W.; Kurcz, A.; Udalski, A.

    2016-10-01

    Quasars, as the most luminous persistent sources in the Universe, have broad applications for cosmological studies. In particular, they can be employed to directly measure the expansion history of the Universe, similarly to SNe Ia. The advantage of quasars is that they are numerous, cover a broad range of redshifts, up to z = 7, and do not show significant evolution of metallicity with redshift. The idea is based on the relation between the time delay of an emission line and the continuum, and the absolute monochromatic luminosity of a quasar. For intermediate redshift quasars, the suitable line is Mg II. Between December 2012 and March 2014, we performed five spectroscopic observations of the QSO CTS C30.10 (z = 0.900) using the South African Large Telesope (SALT), supplemented with photometric monitoring, with the aim of determining the variability of the line shape, changes in the total line intensity and in the continuum. We show that the method is very promising.

  18. A Long-Term Space Astrophysics Research Program: The Evolution of the Quasar Continuum

    NASA Technical Reports Server (NTRS)

    Elvis, M.; Oliversen, Ronald K. (Technical Monitor)

    2001-01-01

    Four papers have been written. One reports on the major study funded by this grant: a pan-chromatic study of the quasar continuum at redshift 3. Two others make use of the quasar continuum shapes to find the minimum total accretion luminosity of the Universe, and hence the efficiency and spin of supermassive black holes; the second shows that the reemission of absorbed quasar radiation alleviates a major problem with galaxy formation and the FIR background. The last paper recognizes the role quasars may play in the initial formation of dust in the early Universe. The major study of a sample of z=3 and its comparison with a sample of z=0.l quasars across the whole X-ray to radio spectrum was completed and accepted for publication in ApJ Supplements. This study comprises the thesis work of Olga Kuhn. The two samples are matched in evolved luminosity, and so should be sampling the same black hole population at different z, and in different accretion states. Despite this no strong differences were found between the samples, except in the 'small bump' region of the optical/UV. This region is dominated by FeII emission, and may indicate abundance evolution in quasars. The lack of overall spectral changes argues strongly against a single population of quasars fading over cosmic time, and for a multiple generation, or multiple outburst model for quasars. A study of the total luminosity absorbed from quasars and re-emitted in the infrared produced two results (reported in two papers): The minimum intrinsic luminosity/Gpc(3) from AGN compared with the measured mass density in supermassive black holes [Gpc(-3)] requires a conversion efficiency of accreted mass into luminosity of greater than 15%. Non-rotating black holes cannot exceed 5% efficiency, while rapidly rotating black holes can reach 47%. Hence our result requires that most supermassive black holes must be rapidly rotating. The second result comes from considering the contribution that the re-radiated quasar

  19. QUASARS PROBING QUASARS. IV. JOINT CONSTRAINTS ON THE CIRCUMGALACTIC MEDIUM FROM ABSORPTION AND EMISSION

    SciTech Connect

    Hennawi, Joseph F.; Prochaska, J. Xavier

    2013-03-20

    We have constructed a sample of 29 close projected quasar pairs where the background quasar spectrum reveals absorption from optically thick H I gas associated with the foreground quasar. These unique sightlines allow us to study the quasar circumgalactic medium (CGM) in absorption and emission simultaneously, because the background quasar pinpoints large concentrations of gas where Ly{alpha} emission, resulting from quasar-powered fluorescence, resonant Ly{alpha} scattering, and/or cooling radiation, is expected. A sensitive search (1{sigma} surface-brightness limits of SB{sub Ly{alpha}}{approx_equal}3 Multiplication-Sign 10{sup -18} erg s{sup -1} cm{sup -2} arcsec{sup -2}) for diffuse Ly{alpha} emission in the environments of the foreground (predominantly radio-quiet) quasars is conducted using Gemini/GMOS and Keck/LRIS slit spectroscopy. We fail to detect large-scale {approx}100 kpc Ly{alpha} emission, either at the location of the optically thick absorbers or in the foreground quasar halos, in all cases except a single system. We interpret these non-detections as evidence that the gas detected in absorption is shadowed from the quasar UV radiation due to obscuration effects, which are frequently invoked in unified models of active galactic nuclei. Small-scale R {approx}< 50 kpc extended Ly{alpha} nebulosities are detected in 34% of our sample, which are likely the high-redshift analogs of the extended emission-line regions (EELRs) commonly observed around low-redshift (z < 0.5) quasars. This may be fluorescent recombination radiation from a population of very dense clouds with a low covering fraction illuminated by the quasar. We also detect a compact high rest-frame equivalent width (W{sub Ly{alpha}} > 50 A) Ly{alpha}-emitter with luminosity L{sub Ly{alpha}} = 2.1 {+-} 0.32 Multiplication-Sign 10{sup 41} erg s{sup -1} at small impact parameter R = 134 kpc from one foreground quasar, and argue that it is more likely to result from quasar-powered fluorescence

  20. Dust in the Quasar Wind (Artist Concept)

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Dusty grains -- including tiny specks of the minerals found in the gemstones peridot, sapphires and rubies -- can be seen blowing in the winds of a quasar, or active black hole, in this artist's concept. The quasar is at the center of a distant galaxy.

    Astronomers using NASA's Spitzer Space Telescope found evidence that such quasar winds might have forged these dusty particles in the very early universe. The findings are another clue in an ongoing cosmic mystery: where did all the dust in our young universe come from?

    Dust is crucial for efficient star formation as it allows the giant clouds where stars are born to cool quickly and collapse into new stars. Once a star has formed, dust is also needed to make planets and living creatures. Dust has been seen as far back as when the universe was less than a tenth of its current age, but how did it get there? Most dust in our current epoch forms in the winds of evolved stars that did not exist when the universe was young.

    Theorists had predicted that winds from quasars growing in the centers of distant galaxies might be a source of this dust. While the environment close to a quasar is too hot for large molecules like dust grains to survive, dust has been found in the cooler, outer regions. Astronomers now have evidence that dust is created in these outer winds.

    Using Spitzer's infrared spectrograph instrument, scientists found a wealth of dust grains in a quasar called PG2112+059 located at the center of a galaxy 8 billion light-years away. The grains - including corundum (sapphires and rubies); forsterite (peridot); and periclase (naturally occurring in marble) - are not typically found in galaxies without quasars, suggesting they might have been freshly formed in the quasar's winds.

  1. Quasar x-ray spectra revisited

    NASA Technical Reports Server (NTRS)

    Shastri, P.; Wilkes, B. J.; Elvis, M.; Mcdowell, J.

    1992-01-01

    A sample of 45 quasars observed by the Imaging Proportional Counter (IPC) on the Einstein satellite is used to re-examine the relationship between the soft (0.2-3.5 keV) X-ray energy index and radio-loudness. We found the following: (1) the tendency for radio-loud quasars to have systematically flatter X-ray slopes than radio-quiet quasars (RQQ's) is confirmed with the soft X-ray excess having negligible effect; (2) there is a tendency for the flatness of the X-ray slope to correlate with radio core-dominance for radio-loud quasars, suggesting that a component of the X-ray emission is relativistically beamed; (3) for the RQQ's the soft X-ray slopes, with a mean of approximately 1.0, are consistent with the slopes found at higher energies (2-10 keV) although steeper than those observed for Seyfert 1 galaxies (also 2-10 keV) where the reflection model gives a good fit to the data; (4) the correlation of FeII emission line strength with X-ray energy index is confirmed for radio-quiet quasars using a subset of 18 quasars. The radio-loud quasars show no evidence for a correlation. This relation suggests a connection between the ionizing continuum and the line emission from the broad emission line region (BELR) of radio-quiet quasars, but in the opposite sense to that predicted by current photoionization models; and (5) the correlations of X-ray slope with radio core dominance and FeII equivalent width within the radio-loud and radio-quiet sub-classes respectively imply that the observed wide range of X-ray spectral slopes is real rather than due to the large measuring uncertainties for individual objects.

  2. Luminosity calibration of low redshift quasars

    NASA Technical Reports Server (NTRS)

    Wampler, E. J.

    1983-01-01

    European (SERC) were combined with U.S. shifts on the IUE in order to obtain the long integration times required to record spectra of faint quasars. LWR spectra of the nearby giant radio galaxy Centarus A(NGC 5548) was attempted in an effort to determine the chemical composition and stellar populations in this unusual galaxy. The IUE results from the low redshift quasar study, combined with the data from an extensive ground based survey, are described.

  3. Understanding Quasar Variability through Kepler

    NASA Astrophysics Data System (ADS)

    Silano, Daniel; Wiita, P. J.; Wehrle, A. E.; Unwin, S. C.

    2012-01-01

    We are monitoring four flat spectrum radio quasars (blazars) and one powerful radio galaxy, Cygnus A, to search for variability on timescales comparable to the light crossing time of the accretion disk around the central supermassive black hole and the base of the relativistic jet. Kepler's essentially continuous monitoring at 1 min and 30 min cadences allows us to obtain high quality light curves extending for months, something not possible from even semi-dedicated collections of ground based optical telescopes. We can characterize the variability on timescales ranging from several minutes through many days to see if some optical variability in quasars might be due to a bright feature in the accretion disk as it approaches the last stable orbit, or, more likely for blazars, nearly coherent inhomogeneities in the jet, possibly in a helical structure or temporarily dominant turbulent cell. We have analyzed both the raw and "corrected” Kepler data to determine the power spectral densities of the four blazars as well as their structure functions. The principal challenge to our Kepler data analysis is that the automatic pipeline removal of day-to-week-scale drifts also removes real astrophysical brightness variations and so we have concentrated so far on the raw data while we work on better removal of only the instrumental drifts. Our preliminary results on short timescale variations indicate that three of the four blazars showed modest ( 15%) variations and relatively slow variability during three months of monitoring, but the fourth also shows many flares ( 3%) on several-day timescales, particularly during one quarter. While a visual inspection of this light curve gives a hint of a quasi-period, this is not borne out by the structure function and PDS analyses. This work is supported by NASA/Kepler grant GO20018.

  4. Quasar clustering in a galaxy and quasar formation model based on ultra high-resolution N-body simulations

    NASA Astrophysics Data System (ADS)

    Oogi, Taira; Enoki, Motohiro; Ishiyama, Tomoaki; Kobayashi, Masakazu A. R.; Makiya, Ryu; Nagashima, Masahiro

    2016-02-01

    We investigate clustering properties of quasars using a new version of our semi-analytic model of galaxy and quasar formation with state-of-the-art cosmological N-body simulations. In this study, we assume that a major merger of galaxies triggers cold gas accretion on to a supermassive black hole and quasar activity. Our model can reproduce the downsizing trend of the evolution of quasars. We find that the median mass of quasar host dark matter haloes increases with cosmic time by an order of magnitude from z = 4 (a few 1011 M⊙) to z = 1 (a few 1012 M⊙), and depends only weakly on the quasar luminosity. Deriving the quasar bias through the quasar-galaxy cross-correlation function in the model, we find that the quasar bias does not depend on the quasar luminosity, similar to observed trends. This result reflects the fact that quasars with a fixed luminosity have various Eddington ratios and thus have various host halo masses that primarily determine the quasar bias. We also show that the quasar bias increases with redshift, which is in qualitative agreement with observations. Our bias value is lower than the observed values at high redshifts, implying that we need some mechanisms that make quasars inactive in low-mass haloes and/or that make them more active in high-mass haloes.

  5. QUASARS PROBING QUASARS. VI. EXCESS H I ABSORPTION WITHIN ONE PROPER Mpc OF z ∼ 2 QUASARS

    SciTech Connect

    Prochaska, J. Xavier; Cantalupo, Sebastiano; Lau, Marie Wingyee; Bovy, Jo; Djorgovski, S. G.; Ellison, Sara L.; Martin, Crystal L.; Simcoe, Robert A.

    2013-10-20

    With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the H I Lyα absorption transverse to luminous, z ∼ 2 quasars at proper separations of 30 kpc < R < 1 Mpc. In contrast to measurements along the line-of-sight, regions transverse to quasars exhibit enhanced H I Lyα absorption and a larger variance than the ambient intergalactic medium, with increasing absorption and variance toward smaller scales. Analysis of composite spectra reveals excess absorption characterized by a Lyα equivalent width profile W = 2.3 Å (R /100 kpc){sup –0.46}. We also observe a high (≅ 60%) covering factor of strong, optically thick H I absorbers (H I column N{sub H{sub I}}>10{sup 17.3} cm{sup -2}) at separations R < 200 kpc, which decreases to ∼20% at R ≅ 1 Mpc, but still represents a significant excess over the cosmic average. This excess of optically thick absorption can be described by a quasar-absorber cross-correlation function ξ{sub QA}(r) = (r/r{sub 0}){sup γ} with a large correlation length r{sub 0} = 12.5{sup +2.7}{sub -1.4} h{sup -1} Mpc (comoving) and γ=1.68{sup +0.14}{sub -0.30}. The H I absorption measured around quasars exceeds that of any previously studied population, consistent with quasars being hosted by massive dark matter halos M{sub halo} ≈ 10{sup 12.5} M{sub ☉} at z ∼ 2.5. The environments of these massive halos are highly biased toward producing optically thick gas, and may even dominate the cosmic abundance of Lyman limit systems and hence the intergalactic opacity to ionizing photons at z ∼ 2.5. The anisotropic absorption around quasars implies the transverse direction is much less likely to be illuminated by ionizing radiation than the line-of-sight.

  6. THE HALO OCCUPATION DISTRIBUTION OF SDSS QUASARS

    SciTech Connect

    Richardson, Jonathan; Chatterjee, Suchetana; Nagai, Daisuke; Zheng Zheng; Shen Yue

    2012-08-10

    We present an estimate of the projected two-point correlation function (2PCF) of quasars in the Sloan Digital Sky Survey (SDSS) over the full range of one- and two-halo scales, 0.02 h{sup -1} Mpc < r{sub p} < 120 h{sup -1} Mpc. This was achieved by combining data from SDSS DR7 on large scales and Hennawi et al. (with appropriate statistical corrections) on small scales. Our combined clustering sample is the largest spectroscopic quasar clustering sample to date, containing {approx}48, 000 quasars in the redshift range 0.4 {approx}< z {approx}< 2.5 with median redshift 1.4. We interpret these precise 2PCF measurements within the halo occupation distribution (HOD) framework and constrain the occupation functions of central and satellite quasars in dark matter halos. In order to explain the small-scale clustering, the HOD modeling requires that a small fraction of z {approx} 1.4 quasars, f{sub sat} = (7.4 {+-} 1.4) Multiplication-Sign 10{sup -4}, be satellites in dark matter halos. At z {approx} 1.4, the median masses of the host halos of central and satellite quasars are constrained to be M{sub cen} = 4.1{sup +0.3}{sub -0.4} Multiplication-Sign 10{sup 12} h{sup -1} M{sub Sun} and M{sub sat} = 3.6{sup +0.8}{sub -1.0} Multiplication-Sign 10{sup 14} h{sup -1} M{sub Sun }, respectively. To investigate the redshift evolution of the quasar-halo relationship, we also perform HOD modeling of the projected 2PCF measured by Shen et al. for SDSS quasars with median redshift 3.2. We find tentative evidence for an increase in the mass scale of quasar host halos-the inferred median mass of halos hosting central quasars at z {approx} 3.2 is M{sub cen} = 14.1{sup +5.8}{sub -6.9} Multiplication-Sign 10{sup 12} h{sup -1} M{sub Sun }. The cutoff profiles of the mean occupation functions of central quasars reveal that quasar luminosity is more tightly correlated with halo mass at higher redshifts. The average quasar duty cycle around the median host halo mass is inferred to be f{sub q

  7. Multi-Sightline Observation of Narrow Absorption Lines in Lensed Quasar SDSS J1029+2623

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Saez, Cristian; Charlton, Jane C.; Eracleous, Michael; Chartas, George; Bauer, Franz E.; Inada, Naohisa; Uchiyama, Hisakazu

    2016-07-01

    We exploit the widely separated images of the lensed quasar SDSS J1029+2623 ({z}{em} = 2.197, θ = 22.″5) to observe its outflowing wind through two different sightlines. We present an analysis of three observations, including two with the Subaru telescope in 2010 February and 2014 April, separated by four years, and one with the Very Large Telescope, separated from the second Subaru observation by ˜2 months. We detect 66 narrow absorption lines (NALs), of which 24 are classified as intrinsic NALs that are physically associated with the quasar based on partial coverage analysis. The velocities of intrinsic NALs appear to cluster around values of {v}{ej} ˜ 59,000, 43,000, and 29,000 km s‑1, which is reminiscent of filamentary structures obtained by numerical simulations. There are no common intrinsic NALs at the same redshift along the two sightlines, implying that the transverse size of the NAL absorbers should be smaller than the sightline distance between two lensed images. In addition to the NALs with large ejection velocities of {v}{ej} > 1000 km s‑1, we also detect broader proximity absorption lines (PALs) at {z}{abs} ˜ {z}{em}. The PALs are likely to arise in outflowing gas at a distance of r ≤ 620 pc from the central black hole with an electron density of n e ≥8.7 × 103 cm‑3. These limits are based on the assumption that the variability of the lines is due to recombination. We discuss the implications of these results on the three-dimensional structure of the outflow.

  8. OUTFLOWS IN SODIUM EXCESS OBJECTS

    SciTech Connect

    Park, Jongwon; Yi, Sukyoung K.; Jeong, Hyunjin

    2015-08-10

    Van Dokkum and Conroy revisited the unexpectedly strong Na i lines at 8200 Å found in some giant elliptical galaxies and interpreted them as evidence for an unusually bottom-heavy initial mass function. Jeong et al. later found a large population of galaxies showing equally extraordinary Na D doublet absorption lines at 5900 Å (Na D excess objects: NEOs) and showed that their origins can be different for different types of galaxies. While a Na D excess seems to be related to the interstellar medium (ISM) in late-type galaxies, smooth-looking early-type NEOs show little or no dust extinction and hence no compelling signs of ISM contributions. To further test this finding, we measured the Doppler components in the Na D lines. We hypothesized that the ISM would have a better (albeit not definite) chance of showing a blueshift Doppler departure from the bulk of the stellar population due to outflow caused by either star formation or AGN activities. Many of the late-type NEOs clearly show blueshift in their Na D lines, which is consistent with the former interpretation that the Na D excess found in them is related to gas outflow caused by star formation. On the contrary, smooth-looking early-type NEOs do not show any notable Doppler components, which is also consistent with the interpretation of Jeong et al. that the Na D excess in early-type NEOs is likely not related to ISM activities but is purely stellar in origin.

  9. FR-II Broad Absorption Line Quasars and the Life Cycle of Quasars

    SciTech Connect

    Gregg, M D; Becker, R H; de Vries, W

    2006-01-05

    By combining the Sloan Digitized Sky Survey Third Data Release quasar list with the VLA FIRST survey, we have identified five objects having both broad absorption lines in their optical spectra and FR-II radio morphologies. We identify an additional example of this class from the FIRST Bright Quasar Survey, J1408+3054. Including the original FR-II-BAL object, J1016+5209, brings the number of such objects to eight. These quasars are relatively rare; finding this small handful has required the 45,000-large quasar sample of SDSS. The FR-II-BAL quasars exhibit a significant anti-correlation between radio-loudness and the strength of the BAL features. This is easily accounted for by the evolutionary picture in which quasars emerge from cocoons of BAL-producing material which stifle the development of radio jets and lobes. There is no such simple explanation for the observed properties of FR-II-BALs in the unification-by-orientation model of quasars. The rarity of the FR-II-BAL class implies that the two phases do not coexist for very long in a single quasar, perhaps less than 10{sup 5} years, with the combined FR-II, high ionization broad absorption phase being even shorter by another factor of 10 or more.

  10. THE PROPERTIES OF QUASAR HOSTS AT THE PEAK OF THE QUASAR ACTIVITY

    SciTech Connect

    Kotilainen, Jari K.; Falomo, Renato; Decarli, Roberto; Treves, Aldo; Uslenghi, Michela; Scarpa, Riccardo E-mail: renato.falomo@oapd.inaf.i E-mail: aldo.treves@uninsubria.i E-mail: riccardo.scarpa@gtc.iac.e

    2009-10-01

    We present near-infrared imaging obtained with ESO VLT/ISAAC of a sample of 16 low luminosity radio-quiet quasars (RQQs) at the epoch around the peak of the quasar activity (2 < z < 3), aimed at investigating their host galaxies. For 11 quasars, we are able to detect the host galaxies and derive their properties, while for the other 5 quasars, upper limits to the host luminosity are estimated. The luminosities of the host galaxies of RQQs at high redshift are in the range of those of massive inactive elliptical galaxies. This work complements our previous systematic study of quasar hosts aimed to trace the cosmological luminosity evolution of the host galaxies up to z approx 2 and extends our pilot study of a few luminous quasars at z > 2. The luminosity trend with a cosmic epoch resembles that observed for massive inactive galaxies, suggesting a similar star formation history. In particular, both quasar host galaxies and massive inactive galaxies appear mostly assembled already at the peak age of the quasar activity. This result is of key importance for testing the models of joint formation and evolution of galaxies and their active nuclei.

  11. The Physical Nature of Polar Broad Absorption Line Quasars

    NASA Technical Reports Server (NTRS)

    Ghost, Kajal; Punsly, Brian

    2007-01-01

    It has been shown based on radio variability arguments that some BALQSOs (broad absorption line quasars) are viewed along the polar axis (o rthogonal to accretion disk) in the recent article of Zhou et a. Thes e arguments are based on the brightness temperature, T(sub b) exceedi ng 10(exp 12) K which leads to the well-known inverse Compton catastr ophe unless the radio jet is relativistic and is viewed along its axi s. In this letter, we expand the Zhou et al sample of polar BALQSOs u sing their techniques applied to SDSS DR5. In the process, we clarify a mistake in their calculation of brightness temperature. The expanded sample of high T(sub b) BALQSOS, has an inordinately large fraction of LoBALQSOs (low ionization BALQSOs). We consider this an important clue to understanding the nature of the polar BALQSOs. This is expec ted in the polar BALQSO analytical/numerical models of Punsly that pr edicted that LoBALQSOs occur when the line of sight is very close to the polar axis, where the outflow density is the highest.

  12. Quasars with Anomalous Hβ Profiles. I. Demographics

    NASA Astrophysics Data System (ADS)

    Steinhardt, Charles L.; Silverman, John D.

    2013-08-01

    The Hβ emission line in a typical Type I quasar is composed of a broad base and a narrow core, with the core velocity characteristic of narrow-line region emission, and line-fitting routines typically assume this picture. We test the effects of removing this constraint, and find a substantial group of Type I quasars in the Sloan Digital Sky Survey catalog with Hβ emission line cores broader than 1200 km s-1 , above the velocity believed possible for gas in the quasar narrow-line region. We identify this group of ``anomalous Hβ quasars'' (AHQs) as a distinct population because of a variety of spectral and photometric signatures common to these AHQs but atypical of other quasars. These features are similar to some aspects of narrow-line Seyfert 1s and correlations identified by Eigenvector 1, but also contain distinct features that make it difficult to classify AHQs. We demonstrate that AHQs comprise at least 11% and most likely approximately one quarter of the SDSS Type I quasar population at 0.2 < z < 0.8. For AHQs, the [O III]λ 4959, 5007 profile is often better fit by de-linking it from the Hβ core, while a more standard linked fit produces a tight correlation between narrow- and broad-line velocities. We find that [O III] in AHQs sometimes has a standard narrow-line profile and other times matches the Hβ core, but is rarely in between the two, implying that the broadened core emission arises from a distinct physical region. Another feature of AHQs is a diminished [O II] line, which might indicate a connection between AHQs and the interstellar mediums of their host galaxies, through reduced photoionization or star formation. We find that it is difficult to produce AHQs using the current quasar standard model.

  13. Quasar evolution - Not a deficit at 'low' redshifts

    NASA Technical Reports Server (NTRS)

    Avni, Y.; Schiller, N.

    1983-01-01

    Hawkins and Stewart (1981) have argued that the conventional interpretation of complete quasar samples in terms of a cosmological evolution of quasars is not unique. It has been suggested that these data can also be interpreted as due to a deficit in the density of quasars. Hawkins and Stewart have argued that such a deficit could be either apparent, due to an observational selection which biases against the inclusion of low-z quasars, or real, due to a lower density of quasars at low redshifts. The present investigation is concerned with this new interpretation. In order to test the interpretation of Hawkins and Stewart (1981) as directly as possible, the investigation is restricted to the same type of quasar samples considered by Hawkins and Stewart. It is found that the obtained results contradict clearly Hawkins and Stewart's assertion. Quasar evolution is not just a deficit of quasars at low redshifts, neither apparent nor real.

  14. Beacons in Time: Maarten Schmidt and the Discovery of Quasars.

    ERIC Educational Resources Information Center

    Preston, Richard

    1988-01-01

    Tells the story of Maarten Schmidt and the discovery of quasars. Discusses the decomposition of light, crucial observations and solving astronomical mysteries. Describes spectroscopic analysis used in astronomy and its application to quasars. (CW)

  15. Discovery of a bright quasar without a massive host galaxy.

    PubMed

    Magain, Pierre; Letawe, Géraldine; Courbin, Frédéric; Jablonka, Pascale; Jahnke, Knud; Meylan, Georges; Wisotzki, Lutz

    2005-09-15

    A quasar is thought to be powered by the infall of matter onto a supermassive black hole at the centre of a massive galaxy. Because the optical luminosity of quasars exceeds that of their host galaxy, disentangling the two components can be difficult. This led in the 1990s to the controversial claim of the discovery of 'naked' quasars. Since then, the connection between quasars and galaxies has been well established. Here we report the discovery of a quasar lying at the edge of a gas cloud, whose size is comparable to that of a small galaxy, but whose spectrum shows no evidence for stars. The gas in the cloud is excited by the quasar itself. If a host galaxy is present, it is at least six times fainter than would normally be expected for such a bright quasar. The quasar is interacting dynamically with a neighbouring galaxy, whose gas might be feeding the black hole.

  16. Bright crater outflows: Possible emplacement mechanisms

    NASA Technical Reports Server (NTRS)

    Chadwick, D. John; Schaber, Gerald G.; Strom, Robert G.; Duval, Darla M.

    1992-01-01

    Lobate features with a strong backscatter are associated with 43 percent of the impact craters cataloged in Magellan's cycle 1. Their apparent thinness and great lengths are consistent with a low-viscosity material. The longest outflow yet identified is about 600 km in length and flows from the 90-km-diameter crater Addams. There is strong evidence that the outflows are largely composed of impact melt, although the mechanisms of their emplacement are not clearly understood. High temperatures and pressures of target rocks on Venus allow for more melt to be produced than on other terrestrial planets because lower shock pressures are required for melting. The percentage of impact craters with outflows increases with increasing crater diameter. The mean diameter of craters without outflows is 14.4 km, compared with 27.8 km for craters with outflows. No craters smaller than 3 km, 43 percent of craters in the 10- to 30-km-diameter range, and 90 percent in the 80- to 100-km-diameter range have associated bright outflows. More melt is produced in the more energetic impact events that produce larger craters. However, three of the four largest craters have no outflows. We present four possible mechanisms for the emplacement of bright outflows. We believe this 'shotgun' approach is justified because all four mechanisms may indeed have operated to some degree.

  17. THE SUBARU HIGH-z QUASAR SURVEY: DISCOVERY OF FAINT z ∼ 6 QUASARS

    SciTech Connect

    Kashikawa, Nobunari; Furusawa, Hisanori; Niino, Yuu; Ishizaki, Yoshifumi; Onoue, Masafusa; Toshikawa, Jun; Ishikawa, Shogo; Willott, Chris J.; Im, Myungshin; Shimasaku, Kazuhiro; Ouchi, Masami; Hibon, Pascale

    2015-01-01

    We present the discovery of one or two extremely faint z ∼ 6 quasars in 6.5 deg{sup 2} utilizing a unique capability of the wide-field imaging of the Subaru/Suprime-Cam. The quasar selection was made in (i'-z{sub B} ) and (z{sub B} -z{sub R} ) colors, where z{sub B} and z{sub R} are bandpasses with central wavelengths of 8842 Å and 9841 Å, respectively. The color selection can effectively isolate quasars at z ∼ 6 from M/L/T dwarfs without the J-band photometry down to z{sub R} < 24.0, which is 3.5 mag deeper than the Sloan Digital Sky Survey (SDSS). We have selected 17 promising quasar candidates. The follow-up spectroscopy for seven targets identified one apparent quasar at z = 6.156 with M {sub 1450} = –23.10. We also identified one possible quasar at z = 6.041 with a faint continuum of M {sub 1450} = –22.58 and a narrow Lyα emission with HWHM =427 km s{sup –1}, which cannot be distinguished from Lyman α emitters. We derive the quasar luminosity function at z ∼ 6 by combining our faint quasar sample with the bright quasar samples by SDSS and CFHQS. Including our data points invokes a higher number density in the faintest bin of the quasar luminosity function than the previous estimate employed. This suggests a steeper faint-end slope than lower z, though it is yet uncertain based on a small number of spectroscopically identified faint quasars, and several quasar candidates still remain to be diagnosed. The steepening of the quasar luminosity function at the faint end does increase the expected emission rate of the ionizing photon; however, it only changes by a factor of approximately two to six. This was found to still be insufficient for the required photon budget of reionization at z ∼ 6.

  18. The Optical Variability of SDSS Quasars from Multi-epoch Spectroscopy. III. A Sudden UV Cutoff in Quasar SDSS J2317+0005

    NASA Astrophysics Data System (ADS)

    Guo, Hengxiao; Malkan, Matthew A.; Gu, Minfeng; Li, Linlin; Prochaska, J. Xavier; Ma, Jingzhe; You, Bei; Zafar, Tayyaba; Liao, Mai

    2016-08-01

    We have collected near-infrared to X-ray data of 20 multi-epoch heavily reddened SDSS quasars to investigate the physical mechanism of reddening. Of these, J2317+0005 is found to be a UV cutoff quasar. Its continuum, which usually appears normal, decreases by a factor 3.5 at 3000 Å, compared to its more typical bright state during an interval of 23 days. During this sudden continuum cut-off the broad emission line fluxes do not change, perhaps due to the large size of the broad-line region (BLR), r \\gt 23/(1+z) days. The UV continuum may have suffered a dramatic drop out. However, there are some difficulties with this explanation. Another possibility is that the intrinsic continuum did not change but was temporarily blocked out, at least toward our line of sight. As indicated by X-ray observations, the continuum rapidly recovers after 42 days. A comparison of the bright state and dim states would imply an eclipse by a dusty cloud with a reddening curve having a remarkably sharp rise shortward of 3500 Å. Under the assumption of being eclipsed by a Keplerian dusty cloud, we characterized the cloud size with our observations, however, which is a little smaller than the 3000 Å continuum-emitting size inferred from accretion disk models. Therefore, we speculate that this is due to a rapid outflow or inflow with a dusty cloud passing through our line of sight to the center.

  19. SIX MORE QUASARS AT REDSHIFT 6 DISCOVERED BY THE CANADA-FRANCE HIGH-z QUASAR SURVEY

    SciTech Connect

    Willott, Chris J.; Crampton, David; Hutchings, John B.; Schade, David; Delorme, Philippe; Delfosse, Xavier; Forveille, Thierry; Reyle, Celine; Albert, Loic; Bergeron, Jacqueline; Omont, Alain; McLure, Ross J.

    2009-03-15

    We present imaging and spectroscopic observations for six quasars at z {>=} 5.9 discovered by the Canada-France High-z Quasar Survey (CFHQS). The CFHQS contains subsurveys with a range of flux and area combinations to sample a wide range of quasar luminosities at z {approx} 6. The new quasars have luminosities 10-75 times lower than the most luminous Sloan Digital Sky Survey quasars at this redshift. The least luminous quasar, CFHQS J0216-0455 at z = 6.01, has absolute magnitude M {sub 1450} = -22.21, well below the likely break in the luminosity function. This quasar is not detected in a deep XMM-Newton survey showing that optical selection is still a very efficient tool for finding high-redshift quasars.

  20. Magnetospheric Sawtooth Oscillations Induced by Ionospheric Outflow

    NASA Astrophysics Data System (ADS)

    Brambles, O. J.; Lotko, W.; Zhang, B.; Lyon, J.; Wiltberger, M. J.

    2010-12-01

    This paper aims to address why sawtooth oscillations occur and what factors affect their periodicity. We use a multifluid version of the LFM global simulation model, driven by a steady solar wind to examine the effects of ion outflow on convection in the magnetosphere. In the simulation model, the properties of cusp and auroral region O+ outflow are causally regulated by electron precipitation and electromagnetic power flowing into the ionosphere. It is found that when ion outflow is included in the simulation, the solar wind-magnetosphere-ionosphere interaction can generate periodic substorms which appear as sawtooth-like oscillations in the geostationary magnetic field. The ion outflow enhances plasma pressure in the inner magnetosphere and the associated diamagnetic ring current stretches the field lines throughout the nightside, essentially from dawn to dusk. If the field lines are sufficiently stretched they reconnect and dipolarize, ejecting a plasmoid downtail. This cycle repeats forming multiple sawtooth oscillations. The periodicity of the sawtooth oscillation depends largely upon the strength of the outflow. The strength of outflow is varied in the simulation by changing both the driving conditions (which affects the power flowing into the ionosphere) and through direct modification of the constants in the empirical relationships. Higher outflow fluences produce oscillations with shorter periods. The period of the oscillation is found to vary in the simulations from approximately 2 hours to 6 hours depending upon the strength of the outflow. For a smaller solar wind electric field the outflow fluence is not large enough to stretch the nightside field lines enough for sawtooth oscillations to form and the magnetosphere goes into a steady magnetosphere convection (SMC) mode. As the solar wind electric field increases the outflow fluence becomes sufficiently large to affect the convection in the magnetosphere and generate sawtooth oscillations. The strength

  1. A new sample of quasars to B = 22.0

    NASA Technical Reports Server (NTRS)

    Marano, B.; Zamorani, G.; Zitelli, V.

    1988-01-01

    A new sample of quasars with complete spectroscopic information down to about 22 mag is presented. The candidate selection and preliminary spectroscopic results are reported. Results are reported from the application of color-color diagrams, grism plates, and variability analysis in the quasar selection. The results on quasar counts, redshift distribution, and luminosity function at high redshift are discussed.

  2. Causes and effects of the first quasars.

    PubMed

    Rees, M J

    1993-06-01

    The light we observe from the most distant known quasars set out when the Universe was about 200 times denser than it is now and less than one-tenth of its present age. The existence of these objects implies that galaxy formation had already, at that early epoch, proceeded to the stage when massive (>10(8)M[symbol, see text]) objects had accumulated in the centers of at least some young galaxies. A specific model is presented to show that the evolution and luminosity function of quasars are compatible with the cold dark matter cosmogony. Most big galaxies probably passed through a quasar phase; the remnant black holes in nearby galaxies may reveal themselves via the flares that occur whenever a star passes too close to them and gets tidally disrupted. The rich absorption spectra of quasars serve as a probe of the intervening medium. The gas responsible for the Lyman alpha absorption lines may be due to primordial gas gravitationally confined in minihalos of dark matter--shallow potential wells whose evolution and relation to dwarf galaxies are briefly discussed. The patchy heat input into the intergalactic medium from early quasars could modulate the environment in which galaxies form, leading to large-scale spatial correlations in the galaxy distribution. This review concludes with general comments on the prospects for a fully quantitative understanding of galaxy formation.

  3. Causes and effects of the first quasars.

    PubMed Central

    Rees, M J

    1993-01-01

    The light we observe from the most distant known quasars set out when the Universe was about 200 times denser than it is now and less than one-tenth of its present age. The existence of these objects implies that galaxy formation had already, at that early epoch, proceeded to the stage when massive (>10(8)M[symbol, see text]) objects had accumulated in the centers of at least some young galaxies. A specific model is presented to show that the evolution and luminosity function of quasars are compatible with the cold dark matter cosmogony. Most big galaxies probably passed through a quasar phase; the remnant black holes in nearby galaxies may reveal themselves via the flares that occur whenever a star passes too close to them and gets tidally disrupted. The rich absorption spectra of quasars serve as a probe of the intervening medium. The gas responsible for the Lyman alpha absorption lines may be due to primordial gas gravitationally confined in minihalos of dark matter--shallow potential wells whose evolution and relation to dwarf galaxies are briefly discussed. The patchy heat input into the intergalactic medium from early quasars could modulate the environment in which galaxies form, leading to large-scale spatial correlations in the galaxy distribution. This review concludes with general comments on the prospects for a fully quantitative understanding of galaxy formation. PMID:11607397

  4. Giant scattering cones in obscured quasars

    NASA Astrophysics Data System (ADS)

    Obied, Georges; Zakamska, Nadia L.; Wylezalek, Dominika; Liu, Guilin

    2016-03-01

    We analyse Hubble Space Telescope observations of scattering regions in 20 luminous obscured quasars at 0.24 < z < 0.65 (11 new observations and nine archival ones) observed at rest frame ˜3000 Å. We find spectacular 5-10 kpc-scale scattering regions in almost all cases. The median scattering efficiency at this wavelength (the ratio of observed to estimated intrinsic flux) is 2.3, and 73 per cent of the observed flux at this wavelength is due to scattered light, which if unaccounted for may strongly bias estimates of quasar hosts' star formation rates. Modelling these regions as illuminated dusty cones, we estimate the radial density distributions of the interstellar medium as well as the geometric properties of circumnuclear quasar obscuration - inclinations and covering factors. Small derived opening angles (median half-angle and standard deviation 27° ± 9°) are inconsistent with a 1:1 type 1/type 2 ratio. We suggest that quasar obscuration is patchy and that the observer has an ˜40 per cent chance of seeing a type 1 source even through the obscuration. We estimate median density profile of the scattering medium to be nH = 0.04-0.5 (1 kpc/r)2 cm-3, depending on the method. Quasars in our sample likely exhibit galaxy-wide winds, but if these consist of optically thick clouds then only a small fraction of the wind mass ( ≲ 10 per cent) contributes to scattering.

  5. Galaxy Clustering Around Nearby Luminous Quasars

    NASA Technical Reports Server (NTRS)

    Fisher, Karl B.; Bahcall, John N.; Kirhakos, Sofia; Schneider, Donald P.

    1996-01-01

    We examine the clustering of galaxies around a sample of 20 luminous low redshift (z approx. less than 0.30) quasars observed with the Wide Field Camera-2 on the Hubble Space Telescope (HST). The HST resolution makes possible galaxy identification brighter than V = 24.5 and as close as 1 min or 2 min to the quasar. We find a significant enhancement of galaxies within a projected separation of approx. less than 100 1/h kpc of the quasars. If we model the QSO/galaxy correlation function as a power law with a slope given by the galaxy/galaxy correlation function, we find that the ratio of the QSO/galaxy to galaxy/galaxy correlation functions is 3.8 +/- 0.8. The galaxy counts within r less than 15 1/h kpc of the quasars are too high for the density profile to have an appreciable core radius (approx. greater than 100 1/h kpc). Our results reinforce the idea that low redshift quasars are located preferentially in groups of 10-20 galaxies rather than in rich clusters. We see no significant difference in the clustering amplitudes derived from radio-loud and radio-quiet subsamples.

  6. Causes and effects of the first quasars.

    PubMed

    Rees, M J

    1993-06-01

    The light we observe from the most distant known quasars set out when the Universe was about 200 times denser than it is now and less than one-tenth of its present age. The existence of these objects implies that galaxy formation had already, at that early epoch, proceeded to the stage when massive (>10(8)M[symbol, see text]) objects had accumulated in the centers of at least some young galaxies. A specific model is presented to show that the evolution and luminosity function of quasars are compatible with the cold dark matter cosmogony. Most big galaxies probably passed through a quasar phase; the remnant black holes in nearby galaxies may reveal themselves via the flares that occur whenever a star passes too close to them and gets tidally disrupted. The rich absorption spectra of quasars serve as a probe of the intervening medium. The gas responsible for the Lyman alpha absorption lines may be due to primordial gas gravitationally confined in minihalos of dark matter--shallow potential wells whose evolution and relation to dwarf galaxies are briefly discussed. The patchy heat input into the intergalactic medium from early quasars could modulate the environment in which galaxies form, leading to large-scale spatial correlations in the galaxy distribution. This review concludes with general comments on the prospects for a fully quantitative understanding of galaxy formation. PMID:11607397

  7. Quasar Selection in the Optical + MIR

    NASA Astrophysics Data System (ADS)

    Richards, Gordon T.; Myers, Adam D.; Peters, Christina M.

    2015-01-01

    We identify 885,503 type 1 quasar candidates to i<22 using the combination of optical and mid-IR photometry. Optical photometry is taken from SDSS-III, while mid-IR photometry comes from a combination of data from ALLWISE and several large-area Spitzer-IRAC fields. Selection was based on a training sample of 157,701 spectroscopically-confirmed type 1 quasars with both optical and mid-IR data. Of these candidates, 306,686 lack spectroscopic confirmation, including 8665 quasar candidates with 3.53.5 than the traditional mid-IR selection ``wedges'' and to 2.2quasars than the SDSS-III/BOSS project. This catalog paves the way for luminosity-dependent clustering investigations of large numbers of faint, high-redshift quasars. This work was supported in part by NASA-ADAP grant NNX12AI49G.

  8. THE SUDDEN DEATH OF THE NEAREST QUASAR

    SciTech Connect

    Schawinski, Kevin; Virani, Shanil; Megan Urry, C.; Natarajan, Priyamvada; Coppi, Paolo; Evans, Daniel A.; Keel, William C.; Manning, Anna; Lintott, Chris J.; Kaviraj, Sugata; Bamford, Steven P.; Jozsa, Gyula I. G.; Garrett, Michael; Van Arkel, Hanny; Gay, Pamela; Fortson, Lucy

    2010-11-20

    Galaxy formation is significantly modulated by energy output from supermassive black holes at the centers of galaxies which grow in highly efficient luminous quasar phases. The timescale on which black holes transition into and out of such phases is, however, unknown. We present the first measurement of the shutdown timescale for an individual quasar using X-ray observations of the nearby galaxy IC 2497, which hosted a luminous quasar no more than 70,000 years ago that is still seen as a light echo in 'Hanny's Voorwerp', but whose present-day radiative output is lower by at least two, and more likely by over four, orders of magnitude. This extremely rapid shutdown provides new insight into the physics of accretion in supermassive black holes and may signal a transition of the accretion disk to a radiatively inefficient state.

  9. Doppler interpretation of quasar red shifts.

    PubMed

    Zapolsky, H S

    1966-08-01

    The hypothesis that the quasistellar sources (quasars) are local objects moving with velocities close to the speed of light is examined. Provided there is no observational cutoff on apparent bolometric magnitude for the quasars, the transverse Doppler effect leads to the expectation of fewer blue shifts than red shifts for an isotropic distribution of velocities. Such a distribution also yields a function N(z), the number of objects with red shift less than z which is not inconsistent with the present data. On the basis of two extreme assumptions concerning the origin of such rapidly moving sources, we computed curves of red shift plotted against magnitude. In particular, the curve obtained on the assumption that the quasars originated from an explosion in or nearby our own galaxy is in as good agreement with the observations as the curve of cosmological red shift plotted against magnitude.

  10. Detecting the First Quasars with ALMA

    NASA Astrophysics Data System (ADS)

    Schleicher, Dominik R. G.; Spaans, Marco; Klessen, Ralf S.

    2010-05-01

    We show that ALMA is the first telescope that can probe the dust-obscured central region of quasars at z > 5 with a maximum resolution of ~ 30 pc employing the 18 km baseline. We explore the possibility of detecting the first quasars with ALMA (Schleicher, Spaans, & Klessen 2009). For this purpose, we adopt the Seyfert 2 galaxy NGC 1068 as a reference system and calculate the expected fluxes if this galaxy were placed at high redshift. This choice is motivated by the detailed observations available for this system and the absence of any indication for an evolution in metallicity in high-redshift quasars. It is a conservative choice due to the moderate column densities in NGC 1068, leading to moderate fluxes.

  11. The resolved outflow from 3C 48

    SciTech Connect

    Shih, Hsin-Yi; Stockton, Alan E-mail: stockton@ifa.hawaii.edu

    2014-10-20

    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 = 10{sup 3}-10{sup 4} cm{sup –3}, the mass is ∼6 × 10{sup 6} M {sub ☉}, 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.

  12. The Extreme Ultraviolet Variability of Quasars

    NASA Astrophysics Data System (ADS)

    Punsly, Brian; Marziani, Paola; Zhang, Shaohua; Muzahid, Sowgat; O’Dea, Christopher P.

    2016-10-01

    We study the extreme ultraviolet (EUV) variability (rest frame wavelengths 500–920 Å) of high-luminosity quasars using Hubble Space Telescope (HST) (low to intermediate redshift sample) and Sloan Digital sky Survey (SDSS) (high redshift sample) archives. The combined HST and SDSS data indicates a much more pronounced variability when the sampling time between observations in the quasar rest frame is \\gt 2× {10}7 {{s}} compared to \\lt 1.5× {10}7 s. Based on an excess variance analysis, for time intervals \\lt 2× {10}7 {{s}} in the quasar rest frame, 10% of the quasars (4/40) show evidence of EUV variability. Similarly, for time intervals \\gt 2× {10}7 {{s}} in the quasar rest frame, 55% of the quasars (21/38) show evidence of EUV variability. The propensity for variability does not show any statistically significant change between 2.5× {10}7 {{s}} and 3.16× {10}7 {{s}} (1 year). The temporal behavior is one of a threshold time interval for significant variability as opposed to a gradual increase on these timescales. A threshold timescale can indicate a characteristic spatial dimension of the EUV region. We explore this concept in the context of the slim disk models of accretion. We find that for rapidly spinning black holes, the radial infall time to the plunge region of the optically thin surface layer of the slim disk that is responsible for the preponderance of the EUV flux emission (primarily within 0–7 black hole radii from the inner edge of the disk) is consistent with the empirically determined variability timescale.

  13. Understanding the near infrared spectrum of quasars

    NASA Astrophysics Data System (ADS)

    Hernán-Caballero, Antonio; Hatziminaoglou, Evanthia; Alonso-Herrero, Almudena; Mateos, Silvia

    2016-08-01

    The rest-frame near infrared (NIR) is a key spectral range for understanding the physics of AGN, but progress has been hindered by the difficulty in defining the NIR spectrum of the accretion disk and removing contamination from stellar emission in the host galaxy. In this talk I will present the analysis of a sample of 85 luminous (L3µm>10^45.5 erg/s) quasars with rest-frame NIR spectroscopy from AKARI and Spitzer/IRS. Their high luminosity allows a direct determination of the NIR shape of the quasar spectrum clean from host galaxy emission. We find that the entire UV-to-MIR SED can be accurately reproduced with a semi-empirical disk+dust model that uses a single template for the accretion disk and two blackbody components (hot and warm) for the dust. The observed diversity in individual SEDs can be accounted for by varying levels of extinction affecting the disk component and differences in the relative luminosities of the disk and dust components. We present a new quasar template [0.1-10µm] as well as separate templates for the disk and dust components, and conclude that previous templates based on less luminous quasars suffer from contamination by stellar emission in the host galaxy, which accounts for up to ~30% of the flux at 1µm. We also perform the first ever measurement of the Paschen_α emission in a large sample of luminous quasars and find that the Paschen_α to optical continuum luminosity ratio is boosted in our sample compared to less luminous quasars.

  14. Theory of MHD Jets and Outflows

    NASA Astrophysics Data System (ADS)

    Tsinganos, Kanaris

    A brief review is given of selected results of our analytical and numerical work on the construction of time-independent and time-dependent MHD models for non relativistic astrophysical outflows and jets. The equations for steady MHD plasma flows are first outlined. Next, 1-D spherically symmetric outflows are briefly discussed, namely the Parker thermally driven nonrotating wind, as the classical prototype of all astrophysical outflows and the Weber-Davis magnetocentrifugally driven wind together with its astrophysical implications for magnetic braking, etc. Then, we turn to the 2-D MHD problem for steady and non steady 2-D axisymmetric magnetized and rotating plasma outflows. The only available exact solutions for such outflows are those in separable coordinates, i.e. those with the symmetry of radial or meridional self-similarity. Physically accepted solutions pass from the fast magnetosonic separatrix surface in order to satisfy MHD causality. An energetic criterion is outlined for selecting radially expanding winds from cylindrically expanding jets. The basics of jet acceleration, collimation, minimum fieldline inclination and angular momentum removal are illustrated in the context of radially self similar models. Numerical simulations of magnetic self-collimation verify several results of analytical steady solutions. The outflow from solar-type inefficient magnetic rotators is very weakly collimated while that from a ten times faster rotating YSO produces a tightly collimated jet. We also propose a two-component model consisting of a wind outflow from the central object and a faster rotating outflow launched from the surrounding accretion disk which plays the role of the flow collimator. We also briefly discuss the problem of shock formation during the magnetic collimation of wind-type outflows into jets.

  15. PROBING THE FERMI BUBBLES IN ULTRAVIOLET ABSORPTION: A SPECTROSCOPIC SIGNATURE OF THE MILKY WAY'S BICONICAL NUCLEAR OUTFLOW

    SciTech Connect

    Fox, Andrew J.; Bordoloi, Rongmon; Hernandez, Svea; Tumlinson, Jason; Savage, Blair D.; Wakker, Bart P.; Lockman, Felix J.; Bland-Hawthorn, Joss; Kim, Tae-Sun; Benjamin, Robert A.

    2015-01-20

    Giant lobes of plasma extend ≈55° above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (ℓ, b = 10.°4, +11.°2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v {sub LSR} = –235 and +250 km s{sup –1}, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of ≳900 km s{sup –1} and a full opening angle of ≈110° (matching the X-ray bicone). This indicates Galactic center activity over the last ≈2.5-4.0 Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles.

  16. Einstein observations of active galaxies and quasars

    NASA Technical Reports Server (NTRS)

    Schreier, E. J.

    1979-01-01

    The radio galaxies Centaurus A and Signus B are discussed. In both these sources, a comparison of the radio and imaged X-ray flux is allowed for the measurement of the magnetic fields. Einstein observations of quasars are discussed. The number of known X-ray emitting QSO's was increased from 3 to 22 and the distances where these QSO's were seen to correspond to an age of 15 billion years. It was shown that these quasars contributed significantly to the X-ray background.

  17. The black hole spins of quasars

    NASA Astrophysics Data System (ADS)

    You, Bei; Cao, Xinwu

    2016-02-01

    We present the estimates of the black hole spins of five quasars. The peaks of the spectra of the accretion discs surrounding massive black holes in quasars are in the far-UV or soft X-ray band, which are usually not observed. However, in the disc corona model, the soft photons from the disc are Comptonized to high energy in the hot corona, and the hard X-ray spectra (luminosity and spectral shape) contain the information of the incident spectra from the disc. The values of black hole spin parameter a are inferred from the spectral fitting, which spread over a large range, ~ -0.94 to 0.998.

  18. Metal enrichment of the CGM through outflows

    NASA Astrophysics Data System (ADS)

    Christensen, Charlotte

    2016-01-01

    Galactic outflows enrich the circumgalactic medium through the redistribution of metals from the disks of galaxies. We examine the history of this enrichment by analyzing the outflows of twenty high-resolution simulated galaxies spanning two and a half orders of magnitude in halo mass. These simulations match many observed trends, including the mass-metallicity relation. By tracking particles in the simulations, we follow the removal and reaccretion of metals between redshift 3.5 and 0. We also determine the enrichment of the outflowing gas compared to the local interstellar media. Finally we compare the redshift zero metal census to observed values.

  19. Dust-free quasars in the early Universe.

    PubMed

    Jiang, Linhua; Fan, Xiaohui; Brandt, W N; Carilli, Chris L; Egami, Eiichi; Hines, Dean C; Kurk, Jaron D; Richards, Gordon T; Shen, Yue; Strauss, Michael A; Vestergaard, Marianne; Walter, Fabian

    2010-03-18

    The most distant quasars known, at redshifts z approximately 6, generally have properties indistinguishable from those of lower-redshift quasars in the rest-frame ultraviolet/optical and X-ray bands. This puzzling result suggests that these distant quasars are evolved objects even though the Universe was only seven per cent of its current age at these redshifts. Recently one z approximately 6 quasar was shown not to have any detectable emission from hot dust, but it was unclear whether that indicated different hot-dust properties at high redshift or if it is simply an outlier. Here we report the discovery of a second quasar without hot-dust emission in a sample of 21 z approximately 6 quasars. Such apparently hot-dust-free quasars have no counterparts at low redshift. Moreover, we demonstrate that the hot-dust abundance in the 21 quasars builds up in tandem with the growth of the central black hole, whereas at low redshift it is almost independent of the black hole mass. Thus z approximately 6 quasars are indeed at an early evolutionary stage, with rapid mass accretion and dust formation. The two hot-dust-free quasars are likely to be first-generation quasars born in dust-free environments and are too young to have formed a detectable amount of hot dust around them.

  20. Outflows in Sodium Excess Objects

    NASA Astrophysics Data System (ADS)

    Park, Jongwon; Jeong, Hyunjin; Yi, Sukyoung

    2016-01-01

    van Dokkum and Conroy reported that some giant elliptical galaxies show extraordinarily strong Na I absorption lines and suggested that this is the evidence of unusually bottom-heavy initial mass function. Jeong et al. later studied galaxies with unexpectedly strong Na D absorption lines (Na D excess objects: NEOs) and showed that the origins of NEOs are different for different types of galaxies. According to their study, the origin of Na D excess seems to be related to interstellar medium (ISM) in late-type galaxies, but there seems to be no contributions from ISM in smooth-looking early-type galaxies. In order to test this finding, we measured the Doppler components in Na D lines of NEOs. We hypothesized that if Na D absorption line is related to ISM, the absorption line is more likely to be blueshifted in the spectrum by the motion of ISM caused by outflow. Many of late-type NEOs show blueshifted Na D absorption lines, so their origin seems related to ISM. On the other hand, smooth-looking early-type NEOs do not show Doppler departure and Na D excess in early-type NEOs is likely not related to ISM, which is consistent with the finding of Jeong et al.

  1. Using quasars as standard clocks for measuring cosmological redshift.

    PubMed

    Dai, De-Chang; Starkman, Glenn D; Stojkovic, Branislav; Stojkovic, Dejan; Weltman, Amanda

    2012-06-01

    We report hitherto unnoticed patterns in quasar light curves. We characterize segments of the quasar's light curves with the slopes of the straight lines fit through them. These slopes appear to be directly related to the quasars' redshifts. Alternatively, using only global shifts in time and flux, we are able to find significant overlaps between the light curves of different pairs of quasars by fitting the ratio of their redshifts. We are then able to reliably determine the redshift of one quasar from another. This implies that one can use quasars as standard clocks, as we explicitly demonstrate by constructing two independent methods of finding the redshift of a quasar from its light curve.

  2. Close companions to two high-redshift quasars

    SciTech Connect

    McGreer, Ian D.; Fan, Xiaohui; Bian, Fuyan; Strauss, Michael A.; Haiman, Zoltàn; Richards, Gordon T.; Jiang, Linhua; Schneider, Donald P.

    2014-10-01

    We report the serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z = 4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit spectroscopy shows excess Lyα emission extending well beyond the quasar's light profile. Further imaging and spectroscopy with LBT/MODS1 confirms the presence of a bright galaxy (i {sub AB} = 23.6) located 2'' (12 kpc projected) from the quasar with strong Lyα emission (EW{sub 0} ≈ 100 Å) at the redshift of the quasar, as well as faint continuum. The second quasar, CFHQS J005006.6+344522 (z = 6.25), is included in our recent HST SNAP survey of z ∼ 6 quasars searching for evidence of gravitational lensing. Deep imaging with ACS and WFC3 confirms an optical dropout ∼4.5 mag fainter than the quasar (Y {sub AB} = 25) at a separation of 0.''9. The red i {sub 775} – Y {sub 105} color of the galaxy and its proximity to the quasar (5 kpc projected if at the quasar redshift) strongly favor an association with the quasar. Although it is much fainter than the quasar, it is remarkably bright when compared to field galaxies at this redshift, while showing no evidence for lensing. Both systems may represent late-stage mergers of two massive galaxies, with the observed light for one dominated by powerful ongoing star formation and for the other by rapid black hole growth. Observations of close companions are rare; if major mergers are primarily responsible for high-redshift quasar fueling then the phase when progenitor galaxies can be observed as bright companions is relatively short.

  3. Magnetosphere sawtooth oscillations induced by ionospheric outflow.

    PubMed

    Brambles, O J; Lotko, W; Zhang, B; Wiltberger, M; Lyon, J; Strangeway, R J

    2011-06-01

    The sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O(+) outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their pressure distends the nightside magnetic field. When the outflow fluence exceeds a threshold, magnetic field tension cannot confine the accumulating fluid; an O(+)-rich plasmoid is ejected, and the field dipolarizes. Below the threshold, the magnetosphere undergoes quasi-steady convection. Repetition and the sawtooth period are controlled by the strength of the SW-M-I interaction, which regulates the outflow fluence. PMID:21636770

  4. Magnetosphere sawtooth oscillations induced by ionospheric outflow.

    PubMed

    Brambles, O J; Lotko, W; Zhang, B; Wiltberger, M; Lyon, J; Strangeway, R J

    2011-06-01

    The sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O(+) outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their pressure distends the nightside magnetic field. When the outflow fluence exceeds a threshold, magnetic field tension cannot confine the accumulating fluid; an O(+)-rich plasmoid is ejected, and the field dipolarizes. Below the threshold, the magnetosphere undergoes quasi-steady convection. Repetition and the sawtooth period are controlled by the strength of the SW-M-I interaction, which regulates the outflow fluence.

  5. A cosmic double helix in the archetypical quasar 3C273.

    PubMed

    Lobanov, A P; Zensus, J A

    2001-10-01

    Finding direct evidence for plasma instability in extragalactic jets is crucial for understanding the nature of relativistic outflows from active galactic nuclei. Our radio interferometric observations of the quasar 3C273 made with the orbiting radio telescope, HALCA, and an array of ground telescopes have yielded an image in which the emission across the jet is resolved, revealing two threadlike patterns that form a double helix inside the jet. This double helical structure is consistent with a Kelvin-Helmholtz instability, and at least five different instability modes can be identified and modeled by a light jet with a Lorentz factor of 2 and Mach number of 3.5. The model reproduces in detail the internal structure of the jet on scales of up to 30 milli-arc seconds ( approximately 300 parsecs) and is consistent with the general morphology of the jet on scales of up to 1 kiloparsec.

  6. THE RADIO PROPERTIES OF TYPE 2 QUASARS

    SciTech Connect

    Lal, Dharam Vir; Ho, Luis C.

    2010-03-15

    This paper presents the first high-resolution and high-sensitivity study of the radio properties of optically selected type 2 quasars. We used the Very Large Array at 8.4 GHz to observe 59 sources drawn from the Sloan Digital Sky Survey sample of Zakamska et al.. The detection rate of our survey is 59% (35/59), comparable to the detection rate in FIRST at 1.4 GHz. Ongoing star formation, although present, contributes negligible radio emission at the current sensitivity limit. Comparing the radio powers with the [O III] {lambda}5007 luminosities, we find that roughly 15% {+-} 5% of the sample can be considered radio loud. Intriguingly, the vast majority of the detected sources in our sample fall in a region intermediate between those traditionally occupied by radio loud and radio quiet quasars. Moreover, most of these 'radio intermediate' sources tend to have flat or inverted radio spectra, which we speculate may be caused by free-free absorption by ionized gas in the narrow-line region. The incidence of flat-spectrum sources in type 2 quasars appears to be much higher than in type 1 quasars, in apparent violation of the simple orientation-based unified model for active galaxies.

  7. Measuring Distances to Remote Galaxies and Quasars.

    ERIC Educational Resources Information Center

    McCarthy, Patrick J.

    1988-01-01

    Describes the use of spectroscopy and the redshift to measure how far an object is by measuring how fast it is receding from earth. Lists the most distant quasars yet found. Tables include "Redshift vs. Distance" and "Distances to Celestial Objects for Various Cosmologies." (CW)

  8. COLD FLOWS AND THE FIRST QUASARS

    SciTech Connect

    Di Matteo, T.; Khandai, N.; DeGraf, C.; Feng, Y.; Croft, R. A. C.; Lopez, J.; Springel, V.

    2012-02-15

    Observations of the most distant bright quasars imply that billion solar mass supermassive black holes (SMBHs) have to be assembled within the first 800 million years. Under our standard galaxy formation scenario such fast growth implies large gas densities providing sustained accretion at critical or supercritical rates onto an initial black hole seed. It has been a long standing question whether and how such high black hole accretion rates can be achieved and sustained at the centers of early galaxies. Here we use our new MassiveBlack cosmological hydrodynamic simulation covering a volume (0.75 Gpc){sup 3} appropriate for studying the rare first quasars to show that steady high density cold gas flows responsible for assembling the first galaxies produce the high gas densities that lead to sustained critical accretion rates and hence rapid growth commensurate with the existence of {approx}10{sup 9} M{sub Sun} black holes as early as z {approx} 7. We find that under these conditions quasar feedback is not effective at stopping the cold gas from penetrating the central regions and hence cannot quench the accretion until the host galaxy reaches M{sub halo} > or approx. 10{sup 1}2{sup M}{sub Sun }. This cold-flow-driven scenario for the formation of quasars implies that they should be ubiquitous in galaxies in the early universe and that major (proto)galaxy mergers are not a requirement for efficient fuel supply and growth, particularly for the earliest SMBHs.

  9. Quasar H II Regions During Cosmic Reionization

    SciTech Connect

    Alvarez, Marcelo A.; Abel, Tom; /KIPAC, Menlo Park

    2007-03-30

    Cosmic reionization progresses as HII regions form around sources of ionizing radiation. Their average size grows continuously until they percolate and complete reionization. We demonstrate how this typical growth can be calculated around the largest, biased sources of UV emission such as quasars by further developing an analytical model based on the excursion set formalism. This approach allows us to calculate the sizes and growth of the HII regions created by the progenitors of any dark matter halo of given mass and redshift with a minimum of free parameters. Statistical variations in the size of these pre-existing HII regions are an additional source of uncertainty in the determination of very high redshift quasar properties from their observed HII region sizes. We use this model to demonstrate that the transmission gaps seen in very high redshift quasars can be understood from the radiation of only their progenitors and associated clustered small galaxies. The fit requires the epoch of overlap to be at z = 5.8 {+-} 0.1. This interpretation makes the transmission gaps independent of the age of the quasars observed. If this interpretation were correct it would raise the prospects of using radio interferometers currently under construction to detect the epoch of reionization.

  10. Quasar Astrophysics with the Space Interferometry Mission

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen; Wehrle, Ann; Meier, David; Jones, Dayton; Piner, Glenn

    2007-01-01

    Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.

  11. Quasars and H II regions during reionization

    NASA Astrophysics Data System (ADS)

    Kramer, Roban Hultman

    The reionization history of the intergalactic medium (IGM) at high redshift (z ≳ 6) is just beginning to be probed by observational astronomy. In this dissertation, I discuss three projects related to the epoch of reionization. The first project explores how the evolution of the IGM neutral fraction was likely shaped by feedback processes. Because the earliest ionizing sources formed at the locations of the rare density peaks, their spatial distribution was strongly clustered. By building a semi-analytical model which includes feedback and clustering simultaneously and applying this model to the suppression of star formation in minihalos due to photoionization, I demonstrate that this clustering significantly boosts the impact of feedback processes operating at high redshift. The second project exploits the fact that high-redshift quasars drive ionization fronts (I-fronts) into the IGM, with the thickness of the front generally increasing with the hardness of the ionizing spectrum. If the thickness of the front can be measured, it can provide a novel constraint on the ionizing spectral energy distribution (SED). I simulate the propagation of an I-front into a uniform IGM, and compute its thickness for a range of possible quasar spectra and ages, and IGM neutral hydrogen densities and clumping factors. With a sufficiently high intrinsic hydrogen column density obscuring the source or a sufficiently hard power-law spectrum and some obscuration, the thickness of the front exceeds ˜ 1 physical Mpc and may be measurable from the three-dimensional morphology of its redshifted 21cm signal. In the third project, I investigate one promising method for probing the tail end of reionization, through the detection and characterization of the Gunn-Peterson damping wing absorption of the IGM in bright quasar spectra. However, the use of quasar spectra to measure the IGM damping wing requires a model of the quasar's intrinsic Lyman-alpha emission line. I quantify uncertainties

  12. Discovery of Broad Soft X-ray Absorption Lines from the Quasar Wind in PDS 456

    NASA Astrophysics Data System (ADS)

    Reeves, J. N.; Braito, V.; Nardini, E.; Behar, E.; O’Brien, P. T.; Tombesi, F.; Turner, T. J.; Costa, M. T.

    2016-06-01

    High-resolution soft X-ray spectroscopy of the prototype accretion disk wind quasar, PDS 456, is presented. Here, the XMM-Newton reflection grating spectrometer spectra are analyzed from the large 2013–2014 XMM-Newton campaign, consisting of five observations of approximately 100 ks in length. During the last observation (OBS. E), the quasar is at a minimum flux level, and broad absorption line (BAL) profiles are revealed in the soft X-ray band, with typical velocity widths of {σ }{{v}}˜ {{10,000}} km s‑1. During a period of higher flux in the third and fourth observations (OBS. C and D, respectively), a very broad absorption trough is also present above 1 keV. From fitting the absorption lines with models of photoionized absorption spectra, the inferred outflow velocities lie in the range ˜ 0.1{--}0.2c. The absorption lines likely originate from He and H-like neon and L-shell iron at these energies. A comparison with earlier archival data of PDS 456 also reveals a similar absorption structure near 1 keV in a 40 ks observation in 2001, and generally the absorption lines appear most apparent when the spectrum is more absorbed overall. The presence of the soft X-ray BALs is also independently confirmed by an analysis of the XMM-Newton EPIC spectra below 2 keV. We suggest that the soft X-ray absorption profiles could be associated with a lower ionization and possibly clumpy phase of the accretion disk wind, where the latter is known to be present in this quasar from its well-studied iron K absorption profile and where the wind velocity reaches a typical value of 0.3c.

  13. Faraday Rotation Measure Synthesis of Intermediate Redshift Quasars as a Probe of Intervening Matter

    NASA Astrophysics Data System (ADS)

    Kim, Kwang Seong; Lilly, Simon J.; Miniati, Francesco; Bernet, Martin L.; Beck, Rainer; O’Sullivan, Shane P.; Gaensler, Bryan M.

    2016-10-01

    There is evidence that magnetized material along the line of sight to distant quasars is detectable in the polarization properties of the background sources. The polarization properties appear to be correlated with the presence of intervening Mg ii absorption, which is thought to arise in outflowing material from star forming galaxies. In order to investigate this further, we have obtained high spectral resolution polarization measurements, with the Very Large Array and the Australia Telescope Compact Array, of a set of 49 unresolved quasars for which we have high quality optical spectra. These enable us to produce a Faraday Depth spectrum for each source, using Rotation Measure (RM) Synthesis. Our new independent radio data confirms that interveners are strongly associated with depolarization. We characterize the complexity of the Faraday Depth spectrum using a number of parameters and show how these are related, or not, to the depolarization and to the presence of Mg ii absorption along the line of sight. We argue that complexity and structure in the Faraday Depth distribution likely arise from both intervening material and intrinsically to the background source and attempt to separate these. We find that the strong radio depolarization effects associated with intervening material at redshifts out to z≈ 1 arise from inhomogeneous Faraday screens producing a dispersion in RM across individual sources of around 10 rad m‑2. This is likely produced by disordered fields with strengths of at least 3 μG.

  14. ACCRETION RATES OF RED QUASARS FROM THE HYDROGEN Pβ LINE

    SciTech Connect

    Kim, Dohyeong; Im, Myungshin; Glikman, Eilat; Woo, Jong-Hak; Urrutia, Tanya E-mail: mim@astro.snu.ac.kr

    2015-10-10

    Red quasars are thought to be an intermediate population between merger-driven star-forming galaxies in dust-enshrouded phase and normal quasars. If so, they are expected to have high accretion ratios, but their intrinsic dust extinction hampers reliable determination of Eddington ratios. Here, we compare the accretion rates of 16 red quasars at z ∼ 0.7 to those of normal type 1 quasars at the same redshift range. The red quasars are selected by their red colors in optical through near-infrared (NIR) and radio detection. The accretion rates of the red quasars are derived from the Pβ line in NIR spectra, which is obtained by the SpeX on the Infrared Telescope Facility in order to avoid the effects of dust extinction. We find that the measured Eddington ratios (L{sub bol}/L{sub Edd} ≃ 0.69) of red quasars are significantly higher than those of normal type 1 quasars, which is consistent with a scenario in which red quasars are the intermediate population and the black holes of red quasars grow very rapidly during such a stage.

  15. Tracing high redshift cosmic web with quasar systems

    NASA Astrophysics Data System (ADS)

    Einasto, Maret

    2016-10-01

    We study the cosmic web at redshifts 1.0 <= <= 1.8 using quasar systems based on quasar data from the SDSS DR7 QSO catalogue. Quasar systems were determined with a friend-of-friend (FoF) algorithm at a series of linking lengths. At the linking lengths l <= 30 h -1 Mpc the diameters of quasar systems are smaller than the diameters of random systems, and are comparable to the sizes of galaxy superclusters in the local Universe. The mean space density of quasar systems is close to the mean space density of local rich superclusters. At larger linking lengths the diameters of quasar systems are comparable with the sizes of supercluster complexes in our cosmic neighbourhood. The richest quasar systems have diameters exceeding 500h Mpc. Very rich systems can be found also in random distribution but the percolating system which penetrate the whole sample volume appears in quasar sample at smaller linking length than in random samples showing that the large-scale distribution of quasar systems differs from random distribution. Quasar system catalogues at our web pages (http://www.aai.ee/maret/QSOsystems.html) serve as a database to search for superclusters of galaxies and to trace the cosmic web at high redshifts.

  16. Correlaciones cruzadas quasar-galaxia y AGN-galaxia

    NASA Astrophysics Data System (ADS)

    Martínez, H. J.; Merchán, M. E.; Valotto, C. A.; García Lambas, D.

    We compute quasar-galaxy and AGN-galaxy cross-correlation functions for samples taken from the Véron-Cetty & Véron (1998) catalog of quasars and active galaxies, using tracer galaxies taken from the Edinburgh/Durham Southern Catalog. The sample of active galaxy targets shows positive correlation at projected separations rp < 6 h-1 ~Mpc consistent with the usual power-law. On the other hand, we do not find a statistically significant positive quasar-galaxy correlation signal except in the range 3 h-1 Mpc < rp < 6 h-1 Mpc where we find similar AGN-galaxy and quasar-galaxy correlation amplitudes. At separations rp<3~h-1 ~Mpc a strong decline of quasar-galaxy correlations is observed, suggesting a significant local influence of quasars in galaxy formation. In an attempt to reproduce the observed cross-correlation between quasars and galaxies, we have performed CDM cosmological hydrodynamical simulations and tested the viability of a scenario based on the model developed by Silk & Rees (1998). In this scheme a fraction of the energy released by quasars is considered to be transferred into the baryonic component of the intergalactic medium in the form of winds. The results of the simulations suggest that the shape of the observed quasar-galaxy cross-correlation function could be understood in a scenario where a substantial amount of energy is transferred to the medium at the redshift of maximum quasar activity.

  17. A Robust Measurement of the Mass Outflow Rate of the Galactic Outflow from NGC 6090

    NASA Astrophysics Data System (ADS)

    Chisholm, John; Tremonti, Christy A.; Leitherer, Claus; Chen, Yanmei

    2016-08-01

    To evaluate the impact of stellar feedback, it is critical to estimate the mass outflow rates of galaxies. Past estimates have been plagued by uncertain assumptions about the outflow geometry, metallicity, and ionization fraction. Here we use Hubble Space Telescope ultraviolet spectroscopic observations of the nearby starburst NGC 6090 to demonstrate that many of these quantities can be constrained by the data. We use the Si IV absorption lines to calculate the scaling of velocity (v), covering fraction (Cf), and density with distance from the starburst (r), assuming the Sobolev optical depth and a velocity law of the form: v~∝(1 - Ri/r)β (where Ri is the inner outflow radius). We find that the velocity (β=0.43) is consistent with an outflow driven by an r-2 force with the outflow radially accelerated, while the scaling of the covering fraction (Cf∝r-0.82) suggests that cool clouds in the outflow are in pressure equilibrium with an adiabatically expanding medium. We use the column densities of four weak metal lines and CLOUDY photoionization models to determine the outflow metallicity, the ionization correction, and the initial density of the outflow. Combining these values with the profile fitting, we find Ri = 63 pc, with most of the mass within 300 pc of the starburst. Finally, we find that the maximum mass outflow rate is 2.3 M⊙ yr-1 and the mass loading factor (outflow divided by the star formation rate) is 0.09, a factor of 10 lower than the value calculated using common assumptions for the geometry, metallicity and ionization structure of the outflow.

  18. A robust measurement of the mass outflow rate of the galactic outflow from NGC 6090

    NASA Astrophysics Data System (ADS)

    Chisholm, John; Tremonti Christy, A.; Leitherer, Claus; Chen, Yanmei

    2016-11-01

    To evaluate the impact of stellar feedback, it is critical to estimate the mass outflow rates of galaxies. Past estimates have been plagued by uncertain assumptions about the outflow geometry, metallicity, and ionization fraction. Here we use Hubble Space Telescope ultraviolet spectroscopic observations of the nearby starburst NGC 6090 to demonstrate that many of these quantities can be constrained by the data. We use the Si IV absorption lines to calculate the scaling of velocity (v), covering fraction (Cf), and density with distance from the starburst (r), assuming the Sobolev optical depth and a velocity law of the form: v ∝ (1 - Ri/r)β (where Ri is the inner outflow radius). We find that the velocity (β = 0.43) is consistent with an outflow driven by an r-2 force with the outflow radially accelerated, while the scaling of the covering fraction (Cf ∝ r-0.82) suggests that cool clouds in the outflow are in pressure equilibrium with an adiabatically expanding medium. We use the column densities of four weak metal lines and CLOUDY photoionization models to determine the outflow metallicity, the ionization correction, and the initial density of the outflow. Combining these values with the profile fitting, we find Ri = 63 pc, with most of the mass within 300 pc of the starburst. Finally, we find that the maximum mass outflow rate is 2.3 M⊙ yr-1 and the mass-loading factor (outflow divided by the star formation rate) is 0.09, a factor of 10 lower than the value calculated using common assumptions for the geometry, metallicity, and ionization structure of the outflow.

  19. Similarity of ionized gas nebulae around unobscured and obscured quasars

    NASA Astrophysics Data System (ADS)

    Liu, Guilin; Zakamska, Nadia L.; Greene, Jenny E.

    2014-08-01

    Quasar feedback is suspected to play a key role in the evolution of massive galaxies, by removing or reheating gas in quasar host galaxies and thus limiting the amount of star formation. In this paper, we continue our investigation of quasar-driven winds on galaxy-wide scales. We conduct Gemini Integral Field Unit spectroscopy of a sample of luminous unobscured (type 1) quasars, to determine the morphology and kinematics of ionized gas around these objects, predominantly via observations of the [O III] λ5007 Å emission line. We find that ionized gas nebulae extend out to ˜13 kpc from the quasar, that they are smooth and round, and that their kinematics are inconsistent with gas in dynamical equilibrium with the host galaxy. The observed morphological and kinematic properties are strikingly similar to those of ionized gas around obscured (type 2) quasars with matched [O III] luminosity, with marginal evidence that nebulae around unobscured quasars are slightly more compact. Therefore, in samples of obscured and unobscured quasars carefully matched in [O III] luminosity, we find support for the standard geometry-based unification model of active galactic nuclei, in that the intrinsic properties of the quasars, of their hosts and of their ionized gas appear to be very similar. Given the apparent ubiquity of extended ionized regions, we are forced to conclude that either the quasar is at least partially illuminating pre-existing gas or that both samples of quasars are seen during advanced stages of quasar feedback. In the latter case, we may be biased by our [O III]-based selection against quasars in the early `blow-out' phase, for example due to dust obscuration.

  20. LBQS 1429-0053: A binary quasar rather than a lensed quasar.

    NASA Astrophysics Data System (ADS)

    Faure, C.; Alloin, D.; Gras, S.; Courbin, F.; Kneib, J.-P.; Hudelot, P.

    2003-07-01

    Very deep ESO/VLT FORS1 and ISAAC images, as well as HST NICMOS2 data are used to infer the nature of the quasar pair LBQS 1429-0053 A and B, either a binary quasar or a doubly-imaged lensed quasar. Direct search of a putative lensing galaxy is unsuccessful down to R=27, J=24, Ks=22.5 and H=22.5. Moreover, no galaxy overdensity close to the quasar pair is found. A weak shear analysis of the FORS1 R-band 6.8 arcmin x 6.8 arcmin field also fails at detecting any concentration of dark matter more massive than sigma =500 km s-1 and weakens the hypothesis of a dark lens. The only sign of a possible lens consists in a group of 5 objects having colors consistent with galaxies at z ~ 1, within a radius of 5 arcsec from the quasar pair. Considering this group as the lensing potential does not allow to reproduce the image position and flux ratio of LBQS 1429-0053 A and B. Our deep R-band image shows a blue, previously unknown, extended object at the position of LBQS 1429-0053 A, which is consistent with either being the lensed quasar A host, or being an intervening galaxy at lower redshift. Unless future very deep optical images demonstrate that this object is actually the lensed host of LBQS 1429-0053, we conclude that there is very little evidence for LBQS 1429-0053 being lensed. Therefore, we are led to declare LBQS 1429-0053 A and B a genuine binary quasar. Based on observations obtained with VLT/ANTU at ESO-Paranal Observatory (program 67.A-0502) and with the Hubble Space Telescope, operated by NASA.

  1. Bursty star formation feedback and cooling outflows

    NASA Astrophysics Data System (ADS)

    Suarez, Teresita; Pontzen, Andrew; Peiris, Hiranya V.; Slyz, Adrianne; Devriendt, Julien

    2016-10-01

    We study how outflows of gas launched from a central galaxy undergoing repeated starbursts propagate through the circum-galactic medium (CGM), using the simulation code RAMSES. We assume that the outflow from the disc can be modelled as a rapidly moving bubble of hot gas at ˜1 kpc above disc, then ask what happens as it moves out further into the halo around the galaxy on ˜100 kpc scales. To do this, we run 60 two-dimensional simulations scanning over parameters of the outflow. Each of these is repeated with and without radiative cooling, assuming a primordial gas composition to give a lower bound on the importance of cooling. In a large fraction of radiative-cooling cases we are able to form rapidly outflowing cool gas from in situ cooling of the flow. We show that the amount of cool gas formed depends strongly on the `burstiness' of energy injection; sharper, stronger bursts typically lead to a larger fraction of cool gas forming in the outflow. The abundance ratio of ions in the CGM may therefore change in response to the detailed historical pattern of star formation. For instance, outflows generated by star formation with short, intense bursts contain up to 60 per cent of their gas mass at temperatures <5 × 104 K; for near-continuous star formation, the figure is ≲5 per cent. Further study of cosmological simulations, and of idealized simulations with e.g. metal-cooling, magnetic fields and/or thermal conduction, will help to understand the precise signature of bursty outflows on observed ion abundances.

  2. Pressurized groundwater outflow experiments and numerical modeling for outflow channels on Mars

    NASA Astrophysics Data System (ADS)

    Marra, Wouter A.; Hauber, Ernst; McLelland, Stuart J.; Murphy, Brendan J.; Parsons, Daniel R.; Conway, Susan J.; Roda, Manuel; Govers, Rob; Kleinhans, Maarten G.

    2014-12-01

    The landscape of Mars shows incised channels that often appear abruptly in the landscape, suggesting a groundwater source. However, groundwater outflow processes are unable to explain the reconstructed peak discharges of the largest outflow channels based on their morphology. Therefore, there is a disconnect between groundwater outflow processes and the resulting morphology. Using a combined approach with experiments and numerical modeling, we examine outflow processes that result from pressurized groundwater. We use a large sandbox flume, where we apply a range of groundwater pressures at the base of a layer of sediment. Our experiments show that different pressures result in distinct outflow processes and resulting morphologies. Low groundwater pressure results in seepage, forming a shallow surface lake and a channel when the lake overflows. At intermediate groundwater pressures, fissures form and groundwater flows out more rapidly. At even higher pressures, the groundwater initially collects in a subsurface reservoir that grows due to flexural deformation of the surface. When this reservoir collapses, a large volume of water is released to the surface. We numerically model the ability of these processes to produce floods on Mars and compare the results to discharge estimates based on previous morphological studies. We show that groundwater seepage and fissure outflow are insufficient to explain the formation of large outflow channels from a single event. Instead, formation of a flexure-induced subsurface reservoir and subsequent collapse generates large floods that can explain the observed morphologies of the largest outflow channels on Mars and their source areas.

  3. SPECTROPOLARIMETRY OF RADIO-SELECTED BROAD ABSORPTION LINE QUASARS

    SciTech Connect

    DiPompeo, M. A.; Brotherton, M. S.; Becker, R. H.; Gregg, M. D.; Tran, H. D.; White, R. L.; Laurent-Muehleisen, S. A.

    2010-07-15

    We report spectropolarimetry of 30 radio-selected broad absorption line (BAL) quasars with the Keck Observatory, 25 from the sample of Becker et al. Both high- and low-ionization BAL quasars are represented, with redshifts ranging from 0.5 to 2.5. The spectropolarimetric properties of radio-selected BAL quasars are very similar to those of radio-quiet BAL quasars: a sizeable fraction (20%) shows large continuum polarization (2%-10%) usually rising toward short wavelengths; emission lines are typically less polarized than the continuum; and absorption line troughs often show large polarization jumps. There are no significant correlations between polarization properties and radio properties, including those indicative of system orientation, suggesting that BAL quasars are not simply normal quasars seen from an edge-on perspective.

  4. Spectral Properties of X-ray-Emitting Quasars

    NASA Astrophysics Data System (ADS)

    Morgan, W. A., Jr.

    1996-12-01

    I present spectral indices obtained from 112 X-ray-selected and fully optically-identified quasars in four sky fields in the southern hemisphere, detected by the Rosat Position Sensitive Proportional Counters. These fields were originally studied by Boyle et al. (1990) for the ultraviolet-excess properties of objects in the fields; only 47 of the quasars in the field were listed in Boyle et al. I determine the quasars' power-law spectral index alpha_E with three different methods: spectral ``stacking'', hardness ratios, and direct fitting. Both spectral stacking and the hardness ratio methods are used because several of the quasars were too dim to reliably calculate spectral indices individually. The spectral stacking method, which involves co-adding quasar spectra energy bins, shows a definite change in quasar spectral index with redshift.

  5. Northwestern Tharsis Latent Outflow Activity Mars

    NASA Technical Reports Server (NTRS)

    Dohm, J. M.; Anderson, R. C.; Baker, V. R.; Ferris, J. C.; Hare, T. M.; Strom, R. G.; Rudd, L.; Rice, J. W., Jr.; Scott, D. H.

    2000-01-01

    Previously defined outflow channels, which are indicated by relict landforms similar to those observed on Earth, signify ancient catastrophic flood events on Mars. These conspicuous geomorphic features are some of the most remarkable yet profound discoveries made by geologists to date. These outflow channels, which debouched tremendous volumes of water into topographic lows such as Chryse, Utopia, Elysium, and Hellas Planitiae, may represent the beginning of warmer and wetter climatic periods unlike the present-day cold and dry Mars. In addition to the previously identified outflow channels, observations permitted by the newly acquired Mars Orbiter Laser Altimeter (MOLA) data have revealed a system of gigantic valleys, referred to as the northwestern slope valleys (NSV), that are located to the northwest of a huge shield volcano, Arsia Mons, western hemisphere of Mars. These features generally correspond spatially to gravity lows similar to the easternmost, circum-Chryse outflow channel systems. Geologic investigations of the Tharsis region suggest that the large valley system pre-dates the construction of Arsia Mons and its extensive associated lava flows of mainly Late Hesperian and Amazonian age and coincides stratigraphically with the early development of the circum-Chryse outflow channel systems that debouch into Chryse Planitia. This newly identified system, the NSV, potentially signifies the largest flood event(s) ever recorded for the solar system. Additional information is contained in original extended abstract.

  6. Imaging and Simulations of CO Molecular Outflows

    NASA Astrophysics Data System (ADS)

    Lee, Chin-Fei; Mundy, Lee; Stone, James; Ostriker, Eve

    1999-10-01

    We have mapped the CO J=1-0 emission from molecular outflows associated with 10 young stellar systems of class 0 to class II with BIMA interferometry array and FCRAO single dish. Many of our outflows are closely related to jet like and bow shock structures detected in H2 or Halpha emission. The CO emission generally forms a hollowed structure around the jet and bow shock structures. Most of the CO outflows show a nested shell structure with velocity increasing with the distance from the star, but the detailed behavior can vary widely. Here, we presents five outflows to illustrate the different kinematics. Two of them are well described by a single parabolic shell with a Hubble law velocity, consistent with a wide-angle wind driven model. Two of them seem better explained with a jet-driven bow shock model, with a broad range of velocity near the bow shock. The last one appears to have elements of both models. To better understand the observations and test specific outflow models, we are performing a number of numerical simulations. This poster presents simulations of a jet propagating into a stratified ambient material. In these simulations, the jet-driven bow shock forms a thin cylindrical shell of swept-up gas around the jet, with the velocity vector of the material perpendicular to the shell surface. The simulations produce a wide range of velocity observed near the bow shock, but fail to produce the other CO kinematics in our observations.

  7. Galaxy ecosystems: gas contents, inflows and outflows

    NASA Astrophysics Data System (ADS)

    Lu, Zhankui; Mo, H. J.; Lu, Yu

    2015-06-01

    We use a set of observational data for galaxy cold gas mass fraction and gas phase metallicity to constrain the content, inflow and outflow of gas in central galaxies hosted by haloes with masses between 1011 and 1012 M⊙. The gas contents in high-redshift galaxies are obtained by combining the empirical star formation histories and star formation models that relate star formation rate with the cold gas mass in galaxies. We find that the total baryon mass in low-mass galaxies is always much less than the universal baryon mass fraction since z = 2, regardless of star formation model adopted. The data for the evolution of the gas phase metallicity require net metal outflow at z ≲ 2, and the metal loading factor is constrained to be about 0.01, or about 60 per cent of the metal yield. Based on the assumption that galactic outflow is more enriched in metal than both the interstellar medium and the material ejected at earlier epochs, we are able to put stringent constraints on the upper limits for both the net accretion rate and the net mass outflow rate. The upper limits strongly suggest that the evolution of the gas phase metallicity and gas mass fraction for low-mass galaxies at z < 2 is not compatible with strong outflow. We speculate that the low star formation efficiency of low-mass galaxies is owing to some preventative processes that prevent gas from accreting into galaxies in the first place.

  8. The `Green Bean' Galaxy SDSS J224024.1-092748: unravelling the emission signature of a quasar ionization echo

    NASA Astrophysics Data System (ADS)

    Davies, Rebecca L.; Schirmer, Mischa; Turner, James E. H.

    2015-05-01

    `Green Bean' galaxies (GBs) are the most [O III]-luminous type-2 active galactic nuclei (AGN) at z ˜ 0.3. However, their infrared luminosities reveal AGN in very low activity states, indicating that their gas reservoirs must be ionized by photons from a recent high activity episode - we are observing quasar ionization echoes. We use integral field spectroscopy from the Gemini Multi-Object Spectrograph to analyse the 3D kinematics, ionization state, temperature and density of ionized gas in the GB SDSS J224024.1-092748. We model the emission-line spectrum of each spaxel as a superposition of up to three Gaussian components and analyse the physical properties of each component individually. Two narrow components, tracing the velocity fields of the disc and an ionized gas cloud, are superimposed over the majority of the galaxy. Fast shocks produce hot (Te ≥ 20 000 K), dense (ne ≥ 100 cm- 3), turbulent (σ ≥ 600 km s- 1), [O III]-bright regions with enhanced [N II]/Hα and [S II]/Hα ratios. The most prominent such spot is consistent with a radio jet shock-heating the interstellar medium. However, the AGN is still responsible for ≳ 82 per cent of the galaxy's total [O III] luminosity, strengthening the case for previous quasar activity. The ionized gas cloud has a strong kinematic link to the central AGN and is corotating with the main body of the galaxy, suggesting that it may be the remnant of a quasar-driven outflow. Our analysis of J224024.1-092748 indicates that GBs provide a unique fossil record of the transformation from the most luminous quasars to weak AGN.

  9. Multi-wavelength Monitoring of Lensed Quasars: Deciphering Quasar Structure at Micro-arcseconds Scales

    NASA Astrophysics Data System (ADS)

    Mosquera, Ana; Morgan, Christopher W.; Kochanek, Christopher S.; Dai, Xinyu; Chen, Bin; MacLeod, Chelsea Louise; Chartas, George

    2016-01-01

    Microlensing in multiply imaged gravitationally lensed quasars provides us with a unique tool to zoom in on the structure of AGN and explore their physics in more detail. Microlensing magnification, caused primarily by stars and white dwarfs close to the line of sight towards the lensed quasar images, is seen as uncorrelated flux variations due to the relative motions of the quasar, the lens, its stars, and the observer, and it depends on the structural and dynamical properties of the source and the lens. Since the magnification depends upon the size of the source, we can use microlensing to measure the size of quasar emission regions. In essence, the amplitude of the microlensing variability encodes the source size, with smaller sources showing larger variability amplitudes. Using state of the art microlensing techniques, our team has performed pioneering research in the field based on multi-wavelength space and ground-based observations. Among the most remarkable results, using Chandra observations we have set the first quantitative constraints on the sizes of the X-ray emission regions of quasars. In this work l briefly describe the methodology, the results from our previous multi-wavelength monitoring programs, and the next frontier of exploring the dependence of the structure of the X-ray emission regions on black hole mass and X-ray energy.

  10. BINARY QUASARS AT HIGH REDSHIFT. I. 24 NEW QUASAR PAIRS AT z {approx} 3-4

    SciTech Connect

    Hennawi, Joseph F.; Myers, Adam D.; Shen, Yue; Strauss, Michael A.; Djorgovski, S. G.; Glikman, Eilat; Mahabal, Ashish; Fan Xiaohui; Martin, Crystal L.; Richards, Gordon T.; Schneider, Donald P.; Shankar, Francesco

    2010-08-20

    The clustering of quasars on small scales yields fundamental constraints on models of quasar evolution and the buildup of supermassive black holes. This paper describes the first systematic survey to discover high-redshift binary quasars. Using color-selection and photometric redshift techniques, we searched 8142 deg{sup 2} of Sloan Digital Sky Survey imaging data for binary quasar candidates, and confirmed them with follow-up spectroscopy. Our sample of 27 high-redshift binaries (24 of them new discoveries) at redshifts 2.9 < z < 4.3 with proper transverse separations 10 kpc < R{sub perpendicular} < 650 kpc increases the number of such objects known by an order of magnitude. Eight members of this sample are very close pairs with R{sub perpendicular} < 100 kpc, and of these close systems four are at z>3.5. The completeness and efficiency of our well-defined selection algorithm are quantified using simulated photometry and we find that our sample is {approx}50% complete. Our companion paper uses this knowledge to make the first measurement of the small-scale clustering (R < 1 h {sup -1} Mpc comoving) of high-redshift quasars. High-redshift binaries constitute exponentially rare coincidences of two extreme (M {approx}> 10{sup 9} M {sub sun}) supermassive black holes. At z {approx} 4, there is about one close binary per 10 Gpc{sup 3}, thus these could be the highest sigma peaks, the analogs of superclusters, in the early universe.

  11. Double Lobed Radio Quasars from the Sloan Digital Sky Survey

    SciTech Connect

    de Vries, W H; Becker, R H; White, R L

    2005-11-10

    We have combined a sample of 44 984 quasars, selected from the Sloan Digital Sky Survey (SDSS) Data Release 3, with the FIRST radio survey. Using a novel technique where the optical quasar position is matched to the complete radio environment within 450'', we are able to characterize the radio morphological make-up of what is essentially an optically selected quasar sample, regardless of whether the quasar (nucleus) itself has been detected in the radio. About 10% of the quasar population have radio cores brighter than 0.75 mJy at 1.4 GHz, and 1.7% have double lobed FR2-like radio morphologies. About 75% of the FR2 sources have a radio core (> 0.75mJy). A significant fraction ({approx}40%) of the FR2 quasars are bent by more than 10 degrees, indicating either interactions of the radio plasma with the ICM or IGM. We found no evidence for correlations with redshift among our FR2 quasars: radio lobe flux densities and radio source diameters of the quasars have similar distributions at low (mean 0.77) and high (mean 2.09) redshifts. Using a smaller high reliability FR2 sample of 422 quasars and two comparison samples of radio-quiet and non-FR2 radio-loud quasars, matched in their redshift distributions, we constructed composite optical spectra from the SDSS spectroscopic data. Based on these spectra we can conclude that the FR2 quasars have stronger high-ionization emission lines compared to both the radio quiet and non-FR2 radio loud sources. This is consistent with the notion that the emission lines are brightened by ongoing shock ionization of ambient gas in the quasar host as the radio source expands.

  12. Zooplankton in the Arctic outflow

    NASA Astrophysics Data System (ADS)

    Soloviev, K. A.; Dritz, A. V.; Nikishina, A. B.

    2009-04-01

    Climate changes in the Arctic cause the changes in the current system that may have cascading effect on the structure of plankton community and consequently on the interlinked and delicately balanced food web. Zooplankton species are by definition incapable to perform horizontal moving. Their transport is connected with flowing water. There are zooplankton species specific for the definite water masses and they can be used as markers for the different currents. That allows us to consider zooplankton community composition as a result of water mixing in the studied area. Little is known however about the mechanisms by which spatial and temporal variability in advection affect dynamics of local populations. Ice conditions are also very important in the function of pelagic communities. Melting time is the trigger to all "plankton blooming" processes, and the duration of ice-free conditions determines the food web development in the future. Fram Strait is one of the key regions for the Arctic: the cold water outflow comes through it with the East Greenland Current and meets warm Atlantic water, the West Spitsbergen Current, producing complicated hydrological situation. During 2007 and 2008 we investigated the structure functional characteristics of zooplankton community in the Fram Strait region onboard KV "Svalbard" (April 2007, April and May 2008) and RV "Jan Mayen" (May 2007, August 2008). This study was conducted in frame of iAOOS Norway project "Closing the loop", which, in turn, was a part of IPY. During this cruises multidisciplinary investigations were performed, including sea-ice observations, CTD and ADCP profiling, carbon flux, nutrients and primary production measurements, phytoplankton sampling. Zooplankton was collected with the Hydro-Bios WP2 net and MultiNet Zooplankton Sampler, (mouth area 0.25 m2, mesh size 180 um).Samples were taken from the depth strata of 2000-1500, 1500-1000, 1000-500,500-200, 200-100, 100-60, 60-30, 30-0 m. Gut fluorescence

  13. Observations of Protostellar Outflow Feedback in Clustered Star Formation

    NASA Astrophysics Data System (ADS)

    Nakamura, F.

    2016-05-01

    We discuss the role of protostellar outflow feedback in clustered star formation using the observational data of recent molecular outflow surveys toward nearby cluster-forming clumps. We found that for almost all clumps, the outflow momentum injection rate is significantly larger than the turbulence dissipation rate. Therefore, the outflow feedback is likely to maintain supersonic turbulence in the clumps. For less massive clumps such as B59, L1551, and L1641N, the outflow kinetic energy is comparable to the clump gravitational energy. In such clumps, the outflow feedback probably affects significantly the clump dynamics. On the other hand, for clumps with masses larger than about 200 M⊙, the outflow kinetic energy is significantly smaller than the clump gravitational energy. Since the majority of stars form in such clumps, we conclude that outflow feedback cannot destroy the whole parent clump. These characteristics of the outflow feedback support the scenario of slow star formation.

  14. THE PHYSICAL CONDITIONS OF THE INTRINSIC N V NARROW ABSORPTION LINE SYSTEMS OF THREE QUASARS

    SciTech Connect

    Wu Jian; Charlton, Jane C.; Misawa, Toru; Eracleous, Michael; Ganguly, Rajib E-mail: misawatr@shinshu-u.ac.j

    2010-10-20

    We employ detailed photoionization models to infer the physical conditions of intrinsic narrow absorption line systems found in high-resolution spectra of three quasars at z = 2.6-3.0. We focus on a family of intrinsic absorbers characterized by N V lines that are strong relative to the Ly{alpha} lines. The inferred physical conditions are similar for the three intrinsic N V absorbers, with metallicities greater than 10 times the solar value (assuming a solar abundance pattern), and with high ionization parameters (log U {approx} 0). Thus, we conclude that the unusual strength of the N V lines results from a combination of partial coverage, a high ionization state, and high metallicity. We consider whether dilution of the absorption lines by flux from the broad emission line region can lead us to overestimate the metallicities and we find that this is an unlikely possibility. The high abundances that we infer are not surprising in the context of scenarios in which metal enrichment takes place very early on in massive galaxies. We estimate that the mass outflow rate in the absorbing gas (which is likely to have a filamentary structure) is less than a few M{sub sun} yr{sup -1} under the most optimistic assumptions, although it may be embedded in a much hotter, more massive outflow.

  15. Broad-band short term X-ray spectral variability of the quasar PDS 456

    NASA Astrophysics Data System (ADS)

    Matzeu, G.; Reeves, J.; Nardini, E.; Braito, V.; Costa, M.; Tombesi, F.

    2015-07-01

    We present an analysis of a recent 500 ks Suzaku observation, carried out in 2013, of the nearby (z=0.184) luminous (L_{bol}˜10^{47} erg s^{-1}) quasar PDS 456 in which the X-ray flux was unusually low. Short term X-ray spectral variability has been detected, which may be caused by two variable coverers of column density log (N_{H,1}/cm^{-2})=22.3±0.1 and log (N_{H,2}/cm(-2) )=23.2±0.1 We find that the partial covering requires an outflow velocity of ˜0.25 c, coincident with the velocity of the highly ionised outflow at the 99.9 % confidence level. Therefore the partial covering clouds could be the denser clumpy part of an inhomogeneous wind. An obscuration event occurs 1250 ks into the observation, where the spectrum becomes totally opaque at Fe K. This implies that the size of the absorber and likewise the X-ray emitter, to be less than 20 Rg. We also analyse the flaring behaviour in the lightcurve. The behaviour of the soft and hard X-ray flux, suggested a corona characterised by an extended "warm" region of ˜20 Rg in size combined with more compact regions of "hot" electrons of ˜8 Rg in size.

  16. Quasars in the MAMBO blank field survey

    NASA Astrophysics Data System (ADS)

    Voss, H.; Bertoldi, F.; Carilli, C.; Owen, F. N.; Lutz, D.; Holdaway, M.; Ledlow, M.; Menten, K. M.

    2006-03-01

    Our MAMBO 1.2 mm blank field imaging survey of ~0.75 sqd has uncovered four unusually bright sources, with flux densities between 10 and 90 mJy, all located in the Abell 2125 field. The three brightest are flat spectrum radio sources with bright optical and X-ray counterparts. Their mm and radio flux densities are variable on timescales of months. Their X-ray luminosities classify them as quasars. The faintest of the four mm bright sources appears to be a bright, radio-quiet starburst at z˜3, similar to the sources seen at lower flux densities in the MAMBO and SCUBA surveys. It may also host a mildly obscured AGN of quasar-like X-ray luminosity. The three non-thermal mm sources imply an areal density of flat spectrum radio sources higher by at least 7 compared with that expected from an extrapolation of the lower frequency radio number counts.

  17. The evolution of the quasar continuum

    NASA Technical Reports Server (NTRS)

    Elvis, M.

    1992-01-01

    We now have in hand a large data base of Roentgen Satellite (ROSAT), optical, and IR complementary data. We are in the process of obtaining a large amount of the International Ultraviolet Explorer (IUE) data for the same quasar sample. For our complementary sample at high redshifts, where the UV was redshifted into the optical, we have just had approved large amounts of observing time to cover the quasar continuum in the near-IR using the new Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) array spectrographs. Ten micron, optical, and VLA radio, data also have approved time. An ISO US key program was approved to extend this work into the far-IR, and the launch of ASTRO-D (early in 1993) promises to extend it to higher energy X-rays.

  18. Microlensing of quasar ultraviolet iron emission

    SciTech Connect

    Guerras, E.; Mediavilla, E.; Kochanek, C. S.; Muñoz, J. A.; Falco, E.; Motta, V.; Rojas, K.

    2013-12-01

    We measure the differential microlensing of the UV Fe II and Fe III emission line blends between 14 quasar image pairs in 13 gravitational lenses. We find that the UV iron emission is strongly microlensed in four cases with amplitudes comparable to that of the continuum. Statistically modeling the magnifications, we infer a typical size of r{sub s}∼4√(M/M{sub ⊙}) light-days for the Fe line-emitting regions, which is comparable to the size of the region generating the UV continuum (∼3-7 light-days). This may indicate that a significant part of the UV Fe II and Fe III emission originates in the quasar accretion disk.

  19. Mining for Dust in Type 1 Quasars

    NASA Astrophysics Data System (ADS)

    Krawczyk, Coleman M.; Richards, Gordon T.; Gallagher, S. C.; Leighly, Karen M.; Hewett, Paul C.; Ross, Nicholas P.; Hall, P. B.

    2015-06-01

    We explore the extinction/reddening of ˜35,000 uniformly selected quasars with 0\\lt z≤slant 5.3 in order to better understand their intrinsic optical/ultraviolet (UV) spectral energy distributions. Using rest-frame optical-UV photometry taken from the Sloan Digital Sky Survey’s (SDSS) 7th data release, cross-matched to WISE in the mid-infrared, 2MASS and UKIDSS in the near-infrared, and GALEX in the UV, we isolate outliers in the color distribution and find them well described by an SMC-like reddening law. A hierarchical Bayesian model with a Markov Chain Monte Carlo sampling method was used to find distributions of power law indices and E(B-V) consistent with both the broad absorption line (BAL) and non-BAL samples. We find that, of the ugriz color-selected type 1 quasars in SDSS, 2.5% (13%) of the non-BAL (BAL) sample are consistent with E(B-V)\\gt 0.1 and 0.1% (1.3%) with E(B-V)\\gt 0.2. Simulations show both populations of quasars are intrinsically bluer than the mean composite, with a mean spectral index ({{α }λ }) of -1.79 (-1.83). The emission and absorption-line properties of both samples reveal that quasars with intrinsically red continua have narrower Balmer lines and stronger high-ionization emission lines, the latter indicating a harder continuum in the extreme-UV and the former pointing to differences in black hole mass and/or orientation.

  20. Inverse compton effect: some consequences for quasars.

    PubMed

    Pfleiderer, J; Grewing, M

    1966-12-16

    The inverse Compton effect can transform enough energy of relativistic electrons into radiation so that an upper limit to the mean energy of the electrons is set. In quasars, the limit is too small to allow the production of any appreciable amount of synchrotron or inverse Compton radiation, unless either the distances are not cosmological or the lifetimes of the relativistic electrons are extremely short, of the order of hours.

  1. The importance of warm, AGN-driven outflows in the nuclear regions of nearby ULIRGs

    NASA Astrophysics Data System (ADS)

    Rodríguez Zaurín, J.; Tadhunter, C. N.; Rose, M.; Holt, J.

    2013-06-01

    We present an optical spectroscopic study of a 90 per cent complete sample of nearby ULIRGs (z < 0.175) with optical Seyfert nuclei, with the aim of investigating the nature of the near-nuclear (r ≲ 3.5 kpc) warm gas outflows. A high proportion (94 per cent) of our sample show disturbed emission line kinematics in the form of broad (FWHM > 500 km s-1) and/or strongly blueshifted (ΔV < -150 km s-1) emission line components. This proportion is significantly higher than found in a comparison sample of nearby ultraluminous infrared galaxies (ULIRGs) that lack optical Seyfert nuclei (19 per cent). We also find evidence that the emission line kinematics of the Sy-ULIRGs are more highly disturbed than those of samples of non-ULIRG Seyferts and Palomar-Green quasars in the sense that, on average, their [O III] λλ5007, 4959 emission lines are broader and more asymmetric. The Sy-ULIRG sample encompasses a wide diversity of emission line profiles. In most individual objects, we are able to fit the profiles of all the emission lines of different ionization with a kinematic model derived from the strong [O III] λλ4959, 5007 lines, using between two and five Gaussian components. From these fits, we derive diagnostic line ratios that are used to investigate the ionization mechanisms for the different kinematic components. We show that, in general, the line ratios are consistent with gas of supersolar abundance photoionized by a combination of AGN and starburst activity, with an increasing contribution from the AGN with increasing FWHM of the individual kinematic components, and the AGN contribution dominating for the broadest components. However, shock ionization cannot be ruled out in some cases. Our derived upper limits on the mass outflows rates and kinetic powers of the emission line outflows show that they can be as energetically significant as the neutral and molecular outflows in ULIRGs - consistent with the requirements of the hydrodynamic simulations that include

  2. Outflows from Accretion Disks around Compact Objects

    NASA Astrophysics Data System (ADS)

    Jiao, Cheng-Liang; Wu, Xue-Bing

    2013-02-01

    We solve the set of hydrodynamic equations for accretion disks in the spherical coordinates (rθφ) to obtain the explicit structure along the θ direction. The results display thinner, quasi-Keplerian disks for Shakura-Sunyaev Disks (SSDs) and thicker, sub-Keplerian disks for Advection Dominated Accretion Flows (ADAFs) and slim disks, which are consistent with previous popular analytical models, while an inflow region and an outflow region always exist, which supports the results of some recent numerical simulation works. Our results indicate that the outflows should be common in various accretion disks and stronger in slim disks and ADAFs.

  3. The Search for Molecular Outflows in Local Volume AGNs with Herschel-PACS

    NASA Astrophysics Data System (ADS)

    Stone, M.; Veilleux, S.; Meléndez, M.; Sturm, E.; Graciá-Carpio, J.; González-Alfonso, E.

    2016-08-01

    We present the results from a systematic search for galactic-scale, molecular (OH 119 μm) outflows in a sample of 52 Local Volume (d\\lt 50 Mpc) Burst Alert Telescope detected active galactic nuclei (BAT AGNs) with Herschel-PACS. We combine the results from our analysis of the BAT AGNs with the published Herschel/PACS data of 43 nearby (z\\lt 0.3) galaxy mergers, mostly ultra-luminous infrared galaxies (ULIRGs) and QSOs. The objects in our sample of BAT AGNs have, on average, ˜ 10{--}100 times lower AGN luminosities, star formation rates, and stellar masses than those of the ULIRG and QSO samples. OH 119 μm is detected in 42 of our BAT AGN targets. Evidence for molecular outflows (i.e., OH absorption profiles with median velocities more blueshifted than -50 km s-1 and/or blueshifted wings with 84% velocities less than -300 km s-1) is seen in only four BAT AGNs (NGC 7479 is the most convincing case). Evidence for molecular inflows (i.e., OH absorption profiles with median velocities more redshifted than 50 km s-1) is seen in seven objects, although an inverted P-Cygni profile is detected unambiguously in only one object (Circinus). Our data show that both the starburst and AGN contribute to driving OH outflows, but the fastest OH winds require AGNs with quasar-like luminosities. We also confirm that the total absorption strength of OH 119 μm is a good proxy for dust optical depth as it correlates strongly with the 9.7 μm silicate absorption feature, a measure of obscuration originating in both the nuclear torus and host galaxy disk. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  4. The Search for Molecular Outflows in Local Volume AGNs with Herschel-PACS

    NASA Astrophysics Data System (ADS)

    Stone, M.; Veilleux, S.; Meléndez, M.; Sturm, E.; Graciá-Carpio, J.; González-Alfonso, E.

    2016-08-01

    We present the results from a systematic search for galactic-scale, molecular (OH 119 μm) outflows in a sample of 52 Local Volume (d\\lt 50 Mpc) Burst Alert Telescope detected active galactic nuclei (BAT AGNs) with Herschel-PACS. We combine the results from our analysis of the BAT AGNs with the published Herschel/PACS data of 43 nearby (z\\lt 0.3) galaxy mergers, mostly ultra-luminous infrared galaxies (ULIRGs) and QSOs. The objects in our sample of BAT AGNs have, on average, ˜ 10{--}100 times lower AGN luminosities, star formation rates, and stellar masses than those of the ULIRG and QSO samples. OH 119 μm is detected in 42 of our BAT AGN targets. Evidence for molecular outflows (i.e., OH absorption profiles with median velocities more blueshifted than ‑50 km s‑1 and/or blueshifted wings with 84% velocities less than ‑300 km s‑1) is seen in only four BAT AGNs (NGC 7479 is the most convincing case). Evidence for molecular inflows (i.e., OH absorption profiles with median velocities more redshifted than 50 km s‑1) is seen in seven objects, although an inverted P-Cygni profile is detected unambiguously in only one object (Circinus). Our data show that both the starburst and AGN contribute to driving OH outflows, but the fastest OH winds require AGNs with quasar-like luminosities. We also confirm that the total absorption strength of OH 119 μm is a good proxy for dust optical depth as it correlates strongly with the 9.7 μm silicate absorption feature, a measure of obscuration originating in both the nuclear torus and host galaxy disk. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  5. Incidence of strong Mg II absorbers towards different types of quasars

    NASA Astrophysics Data System (ADS)

    Joshi, Ravi; Chand, Hum; Gopal-Krishna

    2013-10-01

    We report the first comparative study of strong Mg II absorbers (Wr ≥ 1.0 Å) seen towards radio-loud quasars of core-dominated (CDQ) and lobe-dominated (LDQ) types and normal quasars (QSOs). The CDQ and LDQ samples were derived from the Sloan Digital Sky Survey Data Release 7 after excluding known `broad-absorption-line' quasars and blazars. The Mg II associated absorption systems having a velocity offset v < 5000 km s-1 from the systemic velocity of the background quasar were also excluded. Existing spectroscopic data for redshift-matched sightlines of 3975 CDQs and 1583 LDQs, covering an emission redshift range 0.39-4.87, were analysed and 864 strong Mg II absorbers were found, covering the redshift range 0.45-2.17. The conclusions reached using this well-defined large data set of strong Mg II absorbers are (i) the number density, dN/dz, towards CDQs shows a small, marginally significant excess (˜9 per cent at 1.5σ significance) over the estimate available for QSOs; (ii) in the redshift space, this difference is reflected in terms of a 1.6σ excess of dN/dz over the QSOs, within the narrow redshift interval 1.2-1.8; (iii) the dN/dβ distribution (with β = v/c) for CDQs shows a significant excess (at 3.75σ level) over the distribution found for a redshift- and luminosity-matched sample of QSOs, at β in the range 0.05-0.1. This leads us to infer that a significant fraction of strong Mg II absorption systems seen in this offset velocity range are probably associated with the CDQs and might be accelerated into the line of sight by their powerful jets and/or due to the accretion-disc outflows close to our direction. Support to this scenario comes from a consistency check in which we consider only the spectral range corresponding to β > 0.2. The computed redshift distribution for strong Mg II absorbers towards CDQs now shows excellent agreement with that known for QSOs, as indeed is expected for purely intervening absorption systems. Thus, it appears that for

  6. Photometric Monitoring of Quasars with Kepler

    NASA Astrophysics Data System (ADS)

    Unwin, Stephen C.; Wehrle, A. E.; Wiita, P. J.; Revalski, M.; Silano, D.; Sprague, D.; Di Lorenzo, P.

    2013-01-01

    We have observed the photometric variability of four flat-spectrum radio quasars, and one radio galaxy (Cyg A) with Kepler, since mid-2010. Kepler’s ability to observe uninterrupted for very extended durations provides a unique opportunity to obtain very long time sequences on active galactic nuclei, something that is hard to do even with dedicated ground-based telescope networks. It allows us to examine these light curves for variability on timescales from hours to weeks, and to probe the physical processes involved in accretion around the central black hole and the organization of some of that energy into jets that ultimately power double-lobed radio sources. Kepler was designed to detect exoplanet transits of stars, and the data analysis pipeline is highly optimized for that purpose. We cannot use the standard analysis tools for the quasi-random variability in quasars, so we re-analysed the raw data, and overcame some of the challenges in calibrating these light curves. We briefly discuss some of the issues in producing calibrated light curves for long timescales. For each quasar we computed power spectra, and found power-law slopes of around -2 for most. Although sensitive to quasi-periodic variations, we did not find any convincing evidence for periodicity in any of our targets. This research was carried out, in part, at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Copyright 2012. California Institute of Technology. Government sponsorship acknowledged.

  7. Episodic High-velocity Outflows from V899 Mon: A Constraint On The Outflow Mechanisms

    NASA Astrophysics Data System (ADS)

    Ninan, J. P.; Ojha, D. K.; Philip, N. S.

    2016-07-01

    We report the detection of large variations in the outflow wind velocity from a young eruptive star, V899 Mon, during its ongoing high accretion outburst phase. Such large variations in the outflow velocity (from -722 to -425 km s-1) have never been reported previously in this family of objects. Our continuous monitoring of this source shows that the multi-component, clumpy, and episodic high velocity outflows are stable in the timescale of a few days, and vary over the timescale of a few weeks to months. We detect significant decoupling in the instantaneous outflow strength to accretion rate. From the comparison of various possible outflow mechanisms in magnetospheric accretion of young stellar objects, we conclude magnetically driven polar winds to be the most consistent mechanism for the outflows seen in V899 Mon. The large scale fluctuations in outflow over the short period makes V899 Mon the most ideal source to constrain various magnetohydrodynamics simulations of magnetospheric accretion. Based on observations made with the Southern African Large Telescope (SALT).

  8. Helium Reionization Simulations. I. Modeling Quasars as Radiation Sources

    NASA Astrophysics Data System (ADS)

    La Plante, Paul; Trac, Hy

    2016-09-01

    We introduce a new project to understand helium reionization using fully coupled N-body, hydrodynamics, and radiative transfer simulations. This project aims to capture correctly the thermal history of the intergalactic medium as a result of reionization and make predictions about the Lyα forest and baryon temperature-density relation. The dominant sources of radiation for this transition are quasars, so modeling the source population accurately is very important for making reliable predictions. In this first paper, we present a new method for populating dark matter halos with quasars. Our set of quasar models includes two different light curves, a lightbulb (simple on/off) and symmetric exponential model, and luminosity-dependent quasar lifetimes. Our method self-consistently reproduces an input quasar luminosity function given a halo catalog from an N-body simulation, and propagates quasars through the merger history of halo hosts. After calibrating quasar clustering using measurements from the Baryon Oscillation Spectroscopic Survey, we find that the characteristic mass of quasar hosts is {M}h˜ 2.5× {10}12 {h}-1 {M}⊙ for the lightbulb model, and {M}h˜ 2.3× {10}12 {h}-1 {M}⊙ for the exponential model. In the latter model, the peak quasar luminosity for a given halo mass is larger than that in the former, typically by a factor of 1.5-2. The effective lifetime for quasars in the lightbulb model is 59 Myr, and in the exponential case, the effective time constant is about 15 Myr. We include semi-analytic calculations of helium reionization, and discuss how to include these quasars as sources of ionizing radiation for full hydrodynamics with radiative transfer simulations in order to study helium reionization.

  9. Seeking the epoch of maximum luminosity for dusty quasars

    SciTech Connect

    Vardanyan, Valeri; Weedman, Daniel; Sargsyan, Lusine E-mail: dweedman@isc.astro.cornell.edu

    2014-08-01

    Infrared luminosities νL{sub ν}(7.8 μm) arising from dust reradiation are determined for Sloan Digital Sky Survey (SDSS) quasars with 1.4 quasar Gpc{sup –3} having νL{sub ν}(7.8 μm) > 10{sup 46.6} erg s{sup –1} for all 2 quasars first reached their maximum luminosity has not yet been identified at any redshift below 5. The most ultraviolet luminous quasars, defined by rest frame νL{sub ν}(0.25 μm), have the largest values of the ratio νL{sub ν}(0.25 μm)/νL{sub ν}(7.8 μm) with a maximum ratio at z = 2.9. From these results, we conclude that the quasars most luminous in the ultraviolet have the smallest dust content and appear luminous primarily because of lessened extinction. Observed ultraviolet/infrared luminosity ratios are used to define 'obscured' quasars as those having >5 mag of ultraviolet extinction. We present a new summary of obscured quasars discovered with the Spitzer Infrared Spectrograph and determine the infrared luminosity function of these obscured quasars at z ∼ 2.1. This is compared with infrared luminosity functions of optically discovered, unobscured quasars in the SDSS and in the AGN and Galaxy Evolution Survey. The comparison indicates comparable numbers of obscured and unobscured quasars at z ∼ 2.1 with a possible excess of obscured quasars at fainter luminosities.

  10. Seeking the Epoch of Maximum Luminosity for Dusty Quasars

    NASA Astrophysics Data System (ADS)

    Vardanyan, Valeri; Weedman, Daniel; Sargsyan, Lusine

    2014-08-01

    Infrared luminosities νL ν(7.8 μm) arising from dust reradiation are determined for Sloan Digital Sky Survey (SDSS) quasars with 1.4 ~ 3 with maximum luminosity νL ν(7.8 μm) >~ 1047 erg s-1 luminosity functions show one quasar Gpc-3 having νL ν(7.8 μm) > 1046.6 erg s-1 for all 2 quasars first reached their maximum luminosity has not yet been identified at any redshift below 5. The most ultraviolet luminous quasars, defined by rest frame νL ν(0.25 μm), have the largest values of the ratio νL ν(0.25 μm)/νL ν(7.8 μm) with a maximum ratio at z = 2.9. From these results, we conclude that the quasars most luminous in the ultraviolet have the smallest dust content and appear luminous primarily because of lessened extinction. Observed ultraviolet/infrared luminosity ratios are used to define "obscured" quasars as those having >5 mag of ultraviolet extinction. We present a new summary of obscured quasars discovered with the Spitzer Infrared Spectrograph and determine the infrared luminosity function of these obscured quasars at z ~ 2.1. This is compared with infrared luminosity functions of optically discovered, unobscured quasars in the SDSS and in the AGN and Galaxy Evolution Survey. The comparison indicates comparable numbers of obscured and unobscured quasars at z ~ 2.1 with a possible excess of obscured quasars at fainter luminosities.

  11. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    SciTech Connect

    McGreer, Ian D.; Fan Xiaohui; Jiang Linhua; Richards, Gordon T.; Strauss, Michael A.; Ross, Nicholas P.; White, Martin; Shen Yue; Schneider, Donald P.; Brandt, W. Niel; Myers, Adam D.; DeGraf, Colin; Glikman, Eilat; Ge Jian; Streblyanska, Alina

    2013-05-10

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M{sub 1450} < -26) with Sloan Digital Sky Survey (SDSS) data covering {approx}6000 deg{sup 2}, then extend to lower luminosities (M{sub 1450} < -24) with newly discovered, faint z {approx} 5 quasars selected from 235 deg{sup 2} of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 < z < 5.1 quasars that is highly complete, with 73 spectroscopic identifications out of 92 candidates. Our color selection method is also highly efficient: of the 73 spectra obtained, 71 are high-redshift quasars. These observations reach below the break in the luminosity function (M{sub 1450}{sup *}{approx}-27). The bright-end slope is steep ({beta} {approx}< -4), with a constraint of {beta} < -3.1 at 95% confidence. The break luminosity appears to evolve strongly at high redshift, providing an explanation for the flattening of the bright-end slope reported previously. We find a factor of {approx}2 greater decrease in the number density of luminous quasars (M{sub 1450} < -26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate {approx}30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  12. Helium Reionization Simulations. I. Modeling Quasars as Radiation Sources

    NASA Astrophysics Data System (ADS)

    La Plante, Paul; Trac, Hy

    2016-09-01

    We introduce a new project to understand helium reionization using fully coupled N-body, hydrodynamics, and radiative transfer simulations. This project aims to capture correctly the thermal history of the intergalactic medium as a result of reionization and make predictions about the Lyα forest and baryon temperature–density relation. The dominant sources of radiation for this transition are quasars, so modeling the source population accurately is very important for making reliable predictions. In this first paper, we present a new method for populating dark matter halos with quasars. Our set of quasar models includes two different light curves, a lightbulb (simple on/off) and symmetric exponential model, and luminosity-dependent quasar lifetimes. Our method self-consistently reproduces an input quasar luminosity function given a halo catalog from an N-body simulation, and propagates quasars through the merger history of halo hosts. After calibrating quasar clustering using measurements from the Baryon Oscillation Spectroscopic Survey, we find that the characteristic mass of quasar hosts is {M}h∼ 2.5× {10}12 {h}-1 {M}ȯ for the lightbulb model, and {M}h∼ 2.3× {10}12 {h}-1 {M}ȯ for the exponential model. In the latter model, the peak quasar luminosity for a given halo mass is larger than that in the former, typically by a factor of 1.5–2. The effective lifetime for quasars in the lightbulb model is 59 Myr, and in the exponential case, the effective time constant is about 15 Myr. We include semi-analytic calculations of helium reionization, and discuss how to include these quasars as sources of ionizing radiation for full hydrodynamics with radiative transfer simulations in order to study helium reionization.

  13. Where is the oxygen in protostellar outflows?

    NASA Astrophysics Data System (ADS)

    Kristensen, Lars

    2014-10-01

    Oxygen (O) is the third-most abundant element in the Universe after hydrogen and helium. Despite its high elemental abundance, a good picture of where oxygen is located in low-mass protostellar outflows and jets is missing: we cannot account for > 60% of the oxygen budget in these objects. This hole in our picture means that we currently do not have a good understanding of the dominant cooling processes in outflows jets, despite the fact that [O I] emission at 63 micron is one of the dominant cooling lines, nor how cooling processes evolve with protostellar evolution. To shed light on these processes, we propose to observe the [O I] 63 micron line with SOFIA-GREAT toward five low-mass protostars. As a first step, the velocity-resolved line profile will be decomposed into its constituent components to isolate the relative contributions from the jet and the irradiated outflow. Second, the [O I] line profile will be compared to those of H2O, OH and CO to obtain the relative atomic O abundance with respect to CO, H2O, and OH. Third, the effects of evolution will be examined by observing protostars at different evolutionary stages. These three approaches will allow us to quantify: the oxygen chemistry in warm and hot gas, the relative amounts of material in the outflow and the jet, and finally to start tracing the evolutionary sequence of how feedback evolves with time.

  14. Did ice streams carve martian outflow channels?

    USGS Publications Warehouse

    Lucchitta, B.K.; Anderson, D.M.; Shoji, H.

    1981-01-01

    Outflow channels on Mars1 are long sinuous linear depressions that occur mostly in the equatorial area (??30?? lat.). They differ from small valley networks2 by being larger and arising full born from chaotic terrains. Outflow channels resemble terrestrial stream beds, and their origin has generally been attributed to water3-5 in catastrophic floods6,7 or mudflows8. The catastrophic-flood hypothesis is derived primarily from the morphological similarities of martian outflow channels and features created by the catastrophic Spokane flood that formed the Washington scablands. These similarities have been documented extensively3,6,7, but differences of scale remain a major problemmartian channel features are on the average much larger than their proposed terrestrial analogues. We examine here the problem of channel origin from the perspective of erosional characteristics and the resultant landf orms created by former and present-day ice streams and glaciers on Earth. From morphologic comparisons, an ice-stream origin seems equally well suited to explain the occurrences and form of the outflow channels on Mars, and in contrast with the hydraulic hypothesis, ice streams and ice sheets produce terrestrial features of the same scale as those observed on Mars. ?? 1981 Nature Publishing Group.

  15. A Well-Defined Bipolar Outflow Shell

    NASA Astrophysics Data System (ADS)

    Xie, Taoling; Goldsmith, Paul F.; Patel, Nimesh

    1992-12-01

    A well-defined "eggplant-shaped" thin shell is revealed in the Mon R2 central core region by CO and (13) CO J=1-0 maps obtained with QUARRY. This thin shell outlines the extended blue lobe of the massive bipolar outflow. The projected length and width of the shell are about 5.7 pc and 2.5 pc respectively, and the averaged projected thickness of the shell is ~ 0.3 pc. The shape of this shell can be satisfactorily accounted for quantitatively in terms of limb-brightening within the framework of the Shu et al shell model with radially directed wind, although the model seems to be oversimplified with respect to the complexity that our data reveal. The outflow shell's symmetry axis is estimated to be inclined by ~ 70(deg) with respect to the line of sight. We suggest that the coincident blue- and red-shifted emission and the bending of the red-shifted lobe are the result of the red-shifted shell being compressed, rather than having a second bipolar outflow aligned roughly perpendicular to the axis of the first bipolar outflow.

  16. Protostellar Outflow Evolution in Turbulent Environments

    SciTech Connect

    Cunningham, A; Frank, A; Carroll, J; Blackman, E; Quillen, A

    2008-04-11

    The link between turbulence in star formatting environments and protostellar jets remains controversial. To explore issues of turbulence and fossil cavities driven by young stellar outflows we present a series of numerical simulations tracking the evolution of transient protostellar jets driven into a turbulent medium. Our simulations show both the effect of turbulence on outflow structures and, conversely, the effect of outflows on the ambient turbulence. We demonstrate how turbulence will lead to strong modifications in jet morphology. More importantly, we demonstrate that individual transient outflows have the capacity to re-energize decaying turbulence. Our simulations support a scenario in which the directed energy/momentum associated with cavities is randomized as the cavities are disrupted by dynamical instabilities seeded by the ambient turbulence. Consideration of the energy power spectra of the simulations reveals that the disruption of the cavities powers an energy cascade consistent with Burgers-type turbulence and produces a driving scale-length associated with the cavity propagation length. We conclude that fossil cavities interacting either with a turbulent medium or with other cavities have the capacity to sustain or create turbulent flows in star forming environments. In the last section we contrast our work and its conclusions with previous studies which claim that jets can not be the source of turbulence.

  17. 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

  18. Evolution of Mass Outflow in Protostars

    NASA Astrophysics Data System (ADS)

    Watson, Dan M.; Calvet, Nuria P.; Fischer, William J.; Forrest, W. J.; Manoj, P.; Megeath, S. Thomas; Melnick, Gary J.; Najita, Joan; Neufeld, David A.; Sheehan, Patrick D.; Stutz, Amelia M.; Tobin, John J.

    2016-09-01

    We have surveyed 84 Class 0, Class I, and flat-spectrum protostars in mid-infrared [Si ii], [Fe ii], and [S i] line emission, and 11 of these in far-infrared [O i] emission. We use the results to derive their mass outflow rates, {\\dot{M}}w. Thereby we observe a strong correlation of {\\dot{M}}w with bolometric luminosity, and with the inferred mass accretion rates of the central objects, {\\dot{M}}a, which continues through the Class 0 range the trend observed in Class II young stellar objects. Along this trend from large to small mass flow rates, the different classes of young stellar objects lie in the sequence Class 0-Class I/flat-spectrum-Class II, indicating that the trend is an evolutionary sequence in which {\\dot{M}}a and {\\dot{M}}w decrease together with increasing age, while maintaining rough proportionality. The survey results include two that are key tests of magnetocentrifugal outflow-acceleration mechanisms: the distribution of the outflow/accretion branching ratio b={\\dot{M}}w/{\\dot{M}}a, and limits on the distribution of outflow speeds. Neither rules out any of the three leading outflow-acceleration, angular-momentum-ejection mechanisms, but they provide some evidence that disk winds and accretion-powered stellar winds (APSWs) operate in many protostars. An upper edge observed in the branching-ratio distribution is consistent with the upper bound of b = 0.6 found in models of APSWs, and a large fraction (31%) of the sample have a branching ratio sufficiently small that only disk winds, launched on scales as large as several au, have been demonstrated to account for them.

  19. HOT ELECTROMAGNETIC OUTFLOWS. I. ACCELERATION AND SPECTRA

    SciTech Connect

    Russo, Matthew; Thompson, Christopher

    2013-04-20

    The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such as the breakout of a gamma-ray burst (GRB) jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pulled inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid outflow: a hardening of the radiation spectrum above the peak of the seed photon distribution, driven by bulk Compton scattering. The non-thermal spectrum-obtained by a Monte Carlo method-is most extended when the Lorentz force dominates the acceleration, and the seed photon beam is wider than the Lorentz cone of the MHD fluid. This effect is a generic feature of hot, magnetized outflows interacting with slower relativistic material. It may explain why some GRB spectra appear to peak at photon energies above the original Amati et al. scaling. A companion paper addresses the case of jet breakout, where diverging magnetic flux surfaces yield strong MHD acceleration over a wider range of Lorentz factor.

  20. Evolution of Mass Outflow in Protostars

    NASA Astrophysics Data System (ADS)

    Watson, Dan M.; Calvet, Nuria P.; Fischer, William J.; Forrest, W. J.; Manoj, P.; Megeath, S. Thomas; Melnick, Gary J.; Najita, Joan; Neufeld, David A.; Sheehan, Patrick D.; Stutz, Amelia M.; Tobin, John J.

    2016-09-01

    We have surveyed 84 Class 0, Class I, and flat-spectrum protostars in mid-infrared [Si ii], [Fe ii], and [S i] line emission, and 11 of these in far-infrared [O i] emission. We use the results to derive their mass outflow rates, {\\dot{M}}w. Thereby we observe a strong correlation of {\\dot{M}}w with bolometric luminosity, and with the inferred mass accretion rates of the central objects, {\\dot{M}}a, which continues through the Class 0 range the trend observed in Class II young stellar objects. Along this trend from large to small mass flow rates, the different classes of young stellar objects lie in the sequence Class 0–Class I/flat-spectrum–Class II, indicating that the trend is an evolutionary sequence in which {\\dot{M}}a and {\\dot{M}}w decrease together with increasing age, while maintaining rough proportionality. The survey results include two that are key tests of magnetocentrifugal outflow-acceleration mechanisms: the distribution of the outflow/accretion branching ratio b={\\dot{M}}w/{\\dot{M}}a, and limits on the distribution of outflow speeds. Neither rules out any of the three leading outflow-acceleration, angular-momentum-ejection mechanisms, but they provide some evidence that disk winds and accretion-powered stellar winds (APSWs) operate in many protostars. An upper edge observed in the branching-ratio distribution is consistent with the upper bound of b = 0.6 found in models of APSWs, and a large fraction (31%) of the sample have a branching ratio sufficiently small that only disk winds, launched on scales as large as several au, have been demonstrated to account for them.

  1. Alignment of quasar polarizations with large-scale structures

    NASA Astrophysics Data System (ADS)

    Hutsemékers, D.; Braibant, L.; Pelgrims, V.; Sluse, D.

    2014-12-01

    We have measured the optical linear polarization of quasars belonging to Gpc scale quasar groups at redshift z ~ 1.3. Out of 93 quasars observed, 19 are significantly polarized. We found that quasar polarization vectors are either parallel or perpendicular to the directions of the large-scale structures to which they belong. Statistical tests indicate that the probability that this effect can be attributed to randomly oriented polarization vectors is on the order of 1%. We also found that quasars with polarization perpendicular to the host structure preferentially have large emission line widths while objects with polarization parallel to the host structure preferentially have small emission line widths. Considering that quasar polarization is usually either parallel or perpendicular to the accretion disk axis depending on the inclination with respect to the line of sight, and that broader emission lines originate from quasars seen at higher inclinations, we conclude that quasar spin axes are likely parallel to their host large-scale structures. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 092.A-0221.Table 1 is available in electronic form at http://www.aanda.org

  2. Quasar variability measurements with SDSS repeated imaging and POSS data

    NASA Astrophysics Data System (ADS)

    Ivezic, Ž.; Lupton, R. H.; Juric, M.; Anderson, S.; Hall, P. B.; Richards, G. T.; Rockosi, C. M.; vanden Berk, D. E.; Turner, E. L.; Knapp, G. R.; Gunn, J. E.; Schlegel, D.; Strauss, M. A.; Schneider, D. P.

    2004-11-01

    We analyze the properties of quasar variability using repeated SDSS imaging data in five UV-to-far red photometric bands, accurate to 0.02 mag, for ˜13,000 spectroscopically confirmed quasars. The observed time lags span the range from 3 hours to over 3 years, and constrain the quasar variability for rest-frame time lags of up to two years, and at rest-frame wavelengths from 1000Å to 6000Å. We demonstrate that ˜66,000 SDSS measurements of magnitude differences can be described within the measurement noise by a simple function of only three free parameters. The addition of POSS data constrains the long-term behavior of quasar variability and provides evidence for a turn-over in the structure function. This turn-over indicates that the characteristic time scale for optical variability of quasars is of the order 1 year.

  3. Reddening indicators for quasars and Seyfert 1 galaxies

    NASA Technical Reports Server (NTRS)

    Grandi, S. A.

    1983-01-01

    It is pointed out that a determination of the reddening caused by intervening dust is a prerequisite to understanding the astrophysics of the broad line emission in quasars and their close cousins Seyfert 1 galaxies. Previous discussions of the reddening question have tended to be incomplete. The present investigation represents an attempt to asses critically the various techniques used to measure the reddening to quasars. It is found that if certain arguments presented are correct, there are no useful reddening indicators for the broad lines of quasars and Seyfert 1 galaxies. It seems safest to assume that reddening due to dust associated with quasars is negligible. However, small amounts of reddening toward quasars are certainly possible, and large amounts of reddening, while unlikely, cannot be ruled out.

  4. X-ray studies of quasars with the Einstein Observatory

    NASA Technical Reports Server (NTRS)

    Tananbaum, H.; Branduardi, G.; Fabbiano, G.; Feigelson, E.; Giacconi, R.; Henry, J. P.; Avni, Y.; Elvis, M.; Pye, J. P.; Soltan, A.

    1979-01-01

    Results of an investigation of the X-ray properties of quasars conducted using the Einstein Observatory (HEAO 2) are reported. The positions, fluxes and luminosities of 35 known quasars were observed by the Einstein high-resolution imaging detector and the imaging proportional counter. Assuming optical redshifts as valid distance indicators, 0.5-4.5 keV X-ray luminosities ranging from 10 to the 43rd to 10 to the 47 ergs/sec are obtained, with evidence of very little cold gas absorption. Flux variability on a time scale of less than 10,000 sec is observed for the quasar OX 169, which implies a mass between 8 x 10 to the 5th and 2 x 10 to the 8th solar masses for the black hole assumed to be responsible for the emission. Preliminary results of the quasar survey also indicate that quasars contribute significantly to the diffuse X-ray background.

  5. A SIMPLE LIKELIHOOD METHOD FOR QUASAR TARGET SELECTION

    SciTech Connect

    Kirkpatrick, Jessica A.; Schlegel, David J.; Ross, Nicholas P.; Myers, Adam D.; Hennawi, Joseph F.; Sheldon, Erin S.; Schneider, Donald P.; Weaver, Benjamin A.

    2011-12-20

    We present a new method for quasar target selection using photometric fluxes and a Bayesian probabilistic approach. For our purposes, we target quasars using Sloan Digital Sky Survey (SDSS) photometry to a magnitude limit of g = 22. The efficiency and completeness of this technique are measured using the Baryon Oscillation Spectroscopic Survey (BOSS) data taken in 2010. This technique was used for the uniformly selected (CORE) sample of targets in BOSS year-one spectroscopy to be realized in the ninth SDSS data release. When targeting at a density of 40 objects deg{sup -2} (the BOSS quasar targeting density), the efficiency of this technique in recovering z > 2.2 quasars is 40%. The completeness compared to all quasars identified in BOSS data is 65%. This paper also describes possible extensions and improvements for this technique.

  6. Strong associated C 4 absorption in low redshift quasars

    NASA Technical Reports Server (NTRS)

    Tytler, David

    1990-01-01

    IUE spectra of quasars were used to determine the frequency of occurrence of strong associated C 4 absorption systems at low red shifts. Four systems are found with rest frame equivalent width (REW) greater than 5 angstroms in the spectra of 38 quasars. This rate of occurrence of 0.12 is not significantly different from the rate of 0.064 determined for high red shift quasars. The detected strong associated systems are all in low red shift quasars which have been imaged from the ground. One of the quasars is unusual, having two nuclei, a close companion and distorted isotopes. Two of the others also have close companion galaxies at projected distances of under 100 kpc. The conclusion was made that a much larger sample is needed.

  7. Infrared/optical energy distributions of high redshifted quasars

    NASA Technical Reports Server (NTRS)

    Soifer, B. T.; Neugebauer, G.; Oke, J. B.; Matthews, K.; Lacy, J. H.

    1982-01-01

    Measurements at 1.2, 1.6 and 2.2 microns were combined with visual spectrophotometry of 21 quasars having redshifts z or = 2.66. The primary result is that the rest frame visual/ultraviolet continua of the high redshift quasars are well described by a sum of a power law continuum with slope of approximately -0.4 and a 3000 A bump. The rest frame visual/ultraviolet continua of these quasars are quite similar to that of 3C273, the archetype of low redshift quasars. There does not appear to be any visual/ultraviolet properties distinguishing high redshift quasars selected via visual or radio techniques.

  8. ON THE LINK BETWEEN ASSOCIATED Mg II ABSORBERS AND STAR FORMATION IN QUASAR HOSTS

    SciTech Connect

    Shen Yue; Menard, Brice E-mail: menard@pha.jhu.edu

    2012-04-01

    A few percent of quasars show strong associated Mg II absorption, with velocities (v{sub off}) lying within a few thousand km s{sup -1} from the quasar systemic redshift. These associated absorption line (AAL) systems are usually interpreted as absorbers that are either intrinsic to the quasar and its host, or arising from external galaxies clustering around the quasar. Using composite spectra of {approx}1800 Mg II AAL quasars selected from SDSS DR7 at 0.4 {approx}< z {approx}< 2, we show that quasars with AALs with v{sub off} < 1500 km s{sup -1} have a prominent excess in [O II] {lambda}3727 emission (detected at >7{sigma}) at rest relative to the quasar host, compared to unabsorbed quasars. We interpret this [O II] excess as due to enhanced star formation in the quasar host. Our results suggest that a significant fraction of AALs with v{sub off} < 1500 km s{sup -1} are physically associated with the quasar and its host. AAL quasars also have dust reddening lying between normal quasars and the so-called dust-reddened quasars. We suggest that the unique properties of AAL quasars can be explained if they are the transitional population from heavily dust-reddened quasars to normal quasars in the formation process of quasars and their hosts. This scenario predicts a larger fraction of young bulges, disturbed morphologies, and interactions of AAL quasar hosts compared to normal quasars. The intrinsic link between associated absorbers and quasar hosts opens a new window to probe massive galaxy formation and galactic-scale feedback processes, and provides a crucial test of the evolutionary picture of quasars.

  9. OBSCURATION BY GAS AND DUST IN LUMINOUS QUASARS

    SciTech Connect

    Usman, S. M.; Murray, S. S.; Hickox, R. C.; Brodwin, M.

    2014-06-10

    We explore the connection between absorption by neutral gas and extinction by dust in mid-infrared (IR) selected luminous quasars. We use a sample of 33 quasars at redshifts 0.7 < z ≲ 3 in the 9 deg{sup 2} Boötes multiwavelength survey field that are selected using Spitzer Space Telescope Infrared Array Camera colors and are well-detected as luminous X-ray sources (with >150 counts) in Chandra observations. We divide the quasars into dust-obscured and unobscured samples based on their optical to mid-IR color, and measure the neutral hydrogen column density N {sub H} through fitting of the X-ray spectra. We find that all subsets of quasars have consistent power law photon indices Γ ≈ 1.9 that are uncorrelated with N {sub H}. We classify the quasars as gas-absorbed or gas-unabsorbed if N {sub H} > 10{sup 22} cm{sup –2} or N {sub H} < 10{sup 22} cm{sup –2}, respectively. Of 24 dust-unobscured quasars in the sample, only one shows clear evidence for significant intrinsic N {sub H}, while 22 have column densities consistent with N {sub H} < 10{sup 22} cm{sup –2}. In contrast, of the nine dust-obscured quasars, six show evidence for intrinsic gas absorption, and three are consistent with N {sub H} < 10{sup 22} cm{sup –2}. We conclude that dust extinction in IR-selected quasars is strongly correlated with significant gas absorption as determined through X-ray spectral fitting. These results suggest that obscuring gas and dust in quasars are generally co-spatial, and confirm the reliability of simple mid-IR and optical photometric techniques for separating quasars based on obscuration.

  10. A New Model for Dark Matter Halos Hosting Quasars

    NASA Astrophysics Data System (ADS)

    Cen, Renyue; Safarzadeh, Mohammadtaher

    2015-01-01

    A new model for quasar-hosting dark matter halos, meeting two physical conditions, is put forth. First, significant interactions are taken into consideration to trigger quasar activities. Second, satellites in very massive halos at low redshift are removed from consideration due to their deficiency in cold gas. We analyze the Millennium Simulation to find halos that meet these two conditions and simultaneously match two-point auto-correlation functions of quasars and cross-correlation functions between quasars and galaxies at z = 0.5-3.2. The masses of the quasar hosts found decrease with decreasing redshift, with the mass thresholds being [(2-5) × 1012, (2-5) × 1011, (1-3) × 1011] M ⊙ for median luminosities of ~[1046, 1046, 1045] erg s-1 at z = (3.2, 1.4, 0.53), respectively, an order of magnitude lower than those inferred based on halo occupation distribution modeling. In this model, quasar hosts are primarily massive central halos at z >= 2-3 but increasingly dominated by lower mass satellite halos experiencing major interactions toward lower redshift. However, below z = 1, satellite halos in groups more massive than ~2 × 1013 M ⊙ do not host quasars. Whether for central or satellite halos, imposing the condition of significant interactions substantially boosts the clustering strength compared to the total population with the same mass cut. The inferred lifetimes of quasars at z = 0.5-3.2 of 3-30 Myr are in agreement with observations. Quasars at z ~ 2 would be hosted by halos of mass ~5 × 1011 M ⊙ in this model, compared to ~3 × 1012 M ⊙ previously thought, which would help reconcile with the observed, otherwise puzzling high covering fractions for Lyman limit systems around quasars.

  11. The VLBI structure of radio-loud Broad Absorption Line quasars

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Jiang, D. R.; Gu, M.

    2016-02-01

    The nature and origin of Broad Absorption Line (BAL) quasars and their relationship to non-BAL quasars are an open question. The BAL quasars are probably normal quasars seen along a particular line of sight. Alternatively, they are young or recently refueled. The high resolution radio morphology of BAL quasars is very important to understand the radio properties of BAL quasars. We present VLBA observations at L and C bands for a sample of BAL quasars. The observations will help us to explore the VLBI radio properties, and distinguish the present models of explaining BAL phenomena.

  12. SDSS QUASARS IN THE WISE PRELIMINARY DATA RELEASE AND QUASAR CANDIDATE SELECTION WITH OPTICAL/INFRARED COLORS

    SciTech Connect

    Wu Xuebing; Hao Guoqiang; Jia Zhendong; Zhang Yanxia; Peng Nanbo

    2012-08-15

    We present a catalog of 37,842 quasars in the Sloan Digital Sky Survey (SDSS) Data Release 7, which have counterparts within 6'' in the Wide-field Infrared Survey Explorer (WISE) Preliminary Data Release. The overall WISE detection rate of the SDSS quasars is 86.7%, and it decreases to less than 50.0% when the quasar magnitude is fainter than i = 20.5. We derive the median color-redshift relations based on this SDSS-WISE quasar sample and apply them to estimate the photometric redshifts of the SDSS-WISE quasars. We find that by adding the WISE W1- and W2-band data to the SDSS photometry we can increase the photometric redshift reliability, defined as the percentage of sources with photometric and spectroscopic redshift difference less than 0.2, from 70.3% to 77.2%. We also obtain the samples of WISE-detected normal and late-type stars with SDSS spectroscopy, and present a criterion in the z - W1 versus g - z color-color diagram, z - W1 > 0.66(g - z) + 2.01, to separate quasars from stars. With this criterion we can recover 98.6% of 3089 radio-detected SDSS-WISE quasars with redshifts less than four and overcome the difficulty in selecting quasars with redshifts between 2.2 and 3 from SDSS photometric data alone. We also suggest another criterion involving the WISE color only, W1 - W2 > 0.57, to efficiently separate quasars with redshifts less than 3.2 from stars. In addition, we compile a catalog of 5614 SDSS quasars detected by both WISE and UKIDSS surveys and present their color-redshift relations in the optical and infrared bands. By using the SDSS ugriz, UKIDSS, YJHK, and WISE W1- and W2-band photometric data, we can efficiently select quasar candidates and increase the photometric redshift reliability up to 87.0%. We discuss the implications of our results on the future quasar surveys. An updated SDSS-WISE quasar catalog consisting of 101,853 quasars with the recently released WISE all-sky data is also provided.

  13. The Overdue Discovery of Quasars and AGN

    NASA Astrophysics Data System (ADS)

    Kellermann, Ken I.

    2012-09-01

    The extragalactic nature of quasars as a major new component of the Universe was not recognized until 1963 when Maarten Schmidt somewhat accidentally measured the spectrum of 3C 273 and recognized that the relatively simple hydrogen line Balmer series spectrum implied a redshift of 0.16. Curiously, 3C 48 and other very compact radio sources had been previously identified with ``quasi-stellar'' objects several years earlier. Even though the redshift of 3C48 was measured as early as 1960 as 0.37, it was rejected due to apparent spectroscopic technicalities and preconceived ideas about what appeared to be an unrealistically high luminosity. The strong radio source known as 3C 273 was first catalogued in 1959 and the now recognized magnitude 13 optical counterpart was known at least as early as 1887. Although, since 1960, much fainter optical counterparts were being routinely identified using accurate radio interferometer positions, interestingly, 3C273 eluded identification until a series of lunar occultations by Hazard et al. in 1962 were used to determine the position and morphology of the radio source. Acceptance of the cosmological nature of quasars and the implied excessive radio and optical luminosity was not universal, and claims for a more local population continued for at least several decades, confused perhaps by the recognition of the much larger class of radio quiet quasi stellar objects and active galactic nuclei (AGN), the uncertain connection with previously known Seyfert and other compact galaxies, as well as attempts to classify quasars into numerous sub-categories based on their observed optical, radio, IR and high energy properties.

  14. The high-z quasar Hubble Diagram

    SciTech Connect

    Melia, Fulvio

    2014-01-01

    Two recent discoveries have made it possible for us to begin using high-z quasars as standard candles to construct a Hubble Diagram (HD) at z > 6. These are (1) the recognition from reverberation mapping that a relationship exists between the optical/UV luminosity and the distance of line-emitting gas from the central ionizing source. Thus, together with a measurement of the velocity of the line-emitting gas, e.g., via the width of BLR lines, such as Mg II, a single observation can therefore in principle provide a determination of the black hole's mass; and (2) the identification of quasar ULAS J1120+0641 at z = 7.085, which has significantly extended the redshift range of these sources, providing essential leverage when fitting theoretical luminosity distances to the data. In this paper, we use the observed fluxes and Mg II line-widths of these sources to show that one may reasonably test the predicted high-z distance versus redshift relationship, and we assemble a sample of 20 currently available high-z quasars for this exercise. We find a good match between theory and observations, suggesting that a more complete, high-quality survey may indeed eventually produce an HD to complement the highly-detailed study already underway (e.g., with Type Ia SNe, GRBs, and cosmic chronometers) at lower redshifts. With the modest sample we have here, we show that the R{sub h} = ct Universe and ΛCDM both fit the data quite well, though the smaller number of free parameters in the former produces a more favorable outcome when we calculate likelihoods using the Akaike, Kullback, and Bayes Information Criteria. These three statistical tools result in similar probabilities, indicating that the R{sub h} = ct Universe is more likely than ΛCDM to be correct, by a ratio of about 85% to 15%.

  15. High redshift quasars and high metallicities

    NASA Technical Reports Server (NTRS)

    Ferland, Gary J.

    1997-01-01

    A large-scale code called Cloudy was designed to simulate non-equilibrium plasmas and predict their spectra. The goal was to apply it to studies of galactic and extragalactic emission line objects in order to reliably deduce abundances and luminosities. Quasars are of particular interest because they are the most luminous objects in the universe and the highest redshift objects that can be observed spectroscopically, and their emission lines can reveal the composition of the interstellar medium (ISM) of the universe when it was well under a billion years old. The lines are produced by warm (approximately 10(sup 4)K) gas with moderate to low density (n less than or equal to 10(sup 12) cm(sup -3)). Cloudy has been extended to include approximately 10(sup 4) resonance lines from the 495 possible stages of ionization of the lightest 30 elements, an extension that required several steps. The charge transfer database was expanded to complete the needed reactions between hydrogen and the first four ions and fit all reactions with a common approximation. Radiative recombination rate coefficients were derived for recombination from all closed shells, where this process should dominate. Analytical fits to Opacity Project (OP) and other recent photoionization cross sections were produced. Finally, rescaled OP oscillator strengths were used to compile a complete set of data for 5971 resonance lines. The major discovery has been that high redshift quasars have very high metallicities and there is strong evidence that the quasar phenomenon is associated with the birth of massive elliptical galaxies.

  16. The Fall of the Quasar Population

    NASA Astrophysics Data System (ADS)

    Cavaliere, A.; Vittorini, V.

    2000-11-01

    We derive quantitative predictions of the optical and X-ray luminosity functions for quasars in the redshift range z<~3. Based on accreting black holes as primary sources for the quasar outputs, we investigate how the accretion is controlled by the surrounding structures, as these grow hierarchically from the formation of the host galaxies to their assemblage into poor and eventually into rich groups. We argue that for z<3 efficient black hole fueling is triggered by the encounters of a gas-rich host with its companions in a group; these destabilize the gas and induce accretion, giving rise to the following features. The dispersion of the dynamical parameters in the encounters produces luminosity functions with the shape of a double power law. Strong luminosity evolution is produced as these encounters deplete the gas supply in the host; an additional, milder density evolution obtains, since the interactions become progressively rarer as the groups grow richer but less dense. We carry out these arguments to derive a specific model for the evolving luminosity functions. From the agreement with the optical and the X-ray data, we conclude that the evolution of the bright quasars is driven by the development of cosmic structures in two ways. Earlier than z~3 the gas-rich protogalaxies grow by merging, which also induces parallel growth of central holes accreting at their full Eddington rates. In the later era of group assemblage the host encounters with companions drive onto already existing holes further but meager accretion; these events consume the gas reservoirs in the hosts, while they cause supply-limited emissions that are intermittent, go progressively sub-Eddington, and peter out. Then other fueling processes occurring in the field come to the foreground; we specifically discuss the faint emissions, especially noticeable in X-rays, which are expected when hosts in the field cannibalize satellite galaxies with their scant gaseous contents.

  17. Data mining for gravitationally lensed quasars

    NASA Astrophysics Data System (ADS)

    Agnello, Adriano; Kelly, Brandon C.; Treu, Tommaso; Marshall, Philip J.

    2015-04-01

    Gravitationally lensed quasars are brighter than their unlensed counterparts and produce images with distinctive morphological signatures. Past searches and target-selection algorithms, in particular the Sloan Quasar Lens Search (SQLS), have relied on basic morphological criteria, which were applied to samples of bright, spectroscopically confirmed quasars. The SQLS techniques are not sufficient for searching into new surveys (e.g. DES, PS1, LSST), because spectroscopic information is not readily available and the large data volume requires higher purity in target/candidate selection. We carry out a systematic exploration of machine-learning techniques and demonstrate that a two-step strategy can be highly effective. In the first step, we use catalogue-level information (griz+WISE magnitudes, second moments) to pre-select targets, using artificial neural networks. The accepted targets are then inspected with pixel-by-pixel pattern recognition algorithms (gradient-boosted trees), to form a final set of candidates. The results from this procedure can be used to further refine the simpler SQLS algorithms, with a twofold (or threefold) gain in purity and the same (or 80 per cent) completeness at target-selection stage, or a purity of 70 per cent and a completeness of 60 per cent after the candidate-selection step. Simpler photometric searches in griz+WISE based on colour cuts would provide samples with 7 per cent purity or less. Our technique is extremely fast, as a list of candidates can be obtained from a Stage III experiment (e.g. DES catalogue/data base) in a few CPU hours. The techniques are easily extendable to Stage IV experiments like LSST with the addition of time domain information.

  18. HOST GALAXIES OF z = 4 QUASARS

    SciTech Connect

    McLeod, K. K.; Bechtold, Jill E-mail: jbechtold@as.arizona.ed

    2009-10-10

    We have undertaken a project to investigate the host galaxies and environments of a sample of quasars at z approx 4. In this paper, we describe deep near-infrared imaging of 34 targets using the Magellan I and Gemini North telescopes. We discuss in detail special challenges of distortion and nonlinearity that must be addressed when performing point-spread function (PSF) subtraction with data from these telescopes and their IR cameras, especially in very good seeing. We derive black hole masses from emission-line spectroscopy, and we calculate accretion rates from our K{sub s} -band photometry, which directly samples the rest frame B for these objects. We introduce a new isophotal diameter technique for estimating host galaxy luminosities. We report the detection of four host galaxies on our deepest, sharpest images, and present upper limits for the others. We find that if host galaxies passively evolve such that they brighten by 2 mag or more in the rest-frame B band between the present and z = 4, then high-z hosts are less massive at a given black hole mass than are their low-z counterparts. We argue that the most massive hosts plateau at approx<10 L*. We estimate the importance of selection effects on this survey and the subsequent limitations of our conclusions. These results are in broad agreement with recent semianalytical models for the formation of luminous quasars and their host spheroids by mergers of gas-rich galaxies, with significant dissipation, and self-regulation of black hole growth and star formation by the burst of merger-induced quasar activity.

  19. Tracing outflows in the AGN forbidden region with SINFONI

    NASA Astrophysics Data System (ADS)

    Kakkad, D.; Mainieri, V.; Padovani, P.; Cresci, G.; Husemann, B.; Carniani, S.; Brusa, M.; Lamastra, A.; Lanzuisi, G.; Piconcelli, E.; Schramm, M.

    2016-08-01

    Context. Active galactic nucleus (AGN) driven outflows are invoked in numerical simulations to reproduce several observed properties of local galaxies. The z > 1 epoch is of particular interest as it was during this time that the volume averaged star formation and the accretion rate of black holes were at their maximum. Radiatively driven outflows are therefore believed to be common during this epoch. Aims: We aim to trace and characterize outflows in AGN hosts with high mass accretion rates at z > 1 using integral field spectroscopy. We obtain spatially resolved kinematics of the [O iii] λ5007 line in two targets which reveal the morphology and spatial extension of the outflows. Methods: We present SINFONI observations in the J band and the H + K band of five AGNs at 1.2 < z < 2.2. To maximize the chance of observing radiatively driven outflows, our sample was pre-selected based on peculiar values of the Eddington ratio and the hydrogen column density of the surrounding interstellar medium. We observe high velocity (~600-1900 km s-1) and kiloparsec scale extended ionized outflows in at least three of our targets, using [O iii] λ5007 line kinematics tracing the AGN narrow line region. We estimate the total mass of the outflow, the mass outflow rate, and the kinetic power of the outflows based on theoretical models and report on the uncertainties associated with them. Results: We find mass outflow rates of ~1-10 M⊙/yr for the sample presented in this paper. Based on the high star formation rates of the host galaxies, the observed outflow kinetic power, and the expected power due to the AGN, we infer that both star formation and AGN radiation could be the dominant source for the outflows. The outflow models suffer from large uncertainties, hence we call for further detailed observations for an accurate determination of the outflow properties to confirm the exact source of these outflows.

  20. Parsec-scale radio structures in Quasars

    NASA Astrophysics Data System (ADS)

    Coldwell, G.; Paragi, Z.; Gurvits, L.

    Very Long Baseline Interferometry (VLBI) con su nueva extensión para el radio telescopio orbital, VSOP/HALCA, ofrece una incomparable resolución angular alcanzando escalas de milisegundos y submilisegundos de arco a longitudes de onda de centímetros. En este trabajo presentamos observaciones y análisis de estructuras en radio, en escalas de parsec, para 3 radio fuentes extragalácticas de la muestra de VSOP Survey y 1 quasar, 1442+101, del proyecto `VSOP High Redshift'.

  1. Neutrinos from flat-spectrum radio quasars

    NASA Technical Reports Server (NTRS)

    Mannheim, K.; Stanev, T.; Biermann, P. L.

    1992-01-01

    The GRO observation (Hartman et al., 1992) of a very strong flux of gamma rays with an energy index close to 2 from the distant quasar 3C279 and other extragalactic flat-spectrum radio sources is in very good agreement with models that advocate the important role of very high energy protons and nuclei in the energy transport in AGN. Protons and nuclei cool by interactions on the nonthermal fields in the nuclear jet of the AGN and generate gamma ray and neutrino fluxes. Ultra high energy neutrinos could be observed with sensitive air shower experiments in outbursts as powerful as the one seen by GRO.

  2. OPTICAL MICROVARIABILITY IN QUASARS: SPECTRAL VARIABILITY

    SciTech Connect

    RamIrez, A.; Dultzin, D.; De Diego, J. A. E-mail: deborah@astroscu.unam.m

    2010-05-01

    We present a method that we developed to discern where the optical microvariability (OM) in quasars originates: in the accretion disk (related to thermal processes) or in the jet (related to non-thermal processes). Analyzing nearly simultaneous observations in three different optical bands of continuum emission, we are able to determine the origin of several isolated OM events. In particular, our method indicates that from nine events reported by RamIrez et al., three of them are consistent with a thermal origin, three with non-thermal, and three cannot be discerned. The implications for the emission models of OM are briefly discussed.

  3. Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow

    NASA Astrophysics Data System (ADS)

    Fox, Andrew J.; Bordoloi, Rongmon; Savage, Blair D.; Lockman, Felix J.; Jenkins, Edward B.; Wakker, Bart P.; Bland-Hawthorn, Joss; Hernandez, Svea; Kim, Tae-Sun; Benjamin, Robert A.; Bowen, David V.; Tumlinson, Jason

    2015-01-01

    Giant lobes of plasma extend ≈55° above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (l, b = 10.°4, +11.°2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v LSR = -235 and +250 km s-1, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of gsim900 km s-1 and a full opening angle of ≈110° (matching the X-ray bicone). This indicates Galactic center activity over the last ≈2.5-4.0 Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles. Based on observations taken under program 13448 of 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, and under program 14B-299 of the NRAO Green Bank Telescope, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  4. Towards a comprehensive picture of powerful quasars, their host galaxies and quasar winds at z ˜ 0.5

    NASA Astrophysics Data System (ADS)

    Wylezalek, Dominika; Zakamska, Nadia L.; Liu, Guilin; Obied, Georges

    2016-03-01

    Luminous type-2 quasars in which the glow from the central black hole is obscured by dust are ideal targets for studying their host galaxies and the quasars' effect on galaxy evolution. Such feedback appears ubiquitous in luminous obscured quasars where high-velocity-ionized nebulae have been found. We present rest-frame yellow-band (˜5000 Å) observations using the Hubble Space Telescope (HST) for a sample of 20 luminous quasar host galaxies at 0.2 < z < 0.6 selected from the Sloan Digital Sky Survey. For the first time, we combine host galaxy observations with geometric measurements of quasar illumination using blue-band HST observations and [O III] integral field unit observations probing the quasar winds. The HST images reveal bright merger signatures in about half the galaxies; a significantly higher fraction than in comparison inactive ellipticals. We show that the host galaxies are primarily bulge-dominated, with masses close to M*, but belong to <30 per cent of elliptical galaxies that are highly star forming at z ˜ 0.5. Ionized gas signatures are uncorrelated with faint stellar discs (if present), confirming that the ionized gas is not concentrated in a disc. Scattering cones and [O III] ionized gas velocity field are aligned with the forward scattering cones being co-spatial with the blue-shifted side of the velocity field, suggesting the high-velocity gas is indeed photo-ionized by the quasar. Based on the host galaxies' high star formation rates and bright merger signatures, we suggest that this low-redshift outbreak of luminous quasar activity is triggered by recent minor mergers. Combining these novel observations, we present new quasar unification tests, which are in agreement with expectations of the orientation-based unification model for quasars.

  5. Evolution of Hot Dust Emission in z>6 Quasars

    NASA Astrophysics Data System (ADS)

    Fan, Xiaohui; Brandt, Niel; Carilli, Chris; Hines, Dean; Jiang, Linhua; Meisenheimer, Klaus; Richards, Gordon; Strauss, Michael; Walter, Fabian; Wang, Ran

    2007-05-01

    Strong hot dust emission from dust torus surrounding the central engine is an ubiquitous feature among Type-1 quasars at low redshift. In our previous GTO and GO-1 Spitzer programs, we observed a sample of quasars at 4quasars in this sample also show prominent hot dust emission at 24 micron, two objects at z~6 have extremely weak IR emission with SEDs consistent with power-law or pure disk emission without hot dust contribution. These two quasars also have the smallest black hole (BH) masses and highest Eddington ratios among z~6 quasars, indicative of short BH growth timescale. These observations suggest possible evolution in either dust torus structure or dust properties of quasars at the earliest epoch, constrained by both BH/AGN growth and timescale of dust formation in AGB envelops. In Cycle 4 we propose to carry out IRAC, IRS PUI 16 micron and MIPS 24 micron imaging of a sample of 9 new quasars at z>6 discovered in the last three years. The new observations will more than double the Spitzer sample size at z>6. All objects have excellent multiwavelength data, with BH mass estimates based on broad emission line width, and are GTO targets for Herschel at far-IR. With the combined Cycle 1/4 sample, we will (a) measure the fraction of quasars without hot dust emission at early epoch; (b) test the relation between hot dust properties and emission line properties, BH masses and accretion rates in quasars; (c) improve quasar IR SED measurements at z>6, and (d) probe the relation between hot and warm/cool dust traced by Herschel and sub/mm observations. In particular, three quasars in our new sample have similar emission line and BH properties to the two IR-weak quasars we found previously. We predict that they are likely candidates of new dust-deficient quasars at z>6.

  6. Molecular emission in chemically active protostellar outflows

    NASA Astrophysics Data System (ADS)

    Lefloch, B.

    2011-12-01

    Protostellar outflows play an important role in the dynamical and chemical evolution of cloud through shocks. The Herschel Space Observatory (HSO) brings new insight both on the molecular content and the physical conditions in protostellar shocks through high spectral and angular resolution studies of the emission of major gas cooling agents and hydrides. The Herschel/CHESS key-program is carrying out an in depth study of the prototypical shock region L1157-B1. Analysis of the line profiles detected allows to constrain the formation/destruction route of various molecular species, in relation with the predictions of MHD shock models. The Herschel/WISH key-program investigates the properties and origin of water emission in a broad sample of protostellar outflows and envelopes. Implications of the first results for future studies on mass-loss phenomena are discussed.

  7. Influence of Mediterranean Outflow on climate

    NASA Astrophysics Data System (ADS)

    Rahmstorf, Stefan

    A cover article in Eos last year [Johnson, 1997] called for a dam across the Strait of Gibraltar to prevent a new Ice Age. In this article, R. G. Johnson argued that reduced Nile River flow after building the Aswan Dam increases Mediterranean Sea salinity, leading to enhanced outflow of salty water into the Atlantic Ocean. This, in turn, would alter the thermohaline (that is, temperature and salinity driven) circulation of the Atlantic, heat up the Labrador Sea and enhance evaporation there, and increase snowfall in Canada until a new ice sheet builds up. Ocean circulation model experiments, however, suggest that this fear is unfounded. While Mediterranean saltwater outflow (Figure 1a) does appear to have some effect on North Atlantic circulation and surface climate, the change in Mediterranean salt budget resulting from the Aswan Dam is far too small to have any noticeable impact.

  8. Example of reduced turbulence during thunderstorm outflow

    SciTech Connect

    Bowen, B.M.

    1996-06-01

    This research note describes the effects of a gust front passage resulting from a thunderstorm outflow on wind, turbulence, and other basic meteorological variables in northern Mew Mexico. The purpose of this note is to explain how a thunderstorm outflow can greatly reduce horizontal and vertical turbulence and produce strong winds, thereby promoting the rapid transport of elevated pollutant concentrations. Another goal is to demonstrate the usefulness of a sodar in combination with a tower to provide data for dispersion and transport calculations during an emergency response. Hopefully, this note will motivate other researchers to analyze and document the effects of thunderstorms on turbulence and dispersion by routine monitoring or by experimentation. 12 refs., 3 figs., 1 tab.

  9. Local outflows from turbulent accretion disks

    NASA Astrophysics Data System (ADS)

    Fromang, S.; Latter, H.; Lesur, G.; Ogilvie, G. I.

    2013-04-01

    Aims: The aim of this paper is to investigate the properties of accretion disks threaded by a weak vertical magnetic field, with a particular focus on the interplay between magnetohydrodynamic (MHD) turbulence driven by the magnetorotational instability (MRI) and outflows that might be launched from the disk. Methods: For that purpose, we use a set of numerical simulations performed with the MHD code RAMSES in the framework of the shearing box model. We concentrate on the case of a rather weak vertical magnetic field such that the initial ratio β0 of the thermal and magnetic pressures in the disk midplane equals 104. Results: As reported recently, we find that MHD turbulence drives an efficient outflow out of the computational box. We demonstrate a strong sensitivity of that result to the box size: enlargements in the radial and vertical directions lead to a reduction of up to an order of magnitude in the mass-loss rate. Such a dependence prevents any realistic estimates of disk mass-loss rates being derived using shearing-box simulations. We find however that the flow morphology is robust and independent of the numerical details of the simulations. Its properties display some features and approximate invariants that are reminiscent of the Blandford & Payne launching mechanism, but differences exist. For the magnetic field strength considered in this paper, we also find that angular momentum transport is most likely dominated by MHD turbulence, the saturation of which scales with the magnetic Prandtl number, the ratio of viscosity and resistivity, in a way that is in good agreement with expectations based on unstratified simulations. Conclusions: This paper thus demonstrates for the first time that accretion disks can simultaneously exhibit MRI-driven MHD turbulence along with magneto-centrifugally accelerated outflows. However, in contradiction with previously published results, such outflows probably have little impact on the disk dynamics.

  10. Shaping the outflows of evolved stars

    NASA Astrophysics Data System (ADS)

    Mohamed, Shazrene

    2015-08-01

    Both hot and cool evolved stars, e.g., red (super)giants and Wolf-Rayet stars, lose copious amounts of mass, momentum and mechanical energy through powerful, dense stellar winds. The interaction of these outflows with their surroundings results in highly structured and complex circumstellar environments, often featuring knots, arcs, shells and spirals. Recent improvements in computational power and techniques have led to the development of detailed, multi-dimensional simulations that have given new insight into the origin of these structures, and better understanding of the physical mechanisms driving their formation. In this talk, I will discuss three of the main mechanisms that shape the outflows of evolved stars:- interaction with the interstellar medium (ISM), i.e., wind-ISM interactions- interaction with a stellar wind, either from a previous phase of evolution or the wind from a companion star, i.e., wind-wind interactions- and interaction with a companion star that has a weak or insignicant outflow (e.g., a compact companion such as a neutron star or black hole), i.e., wind-companion interactions.I will also highlight the broader implications and impact of these stellar wind interactions for other phenomena, e.g, for symbiotic and X-ray binaries, supernovae and Gamma-ray bursts.

  11. THE EVOLUTION OF THE DUSTY TORUS COVERING FACTOR IN QUASARS

    SciTech Connect

    Gu Minfeng

    2013-08-20

    We have assembled a large sample of 5996 quasars at 2.0 {<=} z {<=} 2.4 (high-z) or 0.7 {<=} z {<=} 1.1 (low-z) from the Sloan Digital Sky Survey (SDSS) ninth and seventh data release and quasar catalogs. The spectral energy distributions of quasars were constructed by collecting WISE, UKIDSS, and GALEX photometric data in addition to SDSS data, from which the IR luminosity at 1-7 {mu}m and bolometric luminosity at 1100 A-1 {mu}m were calculated. A red tail is clearly seen in the distribution of the spectral index over 1100 A-1 {mu}m for both the high-z and low-z sources; this tail is likely due to red or reddened quasars. The covering factor (CF) of the dusty torus is estimated as the ratio of the IR luminosity to the bolometric luminosity. We find significant anti-correlations between the CF and the bolometric luminosity, in both the high-z and low-z quasars; however, these two groups follow different tracks. At overlapping bolometric luminosities, the CF of high-z quasars is systematically larger than those of low-z quasars, implying an evolution of the CF with redshift.

  12. Distributions of Quasar Hosts on the Galaxy Main Sequence Plane

    NASA Astrophysics Data System (ADS)

    Zhang, Zhoujian; Shi, Yong; Rieke, George H.; Xia, Xiaoyang; Wang, Yikang; Sun, Bingqing; Wan, Linfeng

    2016-03-01

    The relation between star formation rates (SFRs) and stellar masses, i.e., the galaxy main sequence, is a useful diagnostic of galaxy evolution. We present the distributions relative to the main sequence of 55 optically selected PG and 12 near-IR-selected Two Micron All Sky Survey (2MASS) quasars at z ≤ 0.5. We estimate the quasar host stellar masses from Hubble Space Telescope or ground-based AO photometry, and the SFRs through the mid-infrared aromatic features and far-IR photometry. We find that PG quasar hosts more or less follow the main sequence defined by normal star-forming galaxies while 2MASS quasar hosts lie systematically above the main sequence. PG and 2MASS quasars with higher nuclear luminosities seem to have higher specific SFRs (sSFRs), although there is a large scatter. No trends are seen between sSFRs and SMBH masses, Eddington ratios, or even morphology types (ellipticals, spirals, and mergers). Our results could be placed in an evolutionary scenario with quasars emerging during the transition from ULIRGs/mergers to ellipticals. However, combined with results at higher redshift, they suggest that quasars can be widely triggered in normal galaxies as long as they contain abundant gas and have ongoing star formation.

  13. The evolution of star formation in quasar host galaxies

    NASA Astrophysics Data System (ADS)

    Serjeant, Stephen; Hatziminaoglou, Evanthia

    2009-07-01

    We have used far-infrared data from IRAS, Infrared Space Observatory (ISO), Spitzer Wide-Area Infrared Extragalactic (SWIRE), Submillimetre Common User Bolometer Array (SCUBA) and Max-Planck Millimetre Bolometer (MAMBO) to constrain statistically the mean far-infrared luminosities of quasars. Our quasar compilation at redshifts 0 < z < 6.5 and I-band luminosities -20 < IAB < -32 is the first to distinguish evolution from quasar luminosity dependence in such a study. We carefully cross-calibrate IRAS against Spitzer and ISO, finding evidence that IRAS 100-μm fluxes at <1Jy are overestimated by ~30 per cent. We find evidence for a correlation between star formation in quasar hosts and the quasar optical luminosities, varying as star formation rate (SFR) ~ L0.44+/-0.07opt at any fixed redshift below z = 2. We also find evidence for evolution of the mean SFR in quasar host galaxies, scaling as (1 + z)1.6+/-0.3 at z < 2 for any fixed quasar I-band absolute magnitude fainter than -28. We find no evidence for any correlation between SFR and black hole mass at 0.5 < z < 4. Our data are consistent with feedback from black hole accretion regulating stellar mass assembly at all redshifts.

  14. Quasar populations in a cosmological constant-dominated flat universe

    NASA Technical Reports Server (NTRS)

    Malhotra, Sangeeta; Turner, Edwin L.

    1995-01-01

    Most physical properties derived for quasars, as single entities or as a population, depend upon the cosmology assumed. In this paper, we calculate the quasar luminosity function and some related quantities for a flat universe dominated by a cosmological constant Lambda (Lambda = 0.9, Omega = 0.1) and compare them with those deduced for a flat universe with zero cosmological constant (Lambda = 0, Omega = 1). We use the ATT quasar survey data (Boyle et al. 1990) as input in both cases. The data are fitted well by a pure luminosity evolution model for both the cosmologies but with different evolutionary parameters. From the luminosity function, we predict (extrapolate) a greater number of quasars at faint apparent magnitudes (twice the number at B = 24, z is less than 2.2) for the Lambda-dominated universe. This population of faint quasars at high redshift would result in a higher incidence of gravitational lensing. The total luminosity of the quasar population and the total mass tied up in black hole remnants of quasars is not sensitive to the cosmology. However, for a Lambda cosmology, this mass is tied up in fewer but more massive black holes.

  15. Exploiting Kepler to Study Quasar Variability

    NASA Astrophysics Data System (ADS)

    Revalski, Mitchell; Wiita, P. J.; Di Lorenzo, P.; Sprague, D.; Wehrle, A. E.; Unwin, S. C.

    2013-01-01

    Variability of emission across all bands on both short and long-term time scales is a defining feature of active galactic nuclei. We present here an analysis of the optical light curves of four flat spectrum radio loud quasars, highlighting the two most recently released quarters of Kepler satellite data. Long cadence data sets were analyzed to search for flare activity and potential variability. Power spectral densities (PSDs) were used to probe for periodicities and to characterize the variability. We analyzed the raw data and also analyzed that same data after we made corrections to remove artifacts including null values, downlink gaps, and thermally induced irregularities. Often significant differences arose in the PSDs due to these corrections. The standard Kepler pipeline reduction was found to remove nearly all of the long term variations in question. Additionally, we applied end matching to the raw corrected data so as to remove a first order linear term; this should improve the accuracy of the PSDs. Average PSD slopes for the raw and end matched data sets were α = -1.76 and -1.60, respectively. These values are consistent with ground-based analyses of other quasars and blazars. One of our objects showed significant but modest flare activity whereas the others were in low activity states. No significant periodicities or quasiperiodicities were detected for these objects. This work was supported in part by NASA Kepler GO Grant NNX11AB90G to SSI and MUSE funds at The College of New Jersey.

  16. Quasar Absorption Line Survey - Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Bahcall, John

    1994-01-01

    The Absorption Line Survey of bright quasars provides a homogeneous data base for studying fundamental questions about the origin and evolution of gaseous systems in the universe. The initial results determine at small redshifts the number densities of Ly-ALPHA systems, of metal-lines and extragalactic halos, of Lyman-limit systems, of associated absorption systems, and the shapes and intensities of quasar emission lines and spectral energy distributions. The survey reveals that much of the sky is covered by high or very high velocity metal-line clouds present in the Galactic halo. A larger sample, which includes the requested Cycle 3 observations, is required to answer many important questions. For example, what is the correlation function of Ly-ALPHA systems at small redshifts? What fraction of the metal, the Ly-ALPHA, and the Ly-limit systems are associated with galaxies and what are the characteristic sizes of the outer gaseous regions of different types of galaxies? Do absorbing systems show evidence of the large-scale structure seen with galaxies and clusters of galaxies? The observations requested in Cycle 3 will extend the region of coverage of the Key Project sample from the redshift range of z = 0.0 to 1.0 (Cycles 1& 2) to z = 0.0 to 1.6 (Cycles 1-3). THIS FILE CONTAINS THE HIGH PRIORITY OBSERVATIONS FROM CYCLES 2 and 3 WHICH WERE NOT COMPLETED IN THOSE CYCLES.

  17. Camera for Quasars in Early Universe (CQUEAN)

    NASA Astrophysics Data System (ADS)

    Park, Won-Kee; Pak, Soojong; Im, Myungshin; Choi, Changsu; Jeon, Yiseul; Chang, Seunghyuk; Jeong, Hyeonju; Lim, Juhee; Kim, Eunbin

    2012-08-01

    We describe the overall characteristics and the performance of an optical CCD camera system, Camera for Quasars in Early Universe (CQUEAN), which has been used at the 2.1 m Otto Struve Telescope of the McDonald Observatory since 2010 August. CQUEAN was developed for follow-up imaging observations of red sources such as high-redshift quasar candidates (z gsim 5), gamma-ray bursts, brown dwarfs, and young stellar objects. For efficient observations of the red objects, CQUEAN has a science camera with a deep-depletion CCD chip, which boasts a higher quantum efficiency at 0.7-1.1 μm than conventional CCD chips. The camera was developed in a short timescale (~1 yr) and has been working reliably. By employing an autoguiding system and a focal reducer to enhance the field of view on the classical Cassegrain focus, we achieve a stable guiding in 20 minute exposures, an imaging quality with FWHM>=0.6'' over the whole field (4.8' × 4.8'), and a limiting magnitude of z = 23.4 AB mag at 5-σ with 1 hr total integration time. This article includes data taken at the McDonald Observatory of The University of Texas at Austin.

  18. LARGE-SCALE STAR-FORMATION-DRIVEN OUTFLOWS AT 1 < z < 2 IN THE 3D-HST SURVEY

    SciTech Connect

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

    2012-11-20

    We present evidence of large-scale outflows from three low-mass (log(M {sub *}/M {sub Sun }) {approx} 9.75) star-forming (SFR > 4 M {sub Sun} yr{sup -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 {sup {lambda}2796} {sub r} {approx}> 0.8 A) Mg II 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 M {sub Sun} yr{sup -1} kpc{sup -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 {sub 140} {approx}< 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 W{sub r} > 0.8 A 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 W{sub r} > 0.4 A Mg II absorbing gas around star-forming galaxies may evolve from z {approx} 2 to the present, consistent with recent observations of an increasing collimation of star-formation-driven outflows with time from z {approx} 3.

  19. Modeling the Observability of Recoiling Black Holes as Offset Quasars

    NASA Astrophysics Data System (ADS)

    Blecha, Laura; Torrey, Paul; Vogelsberger, Mark; Genel, Shy; Springel, Volker; Sijacki, Debora; Snyder, Gregory; Bird, Simeon; Nelson, Dylan; Xu, Dandan; Hernquist, Lars

    2015-08-01

    The merger of two supermassive black holes (SMBHs) imparts a gravitational-wave (GW) recoil kick to the remnant SMBH. In extreme cases these kicks may be thousands of km/s -- enough to easily eject them from their host galaxies. Moderate recoil kicks may also cause substantial displacements of the SMBH, however. An actively-accreting, recoiling SMBH may be observable as an offset quasar. Prior to the advent of a space-based GW observatory, detections of these offset quasars may offer the best chance for identifying recent SMBH mergers. Indeed, observational searches for recoiling quasars have already identified several promising candidates. However, systematic searches for recoils are currently hampered by large uncertainties regarding how often offset quasars should be observable, where they are most likely to be found, and whether BH spin alignment prior to merger is efficient at suppressing large recoils. Motivated by this, we have developed a model for the observable population of recoiling quasars in a cosmological framework, utilizing detailed information about the progenitor galaxies from state-of-the-art cosmological hydrodynamic simulations (the Illustris Project). The model for offset quasar lifetimes includes a physically-motivated, time-dependent model for accretion onto kicked SMBHs, and results are analyzed for a range of possible BH spin alignment models. We find that the observability of offset quasars depends strongly on the efficiency of pre-merger spin alignment, with promising indications that observations of recoils could distinguish between at least the extreme limits of spin alignment models. Our results also suggest that observable offset quasars should inhabit preferred types of host galaxies, where again these populations depend on the degree of pre-merger spin alignment. These findings will be valuable for planned and future dedicated searches for recoiling quasars, and they indicate that such objects might be used to place indirect

  20. How do optically-similar quasars look elsewhere?

    NASA Astrophysics Data System (ADS)

    Shang, Zhaohui; Ma, Bin; Brotherton, Michael S.

    2016-06-01

    As too many spectroscopic and physical parameters complicates the study of quasars, reducing the number of parameters can help to isolate many problems in general. Using spectral principal component analysis, we selected from SDSS a pilot sample of quasars with virtually identical spectral features in H-beta region. We found that they also show very similar spectral features outside the H-beta region in the optical band. We also explore their properties in other available wavelength bands and plan to study the accretion, ionization, and possibly geometry of quasars using this controlled sample.

  1. Photometric classification of quasars from RCS-2 using Random Forest

    NASA Astrophysics Data System (ADS)

    Carrasco, D.; Barrientos, L. F.; Pichara, K.; Anguita, T.; Murphy, D. N. A.; Gilbank, D. G.; Gladders, M. D.; Yee, H. K. C.; Hsieh, B. C.; López, S.

    2015-12-01

    The classification and identification of quasars is fundamental to many astronomical research areas. Given the large volume of photometric survey data available in the near future, automated methods for doing so are required. In this article, we present a new quasar candidate catalog from the Red-Sequence Cluster Survey 2 (RCS-2), identified solely from photometric information using an automated algorithm suitable for large surveys. The algorithm performance is tested using a well-defined SDSS spectroscopic sample of quasars and stars. The Random Forest algorithm constructs the catalog from RCS-2 point sources using SDSS spectroscopically-confirmed stars and quasars. The algorithm identifies putative quasars from broadband magnitudes (g, r, i, z) and colors. Exploiting NUV GALEX measurements for a subset of the objects, we refine the classifier by adding new information. An additional subset of the data with WISE W1 and W2 bands is also studied. Upon analyzing 542 897 RCS-2 point sources, the algorithm identified 21 501 quasar candidates with a training-set-derived precision (the fraction of true positives within the group assigned quasar status) of 89.5% and recall (the fraction of true positives relative to all sources that actually are quasars) of 88.4%. These performance metrics improve for the GALEX subset: 6529 quasar candidates are identified from 16 898 sources, with a precision and recall of 97.0% and 97.5%, respectively. Algorithm performance is further improved when WISE data are included, with precision and recall increasing to 99.3% and 99.1%, respectively, for 21 834 quasar candidates from 242 902 sources. We compiled our final catalog (38 257) by merging these samples and removing duplicates. An observational follow up of 17 bright (r < 19) candidates with long-slit spectroscopy at DuPont telescope (LCO) yields 14 confirmed quasars. The results signal encouraging progress in the classification of point sources with Random Forest algorithms to search

  2. Tracing a high redshift cosmic web with quasar systems

    NASA Astrophysics Data System (ADS)

    Einasto, Maret; Tago, Erik; Lietzen, Heidi; Park, Changbom; Heinämäki, Pekka; Saar, Enn; Song, Hyunmi; Liivamägi, Lauri Juhan; Einasto, Jaan

    2014-08-01

    Context. To understand the formation, evolution, and present-day properties of the cosmic web we need to study it at low and high redshifts. Aims: We trace the cosmic web at redshifts that range from 1.0 ≤ z ≤ 1.8 by using the quasar (QSO) data from the SDSS DR7 QSO catalogue. Methods: We apply a friend-of-friend algorithm to the quasar and random catalogues to determine systems at a series of linking length and analyse richness and sizes of these systems. Results: At the linking lengths l ≤ 30 h-1 Mpc, the number of quasar systems is larger than the number of systems detected in random catalogues, and the systems themselves have smaller diameters than random systems. The diameters of quasar systems are comparable to the sizes of poor galaxy superclusters in the local Universe. The richest quasar systems have four members. The mean space density of quasar systems, ≈ 10-7 (h-1 Mpc)-3, is close to the mean space density of local rich superclusters. At intermediate linking lengths (40 ≤ l ≤ 70 h-1 Mpc), the richness and length of quasar systems are similar to those derived from random catalogues. Quasar system diameters are similar to the sizes of rich superclusters and supercluster chains in the local Universe. The percolating system, which penetrate the whole sample volume appears in a quasar sample at a smaller linking length than in random samples (85 h-1 Mpc). At the linking length 70 h-1 Mpc, the richest systems of quasars have diameters exceeding 500 h-1 Mpc. Quasar luminosities in systems are not correlated with the system richness. Conclusions: Quasar system catalogues in our web pages and at the Strasbourg Astronomical Data Center (CDS) serve as a database for searching superclusters of galaxies and for tracing the cosmic web at high redshifts. Appendix A is available in electronic form at http://www.aanda.orgThe catalogues are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  3. Observational Cosmology Using Absorption Lines in Quasar Spectra

    NASA Astrophysics Data System (ADS)

    Aghaee, A.

    2016-09-01

    Distant, highly luminous quasars are important cosmological probes for a variety of astrophysical questions: the first generation of galaxies, the star formation history and metal enrichment in the early Universe, the growth of the first super massive black holes (SMBHs), the role of feedback from quasars and SMBHs in galaxy evolution, the epoch of reionization, etc. In addition, they are used as background illuminating source that reveal any object located by chance on the line of sight. I will present our group works in these issues that can be done using absorption lines in the quasar spectra.

  4. The Pan-STARRS1 z>6 quasar survey: More than 100 quasars within the first Gyr of the universe

    NASA Astrophysics Data System (ADS)

    Walter, Fabian; Banados, Eduardo; Venemans, Bram; Decarli, Roberto; Farina, Emanuele; Mazzucchelli, Chiara; Fan, Xiaohui; Chambers, Kenneth C.

    2016-01-01

    Quasars are the most luminous non-transient sources in the Universe. As such, they are ideal probes of the redshift range z=6-7, a critical phase in cosmic history, when the Universe is emerging from the dark ages. Over the last three years we have exploited the Pan-STARRS1 survey, more than doubling the number of known z>5.5 quasars (tripling the number of z>6 quasars in the southern sky, and discovering 4 of the 9 quasars known at z>6.5). This seach significantly extended the sampled parameter space in terms of quasar luminosities and redshift coverage. Pioneering studies already demostrate the intrumental role of QSOs in probing the very early phases of galaxy formation and black hole growth within 1 Gyr from the Big Bang: a) billion solar masses black holes are already in place, b) they are surrounded by massive reservoirs of cold gas, and c) the neutral fraction of the intergalactic medium rapidly drops after z~6, thus marking the end of the epoch of reionization. Our significantly enlarged sample marks the transition phase from studies of individual sources to statistical studies of the high-z quasar population. We present some of the comprehensive multiwavelength characterization of the high-z quasar population and their environment (our on-going efforts include deep NIR spectroscopy, ALMA, NOEMA, HST, Spitzer, and JVLA observations).

  5. THE QUASAR-GALAXY CROSS SDSS J1320+1644: A PROBABLE LARGE-SEPARATION LENSED QUASAR

    SciTech Connect

    Rusu, Cristian E.; Iye, Masanori; Oguri, Masamune; Inada, Naohisa; Kayo, Issha; Shin, Min-Su; Sluse, Dominique; Strauss, Michael A.

    2013-03-10

    We report the discovery of a pair of quasars at z = 1.487, with a separation of 8.''585 {+-} 0.''002. Subaru Telescope infrared imaging reveals the presence of an elliptical and a disk-like galaxy located almost symmetrically between the quasars, in a cross-like configuration. Based on absorption lines in the quasar spectra and the colors of the galaxies, we estimate that both galaxies are located at redshift z = 0.899. This, as well as the similarity of the quasar spectra, suggests that the system is a single quasar multiply imaged by a galaxy group or cluster acting as a gravitational lens, although the possibility of a binary quasar cannot be fully excluded. We show that the gravitational lensing hypothesis implies that these galaxies are not isolated, but must be embedded in a dark matter halo of virial mass {approx}4 Multiplication-Sign 10{sup 14} h {sup -1}{sub 70} M{sub Sun} assuming a Navarro-Frenk-White model with a concentration parameter of c{sub vir} = 6, or a singular isothermal sphere profile with a velocity dispersion of {approx}670 km s{sup -1}. We place constraints on the location of the dark matter halo, as well as the velocity dispersions of the galaxies. In addition, we discuss the influence of differential reddening, microlensing, and intrinsic variability on the quasar spectra and broadband photometry.

  6. A survey of z > 5.7 quasars in the sloan digital sky survey. 4. discovery of seven additional quasars

    SciTech Connect

    Fan, Xiao-Hui; Strauss, Michael A.; Richards, Gordon T.; Hennawi, Joseph F.; Becker, Robert H.; White, Richard L.; Diamond-Stanic, Aleksandar M.; onley, Jennifer L.D; Jiang, Lin-Hua; Kim, J.Serena; Vestergaard, Marianne; Young, Jason E.; Gunn, James E.; Lupton, Robert H.; Knapp, Gillian R.; Schneider, Donald P.; Brandt, W.N.; Bahcall, Neta A.; Barentine, J.C.; Brinkmann, J.; Brewington, Howard J.; /Arizona U., Astron. Dept. - Steward Observ. /Princeton U. Observ. /Johns Hopkins U. /UC, Berkeley, Astron. Dept. /UC, Davis /LLNL, Livermore /Baltimore, Space Telescope Sci. /Penn State U., Astron. Astrophys. /Apache Point Observ. /Tokyo U., ICRR /Mt. Suhora Observ., Cracow /Fermilab /Garching, Max Planck Inst., MPE

    2005-12-01

    We present the discovery of seven quasars at z > 5.7, selected from {approx}2000 deg{sup 2} of multicolor imaging data of the Sloan Digital Sky Survey (SDSS). The new quasars have redshifts z from 5.79 to 6.13. Five are selected as part of a complete flux-limited sample in the SDSS Northern Galactic Cap; two have larger photometric errors and are not part of the complete sample. One of the new quasars, SDSS J1335+3533 (z = 5.93), exhibits no emission lines; the 3-{sigma} limit on the rest-frame equivalent width of Ly{alpha} + NV line is 5 {angstrom}. It is the highest redshift lineless quasar known, and could be a gravitational lensed galaxy, a BL Lac object or a new type of quasar. Two new z > 6 quasars, SDSS 1250+3130 (z = 6.13) and SDSS J1137+3549 (z = 6.01), show deep Gunn-Peterson absorption gaps in Ly{alpha}. These gaps are narrower the complete Gunn-Peterson absorption troughs observed among quasars at z > 6.2 and do not have complete Ly{beta} absorption.

  7. Evidence for Gravitational Infall of Matter onto the Supermassive Black Hole in the Quasar PG 1211+143?

    NASA Astrophysics Data System (ADS)

    Reeves, J. N.; Pounds, K.; Uttley, P.; Kraemer, S.; Mushotzky, R.; Yaqoob, T.; George, I. M.; Turner, T. J.

    2005-11-01

    We report the detection of redshifted iron Kα absorption lines in the Chandra LETG spectrum of the narrow-line quasar PG 1211+143. The absorption lines are observed at 4.22 and 4.93 keV in the quasar spectrum, corresponding to 4.56 and 5.33 keV in the rest frame of PG 1211+143. From Monte Carlo simulations, the chance probability of both lines being false detections is low at 1.36×10-4. Highly redshifted ionized iron Kα (Fe XXV or Fe XXVI) is the most plausible identification for the lines at their observed energies. If identified with H-like iron Kα at 6.97 keV, then the relativistic velocity shifts required are 0.40c and 0.26c. The extreme velocities can be explained by pure gravitational redshift if the matter exists in a stable orbit within 6 gravitational radii of the black hole. This would require a Kerr metric for the black hole. Alternatively, the absorption may be the result of matter infalling directly onto the black hole, with a maximum observed velocity of 0.38c at 6Rg in the Schwarzschild metric. This matter may originate in a failed outflow or jet, which does not escape the gravitational potential of the black hole.

  8. THE REDSHIFT DISTRIBUTION OF INTERVENING WEAK Mg II QUASAR ABSORBERS AND A CURIOUS DEPENDENCE ON QUASAR LUMINOSITY

    SciTech Connect

    Evans, Jessica L.; Churchill, Christopher W.; Nielsen, Nikole M.; Klimek, Elizabeth S.; Murphy, Michael T.

    2013-05-01

    We have identified 469 Mg II {lambda}{lambda}2796, 2803 doublet systems having W{sub r} {>=} 0.02 A in 252 Keck/High Resolution Echelle Spectrometer and UVES/Very Large Telescope quasar spectra over the redshift range 0.1 < z < 2.6. Using the largest sample yet of 188 weak Mg II systems (0.02 A {<=}W{sub r} < 0.3 A), we calculate their absorber redshift path density, dN/dz. We find clear evidence of evolution, with dN/dz peaking at z {approx} 1.2, and that the product of the absorber number density and cross section decreases linearly with increasing redshift; weak Mg II absorbers seem to vanish above z {approx_equal} 2.7. If the absorbers are ionized by the UV background, we estimate number densities of 10{sup 6}-10{sup 9} Mpc{sup -3} for spherical geometries and 10{sup 2}-10{sup 5} Mpc{sup -3} for more sheetlike geometries. We also find that dN/dz toward intrinsically faint versus bright quasars differs significantly for weak and strong (W{sub r} {>=} 1.0 A) absorbers. For weak absorption, dN/dz toward bright quasars is {approx}25% higher than toward faint quasars (10{sigma} at low redshift, 0.4 {<=} z {<=} 1.4, and 4{sigma} at high redshift, 1.4 < z {<=} 2.34). For strong absorption the trend reverses, with dN/dz toward faint quasars being {approx}20% higher than toward bright quasars (also 10{sigma} at low redshift and 4{sigma} at high redshift). We explore scenarios in which beam size is proportional to quasar luminosity and varies with absorber and quasar redshifts. These do not explain dN/dz's dependence on quasar luminosity.

  9. The Redshift Distribution of Intervening Weak Mg II Quasar Absorbers and a Curious Dependence on Quasar Luminosity

    NASA Astrophysics Data System (ADS)

    Evans, Jessica L.; Churchill, Christopher W.; Murphy, Michael T.; Nielsen, Nikole M.; Klimek, Elizabeth S.

    2013-05-01

    We have identified 469 Mg II λλ2796, 2803 doublet systems having Wr >= 0.02 Å in 252 Keck/High Resolution Echelle Spectrometer and UVES/Very Large Telescope quasar spectra over the redshift range 0.1 < z < 2.6. Using the largest sample yet of 188 weak Mg II systems (0.02 Å <=Wr < 0.3 Å), we calculate their absorber redshift path density, dN/dz. We find clear evidence of evolution, with dN/dz peaking at z ~ 1.2, and that the product of the absorber number density and cross section decreases linearly with increasing redshift; weak Mg II absorbers seem to vanish above z ~= 2.7. If the absorbers are ionized by the UV background, we estimate number densities of 106-109 Mpc-3 for spherical geometries and 102-105 Mpc-3 for more sheetlike geometries. We also find that dN/dz toward intrinsically faint versus bright quasars differs significantly for weak and strong (Wr >= 1.0 Å) absorbers. For weak absorption, dN/dz toward bright quasars is ~25% higher than toward faint quasars (10σ at low redshift, 0.4 <= z <= 1.4, and 4σ at high redshift, 1.4 < z <= 2.34). For strong absorption the trend reverses, with dN/dz toward faint quasars being ~20% higher than toward bright quasars (also 10σ at low redshift and 4σ at high redshift). We explore scenarios in which beam size is proportional to quasar luminosity and varies with absorber and quasar redshifts. These do not explain dN/dz's dependence on quasar luminosity.

  10. The Prevalence of Gas Outflows in Type 2 AGNs. II. 3D Biconical Outflow Models

    NASA Astrophysics Data System (ADS)

    Bae, Hyun-Jin; Woo, Jong-Hak

    2016-09-01

    We present 3D models of biconical outflows combined with a thin dust plane for investigating the physical properties of the ionized gas outflows and their effect on the observed gas kinematics in type 2 active galactic nuclei (AGNs). Using a set of input parameters, we construct a number of models in 3D and calculate the spatially integrated velocity and velocity dispersion for each model. We find that three primary parameters, i.e., intrinsic velocity, bicone inclination, and the amount of dust extinction, mainly determine the simulated velocity and velocity dispersion. Velocity dispersion increases as the intrinsic velocity or the bicone inclination increases, while velocity (i.e., velocity shifts with respect to systemic velocity) increases as the amount of dust extinction increases. Simulated emission-line profiles well reproduce the observed [O iii] line profiles, e.g., narrow core and broad wing components. By comparing model grids and Monte Carlo simulations with the observed [O iii] velocity-velocity dispersion distribution of ˜39,000 type 2 AGNs, we constrain the intrinsic velocity of gas outflows ranging from ˜500 to ˜1000 km s-1 for the majority of AGNs, and up to ˜1500-2000 km s-1 for extreme cases. The Monte Carlo simulations show that the number ratio of AGNs with negative [O iii] velocity to AGNs with positive [O iii] velocity correlates with the outflow opening angle, suggesting that outflows with higher intrinsic velocity tend to have wider opening angles. These results demonstrate the potential of our 3D models for studying the physical properties of gas outflows, applicable to various observations, including spatially integrated and resolved gas kinematics.

  11. The Prevalence of Gas Outflows in Type 2 AGNs. II. 3D Biconical Outflow Models

    NASA Astrophysics Data System (ADS)

    Bae, Hyun-Jin; Woo, Jong-Hak

    2016-09-01

    We present 3D models of biconical outflows combined with a thin dust plane for investigating the physical properties of the ionized gas outflows and their effect on the observed gas kinematics in type 2 active galactic nuclei (AGNs). Using a set of input parameters, we construct a number of models in 3D and calculate the spatially integrated velocity and velocity dispersion for each model. We find that three primary parameters, i.e., intrinsic velocity, bicone inclination, and the amount of dust extinction, mainly determine the simulated velocity and velocity dispersion. Velocity dispersion increases as the intrinsic velocity or the bicone inclination increases, while velocity (i.e., velocity shifts with respect to systemic velocity) increases as the amount of dust extinction increases. Simulated emission-line profiles well reproduce the observed [O iii] line profiles, e.g., narrow core and broad wing components. By comparing model grids and Monte Carlo simulations with the observed [O iii] velocity–velocity dispersion distribution of ∼39,000 type 2 AGNs, we constrain the intrinsic velocity of gas outflows ranging from ∼500 to ∼1000 km s‑1 for the majority of AGNs, and up to ∼1500–2000 km s‑1 for extreme cases. The Monte Carlo simulations show that the number ratio of AGNs with negative [O iii] velocity to AGNs with positive [O iii] velocity correlates with the outflow opening angle, suggesting that outflows with higher intrinsic velocity tend to have wider opening angles. These results demonstrate the potential of our 3D models for studying the physical properties of gas outflows, applicable to various observations, including spatially integrated and resolved gas kinematics.

  12. Mass Outflow in the Narrow Line Region of Markarian 573

    NASA Astrophysics Data System (ADS)

    Revalski, Mitchell; Crenshaw, D. Michael; Fischer, Travis C.; Kraemer, Steven B.; Schmitt, Henrique R.

    2016-01-01

    We present our progress toward determining the mass outflow rate in the narrow emission line region (NLR) of the Seyfert 2 galaxy Markarian 573. Mass outflows in Active Galactic Nuclei (AGN) drive gas away from the central supermassive black hole (SMBH) into the circumnuclear environment, and may play an important role in regulating the growth of the SMBH, and its coevolution with the host galaxy bulge. Recent work by Crenshaw et al. (2015, ApJ, 799, 83) found that the mass outflow rate in the NLR of NGC 4151 is too large for the outflowing mass to have originated only from the central region, indicating a significant amount of gas is picked up by the outflow as it travels away from the nucleus. Using archival spectra taken with the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS), we are working to determine the mass outflow rates in a sample of 10 Seyfert galaxies to determine if correlations exist between their outflows and other properties including galaxy luminosity. To accomplish this, we will analyze the emission line spectra using photoionization models to determine the mass of the outflowing gas. Combining this information with previous kinematic modeling from Fischer et al. (2013, ApJS, 209, 1), we can determine the mass outflow rates and kinetic luminosities as a function of radius from the nucleus. These quantities will provide a direct comparison between observation and theoretical feedback models, allowing us to determine the significance of these outflows in regulating AGN feedback.

  13. QUASAR-GALAXY CLUSTERING THROUGH PROJECTED GALAXY COUNTS AT z = 0.6-1.2

    SciTech Connect

    Zhang Shaohua; Zhou Hongyan; Wang Tinggui; Wang Huiyuan E-mail: twang@ustc.edu.cn

    2013-08-20

    We investigate the spatial clustering of galaxies around quasars at z = 0.6-1.2 using photometric data from Sloan Digital Sky Survey Stripe 82. The quasar and galaxy cross-correlation functions are measured through the projected galaxy number density n(r{sub p} ) on scales of 0.05 < r{sub p} < 20 h {sup -1} Mpc around quasars for a sample of 2300 quasars from Schneider et al. We detect strong clustering signals at all redshifts and find that the clustering amplitude increases significantly with redshift. We examine the dependence of quasar-galaxy clustering on quasar and galaxy properties and find that the clustering amplitude is significantly larger for quasars with more massive black holes or with bluer colors, while there is no dependence on quasar luminosity. We also show that quasars have a stronger correlation amplitude with blue galaxies than with red galaxies. We finally discuss the implications of our findings.

  14. The discovery of quasars and its aftermath

    NASA Astrophysics Data System (ADS)

    Kellermann, K. I.

    2014-11-01

    Although the extragalactic nature of quasars was discussed as early as 1960 by John Bolton and others it was rejected largely because of preconceived ideas about what appeared to be an unrealistically-high radio and optical luminosity. Following the 1962 observation of the occultations of the strong radio source 3C 273 with the Parkes Radio Telescope and the subsequent identification by Maarten Schmidt of an apparent stellar object, Schmidt recognized that the simple hydrogen line Balmer series spectrum implied a redshift of 0.16. Successive radio and optical measurements quickly led to the identification of other quasars with increasingly-large redshifts and the general, although for some decades not universal, acceptance of quasars as being by far the most distant and the most luminous objects in the Universe. However, due to an error in the calculation of the radio position, it appears that the occultation position played no direct role in the identification of 3C 273, although it was the existence of a claimed accurate occultation position that motivated Schmidt's 200-in Palomar telescope investigation and his determination of the redshift. Curiously, 3C 273, which is one of the strongest extragalactic sources in the sky, was first catalogued in 1959, and the 13th magnitude optical counterpart was observed at least as early as 1887. Since 1960, much fainter optical counterparts were being routinely identified, using accurate radio interferometer positions which were measured primarily at the Caltech Owens Valley Radio Observatory. However, 3C 273 eluded identification until the series of lunar occultation observations led by Cyril Hazard. Although an accurate radio position had been obtained earlier with the Owens Valley Interferometer, inexplicably 3C 273 was misidentified with a faint galaxy located about one arc minute away from the true position. It appears that the Parkes occultation position played only an indirect role in the identification of the

  15. Sensitive radio survey of obscured quasar candidates

    NASA Astrophysics Data System (ADS)

    Alexandroff, Rachael M.; Zakamska, Nadia L.; van Velzen, Sjoert; Greene, Jenny E.; Strauss, Michael A.

    2016-08-01

    We study the radio properties of moderately obscured quasars in samples at both low (z ˜ 0.5) and high (z ˜ 2.5) redshift to understand the role of radio activity in accretion, using the Karl G. Jansky Very Large Array (VLA) at 6.0GHz and 1.4GHz. Our z ˜ 2.5 sample consists of optically-selected obscured quasar candidates, all of which are radio-quiet, with typical radio luminosities of νLν[1.4 GHz]⪉ 10^{40} erg s-1. Only a single source is individually detected in our deep (rms˜10 μJy) exposures. This population would not be identified by radio-based selection methods used for distinguishing dusty star-forming galaxies and obscured active nuclei. In our pilot A-array study of z ˜ 0.5 radio-quiet quasars, we spatially resolve four of five objects on scales ˜5 kpc and find they have steep spectral indices with an average value of α = -0.75. Therefore, radio emission in these sources could be due to jet-driven or radiatively driven bubbles interacting with interstellar material on the scale of the host galaxy. Finally, we also study the additional population of ˜200 faint (˜40μJy - 40mJy) field radio sources observed over ˜120 arcmin2 of our data. 60% of these detections (excluding our original targets) are matched in the Sloan Digital Sky Survey (SDSS) and/or Wide-Field Infrared Survey Explorer (WISE) and are, in roughly equal shares, active galactic nuclei (AGN) at a broad range of redshifts, passive galaxies with no other signs of nuclear activity and infrared-bright but optically faint sources. Spectroscopically or photometrically confirmed star-forming galaxies constitute only a small minority of the matches. Such sensitive radio surveys allow us to address important questions of AGN evolution and evaluate the AGN contribution to the radio-quiet sky.

  16. Cosmology with AGN: can we use quasars as standard candles?

    NASA Astrophysics Data System (ADS)

    Risaliti, G.

    2016-06-01

    The non-linear relation between X-ray and UV luminosity in quasars can be used to estimate their distance. Recently, we have shown that despite the large dispersion of the relation, a Hubble Diagram made of large samples of quasars can provide unique constraints on cosmology at high redshift. Furthermore, the dispersion of the relation is heavily affected by measurement errors: until now we have used serendipitous X-ray observations, but dedicated observations would significantly increase the precision of the distance estimates. I discuss the future role of XMM in this new field, showing (1) the fundamental contribution of the Serendipitous Source Catalogue and of large surveys, and (2) the breakthrough advancements we may achieve with the observation of a large number of SDSS quasars at high redshift: every 12-15 quasars observed at z~3 would be equivalent to discovering a supernova at that redshift.

  17. Quasars and their emission lines as cosmological probes

    NASA Astrophysics Data System (ADS)

    Marziani, Paola; Sulentic, Jack W.

    2014-10-01

    Quasars are the most luminous sources in the Universe. They are currently observed out to redshift z≈7 when the Universe was less than one tenth of its present age. Since their discovery 50 years ago astronomers have dreamed of using them as standard candles. Unfortunately quasars cover a very large range (8 dex) of luminosity making them far from standard. We briefly review several methods that can potentially exploit quasars properties and allow us to obtain useful constraints on principal cosmological parameters. Using our 4D Eigenvector 1 formalism we have found a way to effectively isolate quasars radiating near the Eddington limit. If the Eddington ratio is known, under several assumptions it is possible to derive distance independent luminosities. We discuss the main statistical and systematic errors involved, and whether these “standard Eddington candles” can be actually used to constrain cosmological models.

  18. The Doppler Effect: A Consideration of Quasar Redshifts.

    ERIC Educational Resources Information Center

    Gordon, Kurtiss J.

    1980-01-01

    Provides information on the calculation of the redshift to blueshift ratio introduced by the transverse Doppler effect at relativistic speeds. Indicates that this shift should be mentioned in discussions of whether quasars are "local" rather than "cosmological" objects. (GS)

  19. CORRELATIONS OF QUASAR OPTICAL SPECTRA WITH RADIO MORPHOLOGY

    SciTech Connect

    Kimball, Amy E.; Ivezic, Zeljko; Wiita, Paul J.; Schneider, Donald P.

    2011-06-15

    Using the largest homogeneous quasar sample with high-quality optical spectra and robust radio morphology classifications assembled to date, we investigate relationships between radio and optical properties with unprecedented statistical power. The sample consists of 4714 radio quasars from FIRST with S{sub 20} {>=} 2 mJy and with spectra from the Sloan Digital Sky Survey (SDSS). Radio morphology classes include core-only (core), core-lobe (lobe), core-jet (jet), lobe-core-lobe (triple), and double-lobe. Electronic tables of the quasar samples, along with spectral composites for individual morphology classes, are made available. We examine the optical colors of these subsamples and find that radio quasars with core emission unresolved by FIRST (on {approx}5'' scale) have a redder color distribution than radio-quiet quasars (S{sub 20} {approx}< 1 mJy); other classes of radio quasars have optical color distributions similar to the radio-quiet quasars. This analysis also suggests that optical colors of z {approx}< 2.7 SDSS quasars are not strongly (<0.1 mag) biased blue. We show that the radio core-to-lobe flux density ratio (R) and the radio-to-optical (i-band) ratio of the quasar core (R{sub I}) are correlated, which supports the hypothesis that both parameters are indicative of line-of-sight orientation. We investigate spectral line equivalent widths (EWs) as a function of R and R{sub I}, including the O [III] narrow line doublet and the C IV {lambda}1549 and Mg II {lambda}2799 broad lines. We find that the rest EWs of the broad lines correlate positively with R{sub I} at the 4{sigma}-8{sigma} level. However, we find no strong dependence of EW on R, in contrast to previously published results. A possible interpretation of these results is that EWs of quasar emission lines increase as the line-of-sight angle to the radio-jet axis decreases. These results are in stark contrast to commonly accepted orientation-based theories, which suggest that continuum emission

  20. Evidence for Collimated Outflow from Sgr A*?

    NASA Astrophysics Data System (ADS)

    Yusef-Zadeh, Farhad; Arendt, R.; Bushouse, H.; Cotton, W.; Haggard, D.; Heinke, C.; Roberts, D. A.; Royster, M.; Wardle, M.

    2012-05-01

    The compact radio source Sgr A* is considered to be coincident with a 4 million solar mass black hole at the dynamical center of the Galaxy. There has been a considerable debate as to whether the jet or the accretion flow model can explain the broad band spectrum of the emission. Here, we present high resolution radio, X-ray continuum and FeII line images showing new structural details within the inner arcminute (2.4pc) of Sgr A*. On a small scale, we find a chain of radio blobs which appear to be emanating from Sgr A*. These blobs are detected beyond the inner 1" of Sgr A* and are distributed along a continuous linear feature that is tilted by 28 degrees with respect to the Galactic plane. In linear polarization images at 3.6cm, three blobs of emission have been detected symmetrically about 1' from Sgr A*. The morphology and polarization of the linear feature suggest a jet outflow from Sgr A*, punching through the orbiting ionized gas and producing X-ray emission as well as a hot bubble of FeIII/FeII line emission. On a scale of about 15pc, we also note a collection of large-scale radio and X-ray "streamers" in the direction perpendicular to the Galactic plane. This complex structure consists of nonthermal and thermal continuum features as well as molecular clouds traced at infrared wavelengths. The base of the outflowing gas appears to be confined by the 2-pc molecular ring, within which a cluster of massive stars lie. These features suggest star-burst driven outflow may be responsible for this energetic activity.

  1. The He II Proximity Effect and The Lifetime of Quasars

    NASA Astrophysics Data System (ADS)

    Khrykin, I. S.; Hennawi, J. F.; McQuinn, M.; Worseck, G.

    2016-06-01

    The lifetime of quasars is fundamental for understanding the growth of supermassive black holes, and is an important ingredient in models of the reionization of the intergalactic medium (IGM). However, despite various attempts to determine quasar lifetimes, current estimates from a variety of methods are uncertain by orders of magnitude. This work combines cosmological hydrodynamical simulations and 1D radiative transfer to investigate the structure and evolution of the He ii Lyα proximity zones around quasars at z ≃ 3-4. We show that the time evolution in the proximity zone can be described by a simple analytical model for the approach of the He ii fraction {x}{He{{II}}}(t) to ionization equilibrium, and use this picture to illustrate how the transmission profile depends on the quasar lifetime, quasar UV luminosity, and the ionization state of Helium in the ambient IGM (i.e., the average He ii fraction, or equivalently the metagalactic He ii ionizing background). A significant degeneracy exists between the lifetime and the average He ii fraction, however the latter can be determined from measurements of the He ii Lyα optical depth far from quasars, allowing the lifetime to be measured. We advocate stacking existing He ii quasar spectra at z ˜ 3, and show that the shape of this average proximity zone profile is sensitive to lifetimes as long as ˜30 Myr. At higher redshift z ˜ 4 where the He ii fraction is poorly constrained, degeneracies will make it challenging to determine these parameters independently. Our analytical model for He ii proximity zones should also provide a useful description of the properties of H i proximity zones around quasars at z ≃ 6-7.

  2. Broad Absorption Line Quasar catalogues with Supervised Neural Networks

    SciTech Connect

    Scaringi, Simone; Knigge, Christian; Cottis, Christopher E.; Goad, Michael R.

    2008-12-05

    We have applied a Learning Vector Quantization (LVQ) algorithm to SDSS DR5 quasar spectra in order to create a large catalogue of broad absorption line quasars (BALQSOs). We first discuss the problems with BALQSO catalogues constructed using the conventional balnicity and/or absorption indices (BI and AI), and then describe the supervised LVQ network we have trained to recognise BALQSOs. The resulting BALQSO catalogue should be substantially more robust and complete than BI-or AI-based ones.

  3. Thermal Emission from Warm Dust in the Most Distant Quasars

    NASA Astrophysics Data System (ADS)

    Wang, Ran; Carilli, Chris L.; Wagg, Jeff; Bertoldi, Frank; Walter, Fabian; Menten, Karl M.; Omont, Alain; Cox, Pierre; Strauss, Michael A.; Fan, Xiaohui; Jiang, Linhua; Schneider, Donald P.

    2008-11-01

    We report new continuum observations of 14 z ~ 6 quasars at 250 GHz and 14 quasars at 1.4 GHz. We summarize all recent millimeter and radio observations of the sample of the 33 quasars known with 5.71 <= z<= 6.43 and present a study of the rest-frame far-infrared (FIR) properties of this sample. These quasars were observed with the Max Planck Millimeter Bolometer Array (MAMBO) at 250 GHz with mJy sensitivity, and 30% of them were detected. We also recover the average 250 GHz flux density of the MAMBO undetected sources at 4 σ by stacking the on-source measurements. The derived mean radio-to-UV spectral energy distributions (SEDs) of the full sample and the 250 GHz nondetections show no significant differences from lower redshift optical quasars. Obvious FIR excesses are seen in the individual SEDs of the strong 250 GHz detections, with FIR-to-radio emission ratios consistent with those of typical star-forming galaxies. Most 250 GHz-detected sources follow the LFIR-Lbol relationship derived from a sample of local IR-luminous quasars (LIR > 1012 L⊙), while the average LFIR/Lbol ratio of the nondetections is consistent with that of the optically selected PG quasars. The MAMBO detections also tend to have weaker Lyα emission than the nondetected sources. We discuss possible FIR dust-heating sources and critically assess the possibility of active star formation in the host galaxies of the z ~ 6 quasars. The average star formation rate of the MAMBO nondetections is likely to be less than a few hundred M⊙ yr-1, but in the strong detections, the host galaxy star formation is probably at a rate of gtrsim103 M⊙ yr-1, which dominates the FIR dust heating.

  4. Fifty Years of Quasars: Physical Insights and Potential for Cosmology

    NASA Astrophysics Data System (ADS)

    Sulentic, J. W.; Marziani, P.; Dultzin, D.; D'Onofrio, M.; del Olmo, A.

    2014-12-01

    Last year (2013) was more or less the 50th anniversary of the discovery of quasars. It is an interesting time to review what we know (and don't know) about them both empirically and theoretically. These compact sources involving line emitting plasma show extraordinary luminosities extending to one thousand times that of our Milky Way in emitting volumes of a few solar system diameters (log Lboi= 44.0 - 48.0 erg s-1: D=1-3 light months ~ 103 - 104 gravitational radii). The advent of 8-10 meter class telescopes enables us to study them spectroscopically in ever greater detail. In 2000 we introduced a 4D Eigenvector 1 parameters space involving optical, UV and X- ray measures designed to serve as a 4D equivalent of the 2D H-R diagram so important for depicting the diversity of stellar types and evolutionary states. This diagram has revealed a principal sequence of quasars distinguished by Eddington ratio (proportional to the accretion rate per unit mass). Thus while stellar differences are primarily driven by the mass of a star, quasar differences are apparently driven by the ratio of luminosity-to-mass. Out of this work has emerged the concept of two quasars populations A and B separated at Eddington ratio around 0.2 which maximizes quasar multispectral differences. The mysterious 8% of quasars that are radio-loud belong to population B which are the lowest accretors with the largest black hole masses. Finally we consider the most extreme population A quasars which are the highest accretors and in some cases are among the youngest quasars. We describe how these sources might be exploited as standard candles for cosmology.

  5. THE FIRST HIGH-REDSHIFT QUASAR FROM Pan-STARRS

    SciTech Connect

    Morganson, Eric; De Rosa, Gisella; Decarli, Roberto; Walter, Fabian; Rix, Hans-Walter; Chambers, Ken; Burgett, William; Flewelling, Heather; Hodapp, Klaus; Kaiser, Nick; Magnier, Eugene; Sweeney, Bill; Waters, Christopher; McGreer, Ian; Fan, Xiaohui; Greiner, Jochen; Price, Paul

    2012-06-15

    We present the discovery of the first high-redshift (z > 5.7) quasar from the Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1 or PS1). This quasar was initially detected as an i{sub P1} dropout in PS1, confirmed photometrically with the SAO Wide-field InfraRed Camera at Arizona's Multiple Mirror Telescope (MMT) and the Gamma-Ray Burst Optical/Near-Infrared Detector at the MPG 2.2 m telescope in La Silla. The quasar was verified spectroscopically with the MMT Spectrograph, Red Channel and the Cassegrain Twin Spectrograph at the Calar Alto 3.5 m telescope. Its near-infrared spectrum was taken at the Large Binocular Telescope Observatory (LBT) with the LBT Near-Infrared Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research. It has a redshift of 5.73, an AB z{sub P1} magnitude of 19.4, a luminosity of 3.8 Multiplication-Sign 10{sup 47} erg s{sup -1}, and a black hole mass of 6.9 Multiplication-Sign 10{sup 9} M{sub Sun }. It is a broad absorption line quasar with a prominent Ly{beta} peak and a very blue continuum spectrum. This quasar is the first result from the PS1 high-redshift quasar search that is projected to discover more than 100 i{sub P1} dropout quasars and could potentially find more than 10 z{sub P1} dropout (z > 6.8) quasars.

  6. Ultraviolet (UV) From Quasars - Skylab Student Experiment ED-23

    NASA Technical Reports Server (NTRS)

    1973-01-01

    This chart describes the Skylab student experiment Ultraviolet (UV) from Quasars, proposed by John C. Hamilton of Aiea, Hawaii. This experiment utilized Skylab's Ultraviolet Stellar Astronomy equipment to photograph quasars in the UV spectrum and compare those images to existing radio and visible data. In March 1972 NASA and the National Science Teachers Association selected 25 experiment proposals for flight on Skylab. Science advisors from the Marshall Space Flight Center aided and assisted the students in developing the proposals for flight on Skylab.

  7. Functional Anatomy of the Outflow Facilities.

    PubMed

    Pizzirani, Stefano; Gong, Haiyan

    2015-11-01

    In order to understand the pathophysiology, select optimal therapeutic options for patients and provide clients with honest expectations for cases of canine glaucoma, clinicians should be familiar with a rational understanding of the functional anatomy of the ocular structures involved in this group of diseases. The topographical extension and the structural and humoral complexity of the regions involved with the production and the outflow of aqueous humor undergo numerous changes with aging and disease. Therefore, the anatomy relative to the fluid dynamics of aqueous has become a pivotal yet flexible concept to interpret the different phenotypes of glaucoma.

  8. Valles Marineris and Chryse Outflow Channels

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A color image of Valles Marineris, the great canyon and the south Chryse basin-Valles Marineris outflow channels of Mars; north toward top. The scene shows the entire Valles Marineris canyon system, over 3,000 km long and averaging 8 km deep, extending from Noctis Labyrinthus, the arcuate system of graben to the west, to the chaotic terrain to the east and related outflow canyons that drain toward the Chryse basin. Eos and Capri Chasmata (south to north) are two canyons connected to Valles Marineris. Ganges Chasma lies directly north. The chaos in the southeast part of the image gives rise to several outflow channels, Shalbatana, Simud, Tiu, and Ares Valles (left to right), that drained north into the Chryse basin. The mouth of Ares Valles is the site of the Mars Pathfinder lander.

    This image is a composite of Viking medium-resolution images in black and white and low-resolution images in color; Mercator projection. The image roughly extends from latitude 20 degrees S. to 20 degrees N. and from longitude 15 degrees to 102.5 degrees.

    The connected chasma or valleys of Valles Marineris may have formed from a combination of erosional collapse and structural activity. Layers of material in the eastern canyons might consist of carbonates deposited in ancient lakes, eolian deposits, or volcanic materials. Huge ancient river channels began from Valles Marineris and from adjacent canyons and ran north. Many of the channels flowed north into Chryse Basin.

    The south Chryse outflow channels are cut an average of 1 km into the cratered highland terrain. This terrain is about 9 km above datum near Valles Marineris and steadily decreases in elevation to 1 km below datum in the Chryse basin. Shalbatana is relatively narrow (10 km wide) but can reach 3 km in depth. The channel begins at a 2- to 3-km-deep circular depression within a large impact crater, whose floor is partly covered by chaotic material, and ends in Simud Valles. Tiu and Simud Valles consist of a

  9. ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

    SciTech Connect

    McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S.; Lockman, F. J.; Dickey, J. M.; Gaensler, B. M.; Green, A. J.

    2013-06-10

    We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of {approx}14 km s{sup -1}, and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at {approx}200 km s{sup -1} in a Galactic wind.

  10. Probing the dark energy with quasar clustering.

    PubMed

    Calvão, M O; de Mello Neto, J R T; Waga, I

    2002-03-01

    We show through Monte Carlo simulations that the Alcock-Paczyński test, as applied to quasar clustering, is a powerful tool to probe the cosmological density and equation of state parameters Omega(m0), Omega(x0), and w. By taking into account the effect of peculiar velocities upon the correlation function we obtain for the Two-Degree Field QSO Redshift Survey the predicted confidence contours for the cosmological constant (w = -1) and spatially flat (Omega(m0)+Omega(x0) = 1) cases. For w = -1, the test is especially sensitive to the difference Omega(m0)-Omega(Lambda0), thus being ideal to combine with cosmic microwave background results. For the flat case, it is competitive with future supernova and galaxy number count tests, besides being complementary to them.

  11. Feedback Mechanisms of Starbursts and AGNs through Molecular Outflows

    NASA Astrophysics Data System (ADS)

    Matsushita, S.; Krips, M.; Lim, J.; Muller, S.; Tsai, A.-L.

    2013-10-01

    Our deep molecular line images of nearby starburst galaxies and AGNs exhibit molecular outflows in most galaxies, and have revealed that the molecular outflows co-exist with outflows or jets seen in other wavelengths. In case of starbursts, X-ray outflows have higher energy and pressure than those of molecular outflows, suggesting that plasma outflows are blowing the molecular gas away from starburst regions, which suggests a strong negative feedback. On the other hand, current starburst regions in M82 can be seen at the inner edge of an expanding molecular bubble, suggesting a positive feedback. In case of AGNs, jets seem to entrain the surrounding molecular gas away from the AGNs, suggesting a negative feedback.

  12. A resolved outflow of matter from a brown dwarf.

    PubMed

    Whelan, Emma T; Ray, Thomas P; Bacciotti, Francesca; Natta, Antonella; Testi, Leonardo; Randich, Sofia

    2005-06-01

    The birth of stars involves not only accretion but also, counter-intuitively, the expulsion of matter in the form of highly supersonic outflows. Although this phenomenon has been seen in young stars, a fundamental question is whether it also occurs among newborn brown dwarfs: these are the so-called 'failed stars', with masses between stars and planets, that never manage to reach temperatures high enough for normal hydrogen fusion to occur. Recently, evidence for accretion in young brown dwarfs has mounted, and their spectra show lines that are suggestive of outflows. Here we report spectro-astrometric data that spatially resolve an outflow from a brown dwarf. The outflow's characteristics appear similar to, but on a smaller scale than, outflows from normal young stars. This result suggests that the outflow mechanism is universal, and perhaps relevant even to the formation of planets.

  13. Quasar Variability in the Mid-Infrared

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon; Kochanek, Christopher S.; Ashby, Matthew L. N.; Assef, Roberto J.; Brodwin, Mark; Eisenhardt, Peter R.; Jannuzi, Buell T.; Stern, Daniel

    2016-02-01

    The Decadal IRAC Boötes Survey is a mid-IR variability survey of the ˜9 sq. deg. of the NDWFS Boötes Field and extends the time baseline of its predecessor, the Spitzer Deep, Wide-Field Survey (SDWFS), from 4 to 10 years. The Spitzer Space Telescope visited the field five times between 2004 and 2014 at 3.6 and 4.5 μm. We provide the difference image analysis photometry for a half a million mostly extragalactic sources. In mid-IR color-color plane, sources with quasar colors constitute the largest variability class (75%), 16% of the variable objects have stellar colors and the remaining 9% have the colors of galaxies. Adding the fifth epoch doubles the number of variable active galactic nuclei (AGNs) for the same false positive rates as in SDWFS, or increases the number of sources by 20% while decreasing the false positive rates by factors of 2-3 for the same variability amplitude. We quantify the ensemble mid-IR variability of ˜1500 spectroscopically confirmed AGNs using single power-law structure functions (SFs), which we find to be steeper (index γ ≈ 0.45) than in the optical (γ ≈ 0.3), leading to much lower amplitudes at short time-lags. This provides evidence for large emission regions, smoothing out any fast UV/optical variations, as the origin of infrared quasar variability. The mid-IR AGN SF slope γ seems to be uncorrelated with both the luminosity and rest-frame wavelength, while the amplitude shows an anti-correlation with the luminosity and a correlation with the rest-frame wavelength.

  14. An astrophysics data program investigation of a synoptic study of quasar continua

    NASA Technical Reports Server (NTRS)

    Elvis, Martin

    1991-01-01

    A summary of the program is presented. The major product of the program, an atlas of quasar energy distributions, is presented in the appendices along with papers written as a result of this research. The topics covered in the papers include: (1) accurate galactic N(sub h) values toward quasars and active galactic nuclei (AGN); (2) weak bump quasars; (3) millimeter measurements of hard x ray selected active galaxies- implications for the nature of the continuous spectrum; (3) persistence and change in the soft x ray spectrum of the quasar PG1211+143; (4) the soft x ray excess in einstein quasar spectra; and (5) EXOSAT x ray spectra of quasars.

  15. Magnification of light from many distant quasars by gravitational lenses.

    PubMed

    Wyithe, J Stuart B; Loeb, Abraham

    2002-06-27

    Exceptionally bright quasars with redshifts up to z = 6.28 have recently been discovered. Quasars are thought to be powered by the accretion of gas onto supermassive black holes at the centres of galaxies. Their maximum (Eddington) luminosity depends on the mass of the black hole, and the brighter quasars are inferred to have black holes with masses of more than a few billion solar masses. The existence of such massive black holes poses a challenge to models for the formation of structures in the early Universe, as it requires their formation within one billion years of the Big Bang. Here we show that up to one-third of known quasars with z approximately equal to 6 will have had their observed flux magnified by a factor of ten or more, as a consequence of gravitational lensing by galaxies along the line of sight. The inferred abundance of quasar host galaxies, as well as the luminosity density provided by the quasars, has therefore been substantially overestimated.

  16. Dissecting the Quasar Main Sequence: Insight from Host Galaxy Properties

    NASA Astrophysics Data System (ADS)

    Sun, Jiayi; Shen, Yue

    2015-05-01

    The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical Fe ii strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/LEdd) of the black hole (BH) accretion. Shen & Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing Fe ii strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion σ* (hence, the BH mass via the M-σ* relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, σ* systematically decreases with increasing Fe ii strength, confirming that the Eddington ratio increases with Fe ii strength. We also found that at fixed luminosity and Fe ii strength, there is little dependence of σ* on the broad Hβ FWHM. These new results reinforce the framework that the Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties.

  17. DISSECTING THE QUASAR MAIN SEQUENCE: INSIGHT FROM HOST GALAXY PROPERTIES

    SciTech Connect

    Sun, Jiayi; Shen, Yue

    2015-05-01

    The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical Fe ii strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L{sub Edd}) of the black hole (BH) accretion. Shen and Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing Fe ii strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion σ{sub *} (hence, the BH mass via the M–σ{sub *} relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, σ{sub *} systematically decreases with increasing Fe ii strength, confirming that the Eddington ratio increases with Fe ii strength. We also found that at fixed luminosity and Fe ii strength, there is little dependence of σ{sub *} on the broad Hβ FWHM. These new results reinforce the framework that the Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties.

  18. A search for quasars in the Virgo cluster region

    NASA Technical Reports Server (NTRS)

    He, X.-T.; Cannon, R. D.; Peacock, J. A.; Smith, M. G.; Oke, J. B.

    1984-01-01

    Using objective-prism plates taken with the 44-arcmin objective prism mounted on the UK Schmidt telescope, 53 emission-line quasar candidates and 29 ultraviolet-excess objects (possible low-redshift quasars) have been found in a 5 x 5-degree field centered on 12 h 27 m, + 13 deg 30 min (1950) in the Virgo cluster of galaxies. Eighteen of these 82 candidates were observed using the double spectrograph on the Palomar 5-meter telescope; 13 of the observed objects proved to be quasars. The broad-absorption-line QSO Q1232 + 134 is the first example of the class to show broad low-ionization absorption lines (such as Mg II 2798 A) in addition to the usual high-excitation lines such as Nv 1240 A. Although no conclusive evidence for quasar-galaxy associations is found in this field, there do exist nonuniformities in the distribution of the quasar candidates which may merit further investigation. These objects will provide a useful network of probes for absorbing material in the Virgo cluster. The lines-of-sight to two of the confirmed quasars pass very close to NGC galaxies; the respective projected QSO-galaxy separations are only 4 and 11 kpc at the assumed distance of the Virgo cluster.

  19. The near-to-mid infrared spectrum of quasars

    NASA Astrophysics Data System (ADS)

    Hernán-Caballero, Antonio; Hatziminaoglou, Evanthia; Alonso-Herrero, Almudena; Mateos, Silvia

    2016-08-01

    We analyse a sample of 85 luminous (log (νLν(3µm)/erg s-1)>45.5) quasars with restframe ˜2-11 µm spectroscopy from AKARI and Spitzer. Their high luminosity allows a direct determination of the near-infrared quasar spectrum free from host galaxy emission. A semi-empirical model consisting of a single template for the accretion disk and two blackbodies for the dust emission successfully reproduces the 0.1-10 µm spectral energy distributions (SEDs). Excess emission at 1-2 µm over the best-fitting model suggests that hotter dust is necessary in addition to the ˜1200 K blackbody and the disk to reproduce the entire near-infrared spectrum. Variation in the extinction affecting the disk and in the relative strength of the disk and dust components accounts for the diversity of individual SEDs. Quasars with higher dust-to-disk luminosity ratios show slightly redder infrared continua and less prominent silicate emission. We find no luminosity dependence in the shape of the average infrared quasar spectrum. We generate a new quasar template that covers the restframe range 0.1-11 µm, and separate templates for the disk and dust components. Comparison with other infrared quasar composites suggests that previous ones are less reliable in the 2-4 µm range. Our template is the first one to provide a detailed view of the infrared emission on both sides of the 4 µm bump.

  20. TRACING THE BIPOLAR OUTFLOW FROM ORION SOURCE I

    SciTech Connect

    Plambeck, R. L.; Wright, M. C. H.; Friedel, D. N.; Widicus Weaver, S. L.; Bolatto, A. D.; Pound, M. W.; Woody, D. P.; Lamb, J. W.; Scott, S. L.

    2009-10-10

    Using CARMA, we imaged the 87 GHz SiO v = 0 J = 2-1 line toward Orion-KL with 0.''45 angular resolution. The maps indicate that radio source I drives a bipolar outflow into the surrounding molecular cloud along a NE-SW axis, in agreement with the model of Greenhill et al. The extended high-velocity outflow from Orion-KL appears to be a continuation of this compact outflow. High-velocity gas extends farthest along a NW-SE axis, suggesting that the outflow direction changes on timescales of a few hundred years.

  1. Endogenous Bioactive Lipids and the Regulation of Conventional Outflow Facility

    PubMed Central

    Wan, Zhou; Woodward, David F.; Stamer, W. Daniel

    2009-01-01

    Summary Perturbation of paracrine signaling within the human conventional outflow pathway influences tissue homeostasis and outflow function. For example, exogenous introduction of the bioactive lipids, sphingosine-1-phosphate, anandamide or prostaglandin F2α, to conventional outflow tissues alters the rate of drainage of aqueous humor through the trabecular meshwork, and into Schlemm’s canal. This review summarizes recent data that characterizes endogenous bioactive lipids, their receptors and associated signaling partners in the conventional outflow tract. We also discuss the potential of targeting such signaling pathways as a strategy for the development of therapeutics to treat ocular hypertension and glaucoma. PMID:19381354

  2. Suppression of galactic outflows by cosmological infall and circumgalactic medium

    NASA Astrophysics Data System (ADS)

    Singh, Priyanka; Rana, Sandeep; Bagla, Jasjeet S.; Nath, Biman B.

    2016-06-01

    We investigate the relative importance of two galactic outflow suppression mechanisms: (a) cosmological infall of the intergalactic gas on to the galaxy, and (b) the existence of a hot circumgalactic medium (CGM). Considering only radial motion, the infall reduces the speed of outflowing gas and even halts the outflow, depending on the mass and redshift of the galaxy. For star-forming galaxies, there exists an upper mass limit beyond which outflows are suppressed by the gravitational field of the galaxy. We find that infall can reduce this upper mass limit approximately by a factor of 2 (independent of the redshift). Massive galaxies (≳1012 M⊙) host large reservoir of hot, diffuse CGM around the central part of the galaxy. The CGM acts as a barrier between the infalling and outflowing gas and provides an additional source of outflow suppression. We find that at low redshifts (z ≲ 3.5), the CGM is more effective than the infall in suppressing the outflows. Together, these two processes give a mass range in which galaxies are unable to have effective outflows. We also discuss the impact of outflow suppression on the enrichment history of the galaxy and its environment.

  3. ALMA OBSERVATIONS OF THE HH 46/47 MOLECULAR OUTFLOW

    SciTech Connect

    Arce, Hector G.; Mardones, Diego; Garay, Guido; Corder, Stuartt A.; Noriega-Crespo, Alberto; Raga, Alejandro C.

    2013-09-01

    The morphology, kinematics, and entrainment mechanism of the HH 46/47 molecular outflow were studied using new ALMA Cycle 0 observations. Results show that the blue and red lobes are strikingly different. We argue that these differences are partly due to contrasting ambient densities that result in different wind components having a distinct effect on the entrained gas in each lobe. A 29 point mosaic, covering the two lobes at an angular resolution of about 3'', detected outflow emission at much higher velocities than previous observations, resulting in significantly higher estimates of the outflow momentum and kinetic energy than previous studies of this source, using the CO(1-0) line. The morphology and the kinematics of the gas in the blue lobe are consistent with models of outflow entrainment by a wide-angle wind, and a simple model describes the observed structures in the position-velocity diagram and the velocity-integrated intensity maps. The red lobe exhibits a more complex structure, and there is evidence that this lobe is entrained by a wide-angle wind and a collimated episodic wind. Three major clumps along the outflow axis show velocity distribution consistent with prompt entrainment by different bow shocks formed by periodic mass ejection episodes which take place every few hundred years. Position-velocity cuts perpendicular to the outflow cavity show gradients where the velocity increases toward the outflow axis, inconsistent with outflow rotation. Additionally, we find evidence for the existence of a small outflow driven by a binary companion.

  4. Strong Lyα Emission in the Proximate Damped Lyα Absorption Trough toward the Quasar SDSS J095253.83+011422.0

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Zhou, Hongyan; Pan, Xiang; Jiang, Ning; Shu, Xinwen; Wang, Huiyuan; Gu, Qiusheng; Li, Zhenzhen; Wu, Maochun; Shi, Xiheng; Ji, Tuo; Tian, Qiguo; Zhang, Shaohua

    2016-04-01

    SDSS J095253.83+011422.0 (J0952+0114) was reported by Hall et al. as an exotic quasar at zem = 3.020. In contrast to prominent broad metal-line emission with FWHM ˜ 9000 km s-1, only a narrow Lyα emission line is present with FWHM ˜ 1000 km s-1. The absence of a broad Lyα emission line has been a mystery for more than a decade. In this paper, we demonstrate that this absence is due to dark proximate damped Lyα absorption (PDLA) at zabs = 3.010 by identifying associated Lyman absorption line series from the damped Lyβ up to Ly9, as well as the Lyman limit absorption edge. The PDLA cloud has a column density of {log}{N}{{H}{{I}}}({{{cm}}}-2)=21.8+/- 0.2, a metallicity of [Zn/H] > -1.0, and a spatial extent exceeding the narrow emission line region (NELR) of the quasar. With a luminosity of {L}{{Ly}α }˜ {10}45 erg s-1, the residual Lyα emission superposed on the PDLA trough is two orders of magnitude stronger than found by previous reports. This is best explained as re-radiated photons arising from the quasar outflowing gas on a larger scale than in the NELR. The PDLA here, acting like a natural coronagraph, provides us with valuable insight into the illuminated gases in the vicinity of the quasar, which are usually hard to resolve due to their small size and the “seeing fuzz” of bright quasars. Notably, J0952+0114 analogs might be easily omitted in the spectroscopic surveys of DLAs and PDLAs because their damped Lyα troughs can be fully filled by additional strong Lyα emissions. Our preliminary survey shows that such systems are not very rare. They could potentially be a unique sample for probing strong quasar feedback phenomena in the early universe.

  5. Transparency parameters from relativistically expanding outflows

    SciTech Connect

    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.

  6. Magnetospheric and Thermospheric Influence on Ionospheric Outflow

    NASA Astrophysics Data System (ADS)

    Garcia-Sage, K.; Moore, T. E.; Mitchell, E. J.; Olson, D. K.

    2013-12-01

    The Fast Auroral SnapshoT (FAST) small explorer has been used extensively to study ionospheric outflow. Past research has used particle and field data to examine the contemporaneous transfer of electromagnetic energy and particle flow downward from the magnetosphere and upward from the ionosphere. Single event studies published by Strangeway et al. [2005] and Brambles et al. [2011, Supporting Online Material] showed that downward electromagnetic energy and particle flow into the ionosphere are correlated with the upward flow of ions out of the ionosphere. It is expected, however, that this correlation will be affected by circumstances that are unique to each specific event, including but not limited to the outflow location (cusp or nightside), preconditioning due to prior geomagnetic activity, and thermospheric neutral densities. Although knowledge of the thermospheric neutral density is usually unavailable, data from the CHAllenging Minisatellite Payload (CHAMP) is able to provide insight into thermospheric populations at altitudes of about 400 km for a few select events. We expand on the previously-mentioned studies by looking at FAST particle and field data for additional events, and we further examine the influence of thermospheric neutral populations, based on CHAMP data.

  7. IONIZED OUTFLOWS FROM COMPACT STEEP SPECTRUM SOURCES

    SciTech Connect

    Shih, Hsin-Yi; Stockton, Alan; Kewley, Lisa E-mail: stockton@ifa.hawaii.edu

    2013-08-01

    Massive outflows are known to exist, in the form of extended emission-line regions (EELRs), around about one-third of powerful FR II radio sources. We investigate the origin of these EELRs by studying the emission-line regions around compact-steep-spectrum (CSS) radio galaxies that are younger (10{sup 3}-10{sup 5} yr old) versions of the FR II radio galaxies. We have searched for and analyzed the emission-line regions around 11 CSS sources by taking integral field spectra using Gemini Multi-Object Spectrograph on Gemini North. We fit the [O III] {lambda}5007 line and present the velocity maps for each detected emission-line region. We find, in most cases, that the emission-line regions have multi-component velocity structures with different velocity dispersions and/or flux distributions for each component. The velocity gradients of the emission-line gas are mostly well aligned with the radio axis, suggesting a direct causal link between the outflowing gas and the radio jets. The complex velocity structure may be a result of different driving mechanisms related to the onset of the radio jets. We also present the results from the line-ratio diagnostics we used to analyze the ionization mechanism of the extended gas, which supports the scenario where the emission-line regions are ionized by a combination of active galactic nucleus radiation and shock excitation.

  8. 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.

  9. X-RAY ABSORPTION OF HIGH-REDSHIFT QUASARS

    SciTech Connect

    Eitan, Assaf; Behar, Ehud E-mail: behar@physics.technion.ac.il

    2013-09-01

    The soft X-ray photoelectric absorption of high-z quasars has been known for two decades, but has no unambiguous astrophysical context. We construct the largest sample to date of 58 high-redshift quasars (z > 0.45) selected from the XMM-Newton archive based on a high photon count criterion (>1800). We measure the optical depth {tau} at 0.5 keV and find that 43% of the quasars show significant absorption. We aim to find which physical parameters of the quasars, e.g., redshift, radio luminosity, radio loudness, or X-ray luminosity, drive their observed absorption. We compare the absorption behavior with redshift with the pattern expected if the diffuse intergalactic medium (IGM) is responsible for the observed absorption. We also compare the absorption with a comparison sample of gamma-ray burst (GRB) X-ray afterglows. Although the z > 2 quasar opacity is consistent with diffuse IGM absorption, many intermediate-z (0.45 < z < 2) quasars are not sufficiently absorbed for this scenario, and are appreciably less absorbed than GRBs. Only 10/37 quasars at z < 2 are absorbed, and only 5/30 radio-quiet quasars are absorbed. We find a weak correlation between {tau} and z, and an even weaker correlation between {tau} and radio luminosity. These findings lead to the conclusion that although a diffuse IGM origin for the quasar absorption is unlikely, the optical depth does seem to increase with redshift, roughly as (1 + z){sup 2.2{+-}0.6}, tending to {tau} Almost-Equal-To 0.4 at high redshifts, similar to the high-z GRBs. This result can be explained by an ionized and clumpy IGM at z < 2, and a cold, diffuse IGM at higher redshift. If, conversely, the absorption occurs at the quasar, and owing to the steep L{sub x} {proportional_to}(1 + z){sup 7.1{+-}0.5} correlation in the present sample, the host column density scales as N{sub H}{proportional_to}L{sub x}{sup 0.7{+-}0.1}.

  10. A NEW MODEL FOR DARK MATTER HALOS HOSTING QUASARS

    SciTech Connect

    Cen, Renyue; Safarzadeh, Mohammadtaher

    2015-01-10

    A new model for quasar-hosting dark matter halos, meeting two physical conditions, is put forth. First, significant interactions are taken into consideration to trigger quasar activities. Second, satellites in very massive halos at low redshift are removed from consideration due to their deficiency in cold gas. We analyze the Millennium Simulation to find halos that meet these two conditions and simultaneously match two-point auto-correlation functions of quasars and cross-correlation functions between quasars and galaxies at z = 0.5-3.2. The masses of the quasar hosts found decrease with decreasing redshift, with the mass thresholds being [(2-5) × 10{sup 12}, (2-5) × 10{sup 11}, (1-3) × 10{sup 11}] M {sub ☉} for median luminosities of ∼[10{sup 46}, 10{sup 46}, 10{sup 45}] erg s{sup –1} at z = (3.2, 1.4, 0.53), respectively, an order of magnitude lower than those inferred based on halo occupation distribution modeling. In this model, quasar hosts are primarily massive central halos at z ≥ 2-3 but increasingly dominated by lower mass satellite halos experiencing major interactions toward lower redshift. However, below z = 1, satellite halos in groups more massive than ∼2 × 10{sup 13} M {sub ☉} do not host quasars. Whether for central or satellite halos, imposing the condition of significant interactions substantially boosts the clustering strength compared to the total population with the same mass cut. The inferred lifetimes of quasars at z = 0.5-3.2 of 3-30 Myr are in agreement with observations. Quasars at z ∼ 2 would be hosted by halos of mass ∼5 × 10{sup 11} M {sub ☉} in this model, compared to ∼3 × 10{sup 12} M {sub ☉} previously thought, which would help reconcile with the observed, otherwise puzzling high covering fractions for Lyman limit systems around quasars.

  11. Star formation in quasar and active galaxy environments

    NASA Astrophysics Data System (ADS)

    Coldwell, Georgina V.; Lambas, Diego G.

    2003-09-01

    We use the 2dF public 100 K data release of galaxies and samples of quasars and active galaxies taken from the Véron-Cetty and Véron catalogue to study the nature of galaxies in the surroundings of active objects with redshifts in the range 0.1 < z < 0.2. We explore the distribution of neighbour 2dF galaxy spectral types, η, at different projected distances from the quasars and active galaxies with radial velocity difference ΔV= 500 km s-1. For comparison, we perform a similar analysis on the environment of typical galaxies in the 2dF catalogue, a sample of bright early-type galaxies, i.e. η < -1.4 and MbJ < -21, and also on a sample of 2dF galaxy groups. We find a higher relative fraction of emission-line galaxies, i.e. with 2dF spectral type indices η >3.5, in the vicinity of quasars and active galaxies compared to that in the neighbourhood of typical galaxies, bright early types and groups. This effect extends up to projected distance rp~ 1 h-1 Mpc for active galaxies and rp~ 3 h-1 Mpc for quasars. We also find a tendency for companion galaxies of quasars to be brighter than the neighbours of active galaxies within rp~ 3 h-1 Mpc. We estimate average star-formation rates for objects at different distances from quasars, active galaxies, galaxies and groups. We find a significantly higher star-formation activity within ~2.0 h-1 Mpc from quasars with respect to typical galaxies, which reinforces the idea that star formation is enhanced in the neighbourhood of quasars. Our tests with the group environment provide evidence against quasars being associated with groups. Also, our analysis of the neighbours of bright early types shows that although these galaxies are typical hosts of quasars, their companion galaxies are significantly different in terms of the star-formation activity.

  12. Broadband short term X-ray variability of the quasar PDS 456

    NASA Astrophysics Data System (ADS)

    Matzeu, G. A.; Reeves, J. N.; Nardini, E.; Braito, V.; Costa, M. T.; Tombesi, F.; Gofford, J.

    2016-05-01

    We present a detailed analysis of a recent 500 ks net exposure Suzaku observation, carried out in 2013, of the nearby (z=0.184) luminous (L_bol˜1047 erg s-1) quasar PDS 456 in which the X-ray flux was unusually low. The short term X-ray spectral variability has been interpreted in terms of variable absorption and/or intrinsic continuum changes. In the former scenario, the spectral variability is due to variable covering factors of two regions of partially covering absorbers. We find that these absorbers are characterised by an outflow velocity comparable to that of the highly ionised wind, i.e. ˜ 0.25 c, at the 99.9% (3.26σ) confidence level. This suggests that the partially absorbing clouds may be the denser clumpy part of the inhomogeneous wind. Following an obscuration event we obtained a direct estimate of the size of the X-ray emitting region, to be not larger than 20 R_g in PDS 456.

  13. Measurement of Outflow Facility Using iPerfusion

    PubMed Central

    Sherwood, Joseph M.; Reina-Torres, Ester; Bertrand, Jacques A.; Rowe, Barnaby; Overby, Darryl R.

    2016-01-01

    Elevated intraocular pressure (IOP) is the predominant risk factor for glaucoma, and reducing IOP is the only successful strategy to prevent further glaucomatous vision loss. IOP is determined by the balance between the rates of aqueous humour secretion and outflow, and a pathological reduction in the hydraulic conductance of outflow, known as outflow facility, is responsible for IOP elevation in glaucoma. Mouse models are often used to investigate the mechanisms controlling outflow facility, but the diminutive size of the mouse eye makes measurement of outflow technically challenging. In this study, we present a new approach to measure and analyse outflow facility using iPerfusion™, which incorporates an actuated pressure reservoir, thermal flow sensor, differential pressure measurement and an automated computerised interface. In enucleated eyes from C57BL/6J mice, the flow-pressure relationship is highly non-linear and is well represented by an empirical power law model that describes the pressure dependence of outflow facility. At zero pressure, the measured flow is indistinguishable from zero, confirming the absence of any significant pressure independent flow in enucleated eyes. Comparison with the commonly used 2-parameter linear outflow model reveals that inappropriate application of a linear fit to a non-linear flow-pressure relationship introduces considerable errors in the estimation of outflow facility and leads to the false impression of pressure-independent outflow. Data from a population of enucleated eyes from C57BL/6J mice show that outflow facility is best described by a lognormal distribution, with 6-fold variability between individuals, but with relatively tight correlation of facility between fellow eyes. iPerfusion represents a platform technology to accurately and robustly characterise the flow-pressure relationship in enucleated mouse eyes for the purpose of glaucoma research and with minor modifications, may be applied in vivo to mice, as

  14. Measurement of Outflow Facility Using iPerfusion.

    PubMed

    Sherwood, Joseph M; Reina-Torres, Ester; Bertrand, Jacques A; Rowe, Barnaby; Overby, Darryl R

    2016-01-01

    Elevated intraocular pressure (IOP) is the predominant risk factor for glaucoma, and reducing IOP is the only successful strategy to prevent further glaucomatous vision loss. IOP is determined by the balance between the rates of aqueous humour secretion and outflow, and a pathological reduction in the hydraulic conductance of outflow, known as outflow facility, is responsible for IOP elevation in glaucoma. Mouse models are often used to investigate the mechanisms controlling outflow facility, but the diminutive size of the mouse eye makes measurement of outflow technically challenging. In this study, we present a new approach to measure and analyse outflow facility using iPerfusion™, which incorporates an actuated pressure reservoir, thermal flow sensor, differential pressure measurement and an automated computerised interface. In enucleated eyes from C57BL/6J mice, the flow-pressure relationship is highly non-linear and is well represented by an empirical power law model that describes the pressure dependence of outflow facility. At zero pressure, the measured flow is indistinguishable from zero, confirming the absence of any significant pressure independent flow in enucleated eyes. Comparison with the commonly used 2-parameter linear outflow model reveals that inappropriate application of a linear fit to a non-linear flow-pressure relationship introduces considerable errors in the estimation of outflow facility and leads to the false impression of pressure-independent outflow. Data from a population of enucleated eyes from C57BL/6J mice show that outflow facility is best described by a lognormal distribution, with 6-fold variability between individuals, but with relatively tight correlation of facility between fellow eyes. iPerfusion represents a platform technology to accurately and robustly characterise the flow-pressure relationship in enucleated mouse eyes for the purpose of glaucoma research and with minor modifications, may be applied in vivo to mice, as

  15. The Discovery of the First He Iλ10830 Broad Absorption Line Quasar

    NASA Astrophysics Data System (ADS)

    Leighly, Karen M.; Dietrich, Matthias; Barber, Sara

    2011-02-01

    We report the discovery of the first He I*λ10830 broad absorption line quasar FBQS J1151+3822. Using new infrared and optical spectra, as well as the SDSS spectrum, we extracted the apparent optical depth profiles as a function of velocity of the 3889 Å and 10830 Å He I* absorption lines. Since these lines have the same lower levels, inhomogeneous absorption models could be used to extract the average true He I* column density; the log of that number was 14.9. The total hydrogen column density was obtained using Cloudy models. A range of ionization parameters and densities were allowed, with the lower limit on the ionization parameter of log U = -1.4 determined by the requirement that there be sufficient He I*, and the upper limit on the density of log n = 8 determined by the lack of Balmer absorption. Simulated UV spectra showed that the ionization parameter could be further constrained in principle using a combination of low- and high-ionization lines (such as Mg II and P V), but the only density-sensitive line predicted to be observable and not significantly blended was C IIIλ1176. We estimated the outflow rate and kinetic energy, finding them to be consistent but on the high side compared with analyses of other objects. Assuming that radiative line driving is the responsible acceleration mechanism, a force multiplier model was constructed. A dynamical argument using the model results strongly constrained the density to be log n >= ~7. Consequently, the log hydrogen column density is constrained to be between 21.7 and 22.9, the mass outflow rate to be between 11 and 56 solar masses per year, the ratio of the mass outflow rate to the accretion rate to be between 1.2 and 5.8, and the kinetic energy to be between 1 and 5 × 1044 erg s-1. We discuss the advantages of using He I* to detect high column density BALQSOs and measure their properties. We find that the large λfik ratio of 23.3 between the 10830 Å and 3889 Å components makes He I* analysis sensitive

  16. XMM-Newton spectroscopy of high-redshift quasars

    NASA Astrophysics Data System (ADS)

    Page, K. L.; Reeves, J. N.; O'Brien, P. T.; Turner, M. J. L.

    2005-11-01

    XMM-Newton observations of 29 high-redshift (z > 2) quasars, including seven radio-quiet, 16 radio-loud and six broad absorption line (BAL) objects, are presented; due to the high redshifts, the rest-frame energy bands extend up to ~30-70 keV. Over 2-10 keV, the quasars can be well fitted in each case by a simple power law, with no strong evidence for iron emission lines. The lack of iron lines is in agreement both with dilution by the radio jet emission (for the radio-loud quasars) and the X-ray Baldwin effect. No Compton reflection humps at higher energies (i.e. above 10 keV in the rest frame) are detected either. Over the broad-band (0.3-10 keV), approximately half (nine out of 16) of the radio-loud quasars are intrinsically absorbed, with the values of NH generally being 1 × 1022 to 2 × 1022cm-2 in the rest frames of the objects. None of the seven radio-quiet objects shows excess absorption, while four of the six BAL quasars are absorbed. The radio-loud quasars have flatter continuum slopes than their radio-quiet counterparts (ΓRL~ 1.55; ΓRQ~ 1.98 over 2-10 keV), while, after modelling the absorption, the underlying photon index for the six BAL quasars is formally consistent with the non-BAL radio-quiet objects.

  17. Measuring Quasar Variability with Pan-STARRS1 and SDSS

    NASA Astrophysics Data System (ADS)

    Morganson, E.; Burgett, W. S.; Chambers, K. C.; Green, P. J.; Kaiser, N.; Magnier, E. A.; Marshall, P. J.; Morgan, J. S.; Price, P. A.; Rix, H.-W.; Schlafly, E. F.; Tonry, J. L.; Walter, F.

    2014-04-01

    We measure quasar variability using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS1 or PS1) and the Sloan Digital Sky Survey (SDSS) and establish a method of selecting quasars via their variability in 104 deg2 surveys. We use 105 spectroscopically confirmed quasars that have been well measured in both PS1 and SDSS and take advantage of the decadal timescales that separate SDSS measurements and PS1 measurements. A power law model fits the data well over the entire time range tested, 0.01-10 yr. Variability in the current PS1-SDSS data set can efficiently distinguish between quasars and nonvarying objects. It improves the purity of a griz quasar color cut from 4.1% to 48% while maintaining 67% completeness. Variability will be very effective at finding quasars in data sets with no u band and in redshift ranges where exclusively photometric selection is not efficient. We show that quasars' rest-frame ensemble variability, measured as a root mean squared in Δ magnitudes, is consistent with V(z, L, t) = A 0(1 + z)0.37(L/L 0)-0.16(t/1 yr)0.246, where L 0 = 1046 erg s-1 and A 0 = 0.190, 0.162, 0.147, or 0.141 in the g P1, r P1, i P1, or z P1filter, respectively. We also fit across all four filters and obtain median variability as a function of z, L, and λ as V(z, L, λ, t) = 0.079(1 + z)0.15(L/L 0)-0.2(λ/1000 nm)-0.44(t/1 yr)0.246.

  18. Measuring quasar variability with Pan-STARRS1 and SDSS

    SciTech Connect

    Morganson, E.; Rix, H.-W.; Schlafly, E. F.; Walter, F.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Magnier, E. A.; Morgan, J. S.; Tonry, J. L.; Green, P. J.; Marshall, P. J.; Price, P. A.

    2014-04-01

    We measure quasar variability using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS1 or PS1) and the Sloan Digital Sky Survey (SDSS) and establish a method of selecting quasars via their variability in 10{sup 4} deg{sup 2} surveys. We use 10{sup 5} spectroscopically confirmed quasars that have been well measured in both PS1 and SDSS and take advantage of the decadal timescales that separate SDSS measurements and PS1 measurements. A power law model fits the data well over the entire time range tested, 0.01-10 yr. Variability in the current PS1-SDSS data set can efficiently distinguish between quasars and nonvarying objects. It improves the purity of a griz quasar color cut from 4.1% to 48% while maintaining 67% completeness. Variability will be very effective at finding quasars in data sets with no u band and in redshift ranges where exclusively photometric selection is not efficient. We show that quasars' rest-frame ensemble variability, measured as a root mean squared in Δ magnitudes, is consistent with V(z, L, t) = A {sub 0}(1 + z){sup 0.37}(L/L {sub 0}){sup –0.16}(t/1 yr){sup 0.246}, where L {sub 0} = 10{sup 46} erg s{sup –1} and A {sub 0} = 0.190, 0.162, 0.147, or 0.141 in the g {sub P1}, r {sub P1}, i {sub P1}, or z {sub P1}filter, respectively. We also fit across all four filters and obtain median variability as a function of z, L, and λ as V(z, L, λ, t) = 0.079(1 + z){sup 0.15}(L/L {sub 0}){sup –0.2}(λ/1000 nm){sup –0.44}(t/1 yr){sup 0.246}.

  19. The ISO View of Palomar-Green Quasars

    NASA Technical Reports Server (NTRS)

    Haas, M.; Klaas, U.; Mueller, S. A. H.; Bertoldi, F.; Camenzind, M.; Chini, R.; Krause, O.; Lemke, D.; Meisenheimer; Richards, P. J.

    2003-01-01

    Mining the ISO data archive we provide the complete ISO view of PG quasars containing 64 infrared spectral energy distributions between 5 and 200 mu m. About half of the sample was supplemented by MAMBO and SCUBA (sub-)millimeter data. Since the PG quasars were selected optically, the high infrared detection rate of more than 80% suggests that every quasar possesses luminous to hyper-luminous dust emission with dust masses comparable to Seyferts and ultra-luminous IR galaxies (ULIRGs). The gas to-dust mass ratio (of those sources where CO measurements are available in the literature) is consistent with the galactic value providing further evidence for the thermal nature of the IR emission of radio quiet quasars. The SEDs represent templates of unprecedented detail and sensitivity. We suggest that the diversity of the SEDs reflects largely the evolution of the dust distribution, and we propose a classification of the SED shapes as well as an evolutionary scheme in which this variety can be understood. During the evolution the surrounding dust redistributes, settling more and more into a torus/disk like configuration, while the SEDs show an initial FIR bump, then an increasing MIR emission and a steeper near- to mid-infrared slope, both of which finally also decrease. Regarding cosmic evolution, our hyper-luminous quasars in the "local" universe at z=l do not show the hyper-luminous (LFIR >? 10(exp 13) L(sub sun)) starburst activity inferred for z=4 quasars detected in several (sub-)millimeter surveys. In view of several caveats this difference should be established further, but it already suggests that in the early dense universe stronger merger events led to more powerful starbursts accompanying the quasar phenomenon, while at later cosmic epochs any coeval starbursts obviously do not reach that high power and are outshone by the AGN. Additional information is included in the original extended abstract.

  20. Long-term optical flux and colour variability in quasars

    NASA Astrophysics Data System (ADS)

    Sukanya, N.; Stalin, C. S.; Jeyakumar, S.; Praveen, D.; Dhani, Arnab; Damle, R.

    2016-02-01

    We have used optical V and R band observations from the Massive Compact Halo Object (MACHO) project on a sample of 59 quasars behind the Magellanic clouds to study their long term optical flux and colour variations. These quasars, lying in the redshift range of 0.2 < z < 2.8 and having apparent V band magnitudes between 16.6 and 20.1 mag, have observations ranging from 49 to 1353 epochs spanning over 7.5 yr with frequency of sampling between 2 to 10 days. All the quasars show variability during the observing period. The normalised excess variance (Fvar) in V and R bands are in the range 0.2% < FVvar < 1.6% and 0.1% < FRvar < 1.5% respectively. In a large fraction of the sources, Fvar is larger in the V band compared to the R band. From the z-transformed discrete cross-correlation function analysis, we find that there is no lag between the V and R band variations. Adopting the Markov Chain Monte Carlo (MCMC) approach, and properly taking into account the correlation between the errors in colours and magnitudes, it is found that the majority of sources show a bluer when brighter trend, while a minor fraction of quasars show the opposite behaviour. This is similar to the results obtained from another two independent algorithms, namely the weighted linear least squares fit (FITEXY) and the bivariate correlated errors and intrinsic scatter regression (BCES). However, the ordinary least squares (OLS) fit, normally used in the colour variability studies of quasars, indicates that all the quasars studied here show a bluer when brighter trend. It is therefore very clear that the OLS algorithm cannot be used for the study of colour variability in quasars.

  1. A Wealth of Dust Grains in Quasar Winds

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Click on image for larger poster version

    This plot of data captured by NASA's Spitzer Space Telescope reveals dust entrained in the winds rushing away from a quasar, or growing black hole. The quasar, called PG2112+059, is located deep inside a galaxy 8 billion light-years away. Astronomers believe the dust might have been forged in the winds, which would help explain where dust in the very early universe came from.

    The data were captured by Spitzer's infrared spectrograph, an instrument that splits apart light from the quasar into a spectrum that reveals telltale signs of different minerals. Each type of mineral, or dust grain, has a unique signature, as can be seen in the graph, or spectrum, above.

    The strongest features are from the mineral amorphous olivine, or glass (purple); the mineral forsterite found in sand (blue); and the mineral corundum found in rubies (light blue). The detection of forsterite and corundum is highly unusual in galaxies without quasars. Therefore, their presence is a key clue that these grains might have been created in the quasar winds and not by dying stars as they are in our Milky Way galaxy. Forsterite is destroyed quickly in normal galaxies by radiation, so it must be continually produced to be detected by Spitzer.

    Corundum is hard, and provides a seed that softer, more common minerals usually cover up. As a result, corundum is usually not seen in spectra of galaxies. Since Spitzer did detect the mineral, it is probably forming in a clumpy environment, which is expected in quasar winds. All together, the signatures of the unusual minerals in this spectrum point towards dust grains forming in the winds blowing away from quasars.

  2. Measuring the seeds of thermal ion outflow

    NASA Astrophysics Data System (ADS)

    Fernandes, Philip A.

    The ionosphere is the primary source for heavy ions which are ubiquitous in the terrestrial magnetosphere. Low-altitude energization in the auroral ionosphere results in bulk heating and transverse acceleration of ions, which begin to upwell and/or be accelerated upward by the mirror force, starting upflow and leading to the outflow process. The details of the processes that seed ion outflow at low altitudes are difficult to measure in situ and thus remain an open question. We examine the observational parameter regime in which ion upflow/outflow initiates. Emphasis is placed on making measurements of the thermal ion kinetic distribution function, allowing for accounting of processes which affect in situ plasma measurements. We consider an electrostatic analyzer (ESA) instrument capable of making the measurements necessary to quantify the roles of various heating mechanisms in initiating ion upflow in the low-altitude auroral ionosphere. We present the difficulties associated with making these measurements and identify instrument design choices that mitigate some of these measurement challenges. Analysis of ESA measurements of the thermal ion distribution function taken on the MICA auroral sounding rocket is presented. Using a Maxwellian model to replicate possible measured spectra, we calculate integrated parameters from the model and compare with equivalent parameters calculated from the in situ data. Through Liouville's theorem and the thin-sheath approximation we couple the measured and forward-modeled parameters such that measurements inside the sheath provide information about the state of the plasma outside the sheath. Throughout the MICA flight, ion upflow is observed and attributed to ambipolar electric fields and/or ion-neutral interactions. Late in the flight we observe quasi-static frictional process driving the ion temperature. Early in the flight we observe ion heating weakly correlated with ELF wave activity; our analysis suggests we must consider

  3. Covering factors of the dusty obscurers in radio-loud and radio-quiet quasars

    NASA Astrophysics Data System (ADS)

    Gupta, Maitrayee; Sikora, Marek; Nalewajko, Krzysztof

    2016-09-01

    We compare covering factors of circumnuclear dusty obscurers in radio-loud and radio-quiet quasars. The radio-loud quasars are represented by a sample of FR II quasars obtained by cross-matching a catalog of the FR II radio sources selected by van Velzen et al. with the SDSS DR7 catalog of quasars. Covering factors of FR II quasars are compared with covering factors of the radio-quiet quasars matched with them in redshift, black hole mass, and Eddington-ratio. We found that covering factors, proxied by the infrared-to-bolometric luminosity ratio, are on average slightly smaller in FR II quasars than in radio-quiet quasars, however, this difference is statistically significant only for the highest Eddington ratios. For both samples, no statistically significant dependence of a median covering factor on Eddington ratio, black hole mass, nor redshift can be claimed.

  4. Confronting the outflow-regulated cluster formation model with observations

    SciTech Connect

    Nakamura, Fumitaka; Li, Zhi-Yun E-mail: zl4h@virginia.edu

    2014-03-10

    Protostellar outflows have been shown theoretically to be capable of maintaining supersonic turbulence in cluster-forming clumps and keeping the star formation rate per free-fall time as low as a few percent. We aim to test two basic predictions of this outflow-regulated cluster formation model, namely, (1) the clump should be close to virial equilibrium and (2) the turbulence dissipation rate should be balanced by the outflow momentum injection rate, using recent outflow surveys toward eight nearby cluster-forming clumps (B59, L1551, L1641N, Serpens Main Cloud, Serpens South, ρ Oph, IC 348, and NGC 1333). We find, for almost all sources, that the clumps are close to virial equilibrium and the outflow momentum injection rate exceeds the turbulence momentum dissipation rate. In addition, the outflow kinetic energy is significantly smaller than the clump gravitational energy for intermediate and massive clumps with M {sub cl} ≳ a few × 10{sup 2} M {sub ☉}, suggesting that the outflow feedback is not enough to disperse the clump as a whole. The number of observed protostars also indicates that the star formation rate per free-fall time is as small as a few percent for all clumps. These observationally based results strengthen the case for outflow-regulated cluster formation.

  5. Collective outflow from a small multiple stellar system

    SciTech Connect

    Peters, Thomas; Klaassen, Pamela D.; Mac Low, Mordecai-Mark; Schrön, Martin; Klessen, Ralf S.; Federrath, Christoph; Smith, Michael D.

    2014-06-10

    The formation of high-mass stars is usually accompanied by powerful protostellar outflows. Such high-mass outflows are not simply scaled-up versions of their lower-mass counterparts, since observations suggest that the collimation degree degrades with stellar mass. Theoretically, the origins of massive outflows remain open to question because radiative feedback and fragmentation of the accretion flow around the most massive stars, with M > 15 M {sub ☉}, may impede the driving of magnetic disk winds. We here present a three-dimensional simulation of the early stages of core fragmentation and massive star formation that includes a subgrid-scale model for protostellar outflows. We find that stars that form in a common accretion flow tend to have aligned outflow axes, so that the individual jets of multiple stars can combine to form a collective outflow. We compare our simulation to observations with synthetic H{sub 2} and CO observations and find that the morphology and kinematics of such a collective outflow resembles some observed massive outflows, such as Cepheus A and DR 21. We finally compare physical quantities derived from simulated observations of our models to the actual values in the models to examine the reliability of standard methods for deriving physical quantities, demonstrating that those methods indeed recover the actual values to within a factor of two to three.

  6. Confronting the Outflow-regulated Cluster Formation Model with Observations

    NASA Astrophysics Data System (ADS)

    Nakamura, Fumitaka; Li, Zhi-Yun

    2014-03-01

    Protostellar outflows have been shown theoretically to be capable of maintaining supersonic turbulence in cluster-forming clumps and keeping the star formation rate per free-fall time as low as a few percent. We aim to test two basic predictions of this outflow-regulated cluster formation model, namely, (1) the clump should be close to virial equilibrium and (2) the turbulence dissipation rate should be balanced by the outflow momentum injection rate, using recent outflow surveys toward eight nearby cluster-forming clumps (B59, L1551, L1641N, Serpens Main Cloud, Serpens South, ρ Oph, IC 348, and NGC 1333). We find, for almost all sources, that the clumps are close to virial equilibrium and the outflow momentum injection rate exceeds the turbulence momentum dissipation rate. In addition, the outflow kinetic energy is significantly smaller than the clump gravitational energy for intermediate and massive clumps with M cl >~ a few × 102 M ⊙, suggesting that the outflow feedback is not enough to disperse the clump as a whole. The number of observed protostars also indicates that the star formation rate per free-fall time is as small as a few percent for all clumps. These observationally based results strengthen the case for outflow-regulated cluster formation.

  7. Hubble Space Telescope Images of Nearby Luminous Quasars. 2; Results for Eight Quasars and Tests of the Detection Sensitivity

    NASA Technical Reports Server (NTRS)

    Bahcall, John N.; Kirhakos, Sofia; Schneider, Donald P.

    1995-01-01

    Observations with the Wide-Field Camera of the Hubble Space Telescope (HST) are presented for eight intrinsically luminous quasars with redshifts between 0.16 and 0.29. These observations, when combined with a similar HST study of the quasar PKS 2349-014, show that luminous nearby quasars exist in a variety of environments. Seven companion galaxies brighter than M(V) = 16.5 (H(sub 0) = 100 km s(sup -1) Mpc(sup -1), Omega(sub 0) = 1.0) lie within a projected distance of 25 kpc of the quasars; three of the companions are located closer than 3'' (6 kpc projected distance) from the quasars, well within the volume that would be enclosed by a typical L* host galaxy. The observed association of quasars and companion galaxies is statistically significant and may he an important element in the luminous-quasar phenomenon. Apparent host galaxies are detected for three of the quasars: PG 1116+215, 3C 273, and PG 1444+407; the hosts have an average absolute magnitude of about 0.6 mag brighter than L*. The agreement between the previously published major-axis directions in ground-based images and in the present HST images of 3C 273 and PG 1444+407 constitutes important evidence supporting the reality of these candidate host galaxies. Upper limits are placed on the visual-band brightnesses of representative galactic hosts for all the quasars. These limits are established by placing galaxy images obtained with HST underneath the quasars and measuring at what faintness level the known galaxies are detected. On average, the HST spirals would have been detected if they were as faint as 1 mag below L*, and the early-type galaxies could have been detected down to a brightness level of about L*, where L* is the Schechter characteristic luminosity of field galaxies. Smooth, featureless galaxy models (exponential disks or de Vaucouleurs profiles) are fitted to the residual light after a best-fitting point source is subtracted from the quasar images. The results show that smooth spiral

  8. Ice sculpture in the Martian outflow channels

    NASA Technical Reports Server (NTRS)

    Lucchitta, B. K.

    1982-01-01

    Viking Orbiter and terrestrial satellite images are examined at similar resolution to compare features of the Martian outflow channels with features produced by the movement of ice on earth, and many resemblances are found. These include the anastomoses, sinuosities, and U-shaped cross profiles of valleys; hanging valleys; linear scour marks on valley walls; grooves and ridges on valley floors; and the streamlining of bedrock highs. Attention is given to the question whether ice could have moved in the Martian environment. It is envisaged that springs or small catastrophic outbursts discharged fluids from structural outlets or chaotic terrains. These fluids built icings that may have grown into substantial masses and eventually flowed like glaciers down preexisting valleys. An alternative is that the fluids formed rivers or floods that in turn formed ice jams and consolidated into icy masses in places where obstacles blocked their flow.

  9. FIRE simulations: galactic outflows and their consequences

    NASA Astrophysics Data System (ADS)

    Keres, Dusan; FIRE team

    2016-06-01

    We study gaseous outflows and their consequences in high-resolution galaxy formation simulations with explicit stellar feedback from the Feedback in Realistic Environments project. Collective, galaxy scale, effect of stellar feedback results in episodic ejections of large amount of gas and heavy elements into the circum-galactic medium. Gas ejection episodes follow strong bursts of star formation. Properties of galactic star formation and ejection episodes depend on galaxy mass and redshift and, together with gas infall and recycling, shape the evolution of the circum-galactic medium and galaxies. As a consequence, our simulated galaxies have masses, star formation histories and heavy element content in good agreement with the observed population of galaxies.

  10. Simulation of Breach Outflow for Earthfill Dam

    NASA Astrophysics Data System (ADS)

    Razad, Azwin Zailti Abdul; Sabri Muda, Rahsidi; Mohd Sidek, Lariyah; Azia, Intan Shafilah Abdul; Hanum Mansor, Faezah; Yalit, Ruzaimei

    2013-06-01

    Dams have been built for many reasons such as irrigation, hydropower, flood mitigation, and water supply to support development for the benefit of human. However, the huge amount of water stored behind the dam can seriously pose adverse impacts to the downstream community should it be released due to unwanted dam break event. To minimise the potential loss of lives and property damages, a workable Emergency Response Plan is required to be developed. As part of a responsible dam owner and operator, TNB initiated a study on dam breach modelling for Cameron Highlands Hydroelectric Scheme to simulate the potential dam breach for Jor Dam. Prediction of dam breach parameters using the empirical equations of Froehlich and Macdonal-Langridge-Monopolis formed the basis of the modelling, coupled with MIKE 11 software to obtain the breach outflow due to Probable Maximum Flood (PMF). This paper will therefore discuss the model setup, simulation procedure and comparison of the prediction with existing equations.

  11. Functional Anatomy of the Outflow Facilities

    PubMed Central

    Pizzirani, Stefano; Gong, Haiyan

    2016-01-01

    The aqueous humor (AH) is the fluid that fills the anterior and posterior chambers of the eye. Its main roles are to provide nourishment and metabolic waste removal to active metabolic ocular structures that are avascular and to contribute maintaining a normal intraocular pressure (IOP) without altering the refractive status of the eye. Its composition and the fluid dynamics associated with its flow are voluble and undergo changes associated with age and disease. Of particular importance is that the resistance to the outflow of AH from the anterior chamber is influenced by morphologic, physiologic, and biochemical dynamic factors.1 Beside aqueous nutritional importance, its solutes also participate in establishing the anterior chamber associate immune deviation, and carry and distribute the different proteins and molecules that promote and direct tissue remodeling and changes in the anterior segment that are associated with both age and disease. PMID:26337760

  12. Optically thick outflows in ultraluminous supersoft sources

    NASA Astrophysics Data System (ADS)

    Urquhart, R.; Soria, R.

    2016-02-01

    Ultraluminous supersoft sources (ULSs) are defined by a thermal spectrum with colour temperatures ˜0.1 keV, bolometric luminosities ˜ a few 1039 erg s-1, and almost no emission above 1 keV. It has never been clear how they fit into the general scheme of accreting compact objects. To address this problem, we studied a sample of seven ULSs with extensive Chandra and XMM-Newton coverage. We find an anticorrelation between fitted temperatures and radii of the thermal emitter, and no correlation between bolometric luminosity and radius or temperature. We compare the physical parameters of ULSs with those of classical supersoft sources, thought to be surface-nuclear-burning white dwarfs, and of ultraluminous X-ray sources (ULXs), thought to be super-Eddington stellar-mass black holes. We argue that ULSs are the sub-class of ULXs seen through the densest wind, perhaps an extension of the soft-ultraluminous regime. We suggest that in ULSs, the massive disc outflow becomes effectively optically thick and forms a large photosphere, shrouding the inner regions from our view. Our model predicts that when the photosphere expands to ≳ 105 km and the temperature decreases below ≈50 eV, ULSs become brighter in the far-UV but undetectable in X-rays. Conversely, we find that harder emission components begin to appear in ULSs when the fitted size of the thermal emitter is smallest (interpreted as a shrinking of the photosphere). The observed short-term variability and absorption edges are also consistent with clumpy outflows. We suggest that the transition between ULXs (with a harder tail) and ULSs (with only a soft thermal component) occurs at blackbody temperatures of ≈150 eV.

  13. Myocardialization of the cardiac outflow tract

    NASA Technical Reports Server (NTRS)

    van den Hoff, M. J.; Moorman, A. F.; Ruijter, J. M.; Lamers, W. H.; Bennington, R. W.; Markwald, R. R.; Wessels, A.

    1999-01-01

    During development, the single-circuited cardiac tube transforms into a double-circuited four-chambered heart by a complex process of remodeling, differential growth, and septation. In this process the endocardial cushion tissues of the atrioventricular junction and outflow tract (OFT) play a crucial role as they contribute to the mesenchymal components of the developing septa and valves in the developing heart. After fusion, the endocardial ridges in the proximal portion of the OFT initially form a mesenchymal outlet septum. In the adult heart, however, this outlet septum is basically a muscular structure. Hence, the mesenchyme of the proximal outlet septum has to be replaced by cardiomyocytes. We have dubbed this process "myocardialization." Our immunohistochemical analysis of staged chicken hearts demonstrates that myocardialization takes place by ingrowth of existing myocardium into the mesenchymal outlet septum. Compared to other events in cardiac septation, it is a relatively late process, being initialized around stage H/H28 and being basically completed around stage H/H38. To unravel the molecular mechanisms that are responsible for the induction and regulation of myocardialization, an in vitro culture system in which myocardialization could be mimicked and manipulated was developed. Using this in vitro myocardialization assay it was observed that under the standard culture conditions (i) whole OFT explants from stage H/H20 and younger did not spontaneously myocardialize the collagen matrix, (ii) explants from stage H/H21 and older spontaneously formed extensive myocardial networks, (iii) the myocardium of the OFT could be induced to myocardialize and was therefore "myocardialization-competent" at all stages tested (H/H16-30), (iv) myocardialization was induced by factors produced by, most likely, the nonmyocardial component of the outflow tract, (v) at none of the embryonic stages analyzed was ventricular myocardium myocardialization-competent, and finally

  14. Searching for molecular outflows in hyperluminous infrared galaxies

    NASA Astrophysics Data System (ADS)

    Calderón, D.; Bauer, F. E.; Veilleux, S.; Graciá-Carpio, J.; Sturm, E.; Lira, P.; Schulze, S.; Kim, S.

    2016-08-01

    We present constraints on the molecular outflows in a sample of five hyperluminous infrared galaxies using Herschel observations of the OH doublet at 119 μm. We have detected the OH doublet in three cases: one purely in emission and two purely in absorption. The observed emission profile has a significant blueshifted wing suggesting the possibility of tracing an outflow. Out of the two absorption profiles, one seems to be consistent with the systemic velocity while the other clearly indicates the presence of a molecular outflow whose maximum velocity is about ˜1500 km s-1. Our analysis shows that this system is in general agreement with previous results on ultraluminous infrared galaxies and QSOs, whose outflow velocities do not seem to correlate with stellar masses or starburst luminosities (star formation rates). Instead, the galaxy outflow likely arises from an embedded active galactic nuclei.

  15. THE 2dF REDSHIFT SURVEY. I. PHYSICAL ASSOCIATION AND PERIODICITY IN QUASAR FAMILIES

    SciTech Connect

    Fulton, C. C.; Arp, H. C. E-mail: arp@mpa-garching.mpg.de

    2012-08-01

    We have tested for physical association of candidate companion quasars with putative parent galaxies by virtue of Karlsson periodicity in quasar redshifts. We examined galaxies from the 2dF Galaxy Redshift Survey (2dFGRS) and quasars from the 2dF Quasar Redshift Survey (2QZ) in the two declination strips (at declinations 0 Degree-Sign and -30 Degree-Sign ) covered by the 2QZ, first filtering out galaxies and quasars using the respective survey masks and observation qualities as described, and using only quasars with z {>=} 0.5 to avoid the redshift region of mixed galaxies and quasars. Around each galaxy, quasars are detected as physically associated with a putative parent galaxy if their respective redshifts conform to empirically derived constraints based on an ejection hypothesis. We ran Monte Carlo control trials against the pure physical associations by replacing the actual redshifts of the candidate companion quasars with quasar redshifts drawn randomly from each respective right ascension hour. The constraints are grouping of quasar redshifts and Karlsson periodicity of quasar redshifts.

  16. Evolution of active region outflows throughout an active region lifetime

    NASA Astrophysics Data System (ADS)

    Zangrilli, L.; Poletto, G.

    2016-10-01

    Context. We have shown previously that SOHO/UVCS data allow us to detect active region (AR) outflows at coronal altitudes higher than those reached by other instrumentation. These outflows are thought to be a component of the slow solar wind. Aims: Our purpose is to study the evolution of the outflows in the intermediate corona from AR 8100, from the time the AR first forms until it dissolves, after several transits at the solar limb. Methods: Data acquired by SOHO/UVCS at the time of the AR limb transits, at medium latitudes and at altitudes ranging from 1.5 to 2.3 R⊙, were used to infer the physical properties of the outflows through the AR evolution. To this end, we applied the Doppler dimming technique to UVCS spectra. These spectra include the H i Lyα line and the O vi doublet lines at 1031.9 and 1037.6 Å. Results: Plasma speeds and electron densities of the outflows were inferred over several rotations of the Sun. AR outflows are present in the newly born AR and persist throughout the entire AR life. Moreover, we found two types of outflows at different latitudes, both possibly originating in the same negative polarity area of the AR. We also analyzed the behavior of the Si xii 520 Å line along the UVCS slit in an attempt to reveal changes in the Si abundance when different regions are traversed. Although we found some evidence for a Si enrichment in the AR outflows, alternative interpretations are also plausible. Conclusions: Our results demonstrate that outflows from ARs are detectable in the intermediate corona throughout the whole AR lifetime. This confirms that outflows contribute to the slow wind.

  17. Development and Morphology of the Ventricular Outflow Tracts.

    PubMed

    Anderson, Robert H; Mori, Shumpei; Spicer, Diane E; Brown, Nigel A; Mohun, Timothy J

    2016-09-01

    It is customary, at the current time, to consider many, if not most, of the lesions involving the ventricular outflow tract in terms of conotruncal malformations. This reflects the introduction, in the early 1940s, of the terms conus and truncus to describe the components of the developing outflow tract. The definitive outflow tracts in the postnatal heart, however, possess three, rather than two, components. These are the intrapericardial arterial trunks, the arterial roots, and the subvalvar ventricular outflow tracts. Congenital lesions afflicting the arterial roots, however, are not currently considered to be conotruncal malformations. This suggests a lack of logic in the description of cardiac development and its use as a means of categorizing congenital malformations. It is our belief that the developing outflow tract, like the postnatal outflow tracts, can readily be described in tripartite fashion, with its distal, intermediate, and proximal components forming the primordiums of the postnatal parts. In this review, we present evidence obtained from developing mice and human hearts to substantiate this notion. We show that the outflow tract, initially with a common lumen, is divided into its aortic and pulmonary components by a combination of an aortopulmonary septum derived from the dorsal wall of the aortic sac and outflow tract cushions that spiral through its intermediate and proximal components. These embryonic septal structures, however, subsequently lose their septal functions as the outflow tracts develop their own discrete walls. We then compare the developmental findings with the anatomic arrangements seen postnatally in the normal human heart. We show how correlations with the embryologic findings permit logical analysis of the congenital lesions involving the outflow tracts. PMID:27587491

  18. Development and Morphology of the Ventricular Outflow Tracts

    PubMed Central

    Mori, Shumpei; Spicer, Diane E.; Brown, Nigel A.; Mohun, Timothy J.

    2016-01-01

    It is customary, at the current time, to consider many, if not most, of the lesions involving the ventricular outflow tract in terms of conotruncal malformations. This reflects the introduction, in the early 1940s, of the terms conus and truncus to describe the components of the developing outflow tract. The definitive outflow tracts in the postnatal heart, however, possess three, rather than two, components. These are the intrapericardial arterial trunks, the arterial roots, and the subvalvar ventricular outflow tracts. Congenital lesions afflicting the arterial roots, however, are not currently considered to be conotruncal malformations. This suggests a lack of logic in the description of cardiac development and its use as a means of categorizing congenital malformations. It is our belief that the developing outflow tract, like the postnatal outflow tracts, can readily be described in tripartite fashion, with its distal, intermediate, and proximal components forming the primordiums of the postnatal parts. In this review, we present evidence obtained from developing mice and human hearts to substantiate this notion. We show that the outflow tract, initially with a common lumen, is divided into its aortic and pulmonary components by a combination of an aortopulmonary septum derived from the dorsal wall of the aortic sac and outflow tract cushions that spiral through its intermediate and proximal components. These embryonic septal structures, however, subsequently lose their septal functions as the outflow tracts develop their own discrete walls. We then compare the developmental findings with the anatomic arrangements seen postnatally in the normal human heart. We show how correlations with the embryologic findings permit logical analysis of the congenital lesions involving the outflow tracts. PMID:27587491

  19. A distance-limited sample of massive molecular outflows

    NASA Astrophysics Data System (ADS)

    Maud, L. T.; Moore, T. J. T.; Lumsden, S. L.; Mottram, J. C.; Urquhart, J. S.; Hoare, M. G.

    2015-10-01

    We have observed 99 mid-infrared-bright, massive young stellar objects and compact H II regions drawn from the Red MSX source survey in the J = 3-2 transition of 12CO and 13CO, using the James Clerk Maxwell Telescope. 89 targets are within 6 kpc of the Sun, covering a representative range of luminosities and core masses. These constitute a relatively unbiased sample of bipolar molecular outflows associated with massive star formation. Of these, 59, 17 and 13 sources (66, 19 and 15 per cent) are found to have outflows, show some evidence of outflow, and have no evidence of outflow, respectively. The time-dependent parameters of the high-velocity molecular flows are calculated using a spatially variable dynamic time-scale. The canonical correlations between the outflow parameters and source luminosity are recovered and shown to scale with those of low-mass sources. For coeval star formation, we find the scaling is consistent with all the protostars in an embedded cluster providing the outflow force, with massive stars up to ˜30 M⊙ generating outflows. Taken at face value, the results support the model of a scaled-up version of the accretion-related outflow-generation mechanism associated with discs and jets in low-mass objects with time-averaged accretion rates of ˜10-3 M⊙ yr-1 on to the cores. However, we also suggest an alternative model, in which the molecular outflow dynamics are dominated by the entrained mass and are unrelated to the details of the acceleration mechanism. We find no evidence that outflows contribute significantly to the turbulent kinetic energy of the surrounding dense cores.

  20. Are quasars accreting at super-Eddington rates?

    NASA Astrophysics Data System (ADS)

    Collin, S.; Boisson, C.; Mouchet, M.; Dumont, A.-M.; Coupé, S.; Porquet, D.; Rokaki, E.

    2002-06-01

    ratio decreases with an increasing black hole mass, while the opposite is found if the accretion rate is assumed to be proportional to the optical-UV luminosity, as is usually done. If these results are extrapolated to all quasars, it implies that the amount of mass locked in massive black holes should be larger than presently thought. If the Eddington ratio is assumed to be smaller than unity, the optical luminosity has to be produced by an additional non-gravitational mechanism. It has to be emitted by a dense and thick medium located at large distances from the center (103 to 104 gravitational radii). It can be due to reprocessing of the X-ray photons from the central source in a geometrically thin warped disc, or in dense ``blobs" forming a geometrically thick system, which can be a part of the accretion flow or can constitute the basis of an outflow. The third possibility is not explored here, as it requires completely new models of accretion discs which are still to be developed.

  1. HST/COS OBSERVATIONS OF THIRTEEN NEW He II QUASARS

    SciTech Connect

    Syphers, David; Anderson, Scott F.; Zheng Wei; Meiksin, Avery; Schneider, Donald P.; York, Donald G.

    2012-04-15

    The full reionization of intergalactic helium was a major event in the history of the intergalactic medium (IGM), and UV observations of the He II Gunn-Peterson trough allow us to characterize the end of this process at z {approx} 3. Due to intervening hydrogen absorption, quasars allowing such study are rare, with only 33 known in the literature, and most of those are very recent discoveries. We expand on our previous discovery work, and present 13 new He II quasars with redshifts 2.82 < z < 3.77, here selected with {approx}80% efficiency, and including several that are much brighter than the vast majority of those previously known. This is the largest sample of uniformly observed He II quasars covering such a broad redshift range, and they show evidence of IGM opacity increasing with redshift, as expected for the helium reionization epoch. No evidence of He II Ly{alpha} quasar emission is seen in individual or averaged spectra, posing a problem for standard models of the broad-line region. The current rapid advance in the study of He II quasars has been greatly facilitated by the Cosmic Origins Spectrograph on the Hubble Space Telescope, and we discuss the instrumental and other subtleties that must be taken into account in IGM He II observations.

  2. X-Ray Absorption of High- Redshift Quasars

    NASA Astrophysics Data System (ADS)

    Behar, Ehud; Eitan, Assaf

    2012-09-01

    Soft X-ray absorption of high-z quasars has been known for more than a decade, but its astrophysical context remains a mystery. In order to better understand this absorption, we have constructed the largest to date high-S/N sample of high-z quasars (z > 0.5) from the XMM-Newton archive. We find that generally, z<2 and radio quiet objects provide only upper limits for the 0.5 keV optical depth (tau). Thus, we use censored statistics methods to seek correlations between tau and other quasar parameters. We find a dramatic increase of tau with z [(1+z)^{2.5}], although the correlation is rather weak. The correlation of tau with radio luminosity (or loudness) is even weaker. We also compare the absorption behavior with redshift with a large sample of GRBs, and with the pattern expected if the diffuse intergalactic medium (IGM) is responsible for the observed absorption. We find that although the z > 2 quasar opacity is consistent with a diffuse IGM effect and with the high-z GRB opacities, absorption of intermediate z (0.5 < z < 2) quasars is too low for this scenario, which leads to the conclusion that a simple IGM origin for this absorption is unlikely.

  3. DISCOVERY OF A RADIO-SELECTED z {approx} 6 QUASAR

    SciTech Connect

    Zeimann, Gregory R.; Becker, Robert H.; Hodge, Jacqueline A.; Stanford, Spencer A.; White, Richard L.; Richards, Gordon T.

    2011-07-20

    We present the discovery of only the second radio-selected z {approx} 6 quasar. We identified SDSS J222843.54+011032.2 (z = 5.95) by matching the optical detections of the deep Sloan Digital Sky Survey Stripe 82 with their radio counterparts in the Stripe 82 Very Large Array Survey. We also matched the Canadian-France-Hawaiian Telescope Legacy Survey Wide with the Faint Images of the Radio Sky at Twenty cm survey but have yet to find any z {approx} 6 quasars in this survey area. The discovered quasar is optically faint, z = 22.3 and M{sub 1450} {approx} -24.5, but radio bright, with a flux density of f{sub 1.4GHz,peak} = 0.31 mJy and a radio loudness of R {approx} 1100 (where R {identical_to} f{sub 5GHz}/f{sub 2500}). The i - z color of the discovered quasar places it outside the color selection criteria for existing optical surveys. We conclude by discussing the need for deeper wide-area radio surveys in the context of high-redshift quasars.

  4. Canada-France Redshift Survey - X. The quasar sample

    NASA Astrophysics Data System (ADS)

    Schade, David; Crampton, David; Hammer, F.; Le Fevre, O.; Lilly, S. J.

    1996-01-01

    Six objects with broad emission lines and redshifts from 0.48 to 2.07 were discovered among 736 extragalactic objects in the Canada-France Redshift Survey (CFRS). Although the luminosities of half of the objects are such that they are in the Seyfert regime (M_B<~-23), all would be designated as quasars in traditional surveys. Since the only selection criterion was that 17.5<=I_AB<=22.5, or approximately B<23 (assuming a continuum power-law slope alpha=-0.5), these quasars represent an unbiased, flux-limited sample. Although uncertain, the implied surface density, 200^-120-80 deg^-2, is the highest yet measured, and is in good agreement with extrapolations from other faint surveys and the evolving luminosity function models of Boyle. The distributions of the continuum properties, emission-line strengths, etc. of the quasars do not differ significantly from those of quasars selected by other means, and therefore they would have been detected in most traditional surveys. Three of the quasars may be associated with clusters or large structures of galaxies at z<~1.

  5. Quasar optical variability: searching for interband time delays

    NASA Astrophysics Data System (ADS)

    Bachev, R. S.

    2009-01-01

    Aims: The main purpose of this paper is to study time delays between the light variations in different wavebands for a sample of quasars. Measuring a reliable time delay for a large number of quasars may help constraint the models of their central engines. The standard accretion disk irradiation model predicts a delay of the longer wavelengths behind the shorter ones, a delay that depends on the fundamental quasar parameters. Since the black hole masses and the accretion rates are approximately known for the sample we use, one can compare the observed time delays with the expected ones. Methods: We applied the interpolation cross-correlation function (ICCF) method to the Giveon et al. sample of 42 quasars, monitored in two (B and R) colors, to find the time lags represented by the ICCF peaks. Different tests were performed to assess the influence of photometric errors, sampling, etc., on the final result. Results: We found that most of the objects show a delay in the red light curve behind the blue one (a positive lag), which on average for the sample is about +4 days (+3 for the median), although the scatter is significant. These results are broadly consistent with the reprocessing model, especially for the well-sampled objects. The normalized time-lag deviations do not seem to correlate significantly with other quasar properties, including optical, radio, or X-ray measurables. On the other hand, many objects show a clear negative lag, which, if real, may have important consequences for the variability models.

  6. QUASAR PG1115+080 AND GRAVITATIONAL LENS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Left: The light from the single quasar PG 1115+080 is split and distorted in this infrared image. PG 1115+080 is at a distance of about 8 billion light years in the constellation Leo, and it is viewed through an elliptical galaxy lens at a distance of 3 billion light years. The NICMOS frame is taken at a wavelength of 1.6 microns and it shows the four images of the quasar (the two on the left are nearly merging) surrounding the galaxy that causes the light to be lensed. The quasar is a variable light source and the light in each image travels a different path to reach the Earth. The time delay of the variations allows the distance scale to be measured directly. The linear streaks on the image are diffraction artifacts in the NICMOS instrument (NASA/Space Telescope Science Institute). Right: In this NICMOS image, the four quasar images and the lens galaxy have been subtracted, revealing a nearly complete ring of infrared light. This ring is the stretched and amplified starlight of the galaxy that contains the quasar, some 8 billion light years away. (NASA/Space Telescope Science Institute). Credit: Christopher D. Impey (University of Arizona)

  7. The intrinsic quasar luminosity function: Accounting for accretion disk anisotropy

    SciTech Connect

    DiPompeo, M. A.; Myers, A. D.; Brotherton, M. S.; Runnoe, J. C.; Green, R. F.

    2014-05-20

    Quasar luminosity functions are a fundamental probe of the growth and evolution of supermassive black holes. Measuring the intrinsic luminosity function is difficult in practice, due to a multitude of observational and systematic effects. As sample sizes increase and measurement errors drop, characterizing the systematic effects is becoming more important. It is well known that the continuum emission from the accretion disk of quasars is anisotropic—in part due to its disk-like structure—but current luminosity function calculations effectively assume isotropy over the range of unobscured lines of sight. Here, we provide the first steps in characterizing the effect of random quasar orientations and simple models of anisotropy on observed luminosity functions. We find that the effect of orientation is not insignificant and exceeds other potential corrections such as those from gravitational lensing of foreground structures. We argue that current observational constraints may overestimate the intrinsic luminosity function by as much as a factor of ∼2 on the bright end. This has implications for models of quasars and their role in the universe, such as quasars' contribution to cosmological backgrounds.

  8. High Energy Continuum of High Redshift Quasars

    NASA Technical Reports Server (NTRS)

    Elvis, Martin

    2000-01-01

    Discussion with the RXTE team at GSFC showed that a sufficiently accurate background subtraction procedure had now, been derived for sources at the flux level of PKS 2126-158. However this solution does not apply to observations carried out before April 1997, including our observation. The prospect of an improved solution becoming available soon is slim. As a result the RXTE team agreed to re-observe PKS2126-158. The new observation was carried out in April 1999. Quasi-simultaneous optical observations were obtained, as Service observing., at the 4-meter Anglo-Australian Telescope, and ftp-ed from the AAT on 22April. The RXTE data was processed in late June, arriving at SAO in early July. Coincidentally, our collaborative Beppo-SAX observation of PKS2126-158 was made later in 1999, and a GTO Chandra observation (with which we are involved) was made on November 16. Since this gives us a unique monitoring data for a high redshift quasar over a broad pass-band we are now combining all three observations into a single comprehensive study Final publication of the RXTE data will thus take place under another grant.

  9. EIGHT NEW QUASAR LENSES FROM THE SLOAN DIGITAL SKY SURVEY QUASAR LENS SEARCH

    SciTech Connect

    Kayo, Issha; Inada, Naohisa; Oguri, Masamune; Morokuma, Tomoki; Hall, Patrick B.; Kochanek, Christopher S.; Schneider, Donald P.

    2010-04-15

    We report the discovery and confirmation of eight new two-image lensed quasars by the Sloan Digital Sky Survey (SDSS) Quasar Lens Search. The lenses are SDSS J0904+1512 (image separation {theta} = 1.''13, source redshift z{sub s} = 1.826), SDSS J1054+2733 ({theta} = 1.''27, z{sub s} = 1.452), SDSS J1055+4628 ({theta} = 1.''15, z{sub s} = 1.249), SDSS J1131+1915 ({theta} = 1.''46, z{sub s} = 2.915), SDSS J1304+2001 ({theta} = 1.''87, z{sub s} = 2.175), SDSS J1349+1227 ({theta} = 3.''00, z{sub s} = 1.722), SDSS J1455+1447 ({theta} = 1.''73, z{sub s} = 1.424), and SDSS J1620+1203 ({theta} = 2.''77, z{sub s} = 1.158). Three of them, SDSS J1055+4628, SDSS J1455+1447, and SDSS J1620+1203, satisfy the criteria for constructing our statistical sample for studying the cosmological model. Based on galactic absorption lines of the lens galaxies, we also derive lens redshifts of z{sub l} = 0.398 and z{sub l} = 0.513 for SDSS J1620+1203 and the previously discovered lens SDSS J0746+4403, respectively.

  10. Modelling the variable broad-band optical/UV/X-ray spectrum of PG1211+143: implications for the ionized outflow

    NASA Astrophysics Data System (ADS)

    Papadakis, I. E.; Nicastro, F.; Panagiotou, C.

    2016-06-01

    Context. We present the results from a detailed analysis of the 2007 Swift monitoring campaign of the quasar PG1211+143. Aims: We study its broad-band optical/UV-X-ray spectral energy distribution and its variations, with the use of physically motivated models. Methods: We constructed broad-band, optical/UV-X-ray spectral energy distributions over three X-ray flux intervals, and we fitted them with a model which accounts for the disc and the X-ray coronal emission. We also added a spectral model component to account for the presence of the warm absorber which has been well established from past observations of the source. Results: We detected no optical/UV variations over the two-month period of the monitoring campaign. On the other hand, the X-rays are highly variable in a correlated way in the soft and hard X-ray bands with an amplitude larger than has been commonly observed in nearby Seyferts, even on longer time scales. The three flux spectra are well fitted by the model we considered. The disc inner temperature remains constant at ~2 eV, while X-rays are variable in slope and normalization. The absorber covers almost 90% of the central source. It is outflowing with a velocity less than 2.3 × 104 km s-1 (3σ upper limit), and has a column density of log NH ~ 23.2. Its ionization parameter varies by a factor of 1.6, and it is in photo-ionizing equilibrium with the ionizing flux. It is located at a distance of less than 0.35 pc from the central source, and its relative thickness, ΔR/R, is less than 0.1. The absorber's ionization parameter variations can explain the larger than average amplitude of the X-ray variations. Conclusions: The absence of optical/UV variations are consistent with the high black hole mass estimate of ~108M⊙ for this object, which implies variability time scales longer than the period of the Swift observations. It argues against the presence of inward propagating fluctuations in the disc as the reason for the flux variability in this

  11. FAR-INFRARED PROPERTIES OF TYPE 1 QUASARS

    SciTech Connect

    Hanish, D. J.; Teplitz, H. I.; Capak, P.; Desai, V.; Armus, L.; Brinkworth, C.; Brooke, T.; Colbert, J.; Fadda, D.; Noriega-Crespo, A.; Paladini, R.; Frayer, D.; Huynh, M.; Lacy, M.; Murphy, E.; Scarlata, C.; Shenoy, S.

    2013-05-01

    We use the Spitzer Space Telescope Enhanced Imaging Products and the Spitzer Archival Far-InfraRed Extragalactic Survey to study the spectral energy distributions (SEDs) of spectroscopically confirmed type 1 quasars selected from the Sloan Digital Sky Survey (SDSS). By combining the Spitzer and SDSS data with the Two Micron All Sky Survey, we are able to construct a statistically robust rest-frame 0.1-100 {mu}m type 1 quasar template. We find that the quasar population is well-described by a single power-law SED at wavelengths less than 20 {mu}m, in good agreement with previous work. However, at longer wavelengths, we find a significant excess in infrared luminosity above an extrapolated power-law, along with significant object-to-object dispersion in the SED. The mean excess reaches a maximum of 0.8 dex at rest-frame wavelengths near 100 {mu}m.

  12. Rapid CIV BAL Variability in an SDSS-RM Quasar

    NASA Astrophysics Data System (ADS)

    Grier, Catherine; Hall, Patrick B.; Brandt, W. Niel; Trump, Jonathan; Shen, Yue; Vivek, M.

    2015-01-01

    The Sloan Digital Sky Survey Reverberation Mapping Project (SDSS-RM) recently completed its first round of spectroscopic observations of a sample of ~850 quasars with the SDSS-III BOSS spectrograph. From 2014 January-July, more than 30 epochs of spectroscopy were obtained for this quasar sample, and supporting observations were carried out at the Canada-France-Hawaii Telescope and the Steward Observatory Bok telescope. A number of quasars observed as a part of this project have broad absorption line (BAL) features in their spectra; we here report on observations of one such target that displays very rapid BAL variability --- the CIV trough is variable on rest frame timescales shorter than a few days. We will discuss the observed short-timescale variability of this BAL and the implications for the physical environment and physics regulating BALs in active galactic nuclei.

  13. Long-term variability of a complete sample of quasars

    SciTech Connect

    Cristiani, S.; Vio, R.; Andreani, P. )

    1990-07-01

    The long-term variability of a complete sample of quasars selected in the field of the SA 94 has been investigated. Using Schmidt plates covering a time baseline of seven years, about one-third of the quasars are found to be variable. It is suggested that all the quasi-stellar objects are variable with amplitudes of a few tenths of a magnitude on timescales of the order of some years in their restframes. The application of the variability technique to the selection of complete samples of quasars is discussed. The timescales estimated can be easily accounted for in the accreting black hole with thermal and viscous timescales. The variability is found to be correlated with the absolute magnitude and/or the redshift. 21 refs.

  14. Quasar variability limits on cosmological density of cosmic strings

    SciTech Connect

    Tuntsov, A. V.; Pshirkov, M. S.

    2010-03-15

    We put robust upper limits on the average cosmological density {Omega}{sub s} of cosmic strings based on the variability properties of a large homogeneous sample of Sloan Digital Sky Survey quasars. We search for an excess of characteristic variations of quasar brightness that are associated with string lensing and use the observed distribution of these variations to constrain the density of strings. The limits obtained do not invoke any clustering of strings. They apply to both open segments and closed loops of strings, usefully extend over a wide range of tensions 10{sup -13}quasar intrinsic variability rather than a mere increase in the volume of data.

  15. 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.

  16. PROTOSTELLAR OUTFLOWS AND RADIATIVE FEEDBACK FROM MASSIVE STARS

    SciTech Connect

    Kuiper, Rolf; Yorke, Harold W.; Turner, Neal J. E-mail: Harold.W.Yorke@jpl.nasa.gov

    2015-02-20

    We carry out radiation hydrodynamical simulations of the formation of massive stars in the super-Eddington regime including both their radiative feedback and protostellar outflows. The calculations start from a prestellar core of dusty gas and continue until the star stops growing. The accretion ends when the remnants of the core are ejected, mostly by the force of the direct stellar radiation in the polar direction and elsewhere by the reradiated thermal infrared radiation. How long the accretion persists depends on whether the protostellar outflows are present. We set the mass outflow rate to 1% of the stellar sink particle's accretion rate. The outflows open a bipolar cavity extending to the core's outer edge, through which the thermal radiation readily escapes. The radiative flux is funneled into the polar directions while the core's collapse proceeds near the equator. The outflow thus extends the ''flashlight effect'', or anisotropic radiation field, found in previous studies from the few hundred AU scale of the circumstellar disk up to the 0.1 parsec scale of the core. The core's flashlight effect allows core gas to accrete on the disk for longer, in the same way that the disk's flashlight effect allows disk gas to accrete on the star for longer. Thus although the protostellar outflows remove material near the core's poles, causing slower stellar growth over the first few free-fall times, they also enable accretion to go on longer in our calculations. The outflows ultimately lead to stars of somewhat higher mass.

  17. PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS

    SciTech Connect

    Machida, Masahiro N.

    2014-11-20

    A protostellar jet and outflow are calculated for ∼270 yr following the protostar formation using a three-dimensional magnetohydrodynamics simulation, in which both the protostar and its parent cloud are spatially resolved. A high-velocity (∼100 km s{sup –1}) jet with good collimation is driven near the disk's inner edge, while a low-velocity (≲ 10 km s{sup –1}) outflow with a wide opening angle appears in the outer-disk region. The high-velocity jet propagates into the low-velocity outflow, forming a nested velocity structure in which a narrow high-velocity flow is enclosed by a wide low-velocity flow. The low-velocity outflow is in a nearly steady state, while the high-velocity jet appears intermittently. The time-variability of the jet is related to the episodic accretion from the disk onto the protostar, which is caused by gravitational instability and magnetic effects such as magnetic braking and magnetorotational instability. Although the high-velocity jet has a large kinetic energy, the mass and momentum of the jet are much smaller than those of the low-velocity outflow. A large fraction of the infalling gas is ejected by the low-velocity outflow. Thus, the low-velocity outflow actually has a more significant effect than the high-velocity jet in the very early phase of the star formation.

  18. Locating star-forming regions in quasar host galaxies

    NASA Astrophysics Data System (ADS)

    Young, J. E.; Eracleous, M.; Shemmer, O.; Netzer, H.; Gronwall, C.; Lutz, Dieter; Ciardullo, R.; Sturm, Eckhard

    2014-02-01

    We present a study of the morphology and intensity of star formation in the host galaxies of eight Palomar-Green quasars using observations with the Hubble Space Telescope. Our observations are motivated by recent evidence for a close relationship between black hole growth and the stellar mass evolution in its host galaxy. We use narrow-band [O II]λ3727, Hβ, [O III]λ5007 and Paα images, taken with the Wide Field Planetary Camera 2 and NICMOS instruments, to map the morphology of line-emitting regions, and, after extinction corrections, diagnose the excitation mechanism and infer star-formation rates. Significant challenges in this type of work are the separation of the quasar light from the stellar continuum and the quasar-excited gas from the star-forming regions. To this end, we present a novel technique for image decomposition and subtraction of quasar light. Our primary result is the detection of extended line-emitting regions with sizes ranging from 0.5 to 5 kpc and distributed symmetrically around the nucleus, powered primarily by star formation. We determine star-formation rates of the order of a few tens of M⊙ yr-1. The host galaxies of our target quasars have stellar masses of the order of 1011 M⊙ and specific star-formation rates on a par with those of M82 and luminous infrared galaxies. As such they fall at the upper envelope or just above the star-formation mass sequence in the specific star formation versus stellar mass diagram. We see a clear trend of increasing star-formation rate with quasar luminosity, reinforcing the link between the growth of the stellar mass of the host and the black hole mass found by other authors.

  19. Near infrared observations of quasars with extended ionized envelopes

    NASA Astrophysics Data System (ADS)

    Márquez, I.; Durret, F.; Petitjean, P.

    1999-02-01

    We have observed a sample of 15 and 8 quasars with redshifts between 0.11 and 0.87 (mean value 0.38) in the J and K' bands respectively. Eleven of the quasars were previously known to be associated with extended emission line regions. After deconvolution of the image, substraction of the PSF when possible, and identification of companions with the help of HST archive images when available, extensions are seen for at least eleven quasars. However, average profiles are different from that of the PSF in only four objects, for which a good fit is obtained with an r(1/4) law, suggesting that the underlying galaxies are ellipticals. Redshifts were available in the literature for surrounding objects in five quasar fields. For these objects, one to five companion galaxies were found. One quasar even belongs to a richness class 1 cluster. Most other quasars in our sample have nearby galaxies in projection which may also be companions. Environmental effects are therefore probably important to account for the properties of these objects. Based on data obtained at the European Southern Observatory, La Silla, Chile. Also based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute; STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France and of the NASA/IPAC extragalactic database (NED), which is operated by the Jet Propulsion Laboratory, Caltech under contract with the National Aeronautics and Space Administration.

  20. Environments of strong/ultrastrong, ultraviolet Fe II emitting quasars

    NASA Astrophysics Data System (ADS)

    Clowes, Roger G.; Raghunathan, Srinivasan; Söchting, Ilona K.; Graham, Matthew J.; Campusano, Luis E.

    2013-08-01

    We have investigated the strength of ultraviolet (UV) Fe II emission from quasars within the environments of large quasar groups (LQGs) in comparison with quasars elsewhere, for 1.1 ≤ zLQG ≤ 1.7, using the DR7QSO catalogue of the Sloan Digital Sky Survey. We use the Weymann et al. W2400 equivalent width, defined between the rest-frame continuum windows 2240-2255 and 2665-2695 Å, as the measure of the UV Fe II emission. We find a significant shift of the W2400 distribution to higher values for quasars within LQGs, predominantly for those LQGs with 1.1 ≤ zLQG ≤ 1.5. There is a tentative indication that the shift to higher values increases with the quasar i magnitude. We find evidence that within LQGs the ultrastrong emitters with W2400 ≥ 45 Å (more precisely, ultrastrong plus with W2400 ≥ 44 Å) have preferred nearest-neighbour separations of ˜30-50 Mpc to the adjacent quasar of any W2400 strength. No such effect is seen for the ultrastrong emitters that are not in LQGs. The possibilities for increasing the strength of the Fe II emission appear to be iron abundance, Lyα fluorescence and microturbulence, and probably all of these operate. The dense environment of the LQGs may have led to an increased rate of star formation and an enhanced abundance of iron in the nuclei of galaxies. Similarly, the dense environment may have led to more active blackholes and increased Lyα fluorescence. The preferred nearest-neighbour separation for the stronger emitters would appear to suggest a dynamical component, such as microturbulence. In one particular LQG, the Huge-LQG (the largest structure known in the early Universe), six of the seven strongest emitters very obviously form three pairings within the total of 73 members.

  1. Gravitational focusing and the association of distant quasars with foreground galaxies

    NASA Technical Reports Server (NTRS)

    Canizares, C. R.

    1981-01-01

    The surface density of quasars brighter than a given threshold is enhanced near a galaxy by the gravitational focusing of light from those quasars that are nearly co-aligned with individual stars in the galaxy halo. The focusing can intensify and make detectable quasars which would otherwise have been below the threshold. If galaxies have massive haloes of macroscopic objects then the resulting enhancement could explain the apparent association between quasars and galaxies with discrepant redshifts found in a statistical analysis. Therefore, such quasar-galaxy associations need not require the abandonment of the cosmological interpretation of the redshift.

  2. Contribution of alluvial groundwater to the outflow of mountainous catchments

    NASA Astrophysics Data System (ADS)

    Käser, Daniel; Hunkeler, Daniel

    2016-02-01

    Alluvial aquifers in mountainous regions cover typically a limited area. Their contribution to catchment storage and outflow is rarely isolated; alluvial groundwater discharge under gauging stations is generally assumed negligible; and hydrological models tend to lump alluvial storage with other units. The role of alluvial aquifers remains therefore unclear: can they contribute significantly to outflow when they cover a few percent of catchment area? Should they be considered a dynamic storage unit or merely a transmission zone? We address these issues based on the continuous monitoring of groundwater discharge, river discharge (one year), and aquifer storage (6 months) in the 6 km2 alluvial system of a 194 km2 catchment. River and groundwater outflow were measured jointly through "coupled gauging stations." The contribution of alluvial groundwater to outflow was highest at the outlet of a subcatchment (52 km2), where subsurface discharge amounted to 15% of mean annual outflow, and 85% of outflow during the last week of a drought. In this period, alluvial-aquifer depletion supported 75% of the subcatchment outflow and 35% of catchment outflow—thus 3% of the entire catchment supported a third of the outflow. Storage fluctuations occurred predominantly in the aquifer's upstream part, where heads varied over 6 m. Not only does this section act as a significant water source, but storage recovers also rapidly at the onset of precipitation. Storage dynamics were best conceptualized along the valley axis, rather than across the more conventional riparian-channel transect. Overall the contribution of alluvial aquifers to catchment outflow deserves more attention.

  3. Emission-line variability and distance of quasars.

    PubMed

    Pfleiderer, J; Grewing, M

    1967-08-01

    The radius of the line-emitting region in quasars is larger than 1 parsec for the cosmological hypothesis and smaller than 1 parsec for the local hypothesis. Variability in emission lines has been reported but not proved beyond doubt. Its time scale would be a direct observational indicator of this radius and would add an important element to the discussion of the origin of quasars. Objects that are variable in their optical continuum seem to be the most promising ones to look at for line variations, and they should be observed spectroscopically at regular intervals.

  4. UNIFICATION OF LUMINOUS TYPE 1 QUASARS THROUGH C IV EMISSION

    SciTech Connect

    Richards, Gordon T.; Kruczek, Nicholas E.; Deo, Rajesh P.; Kratzer, Rachael M.; Gallagher, S. C.; Hall, Patrick B.; Hewett, Paul C.; Leighly, Karen M.; Shen, Yue

    2011-05-15

    Using a sample of {approx}30,000 quasars from the 7th Data Release of the Sloan Digital Sky Survey, we explore the range of properties exhibited by high-ionization, broad emission lines, such as C IV {lambda}1549. Specifically, we investigate the anti-correlation between continuum luminosity and emission-line equivalent width (the Baldwin Effect (BEff)) and the 'blueshifting' of the high-ionization emission lines with respect to low-ionization emission lines. Employing improved redshift determinations from Hewett and Wild, the blueshift of the C IV emission line is found to be nearly ubiquitous, with a mean shift of {approx}810 km s{sup -1} for radio-quiet (RQ) quasars and {approx}360 km s{sup -1} for radio-loud (RL) quasars. The BEff is present in both RQ and RL samples. We consider these phenomena within the context of an accretion disk-wind model that is modulated by the nonlinear correlation between ultraviolet and X-ray continuum luminosity. Composite spectra are constructed as a function of C IV emission-line properties in an attempt to reveal empirical relationships between different line species and the continuum. Within a two-component disk+wind model of the broad emission-line region (BELR), where the wind filters the continuum seen by the disk component, we find that RL quasars are consistent with being dominated by the disk component, while broad absorption line quasars are consistent with being dominated by the wind component. Some RQ objects have emission-line features similar to RL quasars; they may simply have insufficient black hole (BH) spin to form radio jets. Our results suggest that there could be significant systematic errors in the determination of L{sub bol} and BH mass that make it difficult to place these findings in a more physical context. However, it is possible to classify quasars in a paradigm where the diversity of BELR parameters is due to differences in an accretion disk wind between quasars (and over time); these differences are

  5. The quasar luminosity function from a variability-selected sample

    NASA Astrophysics Data System (ADS)

    Hawkins, M. R. S.; Veron, P.

    1993-01-01

    A sample of quasars is selected from a 10-yr sequence of 30 UK Schmidt plates. Luminosity functions are derived in several redshift intervals, which in each case show a featureless power-law rise towards low luminosities. There is no sign of the 'break' found in the recent UVX sample of Boyle et al. It is suggested that reasons for the disagreement are connected with biases in the selection of the UVX sample. The question of the nature of quasar evolution appears to be still unresolved.

  6. The optical variability of the quasar 3C 446

    SciTech Connect

    Barbieri, C.; Vio, R.; Cappellaro, E; Turatto, M Padova Osservatorio Astronomico, Padua )

    1990-08-01

    The optical variability of the quasar 3C 446 is investigated using power spectrum and structure function analysis along with a new set of observations that extend the available data till 1989. No contradiction is found between the PS and SF analyses. The presence of the 1540-day periodicity is strengthened by the occurrence of the 1988 luminosity peak, suggesting that the next burst will occur in the northern spring of 1992. The time series of the quasar is nonstationary. The light variations are determined by a sequence of luminosity bursts, mostly regularly spaced in time and lasting up to 2 yr. 25 refs.

  7. Black holes, quasars, and the universe /2nd edition/

    NASA Technical Reports Server (NTRS)

    Shipman, H. L.

    1980-01-01

    Topics of astronomy are discussed in terms of black holes, galaxies, quasars, and models of the universe. Black holes are approached through consideration of stellar evolution, white dwarfs, supernovae, neutron stars, pulsars, the event horizon, Cygnus X-1, white holes, and worm holes. Attention is also given to radio waves from high speed electrons, the radiation emitted by quasars, active galaxies, galactic energy sources, and interpretations of the redshift. Finally, the life cycle of the universe is deliberated, along with the cosmic time scale, evidence for the Big Bang, and the future of the universe.

  8. Quasar X-Ray Spectra At z=1.5

    NASA Technical Reports Server (NTRS)

    Siemiginowska, Aneta

    2001-01-01

    The predicted counts for ASCA observation was much higher than actually observed counts in the quasar. However, there are three weak hard x-ray sources in the GIS field. We are adding them to the source counts in modeling of hard x-ray background. The work is in progress. We have published a paper in Ap.J. on the luminosity function and the quasar evolution. Based on the theory described in this paper we are predicting a number of sources and their contribution to the x-ray background at different redshifts. These model predictions will be compared to the observed data in the final paper.

  9. Exploring the Full Range of Properties of Quasar Spectral Distribution

    NASA Technical Reports Server (NTRS)

    Wilkes, B.

    1999-01-01

    The aim of this work is to obtain multi-wavelength supporting data for the sample of quasars and active galaxies observed in the far-infrared (IR) by ISO as part of our Key Project on quasars and active galaxies. This dataset then provides complete spectral energy distributions (radio-X-ray) of the ISO sample in order to fully delineate the continuum shapes and to allow detailed modeling of that continuum. The report is made up of a short project summary, and a bibliography of published papers, proceedings and presentations.

  10. The nature of the redshift and directly observed quasar statistics.

    PubMed

    Segal, I E; Nicoll, J F; Wu, P; Zhou, Z

    1991-07-01

    The nature of the cosmic redshift is one of the most fundamental questions in modern science. Hubble's discovery of the apparent Expansion of the Universe is derived from observations on a small number of galaxies at very low redshifts. Today, quasar redshifts have a range more than 1000 times greater than those in Hubble's sample, and represent more than 100 times as many objects. A recent comprehensive compilation of published measurements provides the basis for a study indicating that quasar observations are not in good agreement with the original predictions of the Expanding Universe theory, but are well fit by the predictions of an alternative theory having fewer adjustable parameters.

  11. Ion Outflow from Venus and Mars and the Processes Involved

    NASA Astrophysics Data System (ADS)

    Stenberg Wieser, G.; Holmstrom, M.; Futaana, Y.

    2015-12-01

    We review the ion outflow from Venus and Mars. We present the current best estimates of the escaping fluxes and describe the acceleration processes that have been identified. We discuss which solar wind parameters govern the response of the ionosphere as well as the role of the crustal magnetic fields on Mars. Although the characteristics of the two planets are very different, we find both similarities and differences when investigating the ion escape morphology and dynamics. Finally, we compare Venus and Mars with Earth and discuss the effect of a global intrinsic magnetic field on ion outflow and the potential importance of outflowing cold ions.

  12. Accretion driven outflows across the black hole mass scale

    NASA Astrophysics Data System (ADS)

    King, Ashley L.

    2016-04-01

    Pumping highly relativistic particles and radiation into their environment, accreting black holes co-evolve with their surroundings through their powerful outflows. These outflows are divided into highly collimated, relativistic jets and wide-angle winds, and are primarily associated with a particular accretion states. Understanding just how these outflows couple to the accretion flow will enable us to assess the amount of energy and feedback that is injected into the vicinity of a black hole. During this talk, I will discuss our studies of both stellar-mass and supermassive black hole outlfows, and how the similarities of these flows across the mass scale may point to common driving mechanisms.

  13. The ultraviolet excess of quasars 3: The highly polarized quasars PKS 0736+017 and PKS 1510-089

    NASA Technical Reports Server (NTRS)

    Malkan, M. A.; Moore, R. L.

    1985-01-01

    Ultraviolet/optical/infrared spectrophotometry of the highly-polarized quasars (HPQ's) PKS 0736+017 and PKS 1510-089 is analyzed. A blazar continuum component like that in BL Lac objects (e.g. with violent variability, high polarization, and a steep power-law shape) contributes about half the visual light of 1510-089, and at least three-quarters of that in 0736+017. The remaining light has the same spectrum as normal (low-polarization) quasars, including an ultraviolet excess or blue bump, which is easily detected in the IUE spectra of 1510-089, and weakly detected in 0736+017. The line fluxes do vary, but not as much as the continuum. The ratios of the broad emission lines, and the Balmer continuum are normal in both quasars.

  14. Ionized outflows in luminous type 2 AGNs at z < 0.6: no evidence for significant impact on the host galaxies

    NASA Astrophysics Data System (ADS)

    Villar-Martín, M.; Arribas, S.; Emonts, B.; Humphrey, A.; Tadhunter, C.; Bessiere, P.; Cabrera Lavers, A.; Ramos Almeida, C.

    2016-07-01

    We investigate the presence of extended ionized outflows in 18 luminous type 2 AGNs (11 quasars and 7 high-luminosity Seyfert 2s) at 0.3 < z < 0.6 based on VLT-FORS2 spectroscopy. We infer typical lower limits on the radial sizes of the outflows Ro ≳ several × 100 pc and upper limits Ro ≲ 1-2 kpc. Our results are inconsistent with related studies which suggest that large scale (Ro ˜ several-15 kpc) are ubiquitous in QSO2. We study the possible causes of discrepancy and propose that seeing smearing is the cause of the large inferred sizes. The implications in our understanding of the feedback phenomenon are important since the mass Mo (through the density), mass injection skew3dot{M}_o and energy injection dot{E}_o rates of the outflows become highly uncertain. One conclusion seems unavoidable: Mo, skew3dot{M}_o and dot{E}_o are modest or low compared with previous estimations. We obtain typically Mo ≲ (0.4-22) × 106 M⊙ (median 1.1 × 106 M⊙) assuming n = 1000 cm-3. These are ˜102-104 times lower than values reported in the literature. Even under the most favourable assumptions, we obtain \\dot{M}_o ≲ 10 M⊙ yr-1 in general, 100-1000 times lower than claimed in related studies. Although the uncertainties are large, it is probable that these are lower than typical star-forming rates. In conclusion, no evidence is found supporting that typical outflows can affect the interstellar medium of the host galaxies across spatial scales ≳ 1-2 kpc.

  15. FIRST-2MASS RED QUASARS: TRANSITIONAL OBJECTS EMERGING FROM THE DUST

    SciTech Connect

    Glikman, Eilat; Urrutia, Tanya; Lacy, Mark; Djorgovski, S. George; Mahabal, Ashish; Myers, Adam D.; Ross, Nicholas P.; Petitjean, Patrick; Ge, Jian; Schneider, Donald P.; York, Donald G.

    2012-09-20

    We present a sample of 120 dust-reddened quasars identified by matching radio sources detected at 1.4 GHz in the Faint Images of the Radio Sky at Twenty Centimeters survey with the near-infrared Two Micron All Sky Survey catalog and color-selecting red sources. Optical and/or near-infrared spectroscopy provide broad wavelength sampling of their spectral energy distributions that we use to determine their reddening, characterized by E(B - V). We demonstrate that the reddening in these quasars is best described by Small-Magellanic-Cloud-like dust. This sample spans a wide range in redshift and reddening (0.1 {approx}< z {approx}< 3, 0.1 {approx}< E(B - V) {approx}< 1.5), which we use to investigate the possible correlation of luminosity with reddening. At every redshift, dust-reddened quasars are intrinsically the most luminous quasars. We interpret this result in the context of merger-driven quasar/galaxy co-evolution where these reddened quasars are revealing an emergent phase during which the heavily obscured quasar is shedding its cocoon of dust prior to becoming a 'normal' blue quasar. When correcting for extinction, we find that, depending on how the parent population is defined, these red quasars make up {approx}< 15%-20% of the luminous quasar population. We estimate, based on the fraction of objects in this phase, that its duration is 15%-20% as long as the unobscured, blue quasar phase.

  16. Dust Deficient Palomar-Green Quasars and Their High-redshift Counterparts

    NASA Astrophysics Data System (ADS)

    Lyu, Jianwei; Rieke, G. H.; Shi, Y.

    2016-08-01

    The Elvis 1994 AGN template has been phenomenally successful at matching the SEDs of the vast majority of Type-1 quasars from the local Universe to z~6. Nonetheless, a population of hot-dust-poor or hot-dust-free quasars has been found both at intermediate and high-z. Estimates of the numbers of these anomalous quasars vary widely, along with speculations on their place in quasar evolution, e.g., whether they are related to the early growth of the black holes. To answer some of these questions, we have decomposed the optical-IR SEDs of 87 local Palomar-Green (PG) quasars: we find ~20% of them show only weak hot dust emission, indicating the hot dust deficient (HDD) quasars may be relatively common. Moreover, there is an intermediate population of warm dust deficient (WDD) quasars. Based on the comparison between the IR SEDs and classical torus models, the hot-dust-deficient quasars may have relatively little flaring in the dust density distribution in their circumnuclear tori. Our SED decomposition also indicates that the dust deficient quasars are more likely to show lower Eddington ratios and weaker star formation than the majority of quasars. Given these systematic differences, the HDD, WDD, and normal quasars could indicate a sequence of torus evolution around the accreting super-massive black holes.

  17. Rest-frame optical properties of luminous, radio-selected broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    Runnoe, Jessie C.; Ganguly, R.; Brotherton, M. S.; DiPompeo, M. A.

    2013-08-01

    We have obtained Infrared Telescope Facility/SpeX spectra of eight moderate-redshift (z = 0.7-2.4), radio-selected (log R* ≈ 0.4-1.9) broad absorption line (BAL) quasars. The spectra cover the rest-frame optical band. We compare the optical properties of these quasars to those of canonically radio-quiet (log R* ≲ 1) BAL quasars at similar redshifts and to low-redshift quasars from the Palomar-Green catalogue. As with previous studies of BAL quasars, we find that [O III] λ5007 is weak, and optical Fe II emission is strong, a rare combination in canonically radio-loud (log R* ≳ 1) quasars. With our measurements of the optical properties, particularly the Balmer emission-line widths and the continuum luminosity, we have used empirical scaling relations to estimate black hole masses and Eddington ratios. These lie in the range (0.4-2.6) × 109 M⊙ and 0.1-0.9, respectively. Despite their comparatively extreme radio properties relative to most BAL quasars, their optical properties are quite consistent with those of radio-quiet BAL quasars and dissimilar to those of radio-loud non-BAL quasars. While BAL quasars generally appear to have low values of [O III] λ5007/Fe II an extreme of `Eigenvector 1', the Balmer line widths and Eddington ratios do not appear to significantly differ from those of unabsorbed quasars at similar redshifts and luminosities.

  18. Toward an Understanding of Changing-look Quasars: An Archival Spectroscopic Search in SDSS

    NASA Astrophysics Data System (ADS)

    Ruan, John J.; Anderson, Scott F.; Cales, Sabrina L.; Eracleous, Michael; Green, Paul J.; Morganson, Eric; Runnoe, Jessie C.; Shen, Yue; Wilkinson, Tessa D.; Blanton, Michael R.; Dwelly, Tom; Georgakakis, Antonis; Greene, Jenny E.; LaMassa, Stephanie M.; Merloni, Andrea; Schneider, Donald P.

    2016-08-01

    The uncertain origin of the recently discovered “changing-look” quasar phenomenon—in which a luminous quasar dims significantly to a quiescent state in repeat spectroscopy over ˜10-year timescales—may present unexpected challenges to our understanding of quasar accretion. To better understand this phenomenon, we take a first step toward building a sample of changing-look quasars with a systematic but simple archival search for these objects in the Sloan Digital Sky Survey Data Release 12. By leveraging the >10-year baselines for objects with repeat spectroscopy, we uncover two new changing-look quasars and a third discovered previously. Decomposition of the multiepoch spectra and analysis of the broad emission lines suggest that the quasar accretion disk emission dims because of rapidly decreasing accretion rates (by factors of ≳2.5), while disfavoring changes in intrinsic dust extinction for the two objects where these analyses are possible. Broad emission line energetics also support intrinsic dimming of quasar emission as the origin for this phenomenon rather than transient tidal disruption events or supernovae. Although our search criteria included quasars at all redshifts and transitions from either quasar-like to galaxy-like states or the reverse, all of the clear cases of changing-look quasars discovered were at relatively low redshift (z˜ 0.2{--}0.3) and only exhibit quasar-like to galaxy-like transitions.

  19. Toward an Understanding of Changing-look Quasars: An Archival Spectroscopic Search in SDSS

    NASA Astrophysics Data System (ADS)

    Ruan, John J.; Anderson, Scott F.; Cales, Sabrina L.; Eracleous, Michael; Green, Paul J.; Morganson, Eric; Runnoe, Jessie C.; Shen, Yue; Wilkinson, Tessa D.; Blanton, Michael R.; Dwelly, Tom; Georgakakis, Antonis; Greene, Jenny E.; LaMassa, Stephanie M.; Merloni, Andrea; Schneider, Donald P.

    2016-08-01

    The uncertain origin of the recently discovered “changing-look” quasar phenomenon—in which a luminous quasar dims significantly to a quiescent state in repeat spectroscopy over ˜10-year timescales—may present unexpected challenges to our understanding of quasar accretion. To better understand this phenomenon, we take a first step toward building a sample of changing-look quasars with a systematic but simple archival search for these objects in the Sloan Digital Sky Survey Data Release 12. By leveraging the >10-year baselines for objects with repeat spectroscopy, we uncover two new changing-look quasars and a third discovered previously. Decomposition of the multiepoch spectra and analysis of the broad emission lines suggest that the quasar accretion disk emission dims because of rapidly decreasing accretion rates (by factors of ≳2.5), while disfavoring changes in intrinsic dust extinction for the two objects where these analyses are possible. Broad emission line energetics also support intrinsic dimming of quasar emission as the origin for this phenomenon rather than transient tidal disruption events or supernovae. Although our search criteria included quasars at all redshifts and transitions from either quasar-like to galaxy-like states or the reverse, all of the clear cases of changing-look quasars discovered were at relatively low redshift (z˜ 0.2{--}0.3) and only exhibit quasar-like to galaxy-like transitions.

  20. Distribution of gas and galaxies around the distant quasar PKS 1614 + 051

    SciTech Connect

    Hu, E.M.; Cowie, L.L.

    1987-06-01

    The results of narrow-band and broad-band filter observations of the region surrounding the z = 3.21 quasars, PKS 1614 + 051, made under subarcsec seeing conditions with the 3.6 m CFHT telescope at Mauna Kea are reported. The nuclear region of the Lyman-alpha companion to the quasar is resolved with a FWHM of about 0.9 arcsec A magnitude fainter. Limits on detectable continuum flux from this object suggest that it is a gas cloud interacting with the quasar, and its emission is consistent with simple photoionization by the quasar. However, the presence of several galaxies around the periphery of the quasar is noted. A search of 11 additional quasars at z greater than 3 has failed to show any other such systems. It is argued that this is consistent with the statistics of extended emission line systems in low-z quasars. 11 references.