High energy neutrino absorption and its effects on stars in close X-ray binaries

NASA Technical Reports Server (NTRS)

Gaisser, T. K.; Stecker, F. W.

1986-01-01

The physics and astrophysics of high energy neutrino production and interactions in close X-ray binary systems are studied. These studies were stimulated by recent observations of ultrahigh energy gamma-rays and possibly other ultrahigh energy particles coming from the directions of Cygnus X-3 and other binary systems and possessing the periodicity characteristics of these systems. Systems in which a compact object, such as a neutron star, is a strong source of high energy particles which, in turn, produce photons, neutronos and other secondary particles by interactions in the atmosphere of the companion star were considered. The highest energy neutrinos are absorbed deep in the companion and the associated energy deposition may be large enough to effect its structure or lead to its ultimate disruption. This neutrino heating was evaluated, starting with a detailed numerical calculation of the hadronic cascade induced in the atmosphere of the companion star. For some theoretical models, the resulting energy deposition from neutrino absorption may be so great as to disrupt the companion star over an astronomically small timescale of the order of 10,000 years. Even if the energy deposition is smaller, it may still be high enough to alter the system substantially, perhaps leading to quenching of high energy signals from the source. Given the cosmic ray luminosities required to produce the observed gamma rays from cygnus X-3 and LMX X-4, such a situation may occur in these sources.

Hercules X-1: Pulsed gamma-rays detected above 150 GeV

NASA Technical Reports Server (NTRS)

Cawley, M. F.; Fegan, D. J.; Gibbs, K. G.; Gorham, P. W.; Kenny, S.; Lamb, R. C.; Liebing, D. F.; Porter, N. A.; Stenger, V. J.; Weekes, T. C.

1985-01-01

The 1.24 second binary pulsar Her X-1, first observed in X-rays in 1971 by UHURU has now been seen as a sporadic gamma ray source from 1 TeV up to at least 500 TeV. In addition, reprocessed optical and infrared pulses are seen from the companion star HZ Herculis. Thus measurements of the Her X-1/HZ Herculis system span 15 decades in energy, rivaling both the Crab pulsar and Cygnus X-3 in this respect for a discrete galactic source.

Anatomy of a cosmic-ray neutrino source and the Cygnus X-3 system

NASA Technical Reports Server (NTRS)

Stecker, F. W.; Harding, A. K.; Barnard, J. J.

1985-01-01

The effects of an intense beam of ultra-high energy cosmic rays from a compact object in the Cygnus X-3 binary system hitting the companion star, and of the subsequent production of secondary neutrinos, are examined. A maximum allowable beam luminosity of about 10 to the 42nd erg/s is found for a system containing a 1-10 solar mass main sequence target star. The proton beam must heat a relatively small area of the target star to satisfy observational constraints on the resulting stellar wind. With such a model, the neutrino to gamma-ray flux ratio of about 1000 can result from a combination of gamma-ray absorption and a large neutrino to gamma-ray duty cycle ratio. It is found that the high density of the atmosphere resulting from compression by the beam leads to pion cascading and a neutrino spectrum peaking at 1-10 GeV energies.

Very high energy gamma-ray binary stars.

PubMed

Lamb, R C; Weekes, T C

1987-12-11

One of the major astronomical discoveries of the last two decades was the detection of luminous x-ray binary star systems in which gravitational energy from accretion is released by the emission of x-ray photons, which have energies in the range of 0.1 to 10 kiloelectron volts. Recent observations have shown that some of these binary sources also emit photons in the energy range of 10(12) electron volts and above. Such sources contain a rotating neutron star that is accreting matter from a companion. Techniques to detect such radiation are ground-based, simple, and inexpensive. Four binary sources (Hercules X-1, 4U0115+63, Vela X-1, and Cygnus X-3) have been observed by at least two independent groups. Although the discovery of such very high energy "gamma-ray binaries" was not theoretically anticipated, models have now been proposed that attempt to explain the behavior of one or more of the sources. The implications of these observations is that a significant portion of the more energetic cosmic rays observed on Earth may arise from the action of similar sources within the galaxy during the past few million years.

Formation of a black hole in the dark.

PubMed

Mirabel, I Félix; Rodrigues, Irapuan

2003-05-16

We show that the black hole in the x-ray binary Cygnus X-1 was formed in situ and did not receive an energetic trigger from a nearby supernova. The progenitor of the black hole had an initial mass greater than 40 solar masses, and during the collapse to form the approximately 10-solar mass black hole of Cygnus X-1, the upper limit for the mass that could have been suddenly ejected is approximately 1 solar mass, much less than the mass ejected in a supernova. The observations suggest that high-mass stellar black holes may form promptly, when massive stars disappear silently.

Studying the Warm Layer and the Hardening Factor in Cygnus X-1

NASA Technical Reports Server (NTRS)

Yao, Yangsen; Zhang, Shuangnan; Zhang, Xiaoling; Feng, Yuxin

2002-01-01

As the first dynamically determined black hole X-ray binary system, Cygnus X-1 has been studied extensively. However, its broadband spectrum observed with BeppoSax is still not well understood. Besides the soft excess described by the multi-color disk model (MCD), the power-law hard component and a broad excess feature above 10 keV (a disk reflection component), there is also an additional soft component around 1 keV, whose origin is not known currently. Here we propose that the additional soft component is due to the thermal Comptonization between the soft disk photons and a warm plasma cloud just above the disk, i.e., a warm layer. We use the Monte-Carlo technique to simulate this Compton scattering process and build a table model based on our simulation results. With this table model, we study the disk structure and estimate the hardening factor to the MCD component in Cygnus X-1.

Hadronic gamma-ray and neutrino emission from Cygnus X-3

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

Sahakyan, N.; Piano, G.; Tavani, M., E-mail: narek@icra.it

2014-01-01

Cygnus X-3 (Cyg X-3) is a remarkable Galactic microquasar (X-ray binary) emitting from radio to γ-ray energies. In this paper, we consider the hadronic model of emission of γ-rays above 100 MeV and their implications. We focus on the joint γ-ray and neutrino production resulting from proton-proton interactions within the binary system. We find that the required proton injection kinetic power, necessary to explain the γ-ray flux observed by AGILE and Fermi-LAT, is L{sub p} ∼ 10{sup 38} erg s{sup –1}, a value in agreement with the average bolometric luminosity of the hypersoft state (when Cyg X-3 was repeatedly observedmore » to produce transient γ-ray activity). If we assume an increase of the wind density at the superior conjunction, the asymmetric production of γ-rays along the orbit can reproduce the observed modulation. According to observational constraints and our modeling, a maximal flux of high-energy neutrinos would be produced for an initial proton distribution with a power-law index α = 2.4. The predicted neutrino flux is almost two orders of magnitude less than the two-month IceCube sensitivity at ∼1 TeV. If the protons are accelerated up to PeV energies, the predicted neutrino flux for a prolonged 'soft X-ray state' would be a factor of about three lower than the one-year IceCube sensitivity at ∼10 TeV. This study shows that, for a prolonged soft state (as observed in 2006) possibly related to γ-ray activity and a hard distribution of injected protons, Cyg X-3 might be close to being detectable by cubic-kilometer neutrino telescopes such as IceCube.« less

Theoretical interpretation of the HEAO-3 observations of Cygnus X-3 under the HEAO-3 Guest Investigator Program

NASA Technical Reports Server (NTRS)

Marscher, Alan P.

1987-01-01

A model of the galactic X-ray source Cygnus X-3 (Cyg X-3) is presented which deviates from previous models by positing that the X-rays originate in a jet rather than a binary system consiting of an ordinary star and a collapsed object. In the new model, the 4.8 hour period of Cyg X-3 is caused by variable absorption which occurs as the jet precesses. The primary role of the accretion disk corona (ADC) in modulating Cyg X-3 radiation is to make the observed intensity of a blob of material in a jet appear dimmer by absorption. The needed derivation of the positional dependence of the density of the ADC is freed of some complications by assuming that only the inner regions of the disk are precessing, with a period shorter than 4.8 hours. This model permits the secondary star to be a supergiant, as indicated by the luminosity of the system. The model is especially helpful in interpreting production of radio outbursts and very high energy gamma rays.

REVIEWS OF TOPICAL PROBLEMS: Cygnus X-3: a powerful galactic source of hard radiation

NASA Astrophysics Data System (ADS)

Vladimirskiĭ, B. M.; Gal'per, A. M.; Luchkov, B. I.; Stepanyan, A. A.

1985-02-01

A review is given of experimental and theoretical research on the galactic source Cyg X-3, whose electromagnetic spectrum extends from radio frequencies to ultrahigh-energy (Eγ ~ 1016 eV) γ-rays. Cyg X-3 also has a high x-ray luminosity (1038 erg/sec) and exhibits diversified sporadic and periodic variations, most notably occasional radio outbursts and a 4h.8 infrared, x-ray, and γ-ray cycle. Analysis of the observations indicates that Cyg X-3 is a close binary system comprising a compact relativistic object (neutron star, black hole) and a dwarf companion losing mass. Particles are accelerated to 1016 eV within the system.

Search for cosmic ray sources using muons detected by the MACRO experiment

NASA Astrophysics Data System (ADS)

Ambrosio, M.; Antolini, R.; Auriemma, G.; Bakari, D.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bloise, C.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Choudhary, B. C.; Coutu, S.; Cozzi, M.; de Cataldo, G.; Dekhissi, H.; de Marzo, C.; de Mitri, I.; Derkaoui, J.; de Vincenzi, M.; di Credico, A.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Guarino, F.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longley, N. P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Pistilli, P.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Rrhioua, A.; Satriano, C.; Scapparone, E.; Scholberg, K.; Sciubba, A.; Serra, P.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlè, G.; Togo, V.; Vakili, M.; Walter, C. W.; Webb, R.

2003-03-01

The MACRO underground detector at Gran Sasso Laboratory recorded 60 million secondary cosmic ray muons from February 1989 until December 2000. Different techniques were used to analyze this sample in search for density excesses from astrophysical point-like sources. No evidence for DC excesses for any source in an all-sky survey is reported. In addition, searches for muon excess correlated with the known binary periods of Cygnus X-3 and Hercules X-1, and searches for statistically significant bursting episodes from known γ-ray sources are also proved negative.

The Extreme Spin of the Black Hole in Cygnus X-1

NASA Technical Reports Server (NTRS)

Gou, Lijun; McClintock, Jeffre E.; Reid, Mark J.; Orosz, Jerome A.; Steiner, James F.; Narayan, Ramesh; Xiang, Jingen; Remillard, Ronald A.; Arnaud, Keith A.; Davis, Shane W.

2005-01-01

The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observatIOns. We have recently determined accurate values for its mass and distance, and for the orbital inclination angle of the binary. Building on these.results, which are based on our favored (asynchronous) dynamical model, we have measured the radius of the inner edge of the black hole's accretion disk by fitting its thermal continuum.spectrum to a fully relativistic model of a thin accretion disk. Assuming that the spin axis of the black hole is aligned with the orbital angular momentum vector, we have determined that Cygnus X-I contains a near-extreme Kerr black hole with a spin parameter a* > 0.95 (3(sigma)). For a less probable (synchronous) dynamIcal model, we find a* > 0.92 (3(sigma)). In our analysis, we include the uncertainties in black hole mass orbital inclination angle and distance, and we also include the uncertainty in the calibration of the absolute flux via the Crab. These four sources of uncertainty totally dominate the error budget. The uncertainties introduced by the thin-disk model we employ are particularly small in this case given the extreme spin of the black hole and the disk's low luminosity.

The Extreme Spin of the Black Hole in Cygnus X-1

NASA Technical Reports Server (NTRS)

Gou, Lijun; McClintock, Jeffrey E.; Reid, Mark J.; Orosz, Jerome A.; Steiner, James F.; Narayan, Ramesh; Xiang, Jingen; Remillard, Ronald A.; Arnaud, Keith A.; Davis, Shane W.

2011-01-01

The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observations. We have recently determined accurate values for its mass and distance, and for the orbital inclination angle of the binary. Building on these results, which are based on our favored (asynchronous) dynamical model, we have measured the radius of the inner edge of the black hole s accretion disk by fitting its thermal continuum spectrum to a fully relativistic model of a thin accretion disk. Assuming that the spin axis of the black hole is aligned with the orbital angular momentum vector, we have determined that Cygnus X-1 contains a near-extreme Kerr black hole with a spin parameter a* > 0.95 (3(sigma)). For a less probable (synchronous) dynamical model, we find a. > 0.92 (3 ). In our analysis, we include the uncertainties in black hole mass, orbital inclination angle, and distance, and we also include the uncertainty in the calibration of the absolute flux via the Crab. These four sources of uncertainty totally dominate the error budget. The uncertainties introduced by the thin-disk model we employ are particularly small in this case given the extreme spin of the black hole and the disk s low luminosity.

X-ray observations of LMC X-3 with the monitor proportional counter aboard the HEAO 2 Einstein observatory - A comparison with Cygnus X-1

NASA Technical Reports Server (NTRS)

Weisskopf, M. C.; Darbro, W. A.; Elsner, R. F.; Williams, A. C.; Kahn, S. M.; Grindlay, J. E.; Naranan, S.; Sutherland, P. G.

1983-01-01

A comparison is presented of the black hole candidates LMC X-3 and Cygnus X-1 based on Einstein observations of LMC X-3 with the monitor proportional counter. A spectral analysis shows LMC X-3 to be more like the typical bright galactic X-ray source than Cygnus X-1. A search for periodic pulsations over a period range from 0.2 ms to over 1000 s set upper limits at the 90 percent confidence level of the order of 10 percent. An analysis of the aperiodic variability of LMC X-3 shows none of the shot noise behavior characteristic of Cygnus X-1. The absence of distinctive X-ray properties common to both sources suggests that the identification of black hole candidates on the basis of X-ray properties similar to Cygnus X-1 (or LMC X-3) is not reliable.

Classifying Black Hole States with Machine Learning

NASA Astrophysics Data System (ADS)

Huppenkothen, Daniela

2018-01-01

Galactic black hole binaries are known to go through different states with apparent signatures in both X-ray light curves and spectra, leading to important implications for accretion physics as well as our knowledge of General Relativity. Existing frameworks of classification are usually based on human interpretation of low-dimensional representations of the data, and generally only apply to fairly small data sets. Machine learning, in contrast, allows for rapid classification of large, high-dimensional data sets. In this talk, I will report on advances made in classification of states observed in Black Hole X-ray Binaries, focusing on the two sources GRS 1915+105 and Cygnus X-1, and show both the successes and limitations of using machine learning to derive physical constraints on these systems.

Evidence Of A Black Hole In The X-ray Binary System Cygnus X-3

NASA Astrophysics Data System (ADS)

Lombardi, C.; Virgilli, E.; Titarchuk, L.; Frontera, F.; Farinelli, R.

2011-09-01

Recently a close correlation between the photon index of the power law component and either the frequency of Quasi Periodic Oscillations (QPOs) or the flow of accretion disk has been found in the X-ray data concerning Black Holes (BH) in binary systems. The shape of this relationship, characterized by a saturation index when the system achieves high spectral brightness, finds a natural explanation in the processes of thermal and bulk Comptonization which are unique characteristic of the presence of a BH. For the whole set of observation we adopted a model consisting of the spectral component of BMC (Bulk Motion Comptonization model) that takes into account the direct emission of black body and the Comptonization process.

Cygnus X-1: A Case for a Magnetic Accretion Disk?

NASA Technical Reports Server (NTRS)

Nowak, Michael A.; Vaughan, B. A.; Dove, J.; Wilms, J.

1996-01-01

With the advent of Rossi X-ray Timing Explorer (RXTE), which is capable of broad spectral coverage and fast timing, as well as other instruments which are increasingly being used in multi-wavelength campaigns (via both space-based and ground-based observations), we must demand more of our theoretical models. No current model mimics all facets of a system as complex as an x-ray binary. However, a modern theory should qualitatively reproduce - or at the very least not fundamentally disagree with - all of Cygnus X-l's most basic average properties: energy spectrum (viewed within a broader framework of black hole candidate spectral behavior), power spectrum (PSD), and time delays and coherence between variability in different energy bands. Below we discuss each of these basic properties in turn, and we assess the health of one of the currently popular theories: Comptonization of photons from a cold disk. We find that the data pose substantial challenges for this theory, as well as all other in currently discussed models.

Spectroscopy of the Stellar Wind in the Cygnus X-1 System

NASA Technical Reports Server (NTRS)

Miskovicova, Ivica; Hanke, Manfred; Wilms, Joern; Nowak, Michael A.; Pottschmidt, Katja; Schultz, Norbert

2010-01-01

The X-ray luminosity of black holes is produced through the accretion of material from their companion stars. Depending on the mass of the donor star, accretion of the material falling onto the black hole through the inner Lagrange point of the system or accretion by the strong stellar wind can occur. Cygnus X-1 is a high mass X-ray binary system, where the black hole is powered by accretion of the stellar wind of its supergiant companion star HDE226868. As the companion is close to filling its Roche lobe, the wind is not symmetric, but strongly focused towards the black hole. Chandra-HETGS observations allow for an investigation of this focused stellar wind, which is essential to understand the physics of the accretion flow. We compare observations at the distinct orbital phases of 0.0, 0.2, 0.5 and 0.75. These correspond to different lines of sights towards the source, allowing us to probe the structure and the dynamics of the wind.

Propagating mass accretion rate fluctuations in black hole X-ray binaries: quantitative tests

NASA Astrophysics Data System (ADS)

Rapisarda, S.; Ingram, A.; van der Klis, M.

2017-10-01

Over the past 20 years, a consistent phenomenology has been established to describe the variability properties of Black Hole X-ray Binaries (BHBs). However, the physics behind the observational data is still poorly understood. The recently proposed model PROPFLUC assumes a truncated disc/hot inner flow geometry, with mass accretion rate fluctuations propagating through a precessing inner flow. These two processes give rise respectively to broad band variability and QPO. Because of propagation, the emission from different regions of the disc/hot flow geometry is correlated. In our study we applied the model PROPFLUC on different BHBs (including XTE J1550-564 and Cygnus X-1) in different spectral states, fitting jointly the power spectra in two energy bands and the cross-spectrum between these two bands. This represents the first study to utilize quantitive fitting of a physical model simultaneously to observed power and cross-spectra. For the case of XTE J1550-564, which displays a strong QPO, we found quantitative and qualitative discrepancies between model predictions and data, whereas we find a good fit for the Cygnus X-1 data, which does not display a QPO. We conclude that the discrepancies are generic to the propagating fluctuations paradigm, and may be related to the mechanism originating the QPO.

Polarization Radiation with Turbulent Magnetic Fields from X-Ray Binaries

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

Zhang, Jian-Fu; Xiang, Fu-Yuan; Lu, Ju-Fu, E-mail: jfzhang@xtu.edu.cn, E-mail: fyxiang@xtu.edu.cn, E-mail: lujf@xmu.edu.cn

2017-02-10

We study the properties of polarized radiation in turbulent magnetic fields from X-ray binary jets. These turbulent magnetic fields are composed of large- and small-scale configurations, which result in the polarized jitter radiation when the characteristic length of turbulence is less than the non-relativistic Larmor radius. On the contrary, the polarized synchrotron emission occurs, corresponding to a large-scale turbulent environment. We calculate the spectral energy distributions and the degree of polarization for a general microquasar. Numerical results show that turbulent magnetic field configurations can indeed provide a high degree of polarization, which does not mean that a uniform, large-scale magneticmore » field structure exists. The model is applied to investigate the properties of polarized radiation of the black-hole X-ray binary Cygnus X-1. Under the constraint of multiband observations of this source, our studies demonstrate that the model can explain the high polarization degree at the MeV tail and predict the highly polarized properties at the high-energy γ -ray region, and that the dominant small-scale turbulent magnetic field plays an important role for explaining the highly polarized observation at hard X-ray/soft γ -ray bands. This model can be tested by polarization observations of upcoming polarimeters at high-energy γ -ray bands.« less

Observations of Cygnus X-2 with IUE: Ultraviolet results from a multiwavelength campaign

NASA Technical Reports Server (NTRS)

Vrtilek, S. D.; Raymond, J. C.; Garcia, M. R.; Verbunt, F.; Hasinger, Guenther; Kuerster, M.

1989-01-01

The observations of the low-mass x ray binary, Cyg X-2, taken with the International Ultraviolet Explorer (IUE) in a campaign conducted in June and October of 1988 are reported. A direct relationship between the strength of the UV continuum and line emission and the placement of the x ray spectrum in one of three branches of the so-called Z-shaped curve is found by comparison with simultaneous x ray observations. All three previously known x ray spectral states are detected; the UV continuum and line emission increase monotonically along the Z with the least emission in the horizontal branch, and the most in the flaring branch. Emission lines due to HeII, CIV, NIII, NIV, NV, SiIV, and MgII are observed.

Cygnus X-3 Returns to an Active State

NASA Astrophysics Data System (ADS)

McCollough, Michael L.; Koljonen, Karri; Gurwell, Mark A.; Trushkin, Sergei; Pooley, Guy G.

2017-08-01

Cygnus X-3 is a well-known microquasar composed of a mass-donating Wolf-Rayet star and a compact object. Recently, Cygnus X-3 has been in a quiescent state for an extended period of time (2011-2016) but returned to an active state on two occasions during 2016/2017 including quenched/hypersoft states, gamma-ray emission, and major radio flares. During these two periods of activity, we undertook multi-wavelength observing campaigns with observations in the radio (RATAN-600, AMI-LA, Metsähovi), submillimeter (SMA, EHT), X-ray (Swift/XRT, MAXI), hard X-ray (Swift/BAT, NuSTAR), and gamma-ray (AGILE, Fermi, VERITAS). At the peak of the major radio flare in April 2017 observations were made with VERITAS (TeV), NuSTAR (hard X-ray), and the Event Horizon Telescope (submillimeter). In this presentation, I will review these observing campaigns and the insights they provide about Cygnus X-3.

Using Monte-Carlo Simulations to Study the Disk Structure in Cygnus X-1

NASA Technical Reports Server (NTRS)

Yao, Y.; Zhang, S. N.; Zhang, X. L.; Feng, Y. X.

2002-01-01

As the first dynamically determined black hole X-ray binary system, Cygnus X-1 has been studied extensively. However, its broad-band spectra in hard state with BeppoSAX is still not well understood. Besides the soft excess described by the multi-color disk model (MCD), the power- law component and a broad excess feature above 10 keV (disk reflection component), there is also an additional soft component around 1 keV, whose origin is not known currently.We propose that the additional soft component is due to the thermal Comptonization process between the s oft disk photon and the warm plasma cloud just above the disk.i.e., a warm layer. We use Monte-Carlo technique t o simulate this Compton scattering process and build several table models based on our simulation results.

Ultra high energy gamma rays, cosmic rays and neutrinos from accreting degenerate stars

NASA Technical Reports Server (NTRS)

Brecher, K.; Chanmugam, G.

1985-01-01

Super-Eddington accretion for a recently proposed unipolar induction model of cosmic ray acceleration in accreting binary star systems containing magnetic white dwarfs or neutron stars is considered. For sufficiently high accretion rates and low magnetic fields, the model can account for: (1) acceleration of cosmic ray nuclei up to energies of 10 to the 19th power eV; (2) production of more or less normal solar cosmic ray composition; (3) the bulk of cosmic rays observed with energies above 1 TeV, and probably even down to somewhat lower energies as well; and (4) possibly the observed antiproton cosmic ray flux. It can also account for the high ultra high energy (UHE) gamma ray flux observed from several accreting binary systems (including Cygnus X-3), while allowing the possibility of an even higher neutrino flux from these sources, with L sub nu/L sub gamma is approximately 100.

What is special about Cygnus X-1?. [evidence for a black hole

NASA Technical Reports Server (NTRS)

Boldt, E. A.; Holt, S. S.; Rothschild, R. E.; Serlemitsos, P. J.

1974-01-01

The X-ray evidence from several experiments is reviewed, with special emphasis on those characteristics which appear to distinguish Cygnus X-1 from other compact X-ray emitting objects. Data are examined within the context of a model in which millisecond bursts are superposed upon shot-noise fluctuations arising from events of durations on the order of a second. Possible spectral-temporal correlations are investigated which provide additional evidence that Cygnus X-1 is very likely a black hole.

Absorption dips at low X-ray energies in Cygnus X-1. [observed with Copernicus satellite

NASA Technical Reports Server (NTRS)

Murdin, P. G.

1976-01-01

Absorbing material in Cygnus X-1 jitters near the line joining the two stars, out of the orbital plane is described. Three looks with the Copernicus satellite at Cygnus X-1 have produced four examples of absorption dips (decreases in the 2 to 7 keV flux from Cygnus X-1 with an increase of spectral hardness consistent with photoelectric absorption).

Hard X-ray Flux from Low-Mass Stars in the Cygnus OB2 Association

NASA Astrophysics Data System (ADS)

Caramazza, M.; Drake, J. J.; Micela, G.; Flaccomio, E.

2009-05-01

We investigate the X-ray emission in the 20-40 keV band expected from the flaring low-mass stellar population in Cygnus OB2 assuming that the observed soft X-ray emission is due to a superposition of flares and that the ratio of hard X-ray to soft X-ray emission is described by a scaling found for solar flares by Isola and co-workers. We estimate a low-mass stellar hard X-ray flux in the 20-40 keV band in the range ~7×1031-7×1033 erg/s and speculate the limit of this values. Hard X-ray emission could lie at a level not much below the current observed flux upper limits for Cygnus OB2. Simbol-X, with its broad energy band (10-100 keV) and its sensitivity should be able to detect this emission and would provide insights into the hard X-ray production of flares on pre-main sequence stars.

Gamma-Ray Spectra & Variability of Cygnus X-1 Observed by BATSE

NASA Technical Reports Server (NTRS)

Ling, J. C.; Wheaton, A.; Wallyn, P.; Mahoney, W. A.; Paciesas, W. W.; Harmon, B. A.; Fishman, G. J.; Zhang, S. N.; Hua, X. M.

1996-01-01

We present new BATSE Earth occultation observations of the 25 keV-1.8 MeV spectrum and variability of Cygnus X-1 made between August 1993 and May 1994. We observed that the normal soft gamma-ray spectrum (gamma2) of Cygnus X-1 has two components: a Comptonized part seen below 30keV, and a high-energy tail in the 0.3-2 MeV range.

Very High Energy Emission from the Binary System Cyg X-3

NASA Astrophysics Data System (ADS)

Sinitsyna, V. G.; Sinitsyna, V. Yu.

2018-03-01

Cyg X-3 is actively studied in the entire range of the electromagnetic spectrum from the radio band to ultrahigh energies. Based on the detection of ultrahigh-energy gamma-ray emission, it has been suggested that Cyg X-3 could be one of the most powerful sources of charged cosmic-ray particles in the Galaxy. We present the results of long-term observations of the Cygnus X-3 region at energies 800 GeV-100 TeV by the SHALON mirror Cherenkov telescope. In 1995 the SHALON observations revealed a new Galactic source of very high energy gamma-ray emission coincident in its coordinates with the microquasar Cyg X-3. To reliably identify the detected source with Cyg X-3, an analysis has been performed and an orbital period of 4.8 h has been found, which is a signature of Cyg X-3. A series of flares in Cyg X-3 at energies >800 GeV and their correlation with the activity in the X-ray and radio bands have been observed. The results obtained in a wide energy range for Cyg X-3, including those during the periods of relativistic jet events, are needed to find the connection and to understand the different components of an accreting binary system.

A study of 2-20 KeV X-rays from the Cygnus region

NASA Technical Reports Server (NTRS)

Bleach, R. D.

1972-01-01

Two rocket-borne proportional counters, each with 650 sq c, met area and 1.8 x 7.1 deg FWHM rectangular mechanical collimation, surveyed the Cygnus region in the 2 to 20 keV energy range on two occasions. X-ray spectral data gathered on 21 September 1970 from discrete sources in Cygnus are presented. The data from Cyg X-1, Cyg X-2, and Cyg X-3 have sufficient statistical significance to indicate mutually exclusive spectral forms for the three. Upper limits are presented for X-ray intensities above 2 keV for Cyg X-4 and Cyg X-5 (Cygnus loop). A search was made on 9 August 1971 for a diffuse component of X-rays 1.5 keV associated with an interarm region of the galaxy at galactic longitudes in the vicinity of 60 degrees. A statistically significant excess associated with a narrow disk component was detected. Several possible emission models are discussed, with the most likely candidate being a population of unresolvable low luminosity discrete sources.

Wind collisions in three massive stars of Cygnus OB2

NASA Astrophysics Data System (ADS)

Cazorla, Constantin; Nazé, Yaël; Rauw, Gregor

2014-01-01

Aims: We wish to study the origin of the X-ray emission of three massive stars in the Cyg OB2 association: Cyg OB2 #5, Cyg OB2 #8A, and Cyg OB2 #12. Methods: To this aim, dedicated X-ray observations from XMM-Newton and Swift are used, as well as archival ROSAT and Suzaku data. Results: Our results on Cyg OB2 #8A improve the phase coverage of the orbit and confirm previous studies: the signature of a wind-wind collision is conspicuous. In addition, signatures of a wind-wind collision are also detected in Cyg OB2 #5, but the X-ray emission appears to be associated with the collision between the inner binary and the tertiary component orbiting it with a 6.7 yr period, without a putative collision inside the binary. The X-ray properties strongly constrain the orbital parameters, notably allowing us to discard some proposed orbital solutions. To improve the knowledge of the orbit, we revisit the light curves and radial velocity of the inner binary, looking for reflex motion induced by the third star. Finally, the X-ray emission of Cyg OB2 #12 is also analyzed. It shows a marked decrease in recent years, compatible with either a wind-wind collision in a wide binary or the aftermath of a recent eruption. Based on observations collected at the Observatoire de Haute Provence (OHP) as well as with Swift and XMM-Newton.Tables 1-3 and 5 are available in electronic form at http://www.aanda.org

Gemini/GNIRS infrared spectroscopy of the Wolf-Rayet stellar wind in Cygnus X-3

NASA Astrophysics Data System (ADS)

Koljonen, K. I. I.; Maccarone, T. J.

2017-12-01

The microquasar Cygnus X-3 was observed several times with the Gemini North Infrared Spectrograph while the source was in the hard X-ray state. We describe the observed 1.0-2.4 μm spectra as arising from the stellar wind of the companion star and suggest its classification as a WN 4-6 Wolf-Rayet star. We attribute the orbital variations of the emission line profiles to the variations in the ionization structure of the stellar wind caused by the intense X-ray emission from the compact object. The strong variability observed in the line profiles will affect the mass function determination. We are unable to reproduce earlier results, from which the mass function for the Wolf-Rayet star was derived. Instead, we suggest that the system parameters are difficult to obtain from the infrared spectra. We find that the near-infrared continuum and the line spectra can be represented with non-LTE Wolf-Rayet atmosphere models if taking into account the effects arising from the peculiar ionization structure of the stellar wind in an approximative manner. From the representative models we infer the properties of the Wolf-Rayet star and discuss possible mass ranges for the binary components.

Handbook of X-Ray Astronomy

NASA Technical Reports Server (NTRS)

Arnaud, Keith A. (Editor); Smith, Randall K.; Siemiginowska, Aneta

2011-01-01

X-ray astronomy was born in the aftermath of World War II as military rockets were repurposed to lift radiation detectors above the atmosphere for a few minutes at a time. These early flights detected and studied X-ray emission from the Solar corona. The first sources beyond the Solar System were detected during a rocket flight in 1962 by a team headed by Riccardo Giaccom at American Science and Engineering, a company founded by physicists from MIT. The rocket used Geiger counters with a system designed to reduce non-X-ray backgrounds and collimators limiting the region of sky seen by the counters. As the rocket spun, the field of view (FOV) happened to pass over what was later found to be the brightest non-Solar X-ray source; later designated See X-1. It also detected a uniform background glow which could not be resolved into individual sources. A follow-up campaign using X-ray detectors with better spatial resolution and optical telescopes identified See X-1 as an interacting binary with a compact (neutron star) primary. This success led to further suborbital rocket flights by a number of groups. More X-ray binaries were discovered, as well as X-ray emission from supernova remnants, the radio galaxies M87 and Cygnus-A, and the Coma cluster. Detectors were improved and Geiger counters were replaced by proportional counters, which provided information about energy spectra of the sources. A constant challenge was determining precise positions of sources as only collimators were available.

Acceleration by pulsar winds in binary systems

NASA Technical Reports Server (NTRS)

Harding, Alice K.; Gaisser, T. K.

1990-01-01

In the absence of accretion torques, a pulsar in a binary system will spin down due to electromagnetic dipole radiation and the spin-down power will drive a wind of relativistic electron-positron pairs. Winds from pulsars with short periods will prevent any subsequent accretion but may be confined by the companion star atmosphere, wind, or magnetosphere to form a standing shock. The authors investigate the possibility of particle acceleration at such a pulsar wind shock and the production of very high energy (VHE) and ultra high energy (UHE) gamma rays from interactions of accelerated protons in the companion star's wind or atmosphere. They find that in close binaries containing active pulsars, protons will be shock accelerated to a maximum energy dependent on the pulsar spin-down luminosity. If a significant fraction of the spin-down power goes into particle acceleration, these systems should be sources of VHE and possibly UHE gamma rays. The authors discuss the application of the pulsar wind model to binary sources such as Cygnus X-3, as well as the possibility of observing VHE gamma-rays from known binary radio pulsar systems.

Low Charge States of Si and S: from Cygnus X-1 to the Lab and Back

NASA Astrophysics Data System (ADS)

Hell, Natalie; Miškovičova, I.; Hanke, M.; Brown, G. V.; Wilms, J.; Clementson, J.; Beiersdorfer, P.; Liedahl, D. A.; Pottschmidt, K.; Porter, F.; Kilbourne, C.; Kelley, R. L.; Nowak, M.; Schulz, N. S.

2013-04-01

The X-ray light curves of the high mass X-ray binary (HMXB) Cygnus X-1 are shaped by strong, relatively short, absorption dips. While spectra extracted from the dip free phases are dominated by absorption lines of the Rydberg series of H- and He-like ions, 1s-2p transitions of lower ionized Si and S appear in the dip spectra. This shift in charge balance suggests that we probe “clumps” of cold material embedded in the companion's stellar wind as they cross our line of sight. Determining the bulk motion of these clumps by measuring the Doppler shifts of these lines as a function of dipping strength and ionization state can confirm this theory. Unfortunately, the predicted uncertainty for theoretical calculations - if available at all - is of the order of the expected shifts in the system. To overcome this lack of reliable reference wavelengths, we measured the Kα spectra of H- through F-like Si and S with the EBIT Calorimeter Spectrometer (ECS) and the Lawrence Livermore National Laboratory electron beam ion trap EBIT-I. We then directly apply these new line centers to calculate the Doppler shifts of the lines observed in Cygnus X-1. With this approach, we find shifts consistent with constant velocity of the absorber throughout all ionization states and, hence, provide evidence for an onion-like ion structure of the clumps. Funded by BMWi under DLR grant 50OR1207. Work at LLNL was performed under the auspices of DOE under contract DE-AC52-07NA27344 and supported by NASA grants.

Evidence for a TDE Origin for the Radio Transient in Cygnus A

NASA Astrophysics Data System (ADS)

Wise, Michael W.; de Vries, Martijn; Rowlinson, Antonia; Nulsen, Paul; Snios, Bradford; Birkinshaw, Mark; Worrall, Diana

2017-08-01

Recently new JVLA observations by Perley et al. (2017) have revealed evidence for a luminous radio transient at a projected distance of 0.46 kpc from the nucleus of Cygnus A. Based on data taken between 1989 and 2016, the flux density of this radio transient has risen from an upper limit of <0.5 mJy to 4 mJy at a frequency of 8.5 GHz. Additional VLBA observations at 8 GHz by the same authors confirm this transient source to be compact (<4 pc) and coinciding with a source seen previously in optical and NIR images. Perley et al. (2017) have interpreted this source to be a secondary supermassive black hole in a close orbit around the Cygnus A nucleus. Several explanations have been proposed for the turn-on of the Cygnus A-2 transient over the 9 year timeframe including variability in the accretion onto this secondary BH and alternatively a possible tidal disruption event (TDE).We present the results of a new X-ray analysis utilizing new and archival data from the Chandra and Swift satellites. Cygnus A has been observed multiple times by Chandra between 2000, 2005, and 2015-2017. The Swift satellite performed 9 observations of Cygnus A between 2006 and 2017. Based on these observations, we present evidence for a decline in the flux of the Cygnus A nucleus, with the soft X-ray flux (0.3-1.2 keV) showing a drop by a factor of 2 between 2000 and 2005. The Swift observations confirm the X-ray emission from the Cygnus A continued to fade after 2006. As the radio source was last undetected in 1997, these data constrain the peak of the X-ray emission and the likely onset of brightening in the radio to a window of 3 years or less. This timescale implies a very rapid onset of accretion onto the secondary black hole and strongly favors the TDE interpretation for the origin of the Cygnus A-2 radio transient. Chandra images of the 3 kpc x 3 kpc region around the Cygnus A nucleus show clear evidence for an extended region of soft X-ray emission dimming on this timescale, which we interpret as fading reflected nuclear emission from surrounding dust. In this presentation, we summarize these results and their implications in light of a TDE origin for the observed X-ray and radio variability.

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

NASA Astrophysics Data System (ADS)

Sell, Paul Harrison

2013-12-01

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

The Broad Iron K-alpha line of Cygnus X-1 as Seen by XMM-Newton in the EPIC-pn Modified Timing Mode

NASA Technical Reports Server (NTRS)

Duro, Refiz; Dauser, Thomas; Wilms, Jorn; Pottschmidt, Katja; Nowak, Michael A.; Fritz, Sonja; Kendziorra, Eckhard; Kirsch, Marcus G. F.; Reynolds, Christopher S.; Staubert, Rudiger

2011-01-01

We present the analysis of the broadened, flourescent iron K(alpha) line in simultaneous XMM-Newton and RXTE data from the black hole Cygnus X-I. The XMM-Newton data were taken in a modified version of the Timing Mode of the EPIC-pn camera. In this mode the lower energy threshold of the instrument is increased to 2.8 keV to avoid telemetry drop outs due to the brightness of the source, while at the same time preserving the signal to noise ratio in the Fe K(alpha) band. We find that the best-fit spectrum consists of the sum of an exponentially cut-off power-law and relativistically smeared, ionized reflection. The shape of the broadened Fe K(alpha) feature is due to strong Compton broadening combined with relativistic broadening. Assuming a standard, thin accretion disk, the black hole is close to maximally rotating. Key words. X-rays: binaries - black hole physics - gravitation

Modelling hard and soft states of Cygnus X-1 with propagating mass accretion rate fluctuations

NASA Astrophysics Data System (ADS)

Rapisarda, S.; Ingram, A.; van der Klis, M.

2017-12-01

We present a timing analysis of three Rossi X-ray Timing Explorer observations of the black hole binary Cygnus X-1 with the propagating mass accretion rate fluctuations model PROPFLUC. The model simultaneously predicts power spectra, time lags and coherence of the variability as a function of energy. The observations cover the soft and hard states of the source, and the transition between the two. We find good agreement between model predictions and data in the hard and soft states. Our analysis suggests that in the soft state the fluctuations propagate in an optically thin hot flow extending up to large radii above and below a stable optically thick disc. In the hard state, our results are consistent with a truncated disc geometry, where the hot flow extends radially inside the inner radius of the disc. In the transition from soft to hard state, the characteristics of the rapid variability are too complex to be successfully described with PROPFLUC. The surface density profile of the hot flow predicted by our model and the lack of quasi-periodic oscillations in the soft and hard states suggest that the spin of the black hole is aligned with the inner accretion disc and therefore probably with the rotational axis of the binary system.

A discussion of the H-alpha filamentary nebulae and galactic structure in the Cygnus region

NASA Technical Reports Server (NTRS)

Matthews, T. A.; Simonson, S. C., III

1971-01-01

From observation of the galactic structure in Cygnus, the system of filamentary nebulae was found to lie at a distance of roughly 1.5 kpc, in the same region as about half the thermal radio sources in Cygnus X, the supernova remnant near gamma Cygni, and the association Cygnus OB2, in the direction of which the X-ray source Cygnus XR-3 is observed. The source of excitation was probably the pulse of radiation from a supernova explosion, as proposed in the case of Gum nebula. However continuing excitation by early stars in the region of Cygnus X cannot be excluded.

High-Frequency X-ray Variability Detection in A Black Hole Transient with USA.

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

Shabad, Gayane

2000-10-16

Studies of high-frequency variability (above {approx}100 Hz) in X-ray binaries provide a unique opportunity to explore the fundamental physics of spacetime and matter, since the orbital timescale on the order of several milliseconds is a timescale of the motion of matter through the region located in close proximity to a compact stellar object. The detection of weak high-frequency signals in X-ray binaries depends on how well we understand the level of Poisson noise due to the photon counting statistics, i.e. how well we can understand and model the detector deadtime and other instrumental systematic effects. We describe the preflight timingmore » calibration work performed on the Unconventional Stellar Aspect (USA) X-ray detector to study deadtime and timing issues. We developed a Monte Carlo deadtime model and deadtime correction methods for the USA experiment. The instrumental noise power spectrum can be estimated within {approx}0.1% accuracy in the case when no energy-dependent instrumental effect is present. We also developed correction techniques to account for an energy-dependent instrumental effect. The developed methods were successfully tested on USA Cas A and Cygnus X-1 data. This work allowed us to make a detection of a weak signal in a black hole candidate (BHC) transient.« less

Gamma-ray emission from black holes

NASA Technical Reports Server (NTRS)

Ling, James C.

1991-01-01

Strong continuum gamma-ray emission at about 1 MeV possibly correlated with a narrow annihilation line at 511 keV has been observed from both Cygnus X-1 and the Galactic center. Such correlated emission has been interpreted as a unique gamma-ray signature for theoretically predicted relativistic, positron-electron pair-dominated plasma in regions surrounding the black holes. In this paper, the Cygnus X-1 results, which have provided important new insights about the source, are reviewed. Cygnus X-1 may be considered a canonical reference stellar black hole whose spectral and temporal characteristics can be used for comparison with those of other black-hole candidates including the Galactic center and AGN.

The Formation of Rapidly Rotating Black Holes in High-mass X-Ray Binaries

NASA Astrophysics Data System (ADS)

Batta, Aldo; Ramirez-Ruiz, Enrico; Fryer, Chris

2017-09-01

High-mass X-ray binaries (HMXRBs), such as Cygnus X-1, host some of the most rapidly spinning black holes (BHs) known to date, reaching spin parameters a≳ 0.84. However, there are several effects that can severely limit the maximum BH spin parameter that could be obtained from direct collapse, such as tidal synchronization, magnetic core-envelope coupling, and mass loss. Here, we propose an alternative scenario where the BH is produced by a failed supernova (SN) explosion that is unable to unbind the stellar progenitor. A large amount of fallback material ensues, whose interaction with the secondary naturally increases its overall angular momentum content, and therefore the spin of the BH when accreted. Through SPH hydrodynamic simulations, we studied the unsuccessful explosion of an 8 {M}⊙ pre-SN star in a close binary with a 12 {M}⊙ companion with an orbital period of ≈1.2 days, finding that it is possible to obtain a BH with a high spin parameter a≳ 0.8 even when the expected spin parameter from direct collapse is a≲ 0.3. This scenario also naturally explains the atmospheric metal pollution observed in HMXRB stellar companions.

Global Far-ultraviolet Properties of the Cygnus Loop

NASA Astrophysics Data System (ADS)

Kim, Il-Joong; Seon, Kwang-Il; Lim, Yeo-Myeong; Lee, Dae-Hee; Han, Wonyong; Min, Kyoung-Wook; Edelstein, Jerry

2014-03-01

We present the C III λ977, O VI λλ1032, 1038 and N IV] λ1486 emission line maps of the Cygnus Loop, obtained with the newly processed data of the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR; also known as FIMS) mission. In addition, the Si IV+O IV] line complexes around 1400 Å are resolved into two separate emission lines whose intensity demonstrates a relatively high Si IV region that was predicted in the previous study. The morphological similarity between the O VI and X-ray images, as well as a comparison of the O VI intensity with the value expected from the X-ray results, indicates that large portions of the observed O VI emissions could be produced from X-ray emitting gas. Comparisons of the far-ultraviolet (FUV) images with the optical and H I 21 cm images reveal spatial variations of shock-velocity populations and high FUV extinction in the direction of a previously identified H I cloud. By calculating the FUV line ratios for several subregions of the Cygnus Loop, we investigate the spatial variation of the population of radiative shock velocities as well as the effects of resonance scattering, X-ray emitting gas, and nonradiative shocks. The FUV and X-ray luminosity comparisons between the Cygnus Loop and the Vela supernova remnant suggest that the fraction of shocks in the early evolutionary stages is much larger in the Cygnus Loop.

The Soft State of Cygnus X-1 Observed with NuSTAR: A Variable Corona and a Stable Inner Disk

NASA Technical Reports Server (NTRS)

Walton, D. J.; Tomsick, J. A.; Madsen, K. K.; Grinberg, V.; Barret, D.; Boggs, S. E.; Christensen, F. E.; Clavel, M.; Craig, W. W.; Fabian, A. C.;

The Soft State of Cygnus X-1 Observed with NuSTAR: A Variable Corona and a Stable Inner Disk

NASA Astrophysics Data System (ADS)

Walton, D. J.; Tomsick, J. A.; Madsen, K. K.; Grinberg, V.; Barret, D.; Boggs, S. E.; Christensen, F. E.; Clavel, M.; Craig, W. W.; Fabian, A. C.; Fuerst, F.; Hailey, C. J.; Harrison, F. A.; Miller, J. M.; Parker, M. L.; Rahoui, F.; Stern, D.; Tao, L.; Wilms, J.; Zhang, W.

2016-07-01

We present a multi-epoch hard X-ray analysis of Cygnus X-1 in its soft state based on four observations with the Nuclear Spectroscopic Telescope Array (NuSTAR). Despite the basic similarity of the observed spectra, there is clear spectral variability between epochs. To investigate this variability, we construct a model incorporating both the standard disk-corona continuum and relativistic reflection from the accretion disk, based on prior work on Cygnus X-1, and apply this model to each epoch independently. We find excellent consistency for the black hole spin and the iron abundance of the accretion disk, which are expected to remain constant on observational timescales. In particular, we confirm that Cygnus X-1 hosts a rapidly rotating black hole, 0.93≲ {a}* ≲ 0.96, in broad agreement with the majority of prior studies of the relativistic disk reflection and constraints on the spin obtained through studies of the thermal accretion disk continuum. Our work also confirms the apparent misalignment between the inner disk and the orbital plane of the binary system reported previously, finding the magnitude of this warp to be ˜10°-15°. This level of misalignment does not significantly change (and may even improve) the agreement between our reflection results and the thermal continuum results regarding the black hole spin. The spectral variability observed by NuSTAR is dominated by the primary continuum, implying variability in the temperature of the scattering electron plasma. Finally, we consistently observe absorption from ionized iron at ˜6.7 keV, which varies in strength as a function of orbital phase in a manner consistent with the absorbing material being an ionized phase of the focused stellar wind from the supergiant companion star.

Support for joint infrared and Copernicus X-Ray observations of Cygnus X-3

NASA Technical Reports Server (NTRS)

1979-01-01

Simultaneous X-ray and infrared measurements were carried out of the flares from Cygnus X-3 from the Copernicus spacecraft observatory. The detectors, InSb, were arranged so that 1.65 and 2.2 micrometer broadbend photometry was performed through a common diaphragm. The measurements were used to determine the energy distribution during a flare and thus learn about the infrared spectrum and its changes during the flare.

Observations of Cygnus X-3 above 10(15) eV from 1979 - 1984

NASA Technical Reports Server (NTRS)

Lambert, A.; Lloyd-Evans, J.; Perrett, J. C.; Reid, R. J. O.; Watson, A. A.; West, A. A.

1985-01-01

The ultra high energy gamma-ray source, cygnus X-3, has been observed more or less continuously with an array sensitive to 10 to the 15th power ev primaries between 1 Jan. 1979 and 31 Dec. 1984. There is evidence for time variability in the phase of gamma-ray emission over this period.

Calibration of H-alpha/H-beta Indexes for Emission Line Objects

NASA Astrophysics Data System (ADS)

Hintz, Eric G.; Joner, Michael D.

2016-01-01

In Joner and Hintz (2015) they report on a standard star system for calibration of H-alpha and H-beta observations. This work was based on data obtained with the Dominion Astrophysical Observatory 1.2-m telescope. As part of the data acquisition for that project, a large number of emission line objects were also observed. We will report on the preliminary results for the emission line data set. This will include a comparison of equivalent width measurements of each line with the matching index. We will also examine the relation between the absorption line objects previously published and the emission line objects, along with a discussion of the transition point. Object types included are Be stars, high mass x-ray binaries, one low mass x-ray binary, Herbig Ae/Be stars, pre-main sequence stars, T Tauri stars, young stellar objects, and one BY Draconis star. Some of these objects come from Cygnus OB-2, NGC 659, NGC 663, NGC 869 and NGC 884.

UHE particle production in close binary systems

NASA Technical Reports Server (NTRS)

Hillas, A. M.

1985-01-01

Cygnus X-3 appears to generate so much power in the form of charged particles of up to approx 10 to the 17th power eV that the galaxy may need approx 1 such source on average to maintain its flux of ultra high energy cosmic rays. Accreting gas must supply the energy, and in a surprisingly ordered form, if it is correct to use a Vest-rand-Eichler model for radiation of gammas, modified by the introduction of an accretion wake. Certain relationships between 10 to the 12th power eV and 10 to the 15th power gamma rays are expected.

Search for a periodic signal from Cygnus X-3 usingmuons observed underground in the Frejus detector (4800 mwe)

NASA Technical Reports Server (NTRS)

Bareyre, P.; Barloutaud, R.; Becker, K. H.; Behr, L.; Berger, C.; Bland, R. W.; Chardin, G.; Daum, H. J.; Degrange, B.; Demski, S.

1986-01-01

Periodic signals from Cygnus X-3 in the ultra high energy range were recently reported by air shower arrays and attributed to gamma rays. Although gamma rays are expected to produce muon-poor showers, the preceding observations have stimulated similar studies based on underground muons. Two groups have claimed a significant underground signal coming from Cygnus X-3. The results are, however, extremely difficult to explain in the present framework of particle physics, and clearly need confirmation. The preliminary results obtained from the Frejus underground detector during its first 16 months of operation (March 1984 to June 1985) are presented.

GINGA observations of Cygnus X-2.

NASA Astrophysics Data System (ADS)

Wijnands, R. A. D.; van der Klis, M.; Kuulkers, E.; Asai, K.; Hasinger, G.

1997-07-01

We have analysed all available X-ray data on the low-mass X-ray binary Cygnus X-2 obtained with the Ginga satellite. A detailed analysis of the spectral and fast timing behaviour of these 4 years of data provides new insights in the behaviour of this Z source. We confirm the previously observed recurrent patterns of behaviour in the X-ray colour-colour and hardness-intensity diagrams consisting of shifts and shape changes in the Z track. However, we find a continuous range of patterns rather than a discrete set. The source behaviour in the diagrams is correlated with overall intensity, which varied by a factor of 1.34 in the Ginga data. We find that when the overall intensity increases, the mean velocity and acceleration of the motion along the normal branch of the Z track increase, as well as the width of the normal branch in the hardness-intensity diagram. Contrary to previous results we find that, during different observations, when the source is at the same position in the normal branch of the Z track the rapid X-ray variability differs significantly. During the Kuulkers et al. (1996A&A...311..197K) ``medium'' level, a normal branch quasi-periodic oscillation is detected, which is not seen during the ``high'' overall intensity level. Also, during the high overall intensity level episodes the very-low frequency noise on the lower normal branch is very strong and steep, whereas during the medium overall intensity level episodes this noise component at the same position in the Z track is weak and less steep. The explanation of the different overall intensity levels with a precessing accretion disk is difficult to reconcile with our data. Furthermore, we found that the frequency of the horizontal branch quasi-periodic oscillation decreases when Cygnus X-2 enters the upper normal branch, giving a model dependent upper limit on the magnetic field strength at the magnetic equator of ~8.5x10^9^G. We also report five bursts, with durations between two and eight seconds, whose occurrence seems to be uncorrelated with location in the Z track, overall intensity level or orbital phase. The burst properties indicate that they are not regular type I bursts.

The Formation of Rapidly Rotating Black Holes in High-mass X-Ray Binaries

DOE PAGES

Batta, Aldo; Ramirez-Ruiz, Enrico; Fryer, Chris Lee

2017-09-01

In this paper, high-mass X-ray binaries (HMXRBs), such as Cygnus X-1, host some of the most rapidly spinning black holes (BHs) known to date, reaching spin parametersmore » $$a\\gtrsim 0.84$$. However, there are several effects that can severely limit the maximum BH spin parameter that could be obtained from direct collapse, such as tidal synchronization, magnetic core-envelope coupling, and mass loss. Here, we propose an alternative scenario where the BH is produced by a failed supernova (SN) explosion that is unable to unbind the stellar progenitor. A large amount of fallback material ensues, whose interaction with the secondary naturally increases its overall angular momentum content, and therefore the spin of the BH when accreted. Through SPH hydrodynamic simulations, we studied the unsuccessful explosion of an $$8\\,{M}_{\\odot }$$ pre-SN star in a close binary with a $$12\\,{M}_{\\odot }$$ companion with an orbital period of ≈1.2 days, finding that it is possible to obtain a BH with a high spin parameter $$a\\gtrsim 0.8$$ even when the expected spin parameter from direct collapse is $$a\\lesssim 0.3$$. This scenario also naturally explains the atmospheric metal pollution observed in HMXRB stellar companions.« less

The Formation of Rapidly Rotating Black Holes in High-mass X-Ray Binaries

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

Batta, Aldo; Ramirez-Ruiz, Enrico; Fryer, Chris Lee

In this paper, high-mass X-ray binaries (HMXRBs), such as Cygnus X-1, host some of the most rapidly spinning black holes (BHs) known to date, reaching spin parametersmore » $$a\\gtrsim 0.84$$. However, there are several effects that can severely limit the maximum BH spin parameter that could be obtained from direct collapse, such as tidal synchronization, magnetic core-envelope coupling, and mass loss. Here, we propose an alternative scenario where the BH is produced by a failed supernova (SN) explosion that is unable to unbind the stellar progenitor. A large amount of fallback material ensues, whose interaction with the secondary naturally increases its overall angular momentum content, and therefore the spin of the BH when accreted. Through SPH hydrodynamic simulations, we studied the unsuccessful explosion of an $$8\\,{M}_{\\odot }$$ pre-SN star in a close binary with a $$12\\,{M}_{\\odot }$$ companion with an orbital period of ≈1.2 days, finding that it is possible to obtain a BH with a high spin parameter $$a\\gtrsim 0.8$$ even when the expected spin parameter from direct collapse is $$a\\lesssim 0.3$$. This scenario also naturally explains the atmospheric metal pollution observed in HMXRB stellar companions.« less

Featured Image: Making a Rapidly Rotating Black Hole

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-10-01

These stills from a simulation show the evolution (from left to right and top to bottom) of a high-mass X-ray binary over 1.1 days, starting after the star on the right fails to explode as a supernova and then collapses into a black hole. Many high-mass X-ray binaries like the well-known Cygnus X-1, the first source widely accepted to be a black hole host rapidly spinning black holes. Despite our observations of these systems, however, were still not sure how these objects end up with such high rotation speeds. Using simulations like that shown above, a team of scientists led by Aldo Batta (UC Santa Cruz) has demonstrated how a failed supernova explosion can result in such a rapidly spinning black hole. The authors work shows that in a binary where one star attempts to explode as a supernova and fails it doesnt succeed in unbinding the star the large amount of fallback material can interact with the companion star and then accrete onto the black hole, spinning it up in the process. You can read more about the authors simulations and conclusions in the paper below.CitationAldo Batta et al 2017 ApJL 846 L15. doi:10.3847/2041-8213/aa8506

Topics in gamma ray astronomy

NASA Technical Reports Server (NTRS)

Ramaty, R.; Lingenfelter, R. E.

1986-01-01

Observations of gamma rays from solar flares, gamma ray bursts, the Galactic center, galactic nucleosynthesis, SS433, and Cygnus X-3, and their effects on astrophysical problems are discussed. It is observed that gamma ray spectra from solar flares are applicable to the study of particle acceleration and confinement and the determination of chemical abundances in the solar atmosphere. The gamma ray lines from the compact galactic object SS433 are utilized to examine the acceleration of jets, and analysis of the gamma ray lines of Cygnus X-3 reveal that particles can be accelerated in compact sources to ultrahigh energies.

Hard X-ray Observation of Cygnus X-1 By the Marshall Imaging X-ray Experiment (MIXE2)

NASA Technical Reports Server (NTRS)

Minamitani, Takahisa; Apple, J. A.; Austin, R. A.; Dietz, K. L.; Koloziejczak, J. J.; Ramsey, B. D.; Weisskopf, M. C.

1998-01-01

The second generation of the Marshall Imaging X-ray Experiment (MIXE2) was flown from Fort Sumner, New Mexico on May 7-8, 1997. The experiment consists of coded-aperture telescope with a field of view of 1.8 degrees (FWHM) and an angular resolution of 6.9 arcminutes. The detector is a large (7.84x10(exp 4) sq cm) effective area microstrip proportional counter filled with 2.0x10(exp5) Pascals of xenon with 2% isobutylene. We present MIXE2 observation of the 20-80keV spectrum and timing variability of Cygnus X-1 made during balloon flight.

Chandra X-ray Spectroscopy of the Focused Wind In the Cygnus X-1 System I. The Non-Dip Spectrum in the Low/Hard State

NASA Technical Reports Server (NTRS)

Hanke, Manfred; Wilms, Jorn; Nowak, Michael A.; Pottschmidt, Katja; Schultz, Norbert S.; Lee, Julia C.

2008-01-01

We present analyses of a 50 ks observation of the supergiant X-ray binary system CygnusX-1/HDE226868 taken with the Chandra High Energy Transmission Grating Spectrometer (HETGS). CygX-1 was in its spectrally hard state and the observation was performed during superior conjunction of the black hole, allowing for the spectroscopic analysis of the accreted stellar wind along the line of sight. A significant part of the observation covers X-ray dips as commonly observed for CygX-1 at this orbital phase, however, here we only analyze the high count rate non-dip spectrum. The full 0.5-10 keV continuum can be described by a single model consisting of a disk, a narrow and a relativistically broadened Fe K line, and a power law component, which is consistent with simultaneous RXTE broad band data. We detect absorption edges from overabundant neutral O, Ne and Fe, and absorption line series from highly ionized ions and infer column densities and Doppler shifts. With emission lines of He-like Mg XI, we detect two plasma components with velocities and densities consistent with the base of the spherical wind and a focused wind. A simple simulation of the photoionization zone suggests that large parts of the spherical wind outside of the focused stream are completely ionized, which is consistent with the low velocities (<200 km/s) observed in the absorption lines, as the position of absorbers in a spherical wind at low projected velocity is well constrained. Our observations provide input for models that couple the wind activity of HDE 226868 to the properties of the accretion flow onto the black hole.

The Cosmic-Ray and Gas Content of the Cygnus Region as Measured in Gamma Rays by the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Berenji, B.;

X-ray astronomy in the laboratory with a miniature compact object produced by laser-driven implosion

NASA Astrophysics Data System (ADS)

Fujioka, Shinsuke; Takabe, Hideaki; Yamamoto, Norimasa; Salzmann, David; Wang, Feilu; Nishimura, Hiroaki; Li, Yutong; Dong, Quanli; Wang, Shoujun; Zhang, Yi; Rhee, Yong-Joo; Lee, Yong-Woo; Han, Jae-Min; Tanabe, Minoru; Fujiwara, Takashi; Nakabayashi, Yuto; Zhao, Gang; Zhang, Jie; Mima, Kunioki

2009-11-01

X-ray spectroscopy is an important tool for understanding the extreme photoionization processes that drive the behaviour of non-thermal equilibrium plasmas in compact astrophysical objects such as black holes. Even so, the distance of these objects from the Earth and the inability to control or accurately ascertain the conditions that govern their behaviour makes it difficult to interpret the origin of the features in astronomical X-ray measurements. Here, we describe an experiment that uses the implosion driven by a 3TW, 4kJ laser system to produce a 0.5keV blackbody radiator that mimics the conditions that exist in the neighbourhood of a black hole. The X-ray spectra emitted from photoionized silicon plasmas resemble those observed from the binary stars Cygnus X-3 (refs 7, 8) and Vela X-1 (refs 9, 10 11) with the Chandra X-ray satellite. As well as demonstrating the ability to create extreme radiation fields in a laboratory plasma, our theoretical interpretation of these laboratory spectra contrasts starkly with the generally accepted explanation for the origin of similar features in astronomical observations. Our experimental approach offers a powerful means to test and validate the computer codes used in X-ray astronomy.

Enhanced gamma-ray emission from the microquasar Cygnus X-3 detected by AGILE

NASA Astrophysics Data System (ADS)

Piano, G.; Pittori, C.; Verrecchia, F.; Tavani, M.; Bulgarelli, A.; Fioretti, V.; Zoli, A.; Munar-Adrover, P.; Lucarelli, F.; Donnarumma, I.; Vercellone, S.; Striani, E.; Cardillo, M.; Gianotti, F.; Trifoglio, M.; Giuliani, A.; Mereghetti, S.; Caraveo, P.; Perotti, F.; Chen, A.; Argan, A.; Costa, E.; Del Monte, E.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Lapshov, I.; Pacciani, L.; Soffitta, P.; Sabatini, S.; Vittorini, V.; Pucella, G.; Rapisarda, M.; Di Cocco, G.; Fuschino, F.; Galli, M.; Labanti, C.; Marisaldi, M.; Pellizzoni, A.; Pilia, M.; Trois, A.; Barbiellini, G.; Vallazza, E.; Longo, F.; Morselli, A.; Picozza, P.; Prest, M.; Lipari, P.; Zanello, D.; Cattaneo, P. W.; Rappoldi, A.; Colafrancesco, S.; Parmiggiani, N.; Ferrari, A.; Antonelli, A.; Giommi, P.; Salotti, L.; Valentini, G.; D'Amico, F.

2016-04-01

Integrating from 2016-04-16 00:00 UT to 2016-04-19 00:00 UT, the AGILE-GRID detector is revealing gamma-ray emission above 100 MeV from a source positionally consistent with Cygnus X-3 at Galactic coordinates (l, b) = (79.4, 0.2) +/- 0.6 (stat.) +/- 0.1 (syst.) deg, with flux F( > 100 MeV) = (2.0 +/- 0.8) x 10^-6 photons/cm^2/s, as determined by a multi-source likelihood analysis.

X-rays and gamma-rays from accretion flows onto black holes in Seyferts and X-ray binaries

NASA Technical Reports Server (NTRS)

Zdziarski, Andrzej A.; Johnson, W. Neil; Poutanen, Juri; Magdziarz, Pawel; Gierlinski, Marek

1997-01-01

Observations and theoretical models of X-ray/gamma ray spectra of radio quiet Seyfert galaxies and Galactic black hole candidates are reviewed. The spectra from these objects share the following characteristics: an underlying power law with a high energy cutoff above 200 keV; a Compton reflection component with a Fe K alpha line, and a low energy absorption by intervening cold matter. The X-ray energy spectral index, alpha, is typically in the range between 0.8 and 1 in Seyfert spectra, and that of the hard state spectra of the black hole candidates Cygnus X-1 and GX 339-4 is typically between 0.6 and 0.8. The Compton reflection component corresponds with cold matter covering a solid angle of between 0.8pi and 2pi as seen from the X-ray source. The broadband spectra of both classes of sources are well fitted by Compton upscattering of soft photons in thermal plasma. The fits yield a thermal plasma temperature of 100 keV and the Thomson optical depth of 1. All the spectra presented are cut off before the electron rest energy 511 keV, indicating that electron/positron pair production is an important process.

Long-term studies with the Ariel 5 ASM. 2: The strong Cygnus sources

NASA Technical Reports Server (NTRS)

Holt, S. S.; Kaluzienski, L. J.; Boldt, E. A.; Serlemitsos, P. J.

1979-01-01

The three bright 3-6 keV X-ray sources in Cygnus are examined for regular temporal variability with a 1300-day record from the Ariel 5 All Sky Monitor. The only periods consistently observed are 5.6 days for Cyg X-1, 11.23 days for Cyg X-2, and 4.8 hours for Cyg X-3.

Evolution of Cygnus X-3 through its Radio and X-ray States

NASA Astrophysics Data System (ADS)

Szostek, A.; Zdziarski, A. A.; McCollough, M. L.

2009-05-01

Based on X-ray spectra and studies of the long-term correlated behavior between radio and soft X-ray, we present a detailed evolution of Cyg X-3 through its radio and X-ray states. We comment on the nature of the hard X-ray tail and possible Simbol X contribution in constraining the models.

Disentangling the gamma-ray emission towards Cygnus X: Sh2-104

NASA Astrophysics Data System (ADS)

Gotthelf, Eric

2015-09-01

We have just discovered distinct X-ray emission coincident with VER J2018+363, a TeV source recently resolved from the giant gamma-ray complex MGRO J2019+37 in the Cygnus region. NuSTAR reveals a hard point source and a diffuse nebula adjacent to and possibly part of Sh2-104, a compact HII region containing several young massive stellar clusters. There is reasonable evidence that these X-rays probe the origin of the gamma-ray flux, however, unrelated extragalactic sources need to be excluded. We propose a short Chandra observation to localize the X-ray emission to identify a putative pulsar or stellar counterpart(s). This is an important step to fully understand the energetics of the MGRO J2019+37 complex and the production of gamma-rays in star formation regions, in general.

Discovery of the Red-Skewed K-alpha Iron Line in Cyg X-2 with Suzaku

NASA Technical Reports Server (NTRS)

Shaposhnikov, Nikolai; Titarchuk, Lev; Laurent, Philippe

2008-01-01

We report on the Suzaku observation of neutron star low-mass X-ray binary Cygnus X-2 which reveals strong iron K-alpha emission line. The line profile shows a prominent red wing extending down to 4 keV. This discovery increases the number of neutron star sources where red-skewed iron lines were observed and strongly suggests that this phenomenon is common not only in black holes but also in other types of compact objects. We examine the line profile by fitting it with the model which attributes its production to the relativistic effects due to disk reflection of X-ray radiation. We also apply an alternative model where the red wing is a result of down-scattering effect of the first order with respect to electron velocity in the wind outflow. Both models describe adequately the observed line profile. However, the X-ray variability in a state similar to that in the Suzaku observation which we establish by analysing RXTE observation favors the wind origin of the line formation.

3D Doppler Tomography of the X-Ray Binary System Cygnus X-1 from Spectral Observations in 2007 in the HeII λ 4686 Å Line

NASA Astrophysics Data System (ADS)

Agafonov, M. I.; Karitskaya, E. A.; Sharova, O. I.; Bochkarev, N. G.; Zharikov, S. V.; Butenko, G. Z.; Bondar', A. V.; Sidorov, M. Yu.

2018-02-01

The results of a 3D Doppler tomography analysis for the X-ray binary system Cyg X-1 in the HeII λ 4686 Å line are presented. Information about the motions of gaseous flows outside the orbital plane has been obtained for the first time. Line profiles obtained in June 2007 on the 2-m telescope of the Terskol Branch of the Institute of Astronomy (Russia) and on the 2.1-m telescope of the National Astronomical Observatory of Mexico were used. A detailed analysis of these spectral data is presented: the distribution of the data in time, distribution of orbital phases for the projections, comparison of the line profile shapes for the data from two observatories. The geometry of the total transfer function obtained in the reconstruction is considered. The possibility of applying the profiles obtained to realize 3D tomography is justified. The resolution of the constructed 3D tomogram in velocity space is 60 × 60 × 40 km/s for V x , V y , V z . Fifteen cross sections for 15 different V z values perpendicular to the orbital plane are presented. The intensity distributions corresponding to the velocities of gaseous structures in the binary system are obtained. The reconstruction was realized using the radio-astronomical approach, developed for solving problems in tomography with a limited number of projections.

Experimental results on gamma-ray sources at E sub 0 = 10(13) - 10(14) eV

NASA Technical Reports Server (NTRS)

Morello, C.; Navarra, G.; Periale, L.; Vallania, P.

1985-01-01

The detection of very high energy gamma ray sources has been reported in the last few years by means of extensive air shower observations. The Plateau Rosa array for the registration of the arrival directions of extensive air showers has been operating since 1980 and first results on Cygnus X-3 have been reported. Here, the status of observations of Cygnus X-3 and of the Crab Pulsar are reported.

Spinning-Up: the Case of the Symbiotic X-Ray Binary 3A 1954+319

NASA Technical Reports Server (NTRS)

Fuerst, F.; Marcu, D. M.; Pottschmidt, K.; Grinberg, V.; Wilms, J.; CadolleBel, M.

2011-01-01

We present a timing and spectral analysis of the variable X-ray source 3A 1954+319. Our analysis is mainly based on an outburst serendipitously observed during INTEGRAL Key Program observations of the Cygnus region in 2008 fall and on the Swift/BAT longterm light curve. Previous observations, though sparse, have identified the source to be one of only nine known symbiotic X-ray binaries, i.e., systems composed of an accreting neutron star orbiting in a highly inhomogeneous medium around an M-giant companion. The spectrum of3A 1954+319 above > 20 keV can be best described by a broken power law model. The extremely long pulse period of approx.5.3 hours is clearly visible in the INTEGRAL/ISGRI light curve and confirmed through an epoch folding period search. Furthermore, the light curve allows us to determine a very strong spin up of -2 x 10(exp -4) h/h during the outburst. This spin up is confirmed by the pulse period evolution calculated from Swift/BAT data. The Swift/BAT data also show a long spin-down trend prior to the 2008 outburst, which is confirmed in archival INTEGRAL/ISGRI data. We discuss possible accretion models and geometries allowing for the transfer of such large amounts of angular momentum and investigate the harder spectrum of this outburst compared to previously published results.

Spinning-Up: The Case of the Symbiotic X-Ray Binary 3A 1954+319

NASA Technical Reports Server (NTRS)

Fuerst, F.; Marcu, D. M.; Pottschmidt, K.; Grinberg, V.; Wilms, J.; Bel, M. Cadolle

2010-01-01

We present a timing and spectral analysis of the variable X-ray source 3A 1954+319, Our analysis is mainly based on an outburst serendipitously observed during INTEGRAL Key Program observations of the Cygnus region in 2008 fall and on the Swift/BAT longterm light curve, Previous observations, though sparse, have identified the source to be one of only nine known symbiotic X-ray binaries, i.e., systems composed of an accreting neutron star orbiting in a highly inhomogeneous medium around an M-giant companion. The spectrum of 3A 1954+319 above 20 keY can be best described by a broken power law model. The extremely long pulse period of approx.5.3 hours is clearly visible in the INTEGRAL/ISGRI light curve and confirmed through an epoch folding period search. Furthermore, the light curve allows us to determine a very strong spin up of -2x10(exp 4)h/h during the outburst. This spin up is confirmed by the pulse period evolution calculated from Swift/BAT data. The Swift/BAT data also show a long spin-down trend prior to the 2008 outburst. which is confirmed in archival INTEGRAL/ISGRI data. We discuss possible accretion models and geometries allowing for the transfer of such large amounts of angular momentum and investigate the harder spectrum of this outburst compared to previously published results.

Hard X-ray spectrum of Cygnus X-1

NASA Technical Reports Server (NTRS)

Nolan, P. L.; Gruber, D. E.; Knight, F. K.; Matteson, J. L.; Rothschild, R. E.; Marshall, F. E.; Levine, A. M.; Primini, F. A.

1981-01-01

Long-term measurements of the hard X-ray spectrum from 3 keV to 8 MeV of the black-hole candidate Cygnus X-1 in its low state are reported. Observations were made from October 26 to November 18, 1977 with the A2 (Cosmic X-ray) and A4 (Hard X-ray and Low-Energy Gamma-Ray) experiments on board HEAO 1 in the spacecraft's scanning mode. The measured spectrum below 200 keV is found to agree well with previous spectra which have been fit by a model of the Compton scattering of optical or UV photons in a very hot plasma of electron temperature 32.4 keV and optical depth 3.9 or 1.6 for spherical or disk geometry, respectively. At energies above 300 keV, however, flux excess is observed which may be accounted for by a distribution of electron temperatures from 15 to about 100 keV.

High-energy X-ray spectra of Cygnus XR-1 observed from OSO 8

NASA Technical Reports Server (NTRS)

Dolan, J. F.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.

1979-01-01

X-ray spectra of Cygnus XR-1 were measured with the scintillation spectrometer aboard the OSO 8 satellite during a period of one-and-one-half to three weeks in each of the years from 1975 to 1977. Typical spectra of the source between 15 and 250 keV are presented and the spectra are found to be well represented by a single power-law expression whose photon number spectral index is different for the two intensity states that were considered. The observed pivoting effect is consistent with two-temperature accretion disk models of the X-ray emitting region.

Possible Charge-Exchange X-Ray Emission in the Cygnus Loop Detected with Suzaku

NASA Technical Reports Server (NTRS)

Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Kosugi, Hiroko; Kimura, Masashi; Nakajima, Hiroshi; Takakura, Satoru; Petre, Robert; Hewitt. John W.;

An upper limit on ultraviolet shot noise from Cygnus X-1

NASA Technical Reports Server (NTRS)

Duthie, J. G.; Mcmillan, R. S.

1979-01-01

Rapid photometry of Cygnus X-1 through an ultraviolet filter centered on 0.35 micron has been obtained at 100-ms sampling intervals. The autocorrelation function of these data has been examined for shot noise analogous to the behavior of the X-ray light curve. The ultraviolet data are entirely consistent with white noise. Considering randomly occurring ultraviolet shots with the same duration (0.5 s) and average rate (1 per sec) as the X-ray shots, a 3-sigma upper limit on the ratio of optical to X-ray energies per shot is estimated to be 0.13, before the ultraviolet light is attenuated by interstellar dust. This limit is then generalized for shots of arbitrary duration and rate.

Search for gamma rays of energy 10(15) eV from Cygnus X-3

NASA Technical Reports Server (NTRS)

Bhat, P. N.; Rajeev, M. R.; Ramanamurthy, P. V.; Rao, M. V. S.; Sinha, S.; Sreekantan, B. V.; Tonwar, S. C.; Vishwanath, P. R.

1985-01-01

Finite flux of excess radiation of energy 10 to the 15th power has been reported by two groups from the direction of Cygnus X-3, with the characteristic periodicity of 4.8 hrs. Samorski and Stamm find that the muon content of the showers generated by this excess radiation is about 77% of that in normal cosmic ray showers, whereas the expectation for gamma ray showers is less than 10%. It is thus difficult to understand the nature of the radiation arriving from the direction of Cygnus X-3. Samorski and Stamm measured the muon densities close to the core (approx. 10 m), where contamination due to other components is severe. Even though this does not explain the high ratio of muon densities, measurements should be carried out away from the core to establish the nature of the radiation. In order to establish the signal from Cygnus X-3 and its muon content with better statistical significance, an extensive air shower array, specifically designed for this purpose was operated at Kolar Gold Fields (longitude: 78 deg .3 E; latitude: + 12 deg .95; atmospheric depth: 920 q/square centimeters) since September, 1984. The details of the array and the accuracy of arrival direction measurements are discussed.

Deep X-ray Observations of an Ongoing Merger and 400 Myr of AGN Activity in Cygnus A

NASA Astrophysics Data System (ADS)

Wise, Michael W.; De Vries, Martijn; Nulsen, Paul; Snios, Bradford; Birkinshaw, Mark; Worrall, Diana; Duffy, Ryan; Halbesma, Timo; Donnert, Julius; Hardcastle, Martin

2017-08-01

We present a detailed spatial and spectral analysis of the large-scale X-ray emission associated with the merging cluster of galaxies containing the powerful Cygnus A radio galaxy. Using a new 1 Msec exposure from the ongoing Chandra XVP project, we have mapped the large-scale structure, temperature and abundance of the ICM in a 1 Mpc x 1 Mpc region surrounding Cygnus A. This new, deep exposure resolves unprecedented detail in the jets, lobes, and cocoon shock associated with Cygnus A, and provides new insights into the emission mechanisms that produce these features as well as implications for the ongoing activity of the central AGN. On larger scales, these new data reveal complex and dramatic temperature, pressure, entropy and metallicity structure in the ICM surrounding Cygnus A. We confirm the presence of large-scale X-ray emission associated with the two merging cluster components seen previously in lower resolution data. The temperature structure on the scale of the merger exhibits an asymmetric enhancement to the NW consistent with projected hotter gas from the merger shock. Using the derived density and temperature profiles in the two merging sub-cluster components as inputs, we have constructed a grid of hydro-dynamical simulations to constrain the geometry of the merger system. These models imply a pre-merger system with a 1:1 mass ratio at the virial radius with an inclination toward the line of sight of 35-45 deg. In addition to the merger-induced temperature asymmetry, we find evidence for additional surface brightness and temperature features indicative of previous outburst activity in Cygnus A over the past 400 Myr. Based on the location and strength of these features, we derive the energy associated with these previous outbursts and place constraints on the growth of the black hole in Cygnus A over that timescale.

A study of ultra high energy radiation associated with Hercules X-1

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

Biller, Steven Douglas

1992-01-01

Data from the CYGNUS experiment has been used to examine ultra high energy (UHE) radiation associated with the X-ray binary star system Hercules X-1. A search for both pulsed, and unpulsed emission over time scales ranging from minutes to years has failed to yield a result of comparable significance to that of the previously published observation of July 24, 1986. A reassessment of this result in light of the number of hypotheses that have been examined for Hercules X-1 yields a probability estimate of 0.44% that the data is consistent with background fluctuations. If the number of independent source hypothesesmore » is also accounted for, an overall chance probability of 1.8% is assessed for the observations of the CYGNUS experiment. The extensive air showers corresponding to the episode of July 24, 1986 contain a substantial muon content, in contradiction with traditional predictions for primary gamma-rays. No satisfactory theory has yet been put forward to explain this phenomenon. A further analysis of shower characteristics for events associated with this episode indicates a steeper radial dependence of the showerfront timing width at a chance probability level of 0.16%. This property might be explained by a model that invokes a forward-peaked and/or a deeply interacting component of the hadronic interaction in the atmosphere. The potential importance of UHE observations of Hercules X-1 is great. however the evidence is not yet compelling. Further observations will be necessary, to confirm the potential properties of associated UHE radiation.« less

Thermal and Non-thermal emission in the Jets and Lobes of Cygnus A

NASA Astrophysics Data System (ADS)

De Vries, Martijn; Wise, Michael; Huppenkothen, Daniela; Nulsen, Paul; Snios, Bradford; Hardcastle, Martin

2017-08-01

We present a spatially-resolved, spectral analysis aimed at detecting and characterizing the non-thermal X-ray emission from the jets and lobes in the powerful radio galaxy Cygnus A based on a new, deep 1 Msec Chandra exposure. These jets and lobes are believed to be a primary means by which energy liberated by accretion onto the central supermassive black hole is transported into the outer galaxy and are integral to understanding the mechanisms that drive AGN feedback. Despite being well-studied over the years, we still do not understand how this energy is transported, the connection between the X-ray and radio structures, and the underlying emission mechanisms that produce them. The X-ray jets in Cygnus A show a clear misalignment with the radio and it has been proposed that they are either inverse Compton-emitting relics or a separate electron population emitting X-ray synchrotron emission. Previous X-ray studies of the jets and lobes have been unsuccessful in distinguishing between these possibilities largely due to the difficulty of separating any non-thermal components from thermal emission in the surrounding hot ICM at CCD spectral resolutions.In this presentation, we report on a new statistical analysis using MCMC sampling and Bayesian model selection to characterize the X-ray emission in the jets and lobes of Cygnus A. The model includes a mixture of thermal ICM emission and distinct non-thermal components from both the eastern and western jets and lobes. Our analysis clearly favors the presence of non-thermal emission and we find a distinct asymmetry with the western lobe roughly 20% fainter and with a much steeper photon index. Combining existing radio data with our X-ray fluxes and photon indices, we determine the energy densities and pressures for both synchrotron and inverse Compton (IC) emission models. For the IC model, we derive energy densities in the lobes consistent with the external pressure; however, both the eastern and western jets would be over-pressured by almost an order of magnitude arguing strongly for a synchrotron origin. We discuss these results in the context of the evolution of the jets and lobes and their connection to the ongoing feedback process in Cygnus A.

The 2.35 year itch of Cygnus OB2 #9. I. Optical and X-ray monitoring

NASA Astrophysics Data System (ADS)

Nazé, Y.; Mahy, L.; Damerdji, Y.; Kobulnicky, H. A.; Pittard, J. M.; Parkin, E. R.; Absil, O.; Blomme, R.

2012-10-01

Context. Nonthermal radio emission in massive stars is expected to arise in wind-wind collisions occurring inside a binary system. One such case, the O-type star Cyg OB2 #9, was proven to be a binary only four years ago, but the orbital parameters remained uncertain. The periastron passage of 2011 was the first one to be observable under good conditions since the discovery of binarity. Aims: In this context, we have organized a large monitoring campaign to refine the orbital solution and to study the wind-wind collision. Methods: This paper presents the analysis of optical spectroscopic data, as well as of a dedicated X-ray monitoring performed with Swift and XMM-Newton. Results: In light of our refined orbital solution, Cyg OB2 #9 appears as a massive O+O binary with a long period and high eccentricity; its components (O5-5.5I for the primary and O3-4III for the secondary) have similar masses and similar luminosities. The new data also provide the first evidence that a wind-wind collision is present in the system. In the optical domain, the broad Hα line varies, displaying enhanced absorption and emission components at periastron. X-ray observations yield the unambiguous signature of an adiabatic collision, because as the stars approach periastron, the X-ray luminosity closely follows the 1/D variation expected in that case. The X-ray spectrum appears, however, slightly softer at periastron, which is probably related to winds colliding at slightly lower speeds at that time. Conclusions: It is the first time that such a variation has been detected in O+O systems, and the first case where the wind-wind collision is found to remain adiabatic even at periastron passage. Based on observations collected at OHP, with Swift, and with XMM-Newton.Tables 1 and 2 are available in electronic form at http://www.aanda.org

Multiband observations of Cygnus A: A study of pressure balance in the core of a powerful radio galaxy

NASA Technical Reports Server (NTRS)

Carilli, Chris; Conner, Sam; Dreher, John; Perley, Rick

1990-01-01

Cygnus A is a powerful double radio source associated with a giant elliptical galaxy at the center of a poor cluster of galaxies. The radio source also sits within the core radius of a dense, cooling flow, x ray emitting cluster gas. Optical spectroscopy and narrow band imaging have revealed copious amounts of narrow line emission from the inner 20 kpc of the associated galaxy. Researchers assume H sub o = 75 km sec (-1) Mpc(-1). Discussed here are the pressures in the three components of the Interstellar Medium (ISM) (i.e., the radio, x ray, and line emitting fluids) within a radius of about 15 kpc of the active nucleus of the Cygnus A galaxy.

An X-Ray Reprocessing Model of Disk Thermal Emission in Type 1 Seyfert Galaxies

NASA Technical Reports Server (NTRS)

Chiang, James; White, Nicholas E. (Technical Monitor)

2002-01-01

Using a geometry consisting of a hot central Comptonizing plasma surrounded by a thin accretion disk, we model the optical through hard X-ray spectral energy distributions of the type 1 Seyfert. galaxies NGC 3516 and NGC 7469. As in the model proposed by Poutanen, Krolik, and Ryde for the X-ray binary Cygnus X-1 and later applied to Seyfert galaxies by Zdziarski, Lubifiski, and Smith, feedback between the radiation reprocessed by the disk and the thermal Comptonization emission from the hot central plasma plays a pivotal role in determining the X-ray spectrum, and as we show, the optical and ultraviolet spectra as well. Seemingly uncorrelated optical/UV and X-ray light curves, similar to those which have been observed from these objects can, in principle, be explained by variations in the size, shape, and temperature of the Comptonizing plasma. Furthermore, by positing a disk mass accretion rate which satisfies a condition for global energy balance between the thermal Comptonization luminosity and the power available from accretion, one can predict the spectral properties of the heretofore poorly measured hard X-ray continuum above approximately 50 keV in type 1 Seyfert galaxies. Conversely, forthcoming measurements of the hard X-ray continuum by more sensitive hard X-ray and soft gamma-ray telescopes, such as those aboard the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) in conjunction with simultaneous optical, UV, and soft X-ray monitoring, will allow the mass accretion rates to be directly constrained for these sources in the context of this model.

PREDICTING GAIA’S PARALLAX DISTANCE TO THE CYGNUS OB2 ASSOCIATION WITH ECLIPSING BINARIES

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

Kiminki, Daniel C.; Kobulnicky, Henry A.; Álvarez, Carlos A. Vargas

2015-10-01

The Cygnus OB2 Association is one of the nearest and largest collections of massive stars in the Galaxy. Situated at the heart of the “Cygnus X” complex of star-forming regions and molecular clouds, its distance has proven elusive owing to the ambiguous nature of kinematic distances along this ℓ ≃ 80° sightline and the heavy, patchy extinction. In an effort to refine the three-dimensional geometry of key Cygnus X constituents, we have measured distances to four eclipsing double-lined OB-type spectroscopic binaries that are probable members of Cyg OB2. We find distances of 1.33 ± 0.17, 1.32 ± 0.07, 1.44 ±more » 0.18, and 1.32 ± 0.13 kpc toward MT91 372, MT91 696, CPR2002 A36, and Schulte 3, respectively. We adopt a weighted average distance of 1.33 ± 0.06 kpc. This agrees well with spectrophotometric estimates for the Association as a whole and with parallax measurements of protostellar masers in the surrounding interstellar clouds, thereby linking the ongoing star formation in these clouds with Cyg OB2. We also identify Schulte 3C (O9.5V), a 4″ visual companion to the 4.75 day binary Schulte 3(A+B), as a previously unrecognized Association member.« less

Observation of an excess of cosmic ray muons of energies 2 TeV from the direction of Cygnus X-3

NASA Technical Reports Server (NTRS)

Battistoni, G.; Bellotti, E.; Bloise, C.; Bologna, G.; Campana, P.; Castagnoli, C.; Castellina, A.; Chiarella, V.; Ciocio, A.; Cundy, D.

1985-01-01

A high flux of muons from the Cygnus X-3 direction has been observed in NUSEX experiment at depths greater than 4600 hg/sq cm s.r. The excess muons show the 4.8 hour modulation in arrival time typical of this source. A study of this modulation was done in order to find the best value of the period and of the period derivative. The muon flux underground from NUSEX and SOUDAN (1800 hg/sq cm) experiments are used to determine the energy spectrum at sea level. The shape and the absolute intensities are found similar to those attributed to gamma rays responsible for production of air showers detected in direction of Cygnus X-3 in the energy range 10 to the 12th power to 10 to the 15th power eV.

Highly Ionized Fe-K Absorption Line from Cygnus X-1 in the High/Soft State Observed with Suzaku

NASA Astrophysics Data System (ADS)

Yamada, S.; Torii, S.; Mineshige, S.; Ueda, Y.; Kubota, A.; Gandhi, P.; Done, C.; Noda, H.; Yoshikawa, A.; Makishima, K.

2013-04-01

We present observations of a transient He-like Fe Kα absorption line in Suzaku observations of the black hole binary Cygnus X-1 on 2011 October 5 near superior conjunction during the high/soft state, which enable us to map the full evolution from the start to the end of the episodic accretion phenomena or dips for the first time. We model the X-ray spectra during the event and trace their evolution. The absorption line is rather weak in the first half of the observation, but instantly deepens for ~10 ks, and weakens thereafter. The overall change in equivalent width is a factor of ~3, peaking at an orbital phase of ~0.08. This is evidence that the companion stellar wind feeding the black hole is clumpy. By analyzing the line with a Voigt profile, it is found to be consistent with a slightly redshifted Fe XXV transition, or possibly a mixture of several species less ionized than Fe XXV. The data may be explained by a clump located at a distance of ~1010-12 cm with a density of ~10(- 13)-(- 11) g cm-3, which accretes onto and/or transits the line of sight to the black hole, causing an instant decrease in the observed degree of ionization and/or an increase in density of the accreting matter. Continued monitoring for individual events with future X-ray calorimeter missions such as ASTRO-H and AXSIO will allow us to map out the accretion environment in detail and how it changes between the various accretion states.

Search for gamma-ray events in the BATSE data base

NASA Technical Reports Server (NTRS)

Lewin, Walter

1994-01-01

We find large location errors and error radii in the locations of channel 1 Cygnus X-1 events. These errors and their associated uncertainties are a result of low signal-to-noise ratios (a few sigma) in the two brightest detectors for each event. The untriggered events suffer from similarly low signal-to-noise ratios, and their location errors are expected to be at least as large as those found for Cygnus X-1 with a given signal-to-noise ratio. The statistical error radii are consistent with those found for Cygnus X-1 and with the published estimates. We therefore expect approximately 20 - 30 deg location errors for the untriggered events. Hence, many of the untriggered events occurring within a few months of the triggered activity from SGR 1900 plus 14 are indeed consistent with the SGR source location, although Cygnus X-1 is also a good candidate.

Imagery and spectroscopy of supernova remnants and H-2 regions

NASA Technical Reports Server (NTRS)

Dufour, R. J.

1984-01-01

Research activities relating to supernova remnants were summarized. The topics reviewed include: progenitor stars of supernova remnants, UV/optical/radio/X-ray imagery of selected regions in the Cygnus Loop, UV/optical spectroscopy of the Cygnus Loop spur, and extragalactic supernova remnant spectra.

Development of a mercuric iodide solid state spectrometer for X-ray astronomy

NASA Technical Reports Server (NTRS)

Vallerga, J.

1983-01-01

Mercuric iodide detectors, experimental development for astronomical use, X ray observations of the 1980 Cygnus X-1 High State, astronomical had X ray detectors in current use, detector development, balloon flight of large area (1500 sq cm) Phoswich detectors, had X ray telescope design, shielded mercuric iodide background measurement, Monte Carlo analysis, measurements with a shielded mercuric iodide detector are discussed.

A Multiwavelength Study of Cygnus X-1: The First Mid-Infrared Spectroscopic Detection of Compact Jets

NASA Technical Reports Server (NTRS)

Rahoui, Farid; Lee, Julia C.; Heinz, Sebastian; Hines, Dean C.; Pottschmidt, Katja; Wilms, Joern

2011-01-01

We report on a Spitzer/IRS (mid-infrared), RXTE /PCA+HEXTE (X-ray), and Ryle (radio) simultaneous multi-wavelength study of the micro quasar Cygnus X-I, which aimed at an investigation of the origin of its mid-infrared emission. Compact jets were present in two out of three observations, and we show that they strongly contribute to the mid-infrared continuum. During the first observation, we detect the spectral break - where the transition from the optically thick to the optically thin regime takes place - at about 2.9 x 10(exp 13) Hz. We then show that the jet's optically thin synchrotron emission accounts for the Cygnus X-1's emission beyond 400 keY, although it cannot alone explain its 3-200 keV continuum. A compact jet was also present during the second observation, but we do not detect the break, since it has likely shifted to higher frequencies. In contrast, the compact jet was absent during the last observation, and we show that the 5-30 micron mid-infrared continuum of Cygnus X-I stems from the blue supergiant companion star HD 226868. Indeed, the emission can then be understood as the combination of the photospheric Raleigh-Jeans tail and the bremsstrahlung from the expanding stellar wind. Moreover, the stellar wind is found to be clumpy, with a filling factor f(sub infinity) approx.= 0.09-0.10. Its bremsstrahlung emission is likely anti-correlated to the soft X-ray emission, suggesting an anticorrelation between the mass-loss and mass-accretion rates. Nevertheless, we do not detect any mid-infrared spectroscopic evidence of interaction between the jets and the Cygnus X-1's environment and/or companion star's stellar wind.

The PoGO+ Ballon-Borne Hard X-ray Polarimetry Mission

NASA Astrophysics Data System (ADS)

Friis, Mette; Kiss, Mózsi; Mikhalev, Victor; Pearce, Mark; Takahashi, Hiromitsu

2018-03-01

The PoGO mission, including the PoGOLite Pathfinder and PoGO+, aims to provide polarimetric measurements of the Crab system and Cygnus X-1 in the hard X-ray band. Measurements are conducted from a stabilized balloon-borne platform, launched on a 1 million cubic meter balloon from the Esrange Space Center in Sweden to an altitude of approximately 40 km. Several flights have been conducted, resulting in two independent measurements of the Crab polarization and one of Cygnus X-1. Here, a review of the PoGO mission is presented, including a description of the payload and the flight campaigns, and a discussion of some of the scientific results obtained to date.

SMM/HXRBS observations of Cygnus X-1 from 1986 December to 1988 April

NASA Technical Reports Server (NTRS)

Schwartz, R. A.; Orwig, L. E.; Dennis, B. R.; Ling, J. C.; Wheaton, W. A.

1991-01-01

The Solar Maximum Mission's Hard X-ray Burst Spectrometer made 30 measurements of Cygnus X-1 from December, 1986 to April, 1988, yielding a data set of broad synoptic coverage but limited duration for each data point. The hard X-ray intensity was found to be between the gamma(2) and gamma(3) levels, with a range of fluctuations about the average intensity level. The shape of the photon spectrum was found to be closest to that reported by Ling et al. (1983, 1987) during the time of the gamma(3) level emission, although the spectral shapes reported for the gamma(2) and gamma(1) levels were not precluded.

Performance of large area x-ray proportional counters in a balloon experiment

NASA Astrophysics Data System (ADS)

Roy, J.; Agrawal, P. C.; Dedhia, D. K.; Manchanda, R. K.; Shah, P. B.; Chitnis, V. R.; Gujar, V. M.; Parmar, J. V.; Pawar, D. M.; Kurhade, V. B.

2016-10-01

ASTROSAT is India's first satellite fully devoted to astronomical observations covering a wide spectral band from optical to hard X-rays by a complement of 4 co-aligned instruments and a Scanning Sky X-ray Monitor. One of the instruments is Large Area X-ray Proportional Counter with 3 identical detectors. In order to assess the performance of this instrument, a balloon experiment with two prototype Large Area X-ray Proportional Counters (LAXPC) was carried out on 2008 April 14. The design of these LAXPCs was similar to those on the ASTROSAT except that their field of view (FOV) was 3 ∘ × 3 ∘ versus FOV of 1 ∘ × 1 ∘ for the LAXPCs on the ASTROSAT. The LAXPCs are aimed at the timing and spectral studies of X-ray sources in 3-80 keV region. In the balloon experiment, the LAXPC, associated electronics and support systems were mounted on an oriented platform which could be pre-programmed to track any source in the sky. A brief description of the LAXPC design, laboratory tests, calibration and the detector characteristics is presented here. The details of the experiment and background counting rates of the 2 LAXPCs at the float altitude of about 41 km are presented in different energy bands. The bright black hole X-ray binary Cygnus X-1 (Cyg X-1) was observed in the experiment for ˜ 3 hours. Details of Cyg X-1 observations, count rates measured from it in different energy intervals and the intensity variations of Cyg X-1 detected during the observations are presented and briefly discussed.

The 2010 May Flaring Episode of Cygnus X-3 in Radio, X-Rays, and gamma-Rays

NASA Technical Reports Server (NTRS)

Williams, Peter K. G.; Tomsick, John A.; Bodaghee, Arash; Bower, Geoffrey C.; Pooley, Guy G.; Pottschmidt, Katja; Rodriguez, Jerome; Wilms, Joern; Migliari, Simone; Trushkin, Sergei A.

2011-01-01

In 2009, Cygnus X-3 (Cyg X-3) became the first microquasar to be detected in the GeV gamma-ray regime, via the satellites Fermi and AGILE. The addition of this new band to the observational toolbox holds promise for building a more detailed understanding of the relativistic jets of this and other systems. We present a rich dataset of radio, hard and soft X-ray, and gamma-ray observations of Cyg X-3 made during a flaring episode in 2010 May. We detect a approx.3-d softening and recovery of the X-ray emission, followed almost immediately by a approx.1-Jy radio flare at 15 GHz, followed by a 4.3sigma gamma-ray flare (E > 100 MeV) approx.1.5 d later. The radio sampling is sparse, but we use archival data to argue that it is unlikely the gamma-ray flare was followed by any significant unobserved radio flares. In this case, the sequencing of the observed events is difficult to explain in a model in which the gamma-ray emission is due to inverse Compton scattering of the companion star's radiation field. Our observations suggest that other mechanisms may also be responsible for gamma-ray emission from Cyg X-3.

X-ray Variations at the Orbital Period from Cygnus X-1 IN the High/Soft State

NASA Astrophysics Data System (ADS)

Boroson, Bram; Vrtilek, Saeqa Dil

2010-02-01

Orbital variability has been found in the X-ray hardness of the black hole candidate Cygnus X-1 during the soft/high X-ray state using light curves provided by the Rossi X-ray Timing Explorer's All-Sky Monitor. We are able to set broad limits on how the mass-loss rate and X-ray luminosity vary between the hard and soft states. The folded light curve shows diminished flux in the soft X-ray band at phi = 0 (defined as the time of the superior conjunction of the X-ray source). Models of the orbital variability provide slightly superior fits when the absorbing gas is concentrated in neutral clumps and better explain the strong variability in hardness. In combination with the previously established hard/low state dips, our observations give a lower limit to the mass-loss rate in the soft state (\\dot{M}<2× 10^{-6} M_{⊙} yr-1) than the limit in the hard state (\\dot{M}<4× 10^{-6} M_{⊙} yr-1). Without a change in the wind structure between X-ray states, the greater mass-loss rate during the low/hard state would be inconsistent with the increased flaring seen during the high-soft state.

Study of ultra-high energy emission from Cygnus X-3 and Hercules X-1

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

Dingus, B.L.

1988-11-01

The CYGNUS experiment, consisting of an extensive air shower detector and a muon detector, was built at Los Alamos, New Mexico (latitude 36 N, longitude 107W, altitude 2310 meters), to search for point sources of ultra-high energy (>10/sup 14/ eV) particles. These particles must be long-lived neutral particles because of the long source distances and the presence of the intragalactic magnetic field. Gamma rays are the most likely candidates because of the short neutron lifetime and the small neutrino cross section. Therefore, the muon content of the source showers is examined to determine if these events are muon poor asmore » is expected for gamma-initiated showers. The data set from April 1986 to July 1987 is searched for continual emission from Cygnus X-3 and Hercules X-1, and an upper bound to flux is determined for both sources. The flux limit for Cygnus X-3, 2.0 /times/ 10/sup /minus/13/ cm/sup /minus/2/ sec/sup /minus/1/ above 50 TeV, is lower than previous ultra-high energy observations. Hercules X-1 has never been observed continually at ultra-high energies. Cygnus X-3 is observed for a shorter interval of time, beginning on 17 April 1986 and ending 1 June 1986. There is one chance in 300 that the observation is due to a random fluctuation. The signal is correlated with the 4.8 hour orbital period, and the muon content of the showers in the signal is inconsistent with the conventional prediction of gamma- initiated showers. An episodic signal is also reported for Hercules X-1, and it consists of two bursts of less than one hour duration on 24 July 1986. The probability is one chance in 12,000 that this observation is not associated with Hercules X-1. The signal is pulsed at frequency near, but significantly different from, the x-ray pulsar frequency. The muon content of the signal showers is also anomalous, assuming the showers are initiated by gamma rays. 62 refs., 60 figs.« less

A year-long AGILE observation of Cygnus X-1 in hard spectral state

NASA Astrophysics Data System (ADS)

Del Monte, E.; Feroci, M.; Evangelista, Y.; Costa, E.; Donnarumma, I.; Lapshov, I.; Lazzarotto, F.; Pacciani, L.; Rapisarda, M.; Soffitta, P.; Argan, A.; Barbiellini, G.; Boffelli, F.; Bulgarelli, A.; Caraveo, P.; Cattaneo, P. W.; Chen, A.; D'Ammando, F.; Di Cocco, G.; Fuschino, F.; Galli, M.; Gianotti, F.; Giuliani, A.; Labanti, C.; Lipari, P.; Longo, F.; Marisaldi, M.; Mereghetti, S.; Moretti, E.; Morselli, A.; Pellizzoni, A.; Perotti, F.; Piano, G.; Picozza, P.; Pilia, M.; Prest, M.; Pucella, G.; Rappoldi, A.; Sabatini, S.; Striani, E.; Tavani, M.; Trifoglio, M.; Trois, A.; Vallazza, E.; Vercellone, S.; Vittorini, V.; Zambra, A.; Antonelli, L. A.; Cutini, S.; Pittori, C.; Preger, B.; Santolamazza, P.; Verrecchia, F.; Giommi, P.; Salotti, L.

2010-09-01

Context. Cygnus X-1 (Cyg X-1) is a high mass X-ray binary system, known to be a black hole candidate and one of the brightest sources in the X-ray sky, which shows both variability on all timescales and frequent flares. The source spends most of the time in a hard spectral state, dominated by a power-law emission, with occasional transitions to the soft and intermediate states, where a strong blackbody component emerges. Aims: We present the observation of Cyg X-1 in a hard spectral state performed during the AGILE science verification phase and observing cycle 1 in hard X-rays (with SuperAGILE) and gamma rays (with the gamma ray imaging detector) and lasting for about 160 days with a live time of ~6 Ms. Methods: We investigated the variability of Cyg X-1 in hard X-rays on different timescales, from ~300 s up to one day, and we applied different tools of timing analysis, such as the autocorrelation function, the first-order structure function, and the Lomb-Scargle periodogram, to our data (from SuperAGILE) and to the simultaneous data in soft X-rays (from RXTE/ASM). We concluded our investigation with a search for emission in the energy range above 100 MeV with the maximum likelihood technique. Results: In the hard X-ray band, the flux of Cyg X-1 shows its typical erratic fluctuations on all timescales with variations of about a factor of two that do not significantly affect the shape of the energy spectrum. From the first-order structure function, we find that the X-ray emission of Cyg X-1 is characterized by antipersistence (anticorrelation in the time series, with an increase in the emission likely followed by a decrease), indicative of a negative feedback mechanism at work. In the gamma ray data a statistically significant point-like source at the position of Cyg X-1 is not found, and the upper limit on the flux is 5 × 10-8 ph cm-2 s-1 over the whole observation (160 days). Finally we compared our upper limit in gamma rays with the expectation of various models of the Cyg X-1 emission, both of hadronic and leptonic origin, in the GeV-TeV band. Conclusions: The time history of Cyg X-1 in the hard X-ray band over 13 months (not continuous) is shown. Different analysis tools do not provide fully converging results of the characteristic timescales in the system, suggesting that the timescales found in the structure function are not intrinsic to the physics of the source. While Cyg X-1 is not detected in gamma rays, our upper limit is a factor of two lower than the EGRET one and is compatible with the extrapolation of the flux measured by COMPTEL in the same spectral state.

The Microquasar Cyg X-1: A Short Review

NASA Technical Reports Server (NTRS)

Nowak, M. A.; Wilms, J.; Hanke, M.; Pottschmidt, K.; Markoff, S.

2011-01-01

We review the spectral properties of the black hole candidate Cygnus X-I. Specifically, we discuss two recent sets of multi-satellite observations. One comprises a 0.5-500 keY spectrum, obtained with eve!)' flying X-ray satellite at that time, that is among the hardest Cyg X-I spectra observed to date. The second set is comprised of 0.5-40 keV Chandra-HETG plus RXTE-PCA spectra from a radio-quiet, spectrally soft state. We first discuss the "messy astrophysics" often neglected in the study of Cyg X-I, i.e., ionized absorption from the wind of the secondary and the foreground dust scattering halo. We then discuss components common to both state extremes: a low temperature accretion disk, and a relativistically broadened Fe line and reflection. Hard state spectral models indicate that the disk inner edge does not extend beyond > or approx.= 40 GM/sq c , and may even approach as close as approx. = 6GM/sq c. The soft state exhibits a much more prominent disk component; however, its very low normalization plausibly indicates a spinning black hole in the Cyg X-I system. Key words. accretion, accretion disks - black hole physics - X-rays:binaries

Line structures in the X-ray spectra of Cygnus X-2 observed with Exosat

NASA Technical Reports Server (NTRS)

Freeman, P. E.; Kahn, S. M.; Chiappetti, L.; Tanzi, E. G.; Ciapi, A.; Maraschi, L.; Treves, A.; Branduardi-Raymont, E. G.; Ercan, E. N.

1990-01-01

Cygnus X-2 was observed with Exosat at five phases of a single orbital cycle in September of 1983. The results of spectral fits of the LE + ME (Argon) data are summarized in terms of a superposition of thermal bremsstrahlung and blackbody components. During the first observation, a grating spectrum was obtained, and this is described in some detail. The GSPC data are used to investigate the presence of iron features and their behavior during dips.

A multiwavelength investigation of the massive eclipsing binary Cygnus OB2 #5

NASA Astrophysics Data System (ADS)

Linder, N.; Rauw, G.; Manfroid, J.; Damerdji, Y.; De Becker, M.; Eenens, P.; Royer, P.; Vreux, J.-M.

2009-02-01

Context: The properties of the early-type binary Cyg OB2 #5 have been debated for many years and spectroscopic and photometric investigations yielded conflicting results. Aims: We have attempted to constrain the physical properties of the binary by collecting new optical and X-ray observations. Methods: The optical light curves obtained with narrow-band continuum and line-bearing filters are analysed and compared. Optical spectra are used to map the location of the He ii λ 4686 and Hα line-emission regions in velocity space. New XMM-Newton as well as archive X-ray spectra are analysed to search for variability and constrain the properties of the hot plasma in this system. Results: We find that the orbital period of the system slowly changes though we are unable to discriminate between several possible explanations of this trend. The best fit solution of the continuum light curve reveals a contact configuration with the secondary star being significantly brighter and hotter on its leading side facing the primary. The mean temperature of the secondary star turns out to be only slightly lower than that of the primary, whilst the bolometric luminosity ratio is found to be 3.1. The solution of the light curve yields a distance of 925 ± 25 pc much lower than the usually assumed distance of the Cyg OB2 association. Whilst we confirm the existence of episodes of higher X-ray fluxes, the data reveal no phase-locked modulation with the 6.6 day period of the eclipsing binary nor any clear relation between the X-ray flux and the 6.7 yr radio cycle. Conclusions: The bright region of the secondary star is probably heated by energy transfer in a common envelope in this contact binary system as well as by the collision with the primary's wind. The existence of a common photosphere probably also explains the odd mass-luminosity relation of the stars in this system. Most of the X-ray, non-thermal radio, and possibly γ-ray emission of Cyg OB2 #5 is likely to arise from the interaction of the combined wind of the eclipsing binary with at least one additional star of this multiple system. Based on observations collected at the Observatoire de Haute Provence (France), the Observatorio Astronómico Nacional of San Pedro Mártir (Mexico) and XMM-Newton, an ESA science mission with instruments and contributions funded by ESA member states and the USA (NASA). Light curves of Cyg OB2 #5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/495/231

Long term variability of Cygnus X-1. VII. Orbital variability of the focussed wind in Cyg X-1/HDE 226868 system

NASA Astrophysics Data System (ADS)

Grinberg, V.; Leutenegger, M. A.; Hell, N.; Pottschmidt, K.; Böck, M.; García, J. A.; Hanke, M.; Nowak, M. A.; Sundqvist, J. O.; Townsend, R. H. D.; Wilms, J.

2015-04-01

Binary systems with an accreting compact object offer a unique opportunity to investigate the strong, clumpy, line-driven winds of early-type supergiants by using the compact object's X-rays to probe the wind structure. We analyze the two-component wind of HDE 226868, the O9.7Iab giant companion of the black hole Cyg X-1, using 4.77 Ms Rossi X-ray Timing Explorer (RXTE) observations of the system taken over the course of 16 years. Absorption changes strongly over the 5.6 d binary orbit, but also shows a large scatter at a given orbital phase, especially at superior conjunction. The orbital variability is most prominent when the black hole is in the hard X-ray state. Our data are poorer for the intermediate and soft state, but show signs for orbital variability of the absorption column in the intermediate state. We quantitatively compare the data in the hard state to a toy model of a focussed Castor-Abbott-Klein wind: as it does not incorporate clumping, the model does not describe the observations well. A qualitative comparison to a simplified simulation of clumpy winds with spherical clumps shows good agreement in the distribution of the equivalent hydrogen column density for models with a porosity length on the order of the stellar radius at inferior conjunction; we conjecture that the deviations between data and model at superior conjunction could either be due to lack of a focussed wind component in the model or to a more complicated clump structure. Appendix A is available in electronic form at http://www.aanda.org

Long term variability of Cygnus X-1: VII. Orbital variability of the focussed wind in Cyg X-1/HDE 226868 system

DOE PAGES

Grinberg, V.; Leutenegger, M. A.; Hell, N.; ...

2015-04-16

Binary systems with an accreting compact object offer a unique opportunity to investigate the strong, clumpy, line-driven winds of early-type supergiants by using the compact object’s X-rays to probe the wind structure. In this paper, we analyze the two-component wind of HDE 226868, the O9.7Iab giant companion of the black hole Cyg X-1, using 4.77 Ms Rossi X-ray Timing Explorer (RXTE) observations of the system taken over the course of 16 years. Absorption changes strongly over the 5.6 d binary orbit, but also shows a large scatter at a given orbital phase, especially at superior conjunction. The orbital variability ismore » most prominent when the black hole is in the hard X-ray state. Our data are poorer for the intermediate and soft state, but show signs for orbital variability of the absorption column in the intermediate state. We quantitatively compare the data in the hard state to a toy model of a focussed Castor-Abbott-Klein wind: as it does not incorporate clumping, the model does not describe the observations well. Finally, a qualitative comparison to a simplified simulation of clumpy winds with spherical clumps shows good agreement in the distribution of the equivalent hydrogen column density for models with a porosity length on the order of the stellar radius at inferior conjunction; we conjecture that the deviations between data and model at superior conjunction could either be due to lack of a focussed wind component in the model or to a more complicated clump structure.« less

Long-term studies with the Ariel 5 ASM. II - The strong Cygnus sources

NASA Technical Reports Server (NTRS)

Holt, S. S.; Kaluzienski, L. J.; Boldt, E. A.; Serlemitsos, P. J.

1979-01-01

The three bright 3-6 keV X-ray sources in Cygnus are examined for regular temporal variability with a 1300 day record from the Ariel 5 All-Sky Monitor. The only periods consistently observed are 5.6 days for Cyg X-1, 11.23 days for Cyg X-2, and 4.8 hours for Cyg X-3. The 78.4 day period of Kemp, Herman, and Barbour for Cyg X-1, the 9.843 day period of Cowley, Crampton, and Hutchings for Cyg X-2, and the 16.75 day period of Holt et al. for Cyg X-3 are not confirmed.

Monitoring the Galaxy - Highlights from the MAXI mission

NASA Astrophysics Data System (ADS)

Mihara, Tatehiro

Monitor of All-sky X-ray Image (MAXI) is an X-ray all-sky monitor on the International Space Station. It is equipped with Gas Slit Camera (GSC) and Solid-state Slit Camera (SSC). Since it was mounted to the Japanese experimental module in 2009, it has been scanning the whole sky in every 92 minutes with ISS rotation. The data are processed automatically and distributed through http://maxi.riken.jp homepage. MAXI issued 136 to Astronomers Telegram and 47 to Gamma-ray burst Coordinated Network so far. There are many transient X-ray sources in our galaxy. The most remarkable one is a new source. MAXI discovered 12 MAXI sources, 6 of which are blackhole binaries. MAXI J0158-744 was a source in a new category (Morii et al. 2013). It was a very bright (10(40) erg s(-1) ) and very rapid (< 1 hour) nova consisting of a unusual pair of binary, which was a Ne-white dwarf and a Be star. The monitoring results are published as the 37-month catalog (Hiroi et al. 2012) which contains 500 sources above 0.6 mCrab in 4-10 keV in high Galactic-latitude (|b| > 10 deg). SSC with X-ray CCD has detected diffuse soft X-rays in the all-sky, such as Cygnus super bubble (Kimura et al. 2013) and north polar spur, as well as it found Ne line from the rapid soft X-ray nova MAXI J0158-744. Be X-ray binary pulsars (BeXBP) are also transients. They have outbursts at the periastron passage. However, the outburst does not occur in every orbit. Some sources stay in quiescence for tens of years, then suddenly start outbursts repeating for several years. All-sky monitor is then essential to study such kinds of sources. For example, cyclotron feature is often seen in the high energy X-ray band of BeXBP, from which magnetic fields of the poles are measured. MAXI detection of outburst and following SUZAKU pointing observation are very effective. We observed two BeXBP, GX 304-1 in 2010 and GRO J1008-57 in 2012 in MAXI-Suzaku collaboration and succeeded to catch them at the outburst peaks (600mCrab and 450mCrab) to detect cyclotron feature at 54 keV (Yamamoto et al. 2011) and 76 keV (Yamamoto et al. 2014), respectively. Those are top 1 and 3 of the highest magnetic fields among XBP. Transient low-mass X-ray binaries (LMXB), containing a neutron star or a black hole are also transients. The instability of the acretion disks are proposed to explain the random appearance. The long-term monitoring is also essential to study super orbital modulations of such as supergiant XBP (SMC X-1, LMC X-4 etc.) and LMXB (4U 1820-30 etc.). Monitoring is also useful to detect a rare state, such as a quenched-radio state of Cyg X-3 and rapid end of outburst of Cir X-1.

Integral's first look at the gamma-ray Universe

NASA Astrophysics Data System (ADS)

2002-12-01

The high-energy Universe is a violent place of exploding stars and their collapsed remnants such as the ultra-compressed neutron stars and, at the most extreme, all-consuming black holes. These celestial objects create X-rays and gamma rays that are many times more powerful than the optical radiation we can see with our eyes and optical telescopes. Integral’s Principal Investigators - the scientists responsible for the instruments on board - explain the crucial role that high-energy missions like Integral play in astronomy. “X-ray and gamma-ray astronomy is a pathfinder to unusual objects. At optical wavelengths, the number of stars is staggering. At X-ray and gamma-ray wavelengths, there are fewer objects, but the ones that remain are the really peculiar ones.” As a first test, Integral observed the Cygnus region of the sky, looking particularly at that enigmatic object, Cygnus X-1. Since the 1960s, we have known this object to be a constant generator of high-energy radiation. Most scientists believe that Cygnus X-1 is the site of a black hole, containing around five times the mass of our Sun and devouring a nearby star. Observing Cygnus X-1, which is relatively close by in our own Galaxy - ‘only’ 10 000 light years from us - is a very important step towards understanding black holes. This will also help understand the monstrous black hole - three million times the mass of our Sun - at the centre of our Galaxy. During the initial investigations, scientists had a pleasant surprise when Integral captured its first gamma-ray burst. These extraordinary celestial explosions are unpredictable, occurring from random directions about twice a day. Their precise origin is contentious: they could be the result of massive stars collapsing in the distant Universe or alternatively the result of a collision between two neutron stars. Integral promises to provide vital clues to solving this particular celestial mystery. To study these peculiarities, Integral carries two powerful gamma-ray instruments. It has a camera, or imager, called IBIS and a spectrometer, SPI. Spectrometers are used to measure the energy of the gamma rays received. Gamma-ray sources are often extremely variable and can fluctuate within minutes or seconds. It is therefore crucial to record data simultaneously in different wavelengths. To achieve this, Integral also carries an X-ray and an optical monitor (JEM-X and OMC). All four instruments will observe the same objects, at the same time. In this way they can capture fleeting events completely. Integral sends the data from all the instruments to the Integral Science Data Centre (ISDC) near Geneva, Switzerland, where they are processed for eventual release to the scientific community. “We have been optimising the instruments’ performance to produce the best overall science. We expect to be ready for astronomers around the world to use Integral by the end of the year,” says Arvind Parmar, acting Integral Project Scientist at ESA. “These images and spectra prove that Integral can certainly do the job it was designed to do, and more", which is to unlock some of the secrets of the high-energy Universe. Integral’s primary mission will last for two years, but it is carrying enough fuel to continue for five years, all being well. Notes to Editors Integral was launched on board a Russian Proton rocket from the Baikonur Cosmodrome, Kazakhstan, on 17 October 2002. The satellite was placed in a tilted orbit that looped from 600 to 153 000 kilometres above the Earth and back again. Integral’s own thrusters then steered the spacecraft, in a series of five manoeuvres, into its operational orbit, between 9 000 and 153 000 kilometres above the Earth. Although Integral orbits above the Earth's atmosphere and weather, it still has ‘space weather’ to contend with. Space weather consists of a constant rain of tiny particles that can temporarily blind detectors designed to register gamma radiation. “The flashes last about 0.1 seconds and have to be filtered out with software,” says Pietro Ubertini, IBIS Principal Investigator. JEM-X proved to be particularly susceptible to space weather and scientists had to ‘re-tune’ it. * * * Cygnus X-1 is one of the brightest high-energy emitters in the sky. Relative to its parent constellation, Cygnus - the Swan, Cygnus X-1 it is located about halfway along the row of stars that mark the Swan’s neck, at about 10 000 light years from Earth. Cygnus X-1 was discovered in the 1960s and is thought to be a black hole, ripping its companion star to pieces. The companion star, HDE 226868, is a blue supergiant with a surface temperature of around 31 000K. It orbits the black hole once every 5.6 days.

Combined ultraviolet studies of astronomical source

NASA Technical Reports Server (NTRS)

Dupress, A. K.; Baliunas, S. L.; Blair, W. P.; Hartmann, L. W.; Huchra, J. P.; Raymond, J. C.; Smith, G. H.; Soderblom, D. R.

1985-01-01

As part of its Ultraviolet Studies of Astronomical Sources the Smithsonian Astrophysical Observatory for the period 1 Feb. 1985 to 31 July 1985 observed the following: the Cygnus Loop; oxygen-rich supernova remnants in 1E0102-72; the Large Magellanic Cloud supernova remnants; P Cygni profiles in dwarf novae; soft X-ray photoionization of interstellar gas; spectral variations in AM Her stars; the mass of Feige 24; atmospheric inhomogeneities in Lambda Andromedae and FF Aquarii; photometric and spectroscopic observation of Capella; Alpha Orionis; metal deficient giant stars; M 67 giants; high-velocity winds from giant stars; accretion disk parameters in cataclysmic variables; chromospheric emission of late-type dwarfs in visual binaries; chromospheres and transient regions of stars in the Ursa Major group; and low-metallicity blue galaxies.

The X-ray ribs within the cocoon shock of Cygnus A

NASA Astrophysics Data System (ADS)

Duffy, R. T.; Worrall, D. M.; Birkinshaw, M.; Nulsen, P. E. J.; Wise, M. W.; de Vries, M. N.; Snios, B.; Mathews, W. G.; Perley, R. A.; Hardcastle, M. J.; Rafferty, D. A.; McNamara, B. R.; Edge, A. C.; McKean, J. P.; Carilli, C. L.; Croston, J. H.; Godfrey, L. E. H.; Laing, R. A.

2018-06-01

We use new and archival Chandra observations of Cygnus A, totalling ˜1.9 Ms, to investigate the distribution and temperature structure of gas lying within the projected extent of the cocoon shock and exhibiting a rib-like structure. We confirm that the X-rays are dominated by thermal emission with an average temperature of around 4 keV, and have discovered an asymmetry in the temperature gradient, with the southwestern part of the gas cooler than the rest by up to 2 keV. Pressure estimates suggest that the gas is a coherent structure of single origin located inside the cocoon, with a mass of roughly 2 × 1010 M⊙. We conclude that the gas is debris resulting from disintegration of the cool core of the Cygnus A cluster after the passage of the jet during the early stages of the current epoch of activity. The 4 keV gas now lies on the central inside surface of the hotter cocoon rim. The temperature gradient could result from an offset between the centre of the cluster core and the Cygnus A host galaxy at the switch-on of current radio activity.

On the Determination of the Spin of the Black Hole in Cyg X-1 from X-Ray Reflection Spectra

NASA Technical Reports Server (NTRS)

Fabian, A. C.; Wilkins, D.; Miller, J. M.; Reis, R. C.; Reynolds, C. S.; Cackett, E. M.; Nowak, M. A.; Pooley, G.; Pottschmidt, K.; Sanders, J. S.;

A giant radio flare from Cygnus X-3 with associated γ-ray emission: The 2011 radio and γ-ray flare of Cyg X-3

DOE PAGES

Corbel, S.; Dubus, G.; Tomsick, J. A.; ...

2012-04-10

With frequent flaring activity of its relativistic jets, Cygnus X-3 (Cyg X-3) is one of the most active microquasars and is the only Galactic black hole candidate with confirmed high-energy γ-ray emission, thanks to detections by Fermi Large Area Telescope (Fermi/LAT) and AGILE. In 2011, we observed Cyg X-3 in order to transit to a soft X-ray state, which is known to be associated with high-energy γ-ray emission. We present the results of a multiwavelength campaign covering a quenched state, when radio emission from Cyg X-3 is at its weakest and the X-ray spectrum is very soft. A giant (~20more » Jy) optically thin radio flare marks the end of the quenched state, accompanied by rising non-thermal hard X-rays. Fermi/LAT observations (E≥ 100 MeV) reveal renewed γ-ray activity associated with this giant radio flare, suggesting a common origin for all non-thermal components. In addition, current observations unambiguously show that the γ-ray emission is not exclusively related to the rare giant radio flares. A three-week period of γ-ray emission is also detected when Cyg X-3 was weakly flaring in radio, right before transition to the radio quenched state. There were no γ-rays observed during the ~1-month long quenched state, when the radio flux is weakest. These results suggest transitions into and out of the ultrasoft X-ray (radio-quenched) state trigger γ-ray emission, implying a connection to the accretion process, and also that the γ-ray activity is related to the level of radio flux (and possibly shock formation), strengthening the connection to the relativistic jets.« less

Giant Radio Flare of Cygnus X-3 in September 2016

NASA Astrophysics Data System (ADS)

Trushkin, S. A.; Nizhelskij, N. A.; Tsybulev, P. G.; Zhekanis, G. V.

2017-06-01

In the long-term multi-frequency monitoring program of the microquasars with RATAN-600 we discovered the giant flare from X-ray binary Cyg X-3 on 13 September 2016. It happened after 2000 days of the 'quiescent state' of the source passed after the former giant flare (˜18 Jy) in March 2011. We have found that during this quiet period the hard X-ray flux (Swift/BAT, 15-50 keV) and radio flux (RATAN-600, 11 GHz) have been strongly anti-correlated. Both radio flares occurred after transitions of the microquasar to a 'hypersoft' X-ray state that occurred in February 2011 and in the end of August 2016. The giant flare was predicted by us in the first ATel (Trushkin et al. (2016)). Indeed after dramatic decrease of the hard X-ray Swift 15-50 keV flux and RATAN 4- 11 GHz fluxes (a 'quenched state') a small flare (0.7 Jy at 4-11 GHz) developed on MJD 57632 and then on MJD 57644.5 almost simultaneously with X-rays radio flux rose from 0.01 to 15 Jy at 4.6 GHz during few days. The rise of the flaring flux is well fitted by a exponential law that could be a initial phase of the relativistic electrons generation by internal shock waves in the jets. Initially spectra were optically thick at frequencies lower 2 GHz and optically thin at frequencies higher 8 GHz with typical spectral index about -0.5. After maximum of the flare radio fluxes at all frequencies faded out with exponential law.

Variability in the high energy gamma ray emission from Cyg X-3 over a two-year period (1983 - 1984) at E 4 x 10(11) eV

NASA Technical Reports Server (NTRS)

Cawley, M. F.; Fegan, D. J.; Gibbs, K.; Gorham, P. W.; Lamb, R. C.; Liebing, D. F.; Porter, N. A.; Stenger, V. J.; Weekes, T. C.; Williams, R. J.

1985-01-01

Cygnus X-3 is observed to emit gamma rays with energies in excess of 4 x 10 to the 11th power eV during two out of 9 observational categories over an 18 month time span. The emissions are observed at the 0.6 phase of the characteristic 4.8 hr light curve for this binary system. We estimate a peak flux at phase 0.6 of 5 x 10 to the minus 10th power photons cm-2s-1 at a software threshold of 8 x 10 to the 11th power eV for Oct/Nov 1983. A flux for the June 84 effect cannot be reliably calculated at present due to lack of Monte Carlo simulations for the energy range and spectral region. For the other 7 observational categories the observations are consistent with zero source emission. The light curve would appear to be variable on a time scale of a couple of weeks at these categories. Selection of compact images in accordance with Monte Carlo simulations combined with empirical optimization techniques have led to an enriched gamma ray light curve for the Oct/Nov 1983 data. Selection on the basis of shower orientation, however, has not led to any notable enhancement of the gamma ray content. Individual Cherenko images can be reliably sorted on an event by event basis into either proton-induced or photon-induced showers.

A giant radio flare from Cygnus X-3 with associated γ-ray emission

NASA Astrophysics Data System (ADS)

Corbel, S.; Dubus, G.; Tomsick, J. A.; Szostek, A.; Corbet, R. H. D.; Miller-Jones, J. C. A.; Richards, J. L.; Pooley, G.; Trushkin, S.; Dubois, R.; Hill, A. B.; Kerr, M.; Max-Moerbeck, W.; Readhead, A. C. S.; Bodaghee, A.; Tudose, V.; Parent, D.; Wilms, J.; Pottschmidt, K.

2012-04-01

With frequent flaring activity of its relativistic jets, Cygnus X-3 (Cyg X-3) is one of the most active microquasars and is the only Galactic black hole candidate with confirmed high-energy γ-ray emission, thanks to detections by Fermi Large Area Telescope (Fermi/LAT) and AGILE. In 2011, Cyg X-3 was observed to transit to a soft X-ray state, which is known to be associated with high-energy γ-ray emission. We present the results of a multiwavelength campaign covering a quenched state, when radio emission from Cyg X-3 is at its weakest and the X-ray spectrum is very soft. A giant (˜20 Jy) optically thin radio flare marks the end of the quenched state, accompanied by rising non-thermal hard X-rays. Fermi/LAT observations (E≥ 100 MeV) reveal renewed γ-ray activity associated with this giant radio flare, suggesting a common origin for all non-thermal components. In addition, current observations unambiguously show that the γ-ray emission is not exclusively related to the rare giant radio flares. A three-week period of γ-ray emission is also detected when Cyg X-3 was weakly flaring in radio, right before transition to the radio quenched state. No γ-rays are observed during the ˜1-month long quenched state, when the radio flux is weakest. Our results suggest transitions into and out of the ultrasoft X-ray (radio-quenched) state trigger γ-ray emission, implying a connection to the accretion process, and also that the γ-ray activity is related to the level of radio flux (and possibly shock formation), strengthening the connection to the relativistic jets.

A Giant Radio Flare from Cygnus X-3 with Associated Gamma-Ray Emission

NASA Technical Reports Server (NTRS)

Corbel, S.; Dubus, G.; Tomsick, J. A.; Szostek, A.; Corbet, R. H. D.; Miller-Jones, J. C. A.; Richards, J. L.; Pooley, G.; Trushkin, S.; Dubois, R.;

Aerogel Cherenkov detector for characterizing the intense flash x-ray source, Cygnus, spectrum

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

Kim, Y., E-mail: yhkim@lanl.gov; Herrmann, H. W.; McEvoy, A. M.

2016-11-15

An aerogel Cherenkov detector is proposed to measure the X-ray energy spectrum from the Cygnus—intense flash X-ray source operated at the Nevada National Security Site. An array of aerogels set at a variety of thresholds between 1 and 3 MeV will be adequate to map out the bremsstrahlung X-ray production of the Cygnus, where the maximum energy of the spectrum is normally around 2.5 MeV. In addition to the Cherenkov radiation from aerogels, one possible competing light-production mechanism is optical transition radiation (OTR), which may be significant in aerogels due to the large number of transitions from SiO{sub 2} clustersmore » to vacuum voids. To examine whether OTR is a problem, four aerogel samples were tested using a mono-energetic electron beam (varied in the range of 1–3 MeV) at NSTec Los Alamos Operations. It was demonstrated that aerogels can be used as a Cherenkov medium, where the rate of the light production is about two orders magnitude higher when the electron beam energy is above threshold.« less

Alternative Explanations for Extreme Supersolar Iron Abundances Inferred from the Energy Spectrum of Cygnus X-1

NASA Astrophysics Data System (ADS)

Tomsick, John A.; Parker, Michael L.; García, Javier A.; Yamaoka, Kazutaka; Barret, Didier; Chiu, Jeng-Lun; Clavel, Maïca; Fabian, Andrew; Fürst, Felix; Gandhi, Poshak; Grinberg, Victoria; Miller, Jon M.; Pottschmidt, Katja; Walton, Dominic J.

2018-03-01

Here we study a 1–200 keV energy spectrum of the black hole binary Cygnus X-1 taken with NuSTAR and Suzaku. This is the first report of a NuSTAR observation of Cyg X-1 in the intermediate state, and the observation was taken during the part of the binary orbit where absorption due to the companion’s stellar wind is minimal. The spectrum includes a multi-temperature thermal disk component, a cutoff power-law component, and relativistic and nonrelativistic reflection components. Our initial fits with publicly available constant density reflection models (relxill and reflionx) lead to extremely high iron abundances (>9.96 and {10.6}-0.9+1.6 times solar, respectively). Although supersolar iron abundances have been reported previously for Cyg X-1, our measurements are much higher and such variability is almost certainly unphysical. Using a new version of reflionx that we modified to make the electron density a free parameter, we obtain better fits to the spectrum even with solar iron abundances. We report on how the higher density ({n}e=({3.98}-0.25+0.12)× {10}20 cm‑3) impacts other parameters such as the inner radius and inclination of the disk.

Gamma-ray monitoring of AGN and galactic black hole candidates by the Gamma-Ray Observatory

NASA Technical Reports Server (NTRS)

Wheaton, Wm. A.; Ling, James C.; Skelton, R. T.; Harmon, Alan; Fishman, Gerald J.; Meegan, Charles A.; Paciesas, William S.; Rubin, Brad; Wilson, Robert B.; Gruber, Duane E.

1992-01-01

The Burst and Transient Spectroscopy Experiment (BATSE) on the Compton Gamma-Ray Observatory has a powerful capability to provide nearly uninterrupted monitoring in the 25 keV-10 MeV range of both AGN and Galactic black hole candidates such as Cygnus X-1, using the occultation of cosmic sources by the Earth. Progress in background modeling indicates that the data accept region, or fit window tau, around the occultation step can be substantially increased over that conservatively assumed in earlier estimates of BATSE's Earth occultation sensitivity. We show samples of large-tau fits to background and source edges. As a result we expect to be able to perform long-term monitoring of Cygnus X-1 and many of the brighter AGN for the duration of the CGRO mission.

X-ray superbubbles

NASA Technical Reports Server (NTRS)

Cash, W.

1983-01-01

Four regions of the galaxy, the Cygnus Superbubble, the Eta Carina complex, the Orion/Eridanus complex, and the Gum Nebula, are discussed as examples of collective effects in the interstellar medium. All four regions share certain features, indicating a common structure. The selection effects which determine the observable X-ray properties of the superbubbles are discussed, and it is demonstrated that only a very few more in our Galaxy can be detected in X rays. X-ray observation of extragalactic superbubbles is shown to be possible but requires the capabilities of a large, high quality, AXAF class observatory.

Investigation relative to the Roentgen Satellite (ROSAT)

NASA Technical Reports Server (NTRS)

Elvis, Martin S.; Primini, Francis A.; Fabbiano, Guiseppina; Harris, Daniel E.; Jones-Foreman, Christine; Trinchieri, Ginevra; Golub, Leon; Bookbinder, Jay; Seward, Frederick D.; Zombeck, Martin V.

1994-01-01

Reports include: High Resolution Observations of the Central Region of M31; The X-ray Emission of Low-X-ray-Luminosity Early-Type Galaxies: Gas Versus Compact Sources; Interaction Between Cluster Gas and Radio Features of Cygnus A; Hot Gas and Dark Halos in Early-Type Galaxies; A Gravitational Lens in X-rays - 0957+461; How Massive are Early-Type Galaxies?; Three Crab-Like SNR in the Large Magellanic Cloud; and Soft X-ray Emission from Boundary Layers in Cataclysmic Variables. Papers submitted to the Astrophysical Journal are attached.

A cocoon of freshly accelerated cosmic rays detected by Fermi in the Cygnus superbubble.

PubMed

Ackermann, M; Ajello, M; Allafort, A; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Belfiore, A; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bottacini, E; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; de Angelis, A; de Palma, F; Dermer, C D; do Couto E Silva, E; Drell, P S; Dumora, D; Favuzzi, C; Fegan, S J; Focke, W B; Fortin, P; Fukazawa, Y; Fusco, P; Gargano, F; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Guillemot, L; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hayashi, K; Hays, E; Jóhannesson, G; Johnson, A S; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Latronico, L; Lee, S-H; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Martin, P; Mazziotta, M N; McEnery, J E; Mehault, J; Michelson, P F; Mitthumsiri, W; Mizuno, T; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Naumann-Godo, M; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Okumura, A; Orlando, E; Ormes, J F; Ozaki, M; Paneque, D; Parent, D; Pesce-Rollins, M; Pierbattista, M; Piron, F; Pohl, M; Prokhorov, D; Rainò, S; Rando, R; Razzano, M; Reposeur, T; Ritz, S; Parkinson, P M Saz; Sgrò, C; Siskind, E J; Smith, P D; Spinelli, P; Strong, A W; Takahashi, H; Tanaka, T; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Troja, E; Uchiyama, Y; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Yang, Z; Zimmer, S; Bontemps, S

2011-11-25

The origin of Galactic cosmic rays is a century-long puzzle. Indirect evidence points to their acceleration by supernova shockwaves, but we know little of their escape from the shock and their evolution through the turbulent medium surrounding massive stars. Gamma rays can probe their spreading through the ambient gas and radiation fields. The Fermi Large Area Telescope (LAT) has observed the star-forming region of Cygnus X. The 1- to 100-gigaelectronvolt images reveal a 50-parsec-wide cocoon of freshly accelerated cosmic rays that flood the cavities carved by the stellar winds and ionization fronts from young stellar clusters. It provides an example to study the youth of cosmic rays in a superbubble environment before they merge into the older Galactic population.

SOFT X-RAY SPECTROSCOPY OF THE CYGNUS LOOP SUPERNOVA REMNANT

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

Oakley, Phil; McEntaffer, Randall; Cash, Webster, E-mail: Oakley@mit.edu

2013-03-20

We present the results of a suborbital rocket flight whose scientific target was the Cygnus Loop Supernova Remnant. The payload consists of wire grid collimators, off-plane grating arrays, and gaseous electron multiplier (GEM) detectors. The system is designed for spectral measurements in the 17-107 A bandpass with a resolution up to {approx}60 ({lambda}/{Delta}{lambda}). The Extended X-ray Off-plane Spectrometer (EXOS) was launched on a Terrier-Black Brant rocket on 2009 November 13 from White Sands Missile Range and obtained 340 s of useable scientific data. The X-ray emission is dominated by O VII and O VIII, including the He-like O VII tripletmore » at {approx}22 A. Another emission feature at {approx}45 A is composed primarily of Si XI and Si XII. The best-fit model to this spectrum is an equilibrium plasma model at a temperature of log(T) = 6.4 (0.23 keV).« less

On the Nature of the Variability Power Decay toward Soft Spectral States in X-Ray Binaries: Case Study in Cygnus X-1

NASA Astrophysics Data System (ADS)

Titarchuk, Lev; Shaposhnikov, Nikolai

2008-05-01

A characteristic feature of the Fourier power density spectrum (PDS) observed from black hole X-ray binaries in low/hard and intermediate spectral states is a broadband-limited noise characterized by a constant below some frequency (a "break" frequency) and a power law above this frequency. It has been shown that the variability of this type can be produced by the inward diffusion of the local driving perturbations in a bounded configuration (accretion disk or corona). In the framework of this model, the perturbation diffusion time t0 is related to the phenomenological break frequency, while the PDS power-law slope above the "break" is determined by the viscosity distribution over the configuration. The perturbation diffusion scenario explains the decay of the power of X-ray variability observed in a number of compact sources (containing black holes and neutron stars) during an evolution of these sources from low/hard to high/soft states. We compare the model predictions with the subset of data from Cyg X-1 collected by the Rossi X-Ray Time Explorer (RXTE). Our extensive analysis of the Cyg X-1 PDSs demonstrates that the observed integrated power Px decreases approximately as the square root of the characteristic frequency of the driving oscillations νdr. The RXTE observations of Cyg X-1 allow us to infer Pdr and t0 as a function of νdr. Using the inferred dependences of the integrated power of the driving oscillations Pdr and t0 on νdr we demonstrate that the power predicted by the model also decays as Px,diff propto ν-0.5dr, which is similar to the observed Px behavior. We also apply the basic parameters of observed PDSs, power-law indices, and low-frequency quasi-periodic oscillations to infer the Reynolds number (Re) from the observations using the method developed in our previous paper. Our analysis shows that Re increases from values of about 10 in low/hard state to about 70 during the high/soft state.

Gamma ray monitoring of a AGN and galactic black hole candidates by the Compton Gamma Ray Observatory

NASA Technical Reports Server (NTRS)

Skelton, R. T.; Ling, James C.; Wheaton, William A.; Harmon, Alan; Fishman, G. J.; Meegan, C. A.; Paciesas, William S.; Gruber, Duane E.; Rubin, Brad; Wilson, R. B.

1992-01-01

The Compton Gamma-Ray Observatory's Burst and Transient Source Experiment (BATSE) has a powerful capability to provide nearly uninterrupted monitoring in the 25 keV-10 MeV range of both active galactic nuclei (AGN) and galactic black hole candidates (GBHC) such as Cygnus X-1, using the occultation of cosmic sources by the Earth. Since the Crab is detected by the BATSE Large Area Detectors with roughly 25(sigma) significance in the 15-125 keV range in a single rise or set, a variation by a factor of two of a source having one-tenth the strength of Cygnus X-1 should be detectable within a day. Methods of modeling the background are discussed which will increase the accuracy, sensitivity, and reliability of the results beyond those obtainable from a linear background fit with a single rise or set discontinuity.

Gamma-ray Spectral Characteristics of Thermal and Non-thermal Emission from Three Black Holes

NASA Technical Reports Server (NTRS)

Ling, James C.; Wheaton, William A.

2004-01-01

Cygnus X-1 and the gamma-ray transients GROJ0422+32 and GROJ1719-24 displayed similar spectral properties when they underwent transitions between the high and low gamma-ray (30 keV to few MeV) intensity states. When these sources were in the high (gamma)-ray intensity state ((gamma)2, for Cygnus X-l), their spectra featured two components: a Comptonized shape below 200-300 keV with a soft power-law tail (photon index >= 3) that extended to 1 MeV or beyond. When the sources were in the low-intensity state ((gamma)0, for Cygnus X-l), the Comptonized spectral shape below 200 keV typically vanished and the entire spectrum from 30 keV to 1 MeV can be characterized by a single power law with a relatively harder photon index 2-2.7. Consequently the high- and low-intensity gamma-ray spectra intersect, generally in the 400 KeV - 1 MeV range, in contrast to the spectral pivoting seen previously at lower (10 keV) energies. The presence of the power-law component in both the high- and low-intensity gammaray spectra strongly suggests that the non-thermal process is likely to be at work in both the high and the low-intensity situations. We have suggested a possible scenario (Ling & Wheaton, 2003), by combining the ADAF model of Esin et al. (1998) with a separate jet region that produces the non-thermal gamma-ray emission, and which explains the state transitions. Such a scenario will be discussed in the context of the observational evidence, summarized above, from the database produced by EBOP, JPL's BATSE earth occultation analysis system.

Gamma-Ray Spectra and Variability of Cygnus Z-1 Observed by BATSE

NASA Technical Reports Server (NTRS)

Ling, J. C.; Wheaton, William A.; Wallyn, P.; Mahoney, W. .; Paciesas, W. S.; Harmon, B. A.; Fishman, G. J.; Zhang, S. N.; Hua, X. M.

1998-01-01

We present new BATSE earth occultation observations of the 25 keV-1.8 MeV spectrum and variability of Cygnus X-1 made between August 1993 and May 1994. We observed that the normal soft gamma ray spectrum (gamma2) of Cygnus X-1 has two components: a Comptonized part seen below 300 keV, and a high-energy tail in the 0.3 - 2 MeV range. We interpret it in terms of a two-layer region, consisting of a high-energy core (with an equivalent electron temperature of approximately 210-250 keV) near the event horizon, embedded in an about 50 keV corona. In this scenario, the observed 25-300 keV photons were produced by Compton scattering of soft photons (about 0.5 keV) by the hot electrons in the outer corona. These same hard x rays were further up-scattered by a population of energetic electrons in the inner core, producing the spectral tail above 300 keV. Cygnus X-1 went through an extended sequence of transitions between August 1993 and May 1994, when the 45-140 keV flux first decreased steadily from approximately gamma2 to roughly one-quarter of its intensity over a period of about 140 days. The flux remained at this low level for about 40 days before returning, swiftly (approximately 20 days) to approximately the initial gamma2 level. During the transition, the spectrum evolved to a shape consistent with either a power law with photon index of about 2.6 or a single temperature Compton model with electron temperature kT = 110 +/- 11 keV, and optical depth t = 0.40 +/- 0.06, and then returned essentially to the original gamma2 spectrum at the end of the active period. The overall cooling of the system during the low flux period may be due to an increase in the soft photon population which effectively quenched the hot electrons in these regions through Compton scattering.

Catching Up on State Transitions in Cygnus X-1

NASA Technical Reports Server (NTRS)

Boeck, Moritz; Hanke, Manfred; Wilms, Joern; Pirner, Stefan; Grinberg, Victoria; Markoff, Sera; Pottschmidt, Katja; Nowak, Michael A.; Pooley, Guy

2008-01-01

In 2005 February we observed Cygnus X-1 over a period of 10 days quasi-continuously with the Rossi X-ray Timing Explorer and the Ryle telescope. We present the results of the spectral and timing analysis on a timescale of 90 min and show that the behavior of Cyg X-1 is similar to that found during our years long monitoring campaign. As a highlight we present evidence for a full transition from the hard to the soft state that happened during less than three hours. The observation provided a more complete picture of a state transition than before, especially concerning the evolution of the time lags, due to unique transition coverage and analysis with high time resolution.

A ROSAT Survey of Contact Binary Stars

NASA Astrophysics Data System (ADS)

Geske, M. T.; Gettel, S. J.; McKay, T. A.

2006-01-01

Contact binary stars are common variable stars that are all believed to emit relatively large fluxes of X-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope with X-ray data from the ROSAT All Sky Survey (RASS) to estimate the X-ray volume emissivity of contact binary stars in the Galaxy. We obtained X-ray fluxes for 140 contact binaries from the RASS, as well as two additional stars observed by the XMM-Newton observatory. From these data we confirm the emission of X-rays from all contact binary systems, with typical luminosities of approximately 1.0×1030 ergs s-1. Combining calculated luminosities with an estimated contact binary space density, we find that contact binaries do not have strong enough X-ray emission to account for a significant portion of the Galactic X-ray background.

A deep survey of the X-ray binary populations in the SMC

NASA Astrophysics Data System (ADS)

Zezas, A.; Antoniou, V.

2017-10-01

The Small Magellanic Cloud (SMC) has been the subject of systematic X-ray surveys over the past two decades, which have yielded a rich population of high-mass X-ray binaries consisting predominantly of Be/X-ray binaries. We present results from our deep Chandra survey of the SMC which targeted regions with stellar populations ranging between ˜10-100 Myr. X-ray luminosities down to ˜3×10^{32} erg/s were reached, probing all active accreting binaries and extending well into the regime of quiescent accreting binaries and X-ray emitting normal stars. We measure the dependence of the formation efficiency of X-ray binaries on age. We also detect pulsations from 19 known and one new candidate pulsar. We construct the X-ray luminosity function in different regions of the SMC, which shows clear evidence for the propeller effect the centrifugal inhibition of accretion due to the interaction of the accretion flow with the pulsar's magnetic field. Finally we compare these results with predictions for the formation efficiency of X-ray binaries as a function of age from X-ray binary population synthesis models.

Image of the Black Hole, Cygnus X-1, Taken by the High Energy Astronomy Observatory (HEAO)-2

NASA Technical Reports Server (NTRS)

1980-01-01

This image of the suspected Black Hole, Cygnus X-1, was the first object seen by the High Energy Astronomy Observatory (HEAO)-2/Einstein Observatory. According to the theories to date, one concept of a black hole is a star, perhaps 10 times more massive than the Sun, that has entered the last stages of stelar evolution. There is an explosion triggered by nuclear reactions after which the star's outer shell of lighter elements and gases is blown away into space and the heavier elements in the stellar core begin to collapse upon themselves. Once this collapse begins, the inexorable force of gravity continues to compact the material until it becomes so dense it is squeezed into a mere point and nothing can escape from its extreme gravitational field, not even light. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy.

Laboratory Measurements of the K-Shell Transition Energies in L-Shell Ions of Si and S

NASA Technical Reports Server (NTRS)

Hell, N.; Brown, G.V.; Wilms, J.; Grinberg, V.; Clementson, J.; Liedahl, D.; Porter, F. S.; Kelley, R. L.; Kilbourne, C. A.; Beiersrdorfer, P.

2016-01-01

We have measured the energies of the strongest 1s-2 l (azimuthal quantum number) (l = s, p (s, p are angular momentum states)) transitions in He- through Ne-like silicon and sulfur ions to an accuracy of less than 1 electronvolt using the Lawrence Livermore National Laboratory's electron beam ion traps, EBIT-I and SuperEBIT, and the NASA/GSFC EBIT Calorimeter Spectrometer (ECS). We identify and measure the energies of 18 and 21 X-ray features from silicon and sulfur, respectively. The results are compared to new Flexible Atomic Code calculations and to semi-relativistic Hartree-Fock calculations by Palmeri et al. (2008). These results will be especially useful for wind diagnostics in high-mass X-ray binaries, such as Vela X-1 and Cygnus X-1, where high-resolution spectral measurements using Chandra's high-energy transmission grating has made it possible to measure Doppler shifts of 100 kilometers per second. The accuracy of our measurements is consistent with that needed to analyze Chandra observations, exceeding Chandra's 100 kilometers per second limit. Hence, the results presented here not only provide benchmarks for theory, but also accurate rest energies that can be used to determine the bulk motion of material in astrophysical sources. We show the usefulness of our results by applying them to redetermine Doppler shifts from Chandra observations of Vela X-1.

Formation and Evolution of X-ray Binaries

NASA Astrophysics Data System (ADS)

Fragkos, Anastasios

X-ray binaries - mass-transferring binary stellar systems with compact object accretors - are unique astrophysical laboratories. They carry information about many complex physical processes such as star formation, compact object formation, and evolution of interacting binaries. My thesis work involves the study of the formation and evolution of Galactic and extra-galacticX-ray binaries using both detailed and realistic simulation tools, and population synthesis techniques. I applied an innovative analysis method that allows the reconstruction of the full evolutionary history of known black hole X-ray binaries back to the time of compact object formation. This analysis takes into account all the available observationally determined properties of a system, and models in detail four of its evolutionary evolutionary phases: mass transfer through the ongoing X-ray phase, tidal evolution before the onset of Roche-lobe overflow, motion through the Galactic potential after the formation of the black hole, and binary orbital dynamics at the time of core collapse. Motivated by deep extra-galactic Chandra survey observations, I worked on population synthesis models of low-mass X-ray binaries in the two elliptical galaxies NGC3379 and NGC4278. These simulations were targeted at understanding the origin of the shape and normalization of the observed X-ray luminosity functions. In a follow up study, I proposed a physically motivated prescription for the modeling of transient neutron star low-mass X-ray binary properties, such as duty cycle, outburst duration and recurrence time. This prescription enabled the direct comparison of transient low-mass X-ray binary population synthesis models to the Chandra X-ray survey of the two ellipticals NGC3379 and NGC4278. Finally, I worked on population synthesismodels of black holeX-ray binaries in the MilkyWay. This work was motivated by recent developments in observational techniques for the measurement of black hole spin magnitudes in black hole X-ray binaries. The accuracy of these techniques depend on misalignment of the black hole spin with respect to the orbital angular momentum. In black hole X-ray binaries, this misalignment can occur during the supernova explosion that forms the compact object. In this study, I presented population synthesis models of Galactic black hole X-ray binaries, and examined the distribution of misalignment angles, and its dependence on the model parameters.

Observations of 12-200 keV X-rays from GX 339-4

NASA Technical Reports Server (NTRS)

Nolan, P. L.; Gruber, D. E.; Knight, F. K.; Matteson, J. L.; Peterson, L. E.; Levine, A. M.; Lewin, W. H. G.; Primini, F. A.

1982-01-01

X-ray spectra of GX 339-4 measured on three occasions in 1977 and 1978 are presented. These are the first reported measurements above 10 keV. The spectra can be described as the superposition of a soft component, which is dominant below about 20 keV, and a hard component at higher energy. Simultaneous measurements at lower energy show that the soft component vanished during the observation in early 1978. The behavior of these two components is similar to that of the spectrum of Cygnus X-1; this reinforces the previously noted resemblance in rapid X-ray variability.

Searches for Periodic Neutrino Emission from Binary Systems with 22 and 40 Strings of IceCube

NASA Technical Reports Server (NTRS)

Abassi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.;

RXTE Observations of Cygnus X-3

NASA Technical Reports Server (NTRS)

McCollough, M. L.; Robinson, C. R.; Zhang, S. N.; Harmon, B. A.; Paciesas, W. S.; Dieters, S. W.; Hjellming, R. M.; Rupen, M.; Mioduszewski, A. J.; Waltman, E. B.

1997-01-01

In the period between May 1997 and August 1997 a series of pointed RXTE observations were made of Cyg X-3. During this period Cyg X-3 made a transition from a quiescent radio state to a flare state (including a major flare) and then returned to a quiescent radio state. Analyses of the observations are made in the context of concurrent observations in the hard X-ray (CGRO/BATSE), soft X-ray (RXTE/ASM) and the radio (Green Bank Interferometer, Ryle Telescope, and RATAN-600). Preliminary analyses of the observations are presented.

HERO: Program Status and Fist Images from a Balloon-Borne Focusing Hard-X-ray Telescope

NASA Technical Reports Server (NTRS)

Ramsey, B. D.; Alexander, C. D.; Apple, J. A.; Benson, C. M.; Dietz, K. L.; Elsner, R. F.; Engelhaupt. D. E.; Ghosh, K. K.; Kolodziejczak, J. J.; ODell, S. L.;

Discovery of a Pulsar Wind Nebula Candidate in the Cygnus Loop

NASA Technical Reports Server (NTRS)

Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Petre, Robert; Yamada, Shin'ya; Tamagawa, Toru

2012-01-01

We report on a discovery of a diffuse nebula containing a point-like source in the southern blowout region of the Cygnus Loop supernova remnant, based on Suzaku and XMM-Newton observations. The X-ray spectra from the nebula and the point-like source are well represented by an absorbed power-law model with photon indices of 2.2+/-0.1 and 1.6+/-0.2, respectively. The photon indices as well as the flux ratio of F(sub nebula)/F(sub point-like) approx. 4 lead us to propose that the system is a pulsar wind nebula, although pulsations have not yet been detected. If we attribute its origin to the Cygnus Loop supernova, then the 0.5-8 keV luminosity of the nebula is computed to be 2.1x10(exp 31)(d/540pc)(exp 2)ergss/2, where d is the distance to the Loop. This implies a spin-down loss-energy E approx. 2.6x10(exp 35)(d/540pc)(exp 2)ergs/s. The location of the neutron star candidate, approx.2deg away from the geometric center of the Loop, implies a high transverse velocity of approx.1850(theta/2deg)(d/540pc)(t/10kyr)/k/s assuming the currently accepted age of the Cygnus Loop.

Constraining Accreting Binary Populations in Normal Galaxies

NASA Astrophysics Data System (ADS)

Lehmer, Bret; Hornschemeier, A.; Basu-Zych, A.; Fragos, T.; Jenkins, L.; Kalogera, V.; Ptak, A.; Tzanavaris, P.; Zezas, A.

2011-01-01

X-ray emission from accreting binary systems (X-ray binaries) uniquely probe the binary phase of stellar evolution and the formation of compact objects such as neutron stars and black holes. A detailed understanding of X-ray binary systems is needed to provide physical insight into the formation and evolution of the stars involved, as well as the demographics of interesting binary remnants, such as millisecond pulsars and gravitational wave sources. Our program makes wide use of Chandra observations and complementary multiwavelength data sets (through, e.g., the Spitzer Infrared Nearby Galaxies Survey [SINGS] and the Great Observatories Origins Deep Survey [GOODS]), as well as super-computing facilities, to provide: (1) improved calibrations for correlations between X-ray binary emission and physical properties (e.g., star-formation rate and stellar mass) for galaxies in the local Universe; (2) new physical constraints on accreting binary processes (e.g., common-envelope phase and mass transfer) through the fitting of X-ray binary synthesis models to observed local galaxy X-ray binary luminosity functions; (3) observational and model constraints on the X-ray evolution of normal galaxies over the last 90% of cosmic history (since z 4) from the Chandra Deep Field surveys and accreting binary synthesis models; and (4) predictions for deeper observations from forthcoming generations of X-ray telesopes (e.g., IXO, WFXT, and Gen-X) to provide a science driver for these missions. In this talk, we highlight the details of our program and discuss recent results.

X-ray binaries

NASA Technical Reports Server (NTRS)

1976-01-01

Satellite X-ray experiments and ground-based programs aimed at observation of X-ray binaries are discussed. Experiments aboard OAO-3, OSO-8, Ariel 5, Uhuru, and Skylab are included along with rocket and ground-based observations. Major topics covered are: Her X-1, Cyg X-3, Cen X-3, Cyg X-1, the transient source A0620-00, other possible X-ray binaries, and plans and prospects for future observational programs.

Changes in the Long-Term Intensity Variations in Cygnus X-2 and LMC X-3

NASA Astrophysics Data System (ADS)

Paul, B.; Kitamoto, S.; Makino, F.

2000-01-01

We report the detection of changes in the long-term intensity variations in two X-ray binaries, Cyg X-2 and LMC X-3. In this work, we have used the long-term light curves obtained with the All-Sky Monitors (ASMs) of the Rossi X-Ray Timing Explorer (RXTE), Ginga, Ariel 5, and Vela 5B and the scanning modulation collimator of HEAO 1. It is found that in the light curves of both the sources, obtained with these instruments at various times over the last 30 years, more than one periodic or quasi-periodic component is always present. The multiple prominent peaks in the periodograms have frequencies unrelated to each other. In Cyg X-2, RXTE-ASM data show strong peaks at 40.4 and 68.8 days, and Ginga-ASM data show strong peaks at 53.7 and 61.3 days. Multiple peaks are also observed in LMC X-3. The various strong peaks in the periodograms of LMC X-3 appear at 104, 169, and 216 days (observed with RXTE-ASM) and 105, 214, and 328 days (observed with Ginga-ASM). The present results, when compared with the earlier observations of periodicities in these two systems, demonstrate the absence of any stable long period. The 78 day periodicity detected earlier in Cyg X-2 was probably due to the short time base in the RXTE data that were used, and the periodicity of 198 days in LMC X-3 was due to a relatively short duration of observation with HEAO 1.

An X-ray look at the first head-trail nebula in an X-ray binary

NASA Astrophysics Data System (ADS)

Soleri, Paolo

2011-09-01

Head-tail trails are a common feature in active galactic nuclei and pulsar bow-shocks. Heinz et al. (2008) suggested that also X-ray binaries, being jet sources moving with high velocities in dense media, can leave trails of highly ionized plasma that should be detectable at radio frequencies. During bservations of faint-persistent X-ray binaries, we discovered an optical nebula around the X-ray binary SAX J1712.6-3739, consisting of a bow-shock ring-like nebula in front of the binary and two trails originating close to it. This is the first detection of such structure in a X-ray binary and it opens a new sub-field in the study of these objects. Observations with XMM-Newton and Chandra are now needed to investigate the properties of the surrounding nebula.

An X-ray look at the first head-trail nebula in an X-ray binary

NASA Astrophysics Data System (ADS)

Soleri, Paolo

2010-10-01

Head-tail trails are a common feature in active galactic nuclei and pulsar bow-shocks. Heinz et al. (2008) suggested that also X-ray binaries, being jet sources moving with high velocities in dense media, can leave trails of highly ionized plasma that should be detectable at radio frequencies. During observations of faint-persistent X-ray binaries, we discovered an optical nebula around the X-ray binary SAX J1712.6-3739, consisting of a bow-shock ring-like nebula ``in front'' of the binary and two trails originating close to it. This is the first detection of such structure in a X-ray binary and it opens a new sub-field in the study of these objects. Observations with XMM-Newton and Chandra are now needed to investigate the properties of the surrounding nebula.

Origin of Dips in 4U1915-05

NASA Technical Reports Server (NTRS)

Grindlay, Jonathan E.

2003-01-01

This grant supported our participation in a proposal submitted by Didier Barret to conduct a study of the dipping LMXB 4U1915-05. In this Final Report, we summarize the Scientific Objectives of this investigation and the results achieved. Data analysis is still in progress and publication of results will be forthcoming.Our objectives in this work have been to study: 1. Spectra of dips in 4 Ul916-05: This low mass x-ray binary (LMXB) is a 50min binary system and the first to show x-ray dip behaviour. Our XMM observation was proposed to study the x-ray spectra of the dips to better constrain their physical properties. Of primary interest is the variation of the absorbing column density as a function of flux in the dip. We wish to isolate the absorption from Compton scattering components in the dip spectra, and to use the large throughput of XMM to better constrain short timescale variations of the spectrum in the dips. 2. Period of the dips and long-term ephemeris: We also seek to improve upon the long- term ephemeris of the dips by combining these more recent XMM data with earlier RXTE data to update the ephemeris for dips and the determination of the dip period to further test whether the dip period represents the true binary period of this LMXB. We shall extend the ephemeris published by Chou, Grindlay and Bloser 2001, ApJ, 549, 1135) to test the assertion of Retter, Chou et a1 2002, MNRAS, 330, 37 that the dips are indeed the binary period and not a precession period. 1 3 Results Achieved The observations for this program were delayed, presumably for reasons related to the general difficulty of scheduling XMM targets in this region moderately close to the Cygnus region. 4'171916-05 was finally observed (2lksec) on April 24, 2002, but the data have not been delivered. A second observation was conducted on September 9, 2002 (18ksec) and the data are still being analyzed. 4 Papers Presented and Published A paper is in preparation for Astronomy and Astrophysics in which the full results of this investigation will be reported. 1. Barret, D. et a1 2003, Astron. and Astophys.,in press. 2

Optical/Infrared properties of Be stars in X-ray Binary systems

NASA Astrophysics Data System (ADS)

Naik, Sachindra

2018-04-01

Be/X-ray binaries, consisting of a Be star and a compact object (neutron star), form the largest subclass of High Mass X-ray Binaries. The orbit of the compact object around the Be star is wide and highly eccentric. Neutron stars in the Be/X-ray binaries are generally quiescent in X-ray emission. Transient X-ray outbursts seen in these objects are thought to be due to the interaction between the compact object and the circumstellar disk of the Be star at the periastron passage. Optical/infrared observations of the companion Be star during these outbursts show that the increase in the X-ray intensity of the neutron star is coupled with the decrease in the optical/infrared flux of the companion star. Apart from the change in optical/infrared flux, dramatic changes in the Be star emission line profiles are also seen during X-ray outbursts. Observational evidences of changes in the emission line profiles and optical/infrared continuum flux along with associated X-ray outbursts from the neutron stars in several Be/X-ray binaries are presented in this paper.

Resolving the Cygnus X-3 iron K line

NASA Technical Reports Server (NTRS)

Kitamoto, Shunji; Kawashima, Kenji; Negoro, Hitoshi; Miyamoto, Sigenori; White, N. E.; Nagase, Fumiaki

1994-01-01

An Advanced Satellite for Cosmology and Astrophysics (ASCA) observation of Cygnus X-3 on 1993 June 11, in its X-ray high intensity state, has for the first time resolved the broad iron K line emission into three components: a He-like line at 6.67 +/- 0.01 keV, a H-like line at 6.96 +/- 0.02 keV, and a neutral line at 6.37 +/- 0.03 keV. The line intensities of the 6.67 keV and 6.96 keV lines are modulated with the 4.8 hr orbital period and are maximum when the continuum intensity is minimum. There is a sharp minimum of the line intensity on the rising phase of the continuum intensity. An iron absorption edge is observed at 7.19 +/- 0.02 keV. The optical depth of the absorption edge varies from 0.3 to 0.5 and is in anti-phase with the overall X-ray continuum modulation. The observed complexity of the iron K line region is greater than that had been assumed in previous spectral modeling based on observations with lower resolution detectors.

The iron complex in high mass X-ray binaries

NASA Astrophysics Data System (ADS)

Giménez-García, A.; Torrejón, J. M.; Martínez-Núñez, S.; Rodes-Rocas, J. J.; Bernabéu, G.

2013-05-01

An X-ray binary system consists of a compact object (a white dwarf, a neutron star or a black hole) accreting material from an optical companion star. The spectral type of the optical component strongly affects the mass transfer to the compact object. This is the reason why X-ray binary systems are usually divided in High Mass X-ray Binaries (companion O or B type, denoted HMXB) and Low Mass X-ray Binaries (companion type A or later). The HMXB are divided depending on the partner's luminosity class in two main groups: the Supergiant X-ray Binaries (SGXB) and Be X-ray Binaries (BeXB). We introduce the spectral characterization of a sample of 9 High Mass X-ray Binaries in the iron complex (˜ 6-7 keV). This spectral range is a fundamental tool in the study of the surrounding material of these systems. The sources have been divided into three main groups according to their current standard classification: SGXB, BeXB and γ Cassiopeae-like. The purpose of this work is to look for qualitative patterns in the iron complex, around 6-7 keV, in order to discern between current different classes that make up the group of HMXB. We find significant spectral patterns for each of the sets, reflecting differences in accretion physics thereof.

Discovery of a 7 mHz X-Ray Quasi-Periodic Oscillation from the Most Massive Stellar-Mass Black Hole IC 10 X-1

NASA Technical Reports Server (NTRS)

Pasham, Dheeraj R.; Strohmayer, Tod E.; Mushotzky, Richard F.

2013-01-01

We report the discovery with XMM-Newton of an approx.. = 7 mHz X-ray (0.3-10.0 keV) quasi-periodic oscillation (QPO) from the eclipsing, high-inclination black hole binary IC 10 X-1. The QPO is significant at >4.33 sigma confidence level and has a fractional amplitude (% rms) and a quality factor, Q is identical with nu/delta nu, of approx. = 11 and 4, respectively. The overall X-ray (0.3-10.0 keV) power spectrum in the frequency range 0.0001-0.1 Hz can be described by a power-law with an index of approx. = -2, and a QPO at 7 mHz. At frequencies approx. > 0.02 Hz there is no evidence for significant variability. The fractional amplitude (rms) of the QPO is roughly energy-independent in the energy range of 0.3-1.5 keV. Above 1.5 keV the low signal-to-noise ratio of the data does not allow us to detect the QPO. By directly comparing these properties with the wide range of QPOs currently known from accreting black hole and neutron stars, we suggest that the 7 mHz QPO of IC 10 X-1 may be linked to one of the following three categories of QPOs: (1) the "heartbeat" mHz QPOs of the black hole sources GRS 1915+105 and IGR J17091-3624, or (2) the 0.6-2.4 Hz "dipper QPOs" of high-inclination neutron star systems, or (3) the mHz QPOs of Cygnus X-3.

Classification of X-ray sources in the direction of M31

NASA Astrophysics Data System (ADS)

Vasilopoulos, G.; Hatzidimitriou, D.; Pietsch, W.

2012-01-01

M31 is our nearest spiral galaxy, at a distance of 780 kpc. Identification of X-ray sources in nearby galaxies is important for interpreting the properties of more distant ones, mainly because we can classify nearby sources using both X-ray and optical data, while more distant ones via X-rays alone. The XMM-Newton Large Project for M31 has produced an abundant sample of about 1900 X-ray sources in the direction of M31. Most of them remain elusive, giving us little signs of their origin. Our goal is to classify these sources using criteria based on properties of already identified ones. In particular we construct candidate lists of high mass X-ray binaries, low mass X-ray binaries, X-ray binaries correlated with globular clusters and AGN based on their X-ray emission and the properties of their optical counterparts, if any. Our main methodology consists of identifying particular loci of X-ray sources on X-ray hardness ratio diagrams and the color magnitude diagrams of their optical counterparts. Finally, we examined the X-ray luminosity function of the X-ray binaries populations.

X-Ray Binary Populations in a Cosmological Context, Including NuSTAR Predictions

NASA Technical Reports Server (NTRS)

Cardiff, Ann Hornschemeier

2011-01-01

The new ultradeep 4 Ms Chandra Deep Field South has afforded the deepest view ever of X-ray binary populations. We report on the latest results on both LMXB and HMXB evolution out to redshifts of approximately four, including comparison with the latest theoretical models, using this deepest-ever view of the X-ray universe with Chandra. The upcoming NuSTAR mission will open up X-ray binary populations in the hard X-ray band, similar to the pioneering work of Fabbiano et al. in the Einstein era. We report on plans to study both Local Group and starburst galaxies as well as the implications those observations may have for X-ray binary populations in galaxies contributing to the Cosmic X-ray Background.

Laboratory measurements of the K-shell transition energies in L-shell ions of Si and S [Energy measurements of K-shell transitions in L-shell ions of Si and S

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

Hell, Natalie; Brown, G. V.; Wilms, J.

We have measured the energies of the strongest 1s–2more » $${\\ell }\\ ({\\ell }={\\rm{s}},{\\rm{p}})$$ transitions in He- through Ne-like silicon and sulfur ions to an accuracy of $$\\lt 1\\,\\mathrm{eV}$$ using the Lawrence Livermore National Laboratory's electron beam ion traps, EBIT-I and SuperEBIT, and the NASA/GSFC EBIT Calorimeter Spectrometer (ECS). We identify and measure the energies of 18 and 21 X-ray features from silicon and sulfur, respectively. The results are compared to new Flexible Atomic Code calculations and to semi-relativistic Hartree–Fock calculations by Palmeri et al. (2008). These results will be especially useful for wind diagnostics in high-mass X-ray binaries, such as Vela X-1 and Cygnus X-1, where high-resolution spectral measurements using Chandra's high-energy transmission grating has made it possible to measure Doppler shifts of $$100\\,\\mathrm{km}\\,{{\\rm{s}}}^{-1}$$. The accuracy of our measurements is consistent with that needed to analyze Chandra observations, exceeding Chandra's $$100\\,\\mathrm{km}\\,{{\\rm{s}}}^{-1}$$ limit. Hence, the results presented here not only provide benchmarks for theory, but also accurate rest energies that can be used to determine the bulk motion of material in astrophysical sources. Finally, we show the usefulness of our results by applying them to redetermine Doppler shifts from Chandra observations of Vela X-1.« less

Laboratory measurements of the K-shell transition energies in L-shell ions of Si and S [Energy measurements of K-shell transitions in L-shell ions of Si and S

DOE PAGES

Hell, Natalie; Brown, G. V.; Wilms, J.; ...

2016-10-04

We have measured the energies of the strongest 1s–2more » $${\\ell }\\ ({\\ell }={\\rm{s}},{\\rm{p}})$$ transitions in He- through Ne-like silicon and sulfur ions to an accuracy of $$\\lt 1\\,\\mathrm{eV}$$ using the Lawrence Livermore National Laboratory's electron beam ion traps, EBIT-I and SuperEBIT, and the NASA/GSFC EBIT Calorimeter Spectrometer (ECS). We identify and measure the energies of 18 and 21 X-ray features from silicon and sulfur, respectively. The results are compared to new Flexible Atomic Code calculations and to semi-relativistic Hartree–Fock calculations by Palmeri et al. (2008). These results will be especially useful for wind diagnostics in high-mass X-ray binaries, such as Vela X-1 and Cygnus X-1, where high-resolution spectral measurements using Chandra's high-energy transmission grating has made it possible to measure Doppler shifts of $$100\\,\\mathrm{km}\\,{{\\rm{s}}}^{-1}$$. The accuracy of our measurements is consistent with that needed to analyze Chandra observations, exceeding Chandra's $$100\\,\\mathrm{km}\\,{{\\rm{s}}}^{-1}$$ limit. Hence, the results presented here not only provide benchmarks for theory, but also accurate rest energies that can be used to determine the bulk motion of material in astrophysical sources. Finally, we show the usefulness of our results by applying them to redetermine Doppler shifts from Chandra observations of Vela X-1.« less

Application of cosmic-ray shock theories to the Cygnus Loop - an alternative model

NASA Astrophysics Data System (ADS)

Boulares, Ahmed; Cox, Donald P.

1988-10-01

Steady state cosmic-ray shock models are investigated in light of observations of the Cygnus Loop supernova remnant. In this work the authors find that the model of Völk, Drury, and McKenzie, in which the plasma waves are generated by the streaming instability of the cosmic rays and are dissipated into the gas, can be made consistent with some observed characteristics of Cygnus Loop shocks. The waves heat the gas substantially in the cosmic-ray precursor, in addition to the usual heating in the (possibly weak) gas shock. The model is used to deduce upstream densities and shock velocities using known quantities for Cygnus Loop shocks. Compared to the usual pure gas shock interpretation, it is found that lower densities and approximately 3 times higher velocities are required. If the cosmic-ray models are valid, this could significantly alter our understanding of the Cygnus Loop's distance and age and of the energy released during the initial explosion.

Chandra reveals a black hole X-ray binary within the ultraluminous supernova remnant MF 16

NASA Astrophysics Data System (ADS)

Roberts, T. P.; Colbert, E. J. M.

2003-06-01

We present evidence, based on Chandra ACIS-S observations of the nearby spiral galaxy NGC 6946, that the extraordinary X-ray luminosity of the MF 16 supernova remnant actually arises in a black hole X-ray binary. This conclusion is drawn from the point-like nature of the X-ray source, its X-ray spectrum closely resembling the spectrum of other ultraluminous X-ray sources thought to be black hole X-ray binary systems, and the detection of rapid hard X-ray variability from the source. We briefly discuss the nature of the hard X-ray variability, and the origin of the extreme radio and optical luminosity of MF 16 in light of this identification.

Be/X-ray Binary Science for Future X-ray Timing Missions

NASA Technical Reports Server (NTRS)

Wilson-Hodge, Colleen A.

2011-01-01

For future missions, the Be/X-ray binary community needs to clearly define our science priorities for the future to advocate for their inclusion in future missions. In this talk, I will describe current designs for two potential future missions and Be X-ray binary science enabled by these designs. The Large Observatory For X-ray Timing (LOFT) is an X-ray timing mission selected in February 2011 for the assessment phase from the 2010 ESA M3 call for proposals. The Advanced X-ray Timing ARray (AXTAR) is a NASA explorer concept X-ray timing mission. This talk is intended to initiate discussions of our science priorities for the future.

Optical and X-ray studies of Compact X-ray Binaries in NGC 5904

NASA Astrophysics Data System (ADS)

Bhalotia, Vanshree; Beck-Winchatz, Bernhard

2018-06-01

Due to their high stellar densities, globular cluster systems trigger various dynamical interactions, such as the formation of compact X-ray binaries. Stellar collisional frequencies have been correlated to the number of X-ray sources detected in various clusters and we hope to measure this correlation for NGC 5904. Optical fluxes of sources from archival HST images of NGC 5904 have been measured using a DOLPHOT PSF photometry in the UV, optical and near-infrared. We developed a data analysis pipeline to process the fluxes of tens of thousands of objects using awk, python and DOLPHOT. We plot color magnitude diagrams in different photometric bands in order to identify outliers that could be X-ray binaries, since they do not evolve the same way as singular stars. Aligning previously measured astrometric data for X-ray sources in NGC 5904 from Chandra with archival astrometric data from HST will filter out the outlier objects that are not X-ray producing, and provide a sample of compact binary systems that are responsible for X-ray emission in NGC 5904. Furthermore, previously measured X-ray fluxes of NGC 5904 from Chandra have also been used to measure the X-ray to optical flux ratio and identify the types of compact X-ray binaries responsible for the X-ray emissions in NGC 5904. We gratefully acknowledge the support from the Illinois Space Grant Consortium.

Identification of high-mass X-ray binaries selected from XMM-Newton observations of the LMC★

NASA Astrophysics Data System (ADS)

van Jaarsveld, N.; Buckley, D. A. H.; McBride, V. A.; Haberl, F.; Vasilopoulos, G.; Maitra, C.; Udalski, A.; Miszalski, B.

2018-04-01

The Large Magellanic Cloud (LMC) currently hosts around 23 high-mass X-ray binaries (HMXBs) of which most are Be/X-ray binaries. The LMC XMM-Newton survey provided follow-up observations of previously known X-ray sources that were likely HMXBs, as well as identifying new HMXB candidates. In total, 19 candidate HMXBs were selected based on their X-ray hardness ratios. In this paper we present red and blue optical spectroscopy, obtained with Southern African Large Telescope and the South African Astronomical Observatory 1.9-m telescope, plus a timing analysis of the long-term optical light curves from OGLE to confirm the nature of these candidates. We find that nine of the candidates are new Be/X-ray binaries, substantially increasing the LMC Be/X-ray binary population. Furthermore, we present the optical properties of these new systems, both individually and as a group of all the BeXBs identified by the XMM-Newton survey of the LMC.

A SEARCH FOR X-RAY EMISSION FROM COLLIDING MAGNETOSPHERES IN YOUNG ECCENTRIC STELLAR BINARIES

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

Getman, Konstantin V.; Broos, Patrick S.; Kóspál, Ágnes

Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged samplemore » of all four binaries the current X-ray data show an increasing average X-ray flux near periastron (at a ∼2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries cannot be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.« less

A Search For X-Ray Emission From Colliding Magnetospheres In Young Eccentric Stellar Binaries

NASA Astrophysics Data System (ADS)

Getman, Konstantin V.; Broos, Patrick S.; Kóspál, Ágnes; Salter, Demerese M.; Garmire, Gordon P.

2016-12-01

Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged sample of all four binaries the current X-ray data show an increasing average X-ray flux near periastron (at a ˜2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries cannot be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.

The Extreme Spin of the Black Hole Cygnus X-1

NASA Technical Reports Server (NTRS)

Gou, Lijun; McClintock, Jeffrey E.; Reid, Mark J.; Orosz, Jerome A.; Steiner, James F.; Narayan, Ramesh; Xiang, Jingen; Remillard, Ronald A.; Arnaud, Keith A.; Davis, Shane W.

2011-01-01

Remarkably, an astronomical black hole is completely described by the two numbers that specify its mass and its spin. Knowledge of spin is crucial for understanding how, for example, black holes produce relativistic jets. Recently, it has become possible to measure the spins of black holes by focusing on the very inner region of an accreting disk of hot gas orbiting the black hole. According to General Relativity (GR), this disk is truncated at an inner radius 1 that depends only on the mass and spin of the black hole. We measure the radius of the inner edge of this disk by fitting its continuum X-ray spectrum to a fully relativistic model. Using our measurement of this radius, we deduce that the spin of Cygnus X-1 exceeds 97% of the maximum value allowed by GR.

X-ray spectrum of the entire Cygnus Loop.

NASA Technical Reports Server (NTRS)

Stevens, J. C.; Riegler, G. R.; Garmire, G. P.

1973-01-01

The spectrum of the entire Cygnus Loop has been obtained using gas-filled proportional counters and filters flown on a Nike-Aerobee rocket. The results indicate an average spectral temperature of (2.8 plus or minus 0.2) x 1,000,000 K and the presence of excess emission in the energy range from 0.530 to 0.693 keV. If the excess emission originates in a single line at 0.658 keV, the intensity at the earth corresponds to 1.8 plus or minus 0.7 photons per sq cm per sec, or about 10% of the total energy received from the Loop. The spectrum of the entire Loop is found to be attenuated by an average of (4.8 plus or minus 0.2) x 10 to the 20th hydrogen atoms per sq cm.

Effects of variability of X-ray binaries on the X-ray luminosity functions of Milky Way

NASA Astrophysics Data System (ADS)

Islam, Nazma; Paul, Biswajit

2016-08-01

The X-ray luminosity functions of galaxies have become a useful tool for population studies of X-ray binaries in them. The availability of long term light-curves of X-ray binaries with the All Sky X-ray Monitors opens up the possibility of constructing X-ray luminosity functions, by also including the intensity variation effects of the galactic X-ray binaries. We have constructed multiple realizations of the X-ray luminosity functions (XLFs) of Milky Way, using the long term light-curves of sources obtained in the 2-10 keV energy band with the RXTE-ASM. The observed spread seen in the value of slope of both HMXB and LMXB XLFs are due to inclusion of variable luminosities of X-ray binaries in construction of these XLFs as well as finite sample effects. XLFs constructed for galactic HMXBs in the luminosity range 1036-1039 erg/sec is described by a power-law model with a mean power-law index of -0.48 and a spread due to variability of HMXBs as 0.19. XLFs constructed for galactic LMXBs in the luminosity range 1036-1039 erg/sec has a shape of cut-off power-law with mean power-law index of -0.31 and a spread due to variability of LMXBs as 0.07.

Low energy gamma ray emission from the Cygnus OB2 association

NASA Technical Reports Server (NTRS)

Chen, Wan; White, Richard L.

1992-01-01

According to our newly developed model of gamma-ray emission from chaotic early-type stellar winds, we predict the combined gamma-ray flux from the circumstellar winds of many very luminous early-type stars in the Cyg OB2 association can be detectable by the Energetic Gamma Ray Experiment Telescope (EGRET) (and maybe also by OSSE) on CGRO. Due to different radiation mechanisms, the gamma-ray spectrum from stellar winds can be quite different from that of CYG X-3; this spectral difference and the time-variation of Cyg X-3 flux will help to distinguish the gamma-ray components from different sources in this small region, which is spatially unresolvable by CGRO.

UNDERSTANDING X-RAY STARS:. The Discovery of Binary X-ray Sources

NASA Astrophysics Data System (ADS)

Schreier, E. J.; Tananbaum, H.

2000-09-01

The discovery of binary X-ray sources with UHURU introduced many new concepts to astronomy. It provided the canonical model which explained X-ray emission from a large class of galactic X-ray sources: it confirmed the existence of collapsed objects as the source of intense X-ray emission; showed that such collapsed objects existed in binary systems, with mass accretion as the energy source for the X-ray emission; and provided compelling evidence for the existence of black holes. This model also provided the basis for explaining the power source of AGNs and QSOs. The process of discovery and interpretation also established X-ray astronomy as an essential sub-discipline of astronomy, beginning its incorporation into the mainstream of astronomy.

X-ray Source Populations in Old Open Clusters - Collinder 261

NASA Astrophysics Data System (ADS)

Vats, Smriti

2014-11-01

We are carrying out an X-ray survey of old open clusters (OCs) with the Chandra X-ray Observatory. Single old stars emit very faint X-rays, making X-rays produced by mass transfer in CVs, or by rapid rotation of the stars in tidally-locked, detached binaries detectable, without contamination from single stars. By comparing properties of interacting binaries in different environments, we aim to study binary evolution, and how dynamical encounters with other cluster members affect it. Collinder (Cr) 261 is an old OC(~7Gyr), with one of the richest populations inferred, of close binary populations and blue stragglers of all OCs. We will present the first results, detailing the X-ray population of Cr 261, in conjugation with other OCs, and in comparison with populations in globular clusters.

X-ray Binaries in the Galaxy and the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Cowley, Anne P.

1993-05-01

For more than two decades astronomers have been aware that the most X-ray luminous stellar sources (L_x > 10(35) erg s(-1) ) are interacting binaries where one component is a neutron star or black hole. While other types of single and multiple stars are known X-ray sources, none compare in X-ray luminosity with the ``classical" X-ray binaries. In these systems X-ray emission results from accretion of material from a non-degenerate companion onto the compact star through several alternate mechanisms including Roche lobe overflow, stellar winds, or periastron effects in non-circular orbits. It has been recognized for many years that X-ray binaries divide into two broad groups, characterized primarily by the mass of the non-degenerate star: 1) massive X-ray binaries (MXRB), in which the optical primary is a bright, early-type star, and 2) low-mass X-ray binaries (LMXB), where a lower main-sequence or subgiant star is the mass donor. A broad variety of observational characteristics further subdivide these classes. In the Galaxy these two groups appear to be spatially and kinematically associated with the disk and the halo populations, respectively. A few dozen MXRB are known in the Galaxy. A great deal of information about their physical properties has been learned from observational study. Their optical primaries can be investigated by conventional techniques. Furthermore, most MXRB contain X-ray pulsars, allowing accurate determination of their orbital parameters. From these data masses have been determined for the neutron stars, all of which are ~ 1.4 Msun, within measurement errors. By contrast, the LMXB have been much more difficult to study. Although there are ~ 150 LMXB in the Galaxy, most are distant and faint, requiring use of large telescopes for their study. Their optical light is almost always dominated by an accretion disk, rather than the mass-losing star, making interpretation of their spectral and photometric properties difficult. Their often uncertain distances further complicate our understanding. Thus, although the galactic LMXB greatly outnumber the MXRB, they are much less well understood. The X-ray binaries in the Magellanic Clouds in many ways make an ideal laboratory because they are all at the same, known distance. However, at the present time only a handful of X-ray binaries are known with certainty in these galaxies -- 7 in the LMC and 1 in the SMC. Only 3 of the LMC sources are low-mass X-ray binaries, and their properties are quite different from ``typical" galactic LMXB. In this review we will outline the general properties of X-ray binaries and summarize what types of information we have learned from their study over a wide range of wavelengths. An overall comparison of the global properties of X-ray binaries in the Galaxy and the Magellanic Clouds will be given.

The 4U 0115+63: Another energetic gamma ray binary pulsar

NASA Technical Reports Server (NTRS)

Chadwick, P. M.; Dipper, N. A.; Dowthwaite, J. C.; Kirkman, I. W.; Mccomb, T. J. L.; Orford, K. J.; Turver, K. E.

1985-01-01

Following the discovery of Her X-1 as a source of pulsed 1000 Gev X-rays, a search for emission from an X-ray binary containing a pulsar with similar values of period, period derivative and luminosity was successful. The sporadic X-ray binary 4U 0115-63 has been observed, with probability 2.5 x 10 to the minus 6 power ergs/s to emit 1000 GeV gamma-rays with a time averaged energy flux of 6 to 10 to the 35th power.

A ROTSE-I/ROSAT Survey of X-ray Emission from Contact Binary Stars

NASA Astrophysics Data System (ADS)

Geske, M.; McKay, T.

2005-05-01

Using public data from the ROSAT All Sky Survey (RASS) and the ROTSE-I Sky Patrols, the incidence of strong x-ray emissions from contact binary systems was examined. The RASS data was matched to an expanded catalog of contact binary systems from the ROTSE-I data, using a 35 arc second radius. X-ray luminosities for matching objects were then determined. This information was then used to evaluate the total x-ray emissions from all such objects, in order to determine their contribution to the galactic x-ray background.

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

NASA Astrophysics Data System (ADS)

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

2015-01-01

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

Circinus X-1: a Laboratory for Studying the Accretion Phenomenon in Compact Binary X-Ray Sources. Ph.D. Thesis - Maryland Univ.

NASA Technical Reports Server (NTRS)

Robinson-Saba, J. L.

1983-01-01

Observations of the binary X-ray source Circinus X-1 provide samples of a range of spectral and temporal behavior whose variety is thought to reflect a broad continuum of accretion conditions in an eccentric binary system. The data support an identification of three or more X-ray spectral components, probably associated with distinct emission regions.

What Can Simbol-X Do for Gamma-ray Binaries?

NASA Astrophysics Data System (ADS)

Cerutti, B.; Dubus, G.; Henri, G.; Hill, A. B.; Szostek, A.

2009-05-01

Gamma-ray binaries have been uncovered as a new class of Galactic objects in the very high energy sky (>100 GeV). The three systems known today have hard X-ray spectra (photon index ~1.5), extended radio emission and a high luminosity in gamma-rays. Recent monitoring campaigns of LSI +61°303 in X-rays have confirmed variability in these systems and revealed a spectral hardening with increasing flux. In a generic one-zone leptonic model, the cooling of relativistic electrons accounts for the main spectral and temporal features observed at high energy. Persistent hard X-ray emission is expected to extend well beyond 10 keV. We explain how Simbol-X will constrain the existing models in connection with Fermi Space Telescope measurements. Because of its unprecedented sensitivity in hard X-rays, Simbol-X will also play a role in the discovery of new gamma-ray binaries, giving new insights into the evolution of compact binaries.

Chandra Observation of Luminous and Ultraluminous X-ray Binaries in M101

NASA Technical Reports Server (NTRS)

Mukai, K.; Pence, W. D.; Snowden, S. L.; Kuntz, K. D.; White, Nicholas E. (Technical Monitor)

2002-01-01

X-ray binaries in the Milky Way are among the brightest objects on the X-ray sky. With the increasing sensitivity of recent missions, it is now possible to study X-ray binaries in nearby galaxies. We present data on six ultraluminous binaries in the nearby spiral galaxy, M101, obtained with Chandra ACIS-S. Of these, five appear to be similar to ultraluminous sources in other galaxies, while the brightest source, P098, shows some unique characteristics. We present our interpretation of the data in terms of an optically thick outflow, and discuss implications.

Evidence For Quasi-Periodic X-ray Dips From An Ultraluminous X-ray Source: Implications for the Binary Motion

NASA Technical Reports Server (NTRS)

Pasham, Dheeraj R.; Strohmayer, Tod E.

2013-01-01

We report results from long-term (approx.1240 days) X-ray (0.3-8.0 keV) monitoring of the ultraluminous X-ray source NGC 5408 X-1 with the Swift/X-Ray Telescope. Here we expand on earlier work by Strohmayer (2009) who used only a part of the present data set. Our primary results are: (1) the discovery of sharp, quasi-periodic, energy-independent dips in the X-ray intensity that recur on average every 243 days, (2) the detection of an energy dependent (variability amplitude decreases with increasing energy), quasi-sinusoidal X-ray modulation with a period of 112.6 +/- 4 days, the amplitude of which weakens during the second half of the light curve, and (3) spectral evidence for an increase in photoelectric absorption during the last continuous segment of the data. We interpret the X-ray modulations within the context of binary motion in analogy to that seen in high-inclination accreting X-ray binaries. If correct, this implies that NGC 5408 X-1 is in a binary with an orbital period of 243 +/- 23 days, in contrast to the 115.5 day quasi-sinusoidal period previously reported by Strohmayer (2009). We discuss the overall X-ray modulation within the framework of accretion via Roche-lobe overflow of the donor star. In addition, if the X-ray modulation is caused by vertically structured obscuring material in the accretion disk, this would imply a high value for the inclination of the orbit. A comparison with estimates from accreting X-ray binaries suggests an inclination > or approx.70deg. We note that, in principle, a precessing accretion disk could also produce the observed X-ray modulations.

Detection of non-thermal X-ray emission in the lobes and jets of Cygnus A

NASA Astrophysics Data System (ADS)

de Vries, M. N.; Wise, M. W.; Huppenkothen, D.; Nulsen, P. E. J.; Snios, B.; Hardcastle, M. J.; Birkinshaw, M.; Worrall, D. M.; Duffy, R. T.; McNamara, B. R.

2018-06-01

We present a spectral analysis of the lobes and X-ray jets of Cygnus A, using more than 2 Ms of Chandra observations. The X-ray jets are misaligned with the radio jets and significantly wider. We detect non-thermal emission components in both lobes and jets. For the eastern lobe and jet, we find 1 keV flux densities of 71_{-10}^{+10} nJy and 24_{-4}^{+4} nJy, and photon indices of 1.72_{-0.03}^{+0.03} and 1.64_{-0.04}^{+0.04} respectively. For the western lobe and jet, we find flux densities of 50_{-13}^{+12} nJy and 13_{-5}^{+5} nJy, and photon indices of 1.97_{-0.10}^{+0.23} and 1.86_{-0.12}^{+0.18} respectively. Using these results, we modeled the electron energy distributions of the lobes as broken power laws with age breaks. We find that a significant population of non-radiating particles is required to account for the total pressure of the eastern lobe. In the western lobe, no such population is required and the low energy cutoff to the electron distribution there needs to be raised to obtain pressures consistent with observations. This discrepancy is a consequence of the differing X-ray photon indices, which may indicate that the turnover in the inverse-Compton spectrum of the western lobe is at lower energies than in the eastern lobe. We modeled the emission from both jets as inverse-Compton emission. There is a narrow region of parameter space for which the X-ray jet can be a relic of an earlier active phase, although lack of knowledge about the jet's electron distribution and particle content makes the modelling uncertain.

The emergence of x-ray astronomy, neutron stars and black holes

NASA Astrophysics Data System (ADS)

Gursky, H.

2003-10-01

Remo Ruffini's professional career began just as X-ray astronomy began its second decade. His paper on the maximum mass of cold stars was instrumental in establishing Cygnus X-1 as a black hole. The idea of black holes and neutron stars had originated more than 40 years earlier based on considerations of white dwarfs. It was not until the explosion of technology that emerged after World War II that the observational evidence developed which enabled establishing the existence of these objects. The discovery of X-ray sources in 1962 and the subsequent maturing of that discipline and of radio astronomy were the key elements. By now a large number of stellar objects are found to be neutron stars and black holes.

A Chandra X-ray census of the interacting binaries in old open clusters - NGC 188

NASA Astrophysics Data System (ADS)

Vats, Smriti; Van Den Berg, Maureen

2017-01-01

We present a new X-ray study of NGC 188, one of the oldest open clusters known in the Milky Way (7 Gyr). Our X-ray observation using the Chandra X-ray Observatory is aimed at uncovering the population of close interacting binaries in the cluster. We detect 84 X-ray sources with a limiting X-ray luminosity, LX ~ 4×1029 erg s-1 (0.3-7 keV), of which 28 are within the half-mass radius. Of these, 13 are proper-motion or radial-velocity cluster members, wherein we identify a mix of active binaries (ABs) and blue straggler stars (BSSs). We also identify one tentative cataclysmic variable (CV) candidate which is a known short-period photometric variable, but whose membership to NGC 188 is unknown. We have compared the X-ray luminosity per unit of cluster mass (i.e. the X-ray emissivity) of NGC 188 with those of other old Galactic open clusters and dense globular clusters (47 Tuc, NGC 6397). Our findings confirm the earlier result that old open clusters have higher X-ray emissivities than the globular clusters (LX ≥1×1030 erg s-1). This may be explained by dynamical encounters in globulars, which could have a net effect of destroying binaries, or the typically higher metallicities of open clusters. We find one intriguing X-ray source in NGC 188 that is a BSS and cluster member, whose X-ray luminosity cannot be explained by its currently understood binary configuration. Its X-ray detection invokes the need for a third companion in the system.

A Chandra X-ray Study of Cygnus A. 2; The Nucleus

NASA Technical Reports Server (NTRS)

Young, Andrew J.; Wilson, Andrew; Terashima, Yuichi; Arnaud, Keith A.; Smith, David A.; White, Nicholas E. (Technical Monitor)

2002-01-01

We report Chandra Advanced CCD Imaging Spectrometer and quasi-simultaneous Rossi X-Ray Timing Explorer (RXTE) observations of the nearby, powerful radio galaxy Cygnus A, with the present paper focusing on the properties of the active nucleus. In the Chandra observation, the hard (less than a few keV) X-ray emission is spatially unresolved with a size is approximately 1" (1.5 kpc, H(sub 0) = 50 km/s/Mpc) and coincides with the radio and near-infrared nuclei. In contrast, the soft (less than 2 keV) emission exhibits a bipolar nebulosity that aligns with the optical bipolar continuum and emission-line structures and approximately with the radio jet. In particular, the soft X-ray emission corresponds very well with the [O III] (lambda)5007 and H(alpha) + [N II] lambda(lambda)6548, 6583 nebulosity imaged with Hubble Space Telescope. At the location of the nucleus, there is only weak soft X-ray emission, an effect that may be intrinsic or result from a dust lane that crosses the nucleus perpendicular to the source axis. The spectra of the various X-ray components have been obtained by simultaneous fits to the six detectors. The compact nucleus is detected to 100 keV and is well described by a heavily absorbed power-law spectrum with Gamma(sub h) = 1.52(sup + 0.12, sub -0.12) (similar to other 0.12 narrow-line radio galaxies) and equivalent hydrogen column N(sub H)(nuc) = 2.0(sup +0.1, sub -0.1) x 10(exp 23)/sq cm. This 0.2 column is compatible with the dust obscuration to the near-infrared source for a normal gas-to-dust ratio. The soft (less than 2 keV) emission from the nucleus may be described by a power-law spectrum with the same index (i.e., Gamma(sub l) = Gamma(sub h), although direct fits suggest a slightly larger value for Gamma(sub l). Narrow emission lines from highly ionized neon and silicon, as well as a "neutral" Fe K(alpha) line, are detected in the nucleus and its vicinity (r approximately less than 2 kpc). The equivalent width (EW) of the Fe K(alpha) line (182(sup +40, sub -54) eV) is in good agreement with theoretical predictions for the EW versus N(sub H)(nuc) relationship in various geometries. An Fe K edge is also seen. The RXTE observations indicate a temperature of kT = 6.9(sup +0., sub -1.0) keV for the cluster gas (discussed in Paper III of this series) and cluster emission lines of Fe K(alpha) and Fe K(beta) and/or Ni K(alpha). We consider the possibility that the extended soft X-ray emission is electron-scattered nuclear radiation. Given that 1% of the unabsorbed 2 - 10 keV nuclear radiation would have to be scattered, the necessary gas column [N(sub H)(Scattering) approx. = 3.5 x 10(exp 22)/sq cm] would absorb the X-rays rather than scatter them if the gas is cold. Thus, the scattering plasma must be highly ionized. If this ionization is achieved through photoionization by the nucleus, the ionization parameter zeta greater than 1 ergs cm/s and the electron density n(sub e) approx. = 6 cc given the observed distance of the soft X-ray emission from the nucleus. The electron column density inferred from the X-ray observations is much too low to account for the extended optical scattered light, strongly suggesting that the polarized optical light is scattered by dust. The presence of highly ionized Ne lines in the soft X-ray spectrum requires 20 ergs cm/s approximately less than zeta approximately less than 300 ergs cm/s these lines may originate closer to the nucleus than the extended soft continuum or in a lower density gas. A collisionally ionized thermal model of the extended soft X-rays cannot be ruled out but is unattractive in view of the low metal abundance required (Z = 0.03 Z(mass)). The hard X-ray to far-infrared ratio for the nucleus of Cygnus A is similar to that seen in Seyfert 1 and unobscured radio galaxies. By means of the correlation between hard X-ray luminosity and nuclear optical absolute magnitude for these classes of object, we estimate M(sub B) = -22.4 for Cygnus A, near the .borderline between Seyfert galaxies and QSOs.

Variable millimetre radiation from the colliding-wind binary Cygnus OB2 #8A

NASA Astrophysics Data System (ADS)

Blomme, R.; Fenech, D. M.; Prinja, R. K.; Pittard, J. M.; Morford, J. C.

2017-12-01

Context. Massive binaries have stellar winds that collide. In the colliding-wind region, various physically interesting processes occur, leading to enhanced X-ray emission, non-thermal radio emission, as well as non-thermal X-rays and gamma-rays. Non-thermal radio emission (due to synchrotron radiation) has so far been observed at centimetre wavelengths. At millimetre wavelengths, the stellar winds and the colliding-wind region emit more thermal free-free radiation, and it is expected that any non-thermal contribution will be difficult or impossible to detect. Aims: We aim to determine if the material in the colliding-wind region contributes substantially to the observed millimetre fluxes of a colliding-wind binary. We also try to distinguish the synchrotron emission from the free-free emission. Methods: We monitored the massive binary Cyg OB2 #8A at 3 mm with the NOrthern Extended Millimeter Array (NOEMA) interferometer of the Institut de Radioastronomie Millimétrique (IRAM). The data were collected in 14 separate observing runs (in 2014 and 2016), and provide good coverage of the orbital period. Results: The observed millimetre fluxes range between 1.1 and 2.3 mJy, and show phase-locked variability, clearly indicating that a large part of the emission is due to the colliding-wind region. A simple synchrotron model gives fluxes with the correct order of magnitude, but with a maximum that is phase-shifted with respect to the observations. Qualitatively this phase shift can be explained by our neglect of orbital motion on the shape of the colliding-wind region. A model using only free-free emission results in only a slightly worse explanation of the observations. Additionally, on the map of our observations we also detect the O6.5 III star Cyg OB2 #8B, for which we determine a 3 mm flux of 0.21 ± 0.033 mJy. Conclusions: The question of whether synchrotron radiation or free-free emission dominates the millimetre fluxes of Cyg OB2 #8A remains open. More detailed modelling of this system, based on solving the hydrodynamical equations, is required to give a definite answer. This work is based on observations carried out under project numbers S14AW and S16AU with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

The structure and content of the galaxy and galactic gamma rays. [conferences

NASA Technical Reports Server (NTRS)

Fichtel, C. E.; Stecker, F. W.

1976-01-01

Papers are presented dealing with galactic structure drawing on all branches of galactic astronomy with emphasis on the implications of the new gamma ray observations. Topics discussed include: (1) results from the COS-B gamma ray satellite; (2) results from SAS-2 on gamma ray pulsar, Cygnus X-3, and maps of the galactic diffuse flux; (3) recent data from CO surveys of the galaxy; (4) high resolution radio surveys of external galaxies; (5) results on the galactic distribution of pulsars; and (6) theoretical work on galactic gamma ray emission.

Evidence for Quasi-Periodic X-ray Dips from an ULX: Implications for the Binary Motion and the Orbital Inclination

NASA Technical Reports Server (NTRS)

Pasham, Dheeraj R.; Strohmayer, Tod E.

2012-01-01

We report results from long-term X-ray (0.3-8.0 keY) monitoring of the ultraluminous X-ray source NGC 5408 X-1 with the Swift/X-Ray Telescope. Our primary results are: (1) the discovery of quasi-periodic dips in the X-ray intensity that recur on average every 243 days, (2) the detection of an energy-dependent (variability amplitude decreases with increasing energy), quasi-sinusoidal X-ray modulation with a period of 112.6 +/- 4 days the amplitude of which decreases during the second half of the light curve and (3) energy spectral evidence for an increase in photoelectric absorption during the last continuous segment of the data, possibly due to a change in the ionization state of the circumbinary material. We interpret the X-ray modulations in the context of binary motion in analogy to that seen in high-inclination low-mass X-ray binaries. If correct, this implies that NGC 5408 X-1 is in a binary with an orbital period of 243 +/- 23 days in contrast to the 115.5 day quasi-sinusoidal period previously reported. In addition, if the X-ray modulation is caused by vertically structured obscuring material in the accretion disk (similar to the phenomenon of dipping LMXBs), this would imply a high value for the inclination of the orbit. A comparison with estimates from accreting X-ray binaries suggests an inclination approx > 60 deg. We note that, in principle, a precessing accretion disk could also produce the observed X-ray modulations.

Discovery of a 3.6-hr Eclipsing Luminous X-Ray Binary in the Galaxy NGC 4214

NASA Technical Reports Server (NTRS)

Ghosh, Kajal K.; Rappaport, Saul; Tennant, Allyn F.; Swartz, Douglas A.; Pooley, David; Madhusudhan, N.

2006-01-01

We report the discovery of an eclipsing X-ray binary with a 3.62-hr period within 24 arcsec of the center of the dwarf starburst galaxy NGC 4214. The orbital period places interesting constraints on the nature of the binary, and allows for a few very different interpretations. The most likely possibility is that the source lies within NGC 4214 and has an X-ray luminosity of up to 7e38. In this case the binary may well be comprised of a naked He-burning donor star with a neutron-star accretor, though a stellar-mass black-hole accretor cannot be completely excluded. There is no obvious evidence for a strong stellar wind in the X-ray orbital light curve that would be expected from a massive He star; thus, the mass of the He star should be <3-4 solar masses. If correct, this would represent a new class of very luminous X-ray binary----perhaps related to Cyg X-3. Other less likely possibilities include a conventional low-mass X-ray binary that somehow manages to produce such a high X-ray luminosity and is apparently persistent over an interval of years; or a foreground AM Her binary of much lower luminosity that fortuitously lies in the direction of NGC 4214. Any model for this system must accommodate the lack of an optical counterpart down to a limiting magnitude of 22.6 in the visible.

CYGNUS A: Hot Spots, Bow Shocks, Core Emission, and Exclusion of Cluster Gas by Radio Lobes

NASA Technical Reports Server (NTRS)

Harris, Daniel E.

1999-01-01

This report covers work preformed on three ROSAT projects: (1) Monitoring the X-ray Intensity of the Core and Jet of M87; (2) The radio-optical jet in 3C-120 and (3) A search for cluster emission at high redshift.

Low-mass X-ray binary evolution and the origin of millisecond pulsars

NASA Technical Reports Server (NTRS)

Frank, Juhan; King, Andrew R.; Lasota, Jean-Pierre

1992-01-01

The evolution of low-mass X-ray binaries (LMXBs) is considered. It is shown that X-ray irradiation of the companion stars causes these systems to undergo episodes of rapid mass transfer followed by detached phases. The systems are visible as bright X-ray binaries only for a short part of each cycle, so that their space density must be considerably larger than previously estimated. This removes the difficulty in regarding LMXBs as the progenitors of low-mass binary pulsars. The low-accretion-rate phase of the cycle with the soft X-ray transients is identified. It is shown that 3 hr is likely to be the minimum orbital period for LMXBs with main-sequence companions and it is suggested that the evolutionary endpoint for many LMXBs may be systems which are the sites of gamma-ray bursts.

The superslow pulsation X-ray pulsars in high mass X-ray binaries

NASA Astrophysics Data System (ADS)

Wang, Wei

2013-03-01

There exists a special class of X-ray pulsars that exhibit very slow pulsation of P spin > 1000 s in the high mass X-ray binaries (HMXBs). We have studied the temporal and spectral properties of these superslow pulsation neutron star binaries in hard X-ray bands with INTEGRAL observations. Long-term monitoring observations find spin period evolution of two sources: spin-down trend for 4U 2206+54 (P spin ~ 5560 s with Ṗ spin ~ 4.9 × 10-7 s s-1) and long-term spin-up trend for 2S 0114+65 (P spin ~ 9600 s with Ṗ spin ~ -1 × 10-6 s s-1) in the last 20 years. A Be X-ray transient, SXP 1062 (P spin ~ 1062 s), also showed a fast spin-down rate of Ṗ spin ~ 3 × 10-6 s s-1 during an outburst. These superslow pulsation neutron stars cannot be produced in the standard X-ray binary evolution model unless the neutron star has a much stronger surface magnetic field (B > 1014 G). The physical origin of the superslow spin period is still unclear. The possible origin and evolution channels of the superslow pulsation X-ray pulsars are discussed. Superslow pulsation X-ray pulsars could be younger X-ray binary systems, still in the fast evolution phase preceding the final equilibrium state. Alternatively, they could be a new class of neutron star system - accreting magnetars.

Cygnus OB2: Star Formation Ugly Duckling Causes a Flap

NASA Astrophysics Data System (ADS)

Drake, Jeremy J.; Wright, Nicholas; Guarcello, Mario

2015-08-01

Cygnus OB2 is one of the largest known OB associations in our Galaxy, with a total stellar mass of 30,000 Msun and boasting an estimated 65 O-type stars and hundreds of OB stars. At a distance of only 1.4kpc, it is also the closest truly massive star forming region and provides a valuable testbed for star and planet formation theory. We have performed a deep stellar census using observations from X-ray to infrared, which has enabled studies of sub-structuring, mass segregation and dynamics, while infrared data reveal a story of protoplanetary disk attrition in an extremely harsh radiation environment. I will discuss how Cygnus OB2 challenges the idea that stars must form in dense, compact clusters, and demonstrates that stars as massive as 100 Msun can form in relatively low-density environments. Convincing evidence of disk photoevaporation poses a potential problem for planet formation and growth in starburst environments.

Search for old neutron stars in molecular clouds: Cygnus rift and Cygnus OB7.

NASA Astrophysics Data System (ADS)

Belloni, T.; Zampieri, L.; Campana, S.

1997-03-01

We present the results of a systematic search for old isolated neutron stars (ONSs) in the direction of two giant molecular clouds in Cygnus (Rift and OB7). From theoretical calculations, we expect the detection of a large number of ONSs with the PSPC on board ROSAT. By analyzing the PSPC pointings in the direction of the clouds, we find four sources characterized by count rates (~10^-3^ct/s) and spectral properties consistent with the hypothesis that the X-ray radiation is produced by ONSs and also characterized by the absence of any measurable optical counterpart within their error circle in the digitized red plates of the Palomar All Sky Survey. The importance of follow-up deep observations in the direction of these ONS candidates is discussed. The observational and theoretical approach presented here could be fruitfully applied also to the systematic search for ONSs in other regions of the Galaxy.

Application of cosmic-ray shock theories to the Cygnus Loop - An alternative model

NASA Technical Reports Server (NTRS)

Boulares, Ahmed; Cox, Donald P.

1988-01-01

Steady state cosmic-ray shock models are investigated here in the light of observations of the Cygnus Loop supernova remnant. The predicted downstream temperature is derived for each model. The Cygnus Loop data and the application of the models to them, including wave dissipation, are presented. Heating rate and ionization fraction structures are provided along with an estimate of the cosmic-ray diffusion coefficient. It is found that the model of Voelk, Drury, and McKenzie (1984), in which the plasma waves are generated by the streaming instability of the cosmic rays and are dissipated into the gas, can be made consistent with some observed characteristics of the Cygnus Loop shocks. The model is used to deduce upstream densities and shock velocities and, compared to the usual pure gas shock interpretation, it is found that lower densities and approximately three times higher velocities are required.

Analysis of 3D Doppler Tomography of the X-ray Binary System Cygnus X-1 from Spectral Observations in 2007 in the HeII λ 4686 Å Line

NASA Astrophysics Data System (ADS)

Agafonov, M. I.; Karitskaya, E. A.; Sharova, O. I.; Bochkarev, N. G.; Zharikov, S. V.; Butenko, G. Z.; Bondar', A. V.; Bubukin, I. T.

2018-03-01

This is the second paper in a series dedicated to studies of the X-ray binary Cyg X-1 in the HeII λ 4686 Å line using 3D Doppler tomography. A detailed analysis of the tomogram constructed has made it possible for the first time to obtain information about the motions of gaseous flows including all three velocity components. The observations were obtained in June 2007 at the Terskol Branch of the Institute of Astronomy (Russia) and the National Astronomical Observatory of Mexico. The correctness of the tomographic results and their discussion is analyzed. The results are compared with a 2D Doppler tomogram reconstruction. Model-atmosphere computations of HeII λ 4686 Å line profiles are used to estimate the influence of absorption features of the Osupergiant on the emission structure in the tomogram. The correctness of the 3D solutions is confirmed by the good agreement between the original sequence of spectral data and a control data set computed using the constructed 3D Doppler tomogram. Tomograms constructed using the data of each of the two observatories are compared. The results of the reconstruction for inclinations of the system of 40° and 45° essentially coincide. The maximum absorption (corresponding to the O supergiant) and emission structural features in the 3D tomogram are located in its central ( V x , V y ) section, where the velocity component perpendicular to the orbital plane V z is zero. The emission is generated mainly in the outer part of the accretion structure, close to the supergiant. A gaseous stream from the Lagrangian point L1 with its motion close to the orbital plane can be distinguished. Its maximum velocity reaches 800 km/s. The identification of an emission structure with V z 300 km/s and with V x , V y in the velocity interval corresponding to the donor star was unexpected. Its presence may indicate, for example, an outflow of matter from a magnetic pole of the supergiant.

Formation and Evolution of X-ray Binaries

NASA Astrophysics Data System (ADS)

Shao, Y.

2017-07-01

X-ray binaries are a class of binary systems, in which the accretor is a compact star (i.e., black hole, neutron star, or white dwarf). They are one of the most important objects in the universe, which can be used to study not only binary evolution but also accretion disks and compact stars. Statistical investigations of these binaries help to understand the formation and evolution of galaxies, and sometimes provide useful constraints on the cosmological models. The goal of this thesis is to investigate the formation and evolution processes of X-ray binaries including Be/X-ray binaries, low-mass X-ray binaries (LMXBs), ultraluminous X-ray sources (ULXs), and cataclysmic variables. In Chapter 1 we give a brief review on the basic knowledge of the binary evolution. In Chapter 2 we discuss the formation of Be stars through binary interaction. In this chapter we investigate the formation of Be stars resulting from mass transfer in binaries in the Galaxy. Using binary evolution and population synthesis calculations, we find that in Be/neutron star binaries the Be stars have a lower limit of mass ˜ 8 M⊙ if they are formed by a stable (i.e., without the occurrence of common envelope evolution) and nonconservative mass transfer. We demonstrate that the isolated Be stars may originate from both mergers of two main-sequence stars and disrupted Be binaries during the supernova explosions of the primary stars, but mergers seem to play a much more important role. Finally the fraction of Be stars produced by binary interactions in all B type stars can be as high as ˜ 13%-30% , implying that most of Be stars may result from binary interaction. In Chapter 3 we show the evolution of intermediate- and low-mass X-ray binaries (I/LMXBs) and the formation of millisecond pulsars. Comparing the calculated results with the observations of binary radio pulsars, we report the following results: (1) The allowed parameter space for forming binary pulsars in the initial orbital period-donor mass plane increases with the increasing neutron star mass. This may help to explain why some millisecond pulsars with orbital periods longer than ˜ 60 d seem to have less massive white dwarfs than expected. Alternatively, some of these wide binary pulsars may be formed through mass transfer driven by planet/brown dwarf-involved common envelope evolution; (2) Some of the pulsars in compact binaries might have evolved from intermediate-mass X-ray binaries with an anomalous magnetic braking; (3) The equilibrium spin periods of neutron stars in low-mass X-ray binaries are in general shorter than the observed spin periods of binary pulsars by more than one order of magnitude, suggesting that either the simple equilibrium spin model does not apply, or there are other mechanisms/processes spinning down the neutron stars. In Chapter 4, angular momentum loss mechanisms in the cataclysmic variables below the period gap are presented. By considering several kinds of consequential angular momentum loss mechanisms, we find that neither isotropic wind from the white dwarf nor outflow from the L1 point can explain the extra angular momentum loss rate, while an ouflow from the L2 point or a circumbinary disk can effectively extract the angular momentum provided that ˜ 15%-45% of the transferred mass is lost from the binary. A more promising mechanism is a circumbinary disk exerting a gravitational torque on the binary. In this case the mass loss fraction can be as low as ≲ 10-3. In Chapter 5 we present a study on the population of ultraluminous X-ray sources with an accreting neutron star. Most ULXs are believed to be X-ray binary systems, but previous observational and theoretical studies tend to prefer a black hole rather than a neutron star accretor. The recent discovery of 1.37 s pulsations from the ULX M82 X-2 has established its nature as a magnetized neutron star. In this chapter we model the formation history of neutron star ULXs in an M82- or Milky Way-like galaxy, by use of both binary population synthesis and detailed binary evolution calculations. We find that the birthrate is around 10-4 yr-1 for the incipient X-ray binaries in both cases. We demonstrate the distribution of the ULX population in the donor mass - orbital period plane. Our results suggest that, compared with black hole X-ray binaries, neutron star X-ray binaries may significantly contribute to the ULX population, and high/intermediate-mass X-ray binaries dominate the neutron star ULX population in M82/Milky Way-like galaxies, respectively. In Chapter 6, the population of intermediate- and low-mass X-ray binaries in the Galaxy is explored. We investigate the formation and evolutionary sequences of Galactic intermediate- and low-mass X-ray binaries by combining binary population synthesis (BPS) and detailed stellar evolutionary calculations. Using an updated BPS code we compute the evolution of massive binaries that leads to the formation of incipient I/LMXBs, and present their distribution in the initial donor mass vs. initial orbital period diagram. We then follow the evolution of I/LMXBs until the formation of binary millisecond pulsars (BMSPs). We show that during the evolution of I/LMXBs they are likely to be observed as relatively compact binaries. The resultant BMSPs have orbital periods ranging from about 1 day to a few hundred days. These features are consistent with observations of LMXBs and BMSPs. We also confirm the discrepancies between theoretical predictions and observations mentioned in the literature, that is, the theoretical average mass transfer rates of LMXBs are considerably lower than observed, and the number of BMSPs with orbital periods ˜ 0.1-1 \\unit{d} is severely underestimated. Both imply that something is missing in the modeling of LMXBs, which is likely to be related to the mechanisms of the orbital angular momentum loss. Finally in Chapter 7 we summarize our results and give the prospects for the future work.

Modeling the X-Ray Timing Properties of Cygnus X-1 Caused by Waves Propagating in a Transition Disk

NASA Astrophysics Data System (ADS)

Misra, R.

2000-02-01

We show that waves propagating in a transition disk can explain the short-term temporal behavior of Cygnus X-1. In the transition-disk model, the spectrum is produced by saturated Comptonization within the inner region of the accretion disk where the temperature varies rapidly with radius. Recently, the spectrum from such a disk has been shown to fit the average broadband spectrum of this source better than that predicted by the soft-photon Comptonization model. Here we consider a simple model in which waves are propagating cylindrically symmetrically in the transition disk with a uniform propagation speed (cp). We show that this model can qualitatively explain (1) the variation of the power spectral density with energy, (2) the hard lags as a function of frequency, and (3) the hard lags as a function of energy for various frequencies. Thus, the transition-disk model can explain the average spectrum and the short-term temporal behavior of Cyg X-1.

X-Ray source populations in old open clusters: Collinder 261

NASA Astrophysics Data System (ADS)

Vats, Smriti; van den Berg, Maureen; Wijnands, Rudy

2014-09-01

We are carrying out an X-ray survey of old open clusters with the Chandra X-ray Observatory. Single old stars, being slow rotators, are very faint in X-rays (L_X < 1×10^27 erg/s). Hence, X-rays produced by mass transfer in cataclysmic variables (CVs) or by rapid rotation of the stars in tidally locked, detached binaries (active binaries; ABs) can be detected, without contamination from single stars. By comparing the properties of various types of interacting binaries in different environments (the Galactic field, old open clusters, globular clusters), we aim to study binary evolution and how it may be affected by dynamical encounters with other cluster stars. Stellar clusters are good targets to study binaries, as age, distance, chemical composition, are well constrained. Collinder (Cr) 261 is an old open cluster (age ~ 7 Gyr), with one of the richest populations inferred of close binaries and blue stragglers of all open clusters and is therefore an obvious target to study the products of close encounters in open clusters. We will present the first results of this study, detailing the low-luminosity X-ray population of Cr 261, in conjunction with other open clusters in our survey (NGC 188, Berkeley 17, NGC 6253, M67, NGC 6791) and in comparison with populations in globular clusters.

The First Simultaneous X-Ray/Radio Detection of the First Be/BH System MWC 656

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

Ribó, M.; Paredes, J. M.; Marcote, B.

2017-02-01

MWC 656 is the first known Be/black hole (BH) binary system. Be/BH binaries are important in the context of binary system evolution and sources of detectable gravitational waves because they are possible precursors of coalescing neutron star/BH binaries. X-ray observations conducted in 2013 revealed that MWC 656 is a quiescent high-mass X-ray binary (HMXB), opening the possibility to explore X-ray/radio correlations and the accretion/ejection coupling down to low luminosities for BH HMXBs. Here we report on a deep joint Chandra /VLA observation of MWC 656 (and contemporaneous optical data) conducted in 2015 July that has allowed us to unambiguously identifymore » the X-ray counterpart of the source. The X-ray spectrum can be fitted with a power law with Γ ∼ 2, providing a flux of ≃4 × 10{sup −15} erg cm{sup −2} s{sup −1} in the 0.5–8 keV energy range and a luminosity of L {sub X} ≃ 3 × 10{sup 30} erg s{sup −1} at a 2.6 kpc distance. For a 5 M{sub ⊙} BH this translates into ≃5 × 10{sup −9} L {sub Edd}. These results imply that MWC 656 is about 7 times fainter in X-rays than it was two years before and reaches the faintest X-ray luminosities ever detected in stellar-mass BHs. The radio data provide a detection with a peak flux density of 3.5 ± 1.1 μ Jy beam{sup −1}. The obtained X-ray/radio luminosities for this quiescent BH HMXB are fully compatible with those of the X-ray/radio correlations derived from quiescent BH low-mass X-ray binaries. These results show that the accretion/ejection coupling in stellar-mass BHs is independent of the nature of the donor star.« less

Variability of the symbiotic X-ray binary GX 1+4. Enhanced activity near periastron passage

NASA Astrophysics Data System (ADS)

Iłkiewicz, Krystian; Mikołajewska, Joanna; Monard, Berto

2017-05-01

Context. GX 1+4 belongs to a rare class of X-ray binaries with red giant donors, symbiotic X-ray binaries. It has a history of complicated variability on multiple timescales in the optical light and X-rays. The nature of this variability remains poorly understood. Aims: We aim to study variability of GX 1+4 on long timescale in X-ray and optical bands. Methods: We took X-ray observations from the INTEGRAL Soft Gamma-Ray Imager and RXTE All Sky Monitor. Optical observations were made with the INTEGRAL Optical Monitoring Camera. Results: The variability of GX 1+4 both in optical light and hard X-ray emission (>17 keV) is dominated by 50-70 d quasi-periodic changes. The amplitude of this variability is highest during the periastron passage, while during the potential neutron star eclipse the system is always at minimum. This confirms the 1161 d orbital period that has had been proposed for the system based on radial velocity curve. Neither the quasi-periodic variability or the orbital period are detected in soft X-ray emission (1.3-12.2 keV), where the binary shows no apparent periodicity.

Effects of radiation pressure on the equipotential surfaces in X-ray binaries

NASA Technical Reports Server (NTRS)

Kondo, Y.; Mccluskey, G. E., Jr.; Gulden, S. L.

1976-01-01

Equipotential surfaces incorporating the effect of radiation pressure were computed for the X-ray binaries Cen X-3, Cyg X-1 = HDE 226868, Vela XR-1 = 3U 0900-40 = HD 77581, and 3U 1700-37 = HD 153919. The topology of the equipotential surfaces is significantly affected by radiation pressure. In particular, the so-called critical Roche (Jacobian) lobes, the traditional figure 8's, do not exist. The effects of these results on modeling X-ray binaries are discussed.

Hard X-ray imaging of the Galactic black hole candidate GX 339 - 4

NASA Technical Reports Server (NTRS)

Covault, C. E.; Grindlay, J. E.; Manandhar, R. P.

1992-01-01

Imaging and spectral observations in the energy range 25-250 keV of the black hole candidate GX 339 - 4 have been obtained with the Energetic X-ray Imaging Telescope Experiment. Observations were made during a balloon flight from Alice Springs, Australia on UT 1989 May 8-10. A single source of nearly 6-sigma significance is detected near the center of the 3.4-deg field of view with a position consistent with GX 339 - 4. This is the first imaging observation of GX 339 - 4 at hard X-ray energies. This result confirms previously reported results from nonimaging experiments showing significant hard X-ray flux up to greater than about 60 keV, with a power-law spectral fit similar to the other black hole candidates such as Cygnus X - 1. The source may have been in an outburst state similar to that recently detected with BATSE on GRO.

Tidal tearing of circumstellar disks in Be/X-ray and gamma-ray binaries

NASA Astrophysics Data System (ADS)

Okazaki, Atsuo T.

2017-11-01

About one half of high-mass X-ray binaries host a Be star [an OB star with a viscous decretion (slowly outflowing) disk]. These Be/X-ray binaries exhibit two types of X-ray outbursts (Stella et al. 1986), normal X-ray outbursts (L X~1036-37 erg s-1) and occasional giant X-ray outbursts (L X > 1037 erg s-1). The origin of giant X-ray outbursts is unknown. On the other hand, a half of gamma-ray binaries have a Be star as the optical counterpart. One of these systems [LS I +61 303 (P orb = 26.5 d)] shows the superorbital (1,667 d) modulation in radio through X-ray bands. No consensus has been obtained for its origin. In this paper, we study a possibility that both phenomena are caused by a long-term, cyclic evolution of a highly misaligned Be disk under the influence of a compact object, by performing 3D hydrodynamic simulations. We find that the Be disk cyclically evolves in mildly eccentric, short-period systems. Each cycle consists of the following stages: 1) As the Be disk grows with time, the initially circular disk becomes eccentric by the Kozai-Lidov mechanism. 2) At some point, the disk is tidally torn off near the base and starts precession. 3) Due to precession, a gap opens between the disk base and mass ejection region, which allows the formation of a new disk in the stellar equatorial plane (see Figure 1). 4) The newly formed disk finally replaces the precessing old disk. Such a cyclic disk evolution has interesting implications for the long-term behavior of high energy emission in Be/X-ray and gamma-ray binaries.

Probing the Spatial Distribution of the Interstellar Dust Medium by High Angular Resolution X-ray Halos of Point Sources

NASA Astrophysics Data System (ADS)

Xiang, Jingen

X-rays are absorbed and scattered by dust grains when they travel through the interstellar medium. The scattering within small angles results in an X-ray ``halo''. The halo properties are significantly affected by the energy of radiation, the optical depth of the scattering, the grain size distributions and compositions, and the spatial distribution of dust along the line of sight (LOS). Therefore analyzing the X-ray halo properties is an important tool to study the size distribution and spatial distribution of interstellar grains, which plays a central role in the astrophysical study of the interstellar medium, such as the thermodynamics and chemistry of the gas and the dynamics of star formation. With excellent angular resolution, good energy resolution and broad energy band, the Chandra ACIS is so far the best instrument for studying the X-ray halos. But the direct images of bright sources obtained with ACIS usually suffer from severe pileup which prevents us from obtaining the halos in small angles. We first improve the method proposed by Yao et al to resolve the X-ray dust scattering halos of point sources from the zeroth order data in CC-mode or the first order data in TE mode with Chandra HETG/ACIS. Using this method we re-analyze the Cygnus X-1 data observed with Chandra. Then we studied the X-ray dust scattering halos around 17 bright X-ray point sources using Chandra data. All sources were observed with the HETG/ACIS in CC-mode or TE-mode. Using the interstellar grain models of WD01 model and MRN model to fit the halo profiles, we get the hydrogen column densities and the spatial distributions of the scattering dust grains along the line of sights (LOS) to these sources. We find there is a good linear correlation not only between the scattering hydrogen column density from WD01 model and the one from MRN model, but also between N_{H} derived from spectral fits and the one derived from the grain models WD01 and MRN (except for GX 301-2 and Vela X-1): N_{H,WD01} = (0.720±0.009) × N_{H,abs} + (0.051±0.013) and N_{H, MRN} = (1.156±0.016) × N_{H,abs} + (0.062±0.024) in the units 10^{22} cm^{-2}. Then the correlation between FHI and N_{H} is obtained. Both WD01 model and MRN model fits show that the scattering dust density very close to these sources is much higher than the normal interstellar medium and we consider it is the evidence of molecular clouds around these X-ray binaries. We also find that there is the linear correlation between the effective distance through the galactic dust layer and hydrogen scattering olumn density N_{H} excluding the one in x=0.99-1.0 but the correlation does not exist between he effective distance and the N_{H} in x=0.99-1.0. It shows that the dust nearby the X-ray sources is not the dust from galactic disk. Then we estimate the structure and density of the stellar wind around the special X-ray pulsars Vela X-1 and GX 301-2. Finally we discuss the possibility of probing the three dimensional structure of the interstellar using the X-ray halos of the transient sources, probing the spatial distributions of interstellar dust medium nearby the point sources, even the structure of the stellar winds using higher angular resolution X-ray dust scattering halos and testing the model that the black hole can be formed from the direct collapse of a massive star without supernova using the statistical distribution of the dust density nearby the X-ray binaries.

Low Mass X-ray Binary 4U1705-44 Exiting an Extended High X-ray State

NASA Astrophysics Data System (ADS)

Phillipson, Rebecca; Boyd, Patricia T.; Smale, Alan P.

2017-09-01

The neutron-star low-mass X-ray binary 4U1705-44, which exhibited high amplitude long-term X-ray variability on the order of hundreds of days during the 16-year continuous monitoring by the RXTE ASM (1995-2012), entered an anomalously long high state in July 2012 as observed by MAXI (2009-present).

NuSTAR Discovery of a Possible Black Hole HMXB and Cygnus X-1 Progenitor

NASA Astrophysics Data System (ADS)

Grindlay, Jonathan E.; Hailey, Charles James; Zhang, Shuo; Mori, Kaya; Gomez, Sebastian; Hong, Jaesub; Tomsick, John

2017-01-01

We report on NuSTAR observations of HD96670, a single line spectroscopic binary in the Carina OB association. We selected this source as a possible BH-HMXB candidate based on its 5.53d orbital period and 0.10 Msun mass function, both similar to Cyg X-1. HD96670 is a O8.5V main sequence star, and if its secondary were a BH, and its O star evolves to a O9Ib star like that in Cyg X-1, it would be high luminosity BH-HXMB. HD96670 is detected as a soft source in RASS and in the XMM slew survey. With a 150 ksec exposure with NuSTAR, we found a best-fit power law spectrum with photon index 2.4 - 2.6 and factor of ~2 variability. The mean Lx ~ 5 x 10^32 (5 - 30 keV) is consistent with that expected for accretion from the weak wind that late-type main sequence O stars usually show for plausible assumptions for the secondary if it is a ~5Msun BH. In the poster by Gomez and Grindlay, we show the detailed photometry and spectroscopy and PHOEBE modelling which point to the secondary indeed being a 5 Msun object, either an accreting BH or possibly a B8V star for which the X-ray spectrum would be expected to not show the hard PL component. Additional X-ray observations at or near the optically determined phase of inferiour vs. superior conjunction will resolve the nature of the secondary. If it is indeed a BH, this points the way to a much larger population of low-luminosity (Weak Wind) BH-LMXBs, with longer lifetimes, than the presently explored systems which all (but one) have super-giant donors.

Searching for Exoplanets around X-Ray Binaries with Accreting White Dwarfs, Neutron Stars, and Black Holes

NASA Astrophysics Data System (ADS)

Imara, Nia; Di Stefano, Rosanne

2018-05-01

We recommend that the search for exoplanets around binary stars be extended to include X-ray binaries (XRBs) in which the accretor is a white dwarf, neutron star, or black hole. We present a novel idea for detecting planets bound to such mass transfer binaries, proposing that the X-ray light curves of these binaries be inspected for signatures of transiting planets. X-ray transits may be the only way to detect planets around some systems, while providing a complementary approach to optical and/or radio observations in others. Any planets associated with XRBs must be in stable orbits. We consider the range of allowable separations and find that orbital periods can be hours or longer, while transit durations extend upward from about a minute for Earth-radius planets, to hours for Jupiter-radius planets. The search for planets around XRBs could begin at once with existing X-ray observations of these systems. If and when a planet is detected around an X-ray binary, the size and mass of the planet may be readily measured, and it may also be possible to study the transmission and absorption of X-rays through its atmosphere. Finally, a noteworthy application of our proposal is that the same technique could be used to search for signals from extraterrestrial intelligence. If an advanced exocivilization placed a Dyson sphere or similar structure in orbit around the accretor of an XRB in order to capture energy, such an artificial structure might cause detectable transits in the X-ray light curve.

Sigma observations of the low mass X-ray binaries of the galactic bulge

NASA Technical Reports Server (NTRS)

Goldwurm, A.; Denis, M.; Paul, J.; Faisse, S.; Roques, J. P.; Bouchet, L.; Vedrenne, G.; Mandrou, P.; Sunyaev, R.; Churazov, E.

1995-01-01

The soft gamma-ray telescope (35-1300 keV) SIGMA aboard the high energy GRANAT space observatory has been monitoring the Galactic Bulge region for more than 2000 h of effective time since March 1990. In the resulting average 35-75 keV image we detected ten sources at a level of greater than 5 standard deviations, 6 of which can be identified with low mass X-ray binaries (LMXB). Among them, one is the 1993 X-ray nova in Ophiuchus (GRS 1726-249), one is an X-ray pulsar (GX 1+4), two are associated with X-ray bursters (GX 354-0 and A 1742-294) and two with bursting X-ray binaries in the globular clusters Terzan 2 and Terzan 1. Their spectral and long term variability behavior as measured by SIGMMA are presented and discussed.

Primordial binary populations in low-density star clusters as seen by Chandra: globular clusters versus old open clusters

NASA Astrophysics Data System (ADS)

van den Berg, Maureen C.

2015-08-01

The binaries in the core of a star cluster are the energy source that prevents the cluster from experiencing core collapse. To model the dynamical evolution of a cluster, it is important to have constraints on the primordial binary content. X-ray observations of old star clusters are very efficient in detecting the close interacting binaries among the cluster members. The X-ray sources in star clusters are a mix of binaries that were dynamically formed and primordial binaries. In massive, dense star clusters, dynamical encounters play an important role in shaping the properties and numbers of the binaries. In contrast, in the low-density clusters the impact of dynamical encounters is presumed to be very small, and the close binaries detected in X-rays represent a primordial population. The lowest density globular clusters have current masses and central densities similar to those of the oldest open clusters in our Milky Way. I will discuss the results of studies with the Chandra X-ray Observatory that have nevertheless revealed a clear dichotomy: far fewer (if any at all) X-ray sources are detected in the central regions of the low-density globular clusters compared to the number of secure cluster members that have been detected in old open clusters (above a limiting X-ray luminosity of typically 4e30 erg/s). The low stellar encounter rates imply that dynamical destruction of binaries can be ignored at present, therefore an explanation must be sought elsewhere. I will discuss several factors that can shed light on the implied differences between the primordial close binary populations in the two types of star clusters.

The Ultracompact Nature of the Black Hole Candidate X-Ray Binary 47 Tuc X9

NASA Technical Reports Server (NTRS)

Bahramian, Arash; Heinke, Craig O.; Tudor, Vlad; Miller-Jones, James C. A.; Bogdanov, Slavko; Maccarone, Thomas J.; Knigge, Christian; Sivakoff, Gregory R.; Chomiuk, Laura; Strader, J.;

NuSTAR Hard X-Ray Observation of the Gamma-Ray Binary Candidate HESS J1832-093

NASA Astrophysics Data System (ADS)

Mori, Kaya; Gotthelf, E. V.; Hailey, Charles J.; Hord, Ben J.; de Oña Wilhelmi, Emma; Rahoui, Farid; Tomsick, John A.; Zhang, Shuo; Hong, Jaesub; Garvin, Amani M.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Harrison, Fiona A.; Stern, Daniel; Zhang, William W.

2017-10-01

We present a hard X-ray observation of the TeV gamma-ray binary candidate HESS J1832-093, which is coincident with the supernova remnant G22.7-0.2, using the Nuclear Spectroscopic Telescope Array. Non-thermal X-ray emission from XMMU J183245-0921539, the X-ray source associated with HESS J1832-093, is detected up to ˜30 keV and is well-described by an absorbed power-law model with a best-fit photon index {{Γ }}=1.5+/- 0.1. A re-analysis of archival Chandra and XMM-Newton data finds that the long-term X-ray flux increase of XMMU J183245-0921539 is {50}-20+40 % (90% C.L.), much less than previously reported. A search for a pulsar spin period or binary orbit modulation yields no significant signal to a pulse fraction limit of {f}p< 19 % in the range 4 ms < P< 40 ks. No red noise is detected in the FFT power spectrum to suggest active accretion from a binary system. While further evidence is required, we argue that the X-ray and gamma-ray properties of XMMU J183245-0921539 are most consistent with a non-accreting binary generating synchrotron X-rays from particle acceleration in the shock formed as a result of the pulsar and stellar wind collision. We also report on three nearby hard X-ray sources, one of which may be associated with diffuse emission from a fast-moving supernova fragment interacting with a dense molecular cloud.

X-ray Spectral Formation In High-mass X-ray Binaries: The Case Of Vela X-1

NASA Astrophysics Data System (ADS)

Akiyama, Shizuka; Mauche, C. W.; Liedahl, D. A.; Plewa, T.

2007-05-01

We are working to develop improved models of radiatively-driven mass flows in the presence of an X-ray source -- such as in X-ray binaries, cataclysmic variables, and active galactic nuclei -- in order to infer the physical properties that determine the X-ray spectra of such systems. The models integrate a three-dimensional time-dependent hydrodynamics capability (FLASH); a comprehensive and uniform set of atomic data, improved calculations of the line force multiplier that account for X-ray photoionization and non-LTE population kinetics, and X-ray emission-line models appropriate to X-ray photoionized plasmas (HULLAC); and a Monte Carlo radiation transport code that simulates Compton scattering and recombination cascades following photoionization. As a test bed, we have simulated a high-mass X-ray binary with parameters appropriate to Vela X-1. While the orbital and stellar parameters of this system are well constrained, the physics of X-ray spectral formation is less well understood because the canonical analytical wind velocity profile of OB stars does not account for the dynamical and radiative feedback effects due to the rotation of the system and to the irradiation of the stellar wind by X-rays from the neutron star. We discuss the dynamical wind structure of Vela X-1 as determined by the FLASH simulation, where in the binary the X-ray emission features originate, and how the spatial and spectral properties of the X-ray emission features are modified by Compton scattering, photoabsorption, and fluorescent emission. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

The coupling of a disk corona and a jet for the radio/X-ray correlation in black hole X-ray binaries

NASA Astrophysics Data System (ADS)

Qiao, Erlin

2015-08-01

We interpret the radio/X-ray correlation of LR ∝ LX1.4 for LX/LEdd >10-3 in black hole X-ray binaries with a detailed disk corona-jet model, in which the accretion flow and the jet are connected by a parameter, ‘η’, describing the fraction of the matter in the accretion flow ejected outward to form the jet. We calculate LR and LX at different mass accretion rates, adjusting η to fit the observed radio/X-ray correlation of the black hole X-ray transient H1743-322 for LX/LEdd > 10-3. It is found that the value of η for this radio/X-ray correlation for LX/LEdd > 10-3, is systematically less than that of the case for LX/LEdd < 10-3, which is consistent with the general idea that the jet is often relatively suppressed at the high luminosity phase in black hole X-ray binaries.

Exploring X-ray Emission from Winds in Two Early B-type Binary Systems

NASA Astrophysics Data System (ADS)

Rotter, John P.; Hole, Tabetha; Ignace, Richard; Oskinova, Lida

2017-01-01

The winds of the most massive (O-type) stars have been well studied, but less is known about the winds of early-type B stars, especially in binaries. Extending O-star wind theory to these smaller stars, we would expect them to emit X-rays, and when in a B-star binary system, the wind collision should emit additional X-rays. This combined X-ray flux from nearby B-star binary systems should be detectable with current telescopes. Yet X-ray observations of two such systems with the Chandra Observatory not only show far less emission than predicted, but also vary significantly from each other despite having very similar observed characteristics. We will present these observations, and our work applying the classic Castor, Abbott, and Klein (CAK) wind theory, combined with more recent analytical wind-shock models, attempting to reproduce this unexpected range of observations.

SETI at X-energies - parasitic searches from astrophysical observations.

NASA Astrophysics Data System (ADS)

Corbet, R. H. D.

1997-01-01

If a sufficiently advanced civilization can either modulate the emission from an X-ray binary, or make use of the natural high luminosity to power an artificial transmitter, these can serve as good beacons for interstellar communication without involving excessive energy costs to the broadcasting civilization. In addition, the small number of X-ray binaries in the Galaxy considerably reduces the number of targets that must be investigated compared to searches in other energy bands. Low mass X-ray binaries containing neutron stars in particular are considered as prime potential natural and artificial beacons and high time resolution (better than 1ms) observations are encouraged. All sky monitors provide the capability of detecting brief powerful artificial signals from isolated neutron stars. New capabilities of X-ray astronomy satellites developed for astrophysical purposes are enabling SETI in new parameter regimes. For example, the X-ray Timing Explorer satellite provides the capability of exploring the sub-millisecond region. Other planned X-ray astronomy satellites should provide significantly improved spectral resolution. While SETI at X-ray energies is highly speculative (and rather unfashionable) by using a parasitic approach little additional cost is involved. The inclusion of X-ray binaries in target lists for SETI at radio and other wavebands is also advocated.

X-ray astronomy from Uhuru to HEAO-1

NASA Technical Reports Server (NTRS)

Clark, G. W.

1981-01-01

The nature of galactic and extragalactic X-ray sources is investigated using observations made with nine satellites and several rockets. The question of X-ray pulsars being neutron stars or white dwarfs is considered, as is the nature of Population II and low-luminosity X-ray stars, the diffuse X-ray emission from clusters of galaxies, the unidentified high-galactic-latitude (UHGL) sources, and the unresolved soft X-ray background. The types of sources examined include binary pulsars, Population II X-ray stars (both nonbursters and bursters) inside and outside globular clusters, coronal X-ray emitters, and active galactic nuclei. It is concluded that: (1) X-ray pulsars are strongly magnetized neutron stars formed in the evolution of massive close binaries; (2) all Population II X-ray stars are weakly magnetized or nonmagnetic neutron stars accreting from low-mass companions in close binary systems; (3) the diffuse emission from clusters is thermal bremsstrahlung of hot matter processed in stars and swept out by ram pressure exerted by the intergalactic gas; (4) most or all of the UHGL sources are active galactic nuclei; and (5) the soft X-ray background is emission from a hot component of the interstellar medium.

Accreting binary population synthesis and feedback prescriptions

NASA Astrophysics Data System (ADS)

Fragos, Tassos

2016-04-01

Studies of extagalactic X-ray binary populations have shown that the characteristics of these populations depend strongly on the characteristics of the host galaxy's parent stellar population (e.g. star-formation history and metallicity). These dependencies not only make X-ray binaries promising for aiding in the measurement of galaxy properties themselves, but they also have important astrophysical and cosmological implications. For example, due to the relatively young stellar ages and primordial metallicities in the early Universe (z > 3), it is predicted that X-ray binaries were more luminous than today. The more energetic X-ray photons, because of their long mean-free paths, can escape the galaxies where they are produced, and interact at long distances with the intergalactic medium. This could result in a smoother spatial distribution of ionized regions, and more importantly in an overall warmer intergalactic medium. The energetic X-ray photons emitted from X-ray binaries dominate the X-ray radiation field over active galactic nuclei at z > 6 - 8, and hence Χ-ray binary feedback can be a non-negligible contributor to the heating and reionization of the inter-galactic medium in the early universe. The spectral energy distribution shape of the XRB emission does not change significantly with redshift, suggesting that the same XRB subpopulation, namely black-hole XRBs in the high-soft state, dominates the cumulative emission at all times. On the contrary, the normalization of the spectral energy distribution does evolve with redshift. To zeroth order, this evolution is driven by the cosmic star-formation rate evolution. However, the metallicity evolution of the universe and the mean stellar population age are two important factors that affect the X-ray emission from high-mass and low-mass XRBs, respectively. In this talk, I will review recent studies on the potential feedback from accreting binary populations in galactic and cosmological scales. Furthermore, I will discuss which are the next steps towards a more physically realisitc modelling of accreting compact object populations in the early Universe.

Accretion disk dynamics in X-ray binaries

NASA Astrophysics Data System (ADS)

Peris, Charith Srian

Accreting X-ray binaries consist of a normal star which orbits a compact object with the former transferring matter onto the later via an accretion disk. These accretion disks emit radiation across the entire electromagnetic spectrum. This thesis exploits two regions of the spectrum, exploring the (1) inner disk regions of an accreting black hole binary, GRS1915+105, using X-ray spectral analysis and (2) the outer accretion disks of a set of neutron star and black hole binaries using Doppler Tomography applied on optical observations. X-ray spectral analysis of black hole binary GRS1915+105: GRS1915+105 stands out as an exceptional black hole primarily due to the wild variability exhibited by about half of its X-ray observations. This study focused on the steady X-ray observations of the source, which were found to exhibit significant curvature in the harder coronal component within the RXTE/PCA band-pass. The roughly constant inner-disk radius seen in a majority of the steady-soft observations is strongly reminiscent of canonical soft state black-hole binaries. Remarkably, the steady-hard observations show the presence of growing truncation in the inner-disk. A majority of the steady observations of GRS1915+105 map to the states observed in canonical black hole binaries which suggests that within the complexity of this source is a simpler underlying basis of states. Optical tomography of X-ray binary systems: Doppler tomography was applied to the strong line features present in the optical spectra of X-ray binaries in order to determine the geometric structure of the systems' emitting regions. The point where the accretion stream hits the disk, also referred to as the "hotspot'', is clearly identified in the neutron star system V691 CrA and the black hole system Nova Muscae 1991. Evidence for stream-disk overflows exist in both systems, consistent with relatively high accretion rates. In contrast, V926 Sco does not show evidence for the presence of a hotspot which is consistent with its lower accretion state. The donor stars in V691 CrA and Nova Muscae 1991 were also detected.

X-ray Observations of Binary and Single Wolf-Rayet Stars with XMM-Newton and Chandra

NASA Technical Reports Server (NTRS)

Skinner, Stephen; Gudel, Manuel; Schmutz, Werner; Zhekov, Svetozar

2006-01-01

We present an overview of recent X-ray observations of Wolf-Rayet (WR) stars with XMM-Newton and Chandra. These observations are aimed at determining the differences in X-ray properties between massive WR + OB binary systems and putatively single WR stars. A new XMM spectrum of the nearby WN8 + OB binary WR 147 shows hard absorbed X-ray emission (including the Fe Ka line complex), characteristic of colliding wind shock sources. In contrast, sensitive observations of four of the closest known single WC (carbon-rich) WR stars have yielded only nondetections. These results tentatively suggest that single WC stars are X-ray quiet. The presence of a companion may thus be an essential factor in elevating the X-ray emission of WC + OB stars to detectable levels.

A Chandra Survey of Milky Way Globular Clusters. I. Emissivity and Abundance of Weak X-Ray Sources

NASA Astrophysics Data System (ADS)

Cheng, Zhongqun; Li, Zhiyuan; Xu, Xiaojie; Li, Xiangdong

2018-05-01

Based on archival Chandra data, we have carried out an X-ray survey of 69, or nearly half the known population of, Milky Way globular clusters (GCs), focusing on weak X-ray sources, mainly cataclysmic variables (CVs) and coronally active binaries (ABs). Using the cumulative X-ray luminosity per unit stellar mass (i.e., X-ray emissivity) as a proxy of the source abundance, we demonstrate a paucity (lower by 41% ± 27% on average) of weak X-ray sources in most GCs relative to the field, which is represented by the Solar Neighborhood and Local Group dwarf elliptical galaxies. We also revisit the mutual correlations among the cumulative X-ray luminosity (L X), cluster mass (M), and stellar encounter rate (Γ), finding {L}{{X}}\\propto {M}0.74+/- 0.13, {L}{{X}}\\propto {{{Γ }}}0.67+/- 0.07 and {{Γ }}\\propto {M}1.28+/- 0.17. The three quantities can further be expressed as {L}{{X}}\\propto {M}0.64+/- 0.12 {{{Γ }}}0.19+/- 0.07, which indicates that the dynamical formation of CVs and ABs through stellar encounters in GCs is less dominant than previously suggested, and that the primordial formation channel has a substantial contribution. Taking these aspects together, we suggest that a large fraction of primordial, soft binaries have been disrupted in binary–single or binary–binary stellar interactions before they could otherwise evolve into X-ray-emitting close binaries, whereas the same interactions also have led to the formation of new close binaries. No significant correlations between {L}{{X}}/{L}K and cluster properties, including dynamical age, metallicity, and structural parameters, are found.

A search for X-ray binary stars in their quiescent phase

NASA Technical Reports Server (NTRS)

Helfand, D. J.

1980-01-01

Fourteen early-type stars representative of systems which may be harboring a neutron star companion and are thus potential progenitors of massive X-ray binaries have been examined for X-ray emission with the HEAO A-1 experiment. Limits on the 0.5-20 keV luminosity for these objects lie in the range 10 to the 31-33 erg/sec. In several cases, the hypothesis of a collapsed companion, in combination with the X-ray limit, places a serious constraint on the mass-loss rate of the primary star. In one instance, an X-ray source was discovered coincident with a candidate star, although the luminosity of 5 x 10 to the 31 is consistent with that expected from a single star of the same spectral type. The prospects for directly observing the quiescent phase of a binary X-ray source with the Einstein Observatory are discussed in the context of these results.

Accreting Binary Populations in the Earlier Universe

NASA Technical Reports Server (NTRS)

Hornschemeier, Ann

2010-01-01

It is now understood that X-ray binaries dominate the hard X-ray emission from normal star-forming galaxies. Thanks to the deepest (2-4 Ms) Chandra surveys, such galaxies are now being studied in X-rays out to z approximates 4. Interesting X-ray stacking results (based on 30+ galaxies per redshift bin) suggest that the mean rest-frame 2-10 keV luminosity from z=3-4 Lyman break galaxies (LBGs), is comparable to the most powerful starburst galaxies in the local Universe. This result possibly indicates a similar production mechanism for accreting binaries over large cosmological timescales. To understand and constrain better the production of X-ray binaries in high-redshift LBGs, we have utilized XMM-Newton observations of a small sample of z approximates 0.1 GALEX-selected Ultraviolet-Luminous Galaxies (UVLGs); local analogs to high-redshift LBGs. Our observations enable us to study the X-ray emission from LBG-like galaxies on an individual basis, thus allowing us to constrain object-to-object variances in this population. We supplement these results with X-ray stacking constraints using the new 3.2 Ms Chandra Deep Field-South (completed spring 2010) and LBG candidates selected from HST, Swift UVOT, and ground-based data. These measurements provide new X-ray constraints that sample well the entire z=0-4 baseline

Discovery of very high energy gamma rays associated with an x-ray binary.

PubMed

Aharonian, F; Akhperjanian, A G; Aye, K-M; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Berghaus, P; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Breitling, F; Brown, A M; Bussons Gordo, J; Chadwick, P M; Chounet, L-M; Cornils, R; Costamante, L; Degrange, B; Dickinson, H J; Djannati-Ataï, A; Drury, L O'c; Dubus, G; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Fleury, P; Fontaine, G; Fuchs, Y; Funk, S; Gallant, Y A; Giebels, B; Gillessen, S; Glicenstein, J F; Goret, P; Hadjichristidis, C; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; Jacholkowska, A; de Jager, O C; Khélifi, B; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemière, A; Lemoine-Goumard, M; Leroy, N; Lohse, T; Marcowith, A; Martin, J-M; Martineau-Huynh, O; Masterson, C; McComb, T J L; de Naurois, M; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Raux, J; Rayner, S M; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V; Saugé, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Spangler, D; Steenkamp, R; Stegmann, C; Tavernet, J-P; Terrier, R; Théoret, C G; Tluczykont, M; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J

2005-07-29

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

The optical counterpart to the Be/X-ray binary SAX J2239.3+6116

NASA Astrophysics Data System (ADS)

Reig, P.; Blay, P.; Blinov, D.

2017-02-01

Context. Be/X-ray binaries represent the main group of high-mass X-ray binaries. The determination of the astrophysical parameters of the counterparts of these high-energy sources is important for the study of X-ray binary populations in our Galaxy. X-ray observations suggest that SAX J2239.3+6116 is a Be/X-ray binary. However, little is known about the astrophysical parameters of its massive companion. Aims: The main goal of this work is to perform a detailed study of the optical variability of the Be/X-ray binary SAX J2239.3+6116. Methods: We obtained multi-colour BVRI photometry and polarimetry and 4000-7000 Å spectroscopy. The 4000-5000 Å spectra allowed us to determine the spectral type and projected rotational velocity of the optical companion; the 6000-7000 Å spectra, together with the photometric magnitudes, were used to derive the colour excess E(B-V), estimate the distance, and to study the variability of the Hα line. Results: The optical counterpart to SAX J2239.3+6116 is a V = 14.8 B0Ve star located at a distance of 4.9 kpc. The interstellar reddening in the direction of the source is E(B-V) = 1.70 ± 0.03 mag. The monitoring of the Hα line reveals a slow long-term decline of its equivalent width since 2001. The line profile is characterized by a stable double-peak profile with no indication of large-scale distortions. We measured intrinsic optical polarization for the first time. Although somewhat higher than predicted by the models, the optical polarization is consistent with electron scattering in the circumstellar disk. Conclusions: We attribute the long-term decrease in the intensity of the Hα line to the dissipation of the circumstellar disk of the Be star. The longer variability timescales observed in SAX J2239.3+6116 compared to other Be/X-ray binaries may be explained by the wide orbit of the system.

An X-ray spectral study of colliding wind binaries

NASA Astrophysics Data System (ADS)

Sugawara, Yasuharu; Maeda, Yoshitomo; Tsuboi, Yohko

2012-03-01

We present results of spectral studies of two Wolf-Rayet colliding wind binaries (WR 140 and WR 30a), using the data obtained by the Suzaku and XMM-Newton satellites. WR 140 is one of the best known examples of a Wolf-Rayet star. We executed the Suzaku X-ray observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. We detected hard X-ray excess in the HXD band (> 10 keV) for the first time from a W-R binary. The emission measure of the dominant, high temperature component is not inversely proportional to the distance between the two stars. WR 30a is the rare WO-type W-R binary. We executed XMM-Newton observations and detected X-ray emission for the first time. The broad-band spectrum was well-fitted with double-absorption model. The hard X-ray emission was heavily absorbed. This can be interpreted that the hard X-ray emitting plasma exist near WO star.

Binary model of Circinus X-1. I - Eccentricity from combined X-ray and radio observations

NASA Technical Reports Server (NTRS)

Murdin, P.; Jauncey, D. L.; Lerche, I.; Nicolson, G. D.; Kaluzienski, L. J.; Holt, S. S.; Haynes, R. F.

1980-01-01

A binary star model is used to account for the 16.59-d flaring behavior of the X-ray emission from Circinus X-1. The orbital eccentricity of 0.8 + or - 0.1 is derived from the X-ray light curve by assuming that the sharp X-ray cut-off every 16.59-d is a result of bound-free absorption in the primary star's stellar wind. The shape of the light curve has changed over the last eight years, and this is interpreted as due to orbital precession of the binary system. Simultaneous radio and X-ray observations of the flare from Circinus X-1 on February 1-5, 1978 are reported. These are accounted for within the framework of the model. The radio observations at 5 GHz are used independently to derive a high value of the orbital eccentricity (e = 0.7).

X-Ray Background from Early Binaries

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-11-01

What impact did X-rays from the first binary star systems have on the universe around them? A new study suggests this radiation may have played an important role during the reionization of our universe.Ionizing the UniverseDuring the period of reionization, the universe reverted from being neutral (as it was during recombination, the previous period)to once again being ionized plasma a state it has remained in since then. This transition, which occurred between 150 million and one billion years after the Big Bang (redshift of 6 z 20), was caused by the formation of the first objects energetic enough to reionize the universes neutral hydrogen.ROSAT image of the soft X-ray background throughout the universe. The different colors represent different energy bands: 0.25 keV (red), 0.75 keV (green), 1.5 keV (blue). [NASA/ROSAT Project]Understanding this time period in particular, determining what sources caused the reionization, and what the properties were of the gas strewn throughout the universe during this time is necessary for us to be able to correctly interpret cosmological observations.Conveniently, the universe has provided us with an interesting clue: the large-scale, diffuse X-ray background we observe all around us. What produced these X-rays, and what impact did this radiation have on the intergalactic medium long ago?The First BinariesA team of scientists led by Hao Xu (UC San Diego) has suggested that the very first generation of stars might be an important contributor to these X-rays.This hypothetical first generation, Population III stars, are thought to have formed before and during reionization from large clouds of gas containing virtually no metals. Studies suggest that a large fraction of Pop III stars formed in binaries and when those stars ended their lives as black holes, ensuing accretion from their companions could produceX-ray radiation.The evolution with redshift of the mean X-ray background intensities. Each curve represents a different observed X-ray energy (and the total X-ray background is given by the sum of the curves). The two panels show results from two different calculation methods. [Xu et al. 2016]Xu and collaborators have now attempted to model to the impact of this X-ray production from Pop III binaries on the intergalactic medium and determine how much it could have contributed to reionization and the diffuse X-ray background we observe today.Generating a BackgroundThe authorsestimated the X-ray luminosities from Pop III binaries using the results of a series of galaxy-formation simulations, beginning at a redshift of z 25 and evolving up to z = 7.6. They then used these luminosities to calculate the resulting X-ray background.Xu and collaborators find that Pop III binaries can produce significant X-ray radiation throughout the period of reionization, and this radiation builds up gradually into an X-ray background. The team shows that X-rays from Pop III binaries might actually dominate more commonly assumed sources of the X-ray background at high redshifts (such as active galactic nuclei), and this radiation isstrong enough to heat the intergalactic medium to 1000K and ionize a few percent of the neutral hydrogen.If Pop III binaries are indeed this large of a contributor to the X-ray background and to the local and global heating of the intergalactic medium, then its important that we follow up with more detailed modeling to understand what this means for our interpretation of cosmological observations.CitationHao Xu et al 2016 ApJL 832 L5. doi:10.3847/2041-8205/832/1/L5

X-ray illumination of globular cluster puzzles. [globular cluster X ray sources as clues to Milky Way Galaxy age and evolution

NASA Technical Reports Server (NTRS)

Lightman, A. P.; Grindlay, J. E.

1982-01-01

Globular clusters are thought to be among the oldest objects in the Galaxy, and provide, in this connection, important clues for determining the age and process of formation of the Galaxy. The present investigation is concerned with puzzles relating to the X-ray emission of globular clusters, taking into account questions regarding the location of X-ray emitting clusters (XEGC) unusually near the galactic plane and/or galactic center. An adopted model is discussed for the nature, formation, and lifetime of X-ray sources in globular clusters. An analysis of the available data is conducted in connection with a search for correlations between binary formation time scales, central relaxation times, galactic locations, and X-ray emission. The positive correlation found between distance from galactic center and two-body binary formation time for globular clusters, explanations for this correlation, and the hypothesis that X-ray sources in globular clusters require binary star systems provide a possible explanation of the considered puzzles.

The X-Ray Binary Population of the Nearby Dwarf Starburst Galaxy IC 10: Variable and Transient X-Ray Sources

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

Laycock, Silas; Cappallo, Rigel; Williams, Benjamin F.

We have monitored the Cassiopeia dwarf galaxy (IC 10) in a series of 10 Chandra ACIS-S observations to capture its variable and transient X-ray source population, which is expected to be dominated by High Mass X-ray Binaries (HMXBs). We present a sample of 21 X-ray sources that are variable between observations at the 3 σ level, from a catalog of 110 unique point sources. We find four transients (flux variability ratio greater than 10) and a further eight objects with ratios >5. The observations span the years 2003–2010 and reach a limiting luminosity of >10{sup 35} erg s{sup −1}, providingmore » sensitivity to X-ray binaries in IC 10 as well as flare stars in the foreground Milky Way. The nature of the variable sources is investigated from light curves, X-ray spectra, energy quantiles, and optical counterparts. The purpose of this study is to discover the composition of the X-ray binary population in a young starburst environment. IC 10 provides a sharp contrast in stellar population age (<10 My) when compared to the Magellanic Clouds (40–200 My) where most of the known HMXBs reside. We find 10 strong HMXB candidates, 2 probable background Active Galactic Nuclei, 4 foreground flare-stars or active binaries, and 5 not yet classifiable sources. Complete classification of the sample requires optical spectroscopy for radial velocity analysis and deeper X-ray observations to obtain higher S/N spectra and search for pulsations. A catalog and supporting data set are provided.« less

NuSTAR Observations of Two New Black Hole X-ray Binary Candidates within 1 pc of Sgr A*

NASA Astrophysics Data System (ADS)

Hord, Benjamin; Hailey, Charles; Mori, Kaya; Mandel, Shifra

2018-01-01

Remarkably, two new X-ray transients were discovered in outburst within ~1 pc of the Galactic Center by the Swift X-ray Telescope in the first half of 2016. A few weeks after each outburst began, NuSTAR ToO observations were triggered for both of the objects. These sources have no known counterparts at other energies. Both objects exhibit relativistically broadened Fe lines in their spectra and possible quasi-periodic oscillations (QPO) in their power spectra, which are features seen in many black hole X-ray binaries. Combined with the fact that there have been no previously observed large outbursts at these positions over the decade of the Swift X-ray Telescope galactic center monitoring campaign, these sources make for prime black hole binary candidates (BHC) rather than neutron star low-mass X-ray binaries (NS-LMXB), which have a known short (<~5 year) recurrence time. We will present 3-79 keV NuSTAR spectra and timing analysis of these sources that supports a black hole binary interpretation over a neutron star scenario. These new BHC, combined with at least one other previously discovered BHC near the Galactic Center, hint at a potentially substantive black hole population in the vicinity of the supermassive black hole at Sgr A*.

The cosmic-ray and gas content of the Cygnus region as measured in γ -rays by the Fermi Large Area Telescope

DOE PAGES

Ackermann, M.

2012-02-01

Context. The Cygnus region hosts a giant molecular-cloud complex that actively forms massive stars. Interactions of cosmic rays with interstellar gas and radiation fields make it shine at γ-ray energies. Several γ-ray pulsars and other energetic sources are seen in this direction. Aims. In this paper we analyze the γ-ray emission measured by the Fermi Large Area Telescope in the energy range from 100 MeV to 100 GeV in order to probe the gas and cosmic-ray content on the scale of the whole Cygnus complex. The γ-ray emission on the scale of the central massive stellar clusters and from individualmore » sources is addressed elsewhere. Methods. The signal from bright pulsars is greatly reduced by selecting photons in their off-pulse phase intervals. We compare the diffuse γ-ray emission with interstellar gas maps derived from radio/mm-wave lines and visual extinction data. A general model of the region, including other pulsars and γ-ray sources, is sought. Results. The integral Hi emissivity above 100 MeV averaged over the whole Cygnus complex amounts to [2.06 ± 0.11 (stat.) +0.15 -0.84 (syst.)] × 10 -26 photons s -1 sr -1 H-atom -1, where the systematic error is dominated by the uncertainty on the Hi opacity to calculate its column densities. The integral emissivity and its spectral energy distribution are both consistent within the systematics with LAT measurements in the interstellar space near the solar system. The average XCO = N(H2)/WCO ratio is found to be [1.68 ± 0.05 (stat.) +0.87 -0.10 (Hi opacity)] × 1020 molecules cm -2 (K km s -1) -1, consistent with other LAT measurements in the Local Arm. We detect significant γ-ray emission from dark neutral gas for a mass corresponding to ~ 40% of what is traced by CO. The total interstellar mass in the Cygnus complex inferred from its γ-ray emission amounts to 8 +5 -1 × 106M⊙ at a distance of 1.4 kpc. Conclusions. Despite the conspicuous star formation activity and high masses of the interstellar clouds, the cosmic-ray population in the Cygnus complex averaged over a few hundred parsecs is similar to that of the local interstellar space.« less

Temporal X-ray astronomy with a pinhole camera. [cygnus and scorpius constellation

NASA Technical Reports Server (NTRS)

Holt, S. S.

1975-01-01

Preliminary results from the Ariel-5 all-sky X-ray monitor are presented, along with sufficient experiment details to define the experiment sensitivity. Periodic modulation of the X-ray emission was investigated from three sources with which specific periods were associated, with the results that the 4.8 hour variation from Cyg X-3 was confirmed, a long-term average 5.6 day variation from Cyg X-1 was discovered, and no detectable 0.787 day modulation of Sco X-1 was observed. Consistency of the long-term Sco X-1 emission with a shot-noise model is discussed, wherein the source behavior is shown to be interpretable as approximately 100 flares per day, each with a duration of several hours. A sudden increase in the Cyg X-1 intensity by almost a factor of three on 22 April 1975 is reported, after 5 months of relative source constancy. The light curve of a bright nova-like transient source in Triangulum is presented, and compared with previously observed transient sources. Preliminary evidence for the existence of X-ray bursts with duration less than 1 hour is offered.

Research in astrophysical processes

NASA Technical Reports Server (NTRS)

Ruderman, Malvin A.

1994-01-01

Work completed under this grant is summarized in the following areas:(1) radio pulsar turn on and evaporation of companions in very low mass x-ray binaries and in binary radio pulsar systems; (2) effects of magnetospheric pair production on the radiation from gamma-ray pulsars; (3) radiation transfer in the atmosphere of an illuminated companion star; (4) evaporation of millisecond pulsar companions;(5) formation of planets around pulsars; (6) gamma-ray bursts; (7) quasi-periodic oscillations in low mass x-ray binaries; (8) origin of high mass x-ray binaries, runaway OB stars, and the lower mass cutoff for core collapse supernovae; (9) dynamics of planetary atmospheres; (10) two point closure modeling of stationary, forced turbulence; (11) models for the general circulation of Saturn; and (12) compressible convection in stellar interiors.

On the Binary Nature of Massive Blue Hypergiants: High-resolution X-Ray Spectroscopy Suggests That Cyg OB2 12 is a Colliding Wind Binary

NASA Astrophysics Data System (ADS)

Oskinova, L. M.; Huenemoerder, D. P.; Hamann, W.-R.; Shenar, T.; Sander, A. A. C.; Ignace, R.; Todt, H.; Hainich, R.

2017-08-01

The blue hypergiant Cyg OB2 12 (B3Ia+) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using the Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism depopulating the metastable upper levels of the forbidden lines of the He-like ions Si xiv and Mg xii. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only at the photosphere or in a colliding wind zone between binary components. The observed X-ray spectra are well-fitted by thermal plasma models, with average temperatures in excess of 10 MK. The wind speed in Cyg OB2 12 is not high enough to power such high temperatures, but the collision of two winds in a binary system can be sufficient. We used archival data to investigate the X-ray properties of other blue hypergiants. In general, stars of this class are not detected as X-ray sources. We suggest that our new Chandra observations of Cyg OB2 12 can be best explained if Cyg OB2 12 is a colliding wind binary possessing a late O-type companion. This makes Cyg OB2 12 only the second binary system among the 16 known Galactic hypergiants. This low binary fraction indicates that the blue hypergiants are likely products of massive binary evolution during which they either accreted a significant amount of mass or already merged with their companions.

On the Binary Nature of Massive Blue Hypergiants: High-resolution X-Ray Spectroscopy Suggests That Cyg OB2 12 is a Colliding Wind Binary

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

Oskinova, L. M.; Hamann, W.-R.; Shenar, T.

The blue hypergiant Cyg OB2 12 (B3Ia{sup +}) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using the Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism depopulating the metastable upper levels of the forbidden lines of the He-like ions Si xiv and Mg xii. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only atmore » the photosphere or in a colliding wind zone between binary components. The observed X-ray spectra are well-fitted by thermal plasma models, with average temperatures in excess of 10 MK. The wind speed in Cyg OB2 12 is not high enough to power such high temperatures, but the collision of two winds in a binary system can be sufficient. We used archival data to investigate the X-ray properties of other blue hypergiants. In general, stars of this class are not detected as X-ray sources. We suggest that our new Chandra observations of Cyg OB2 12 can be best explained if Cyg OB2 12 is a colliding wind binary possessing a late O-type companion. This makes Cyg OB2 12 only the second binary system among the 16 known Galactic hypergiants. This low binary fraction indicates that the blue hypergiants are likely products of massive binary evolution during which they either accreted a significant amount of mass or already merged with their companions.« less

Contact binary stars. I - An X-ray survey

NASA Technical Reports Server (NTRS)

Cruddace, R. G.; Dupree, A. K.

1984-01-01

X-ray emission from a contact binary star was first detected by the HEAO 1 satellite in 1977. Spectroscopic observations of 44i Boo and VW Cep by IUE established the presence of high-temperature chromospheric and transition region emission lines in the spectra of these stars. The HEAO 1 and IUE results implied that the processes causing X-ray emission from VW Cep might be similar to those energizing the solar corona, and that X-ray emission might be a common occurrence among contact binary stars. A series of observations of these stars was, therefore, conducted with the aid of the HEAO 2 (Einstein) Observatory. The present investigation is concerned with the results of these observations, giving attention to their implications with respect to the nature of contact binary stars. The results are compared with similar HEAO 2 studies of coronal X-ray sources in the local region of the Galaxy, in the Hyades, and other rapidly rotating systems.

ASCA Observation of MS 1603.6+2600 (=UW Coronae Borealis): A Dipping Low-Mass X-ray Binary in the Outer Halo?

NASA Technical Reports Server (NTRS)

Mukai, Koji; Smale, Alan; Stahle, Caroline K.; Schlegel, Eric M.; Wijnands, Rudy; White, Nicholas E. (Technical Monitor)

2001-01-01

MS 1603.6+2600 is a high-latitude X-ray binary with a 111 min orbital period, thought to be either an unusual cataclysmic variable or an unusual low-mass X-ray binary. In an ASCA observation in 1997 August, we find a burst whose light curve suggests a Type 1 (thermonuclear flash) origin. We also find an orbital X-ray modulation in MS 1603.6+2600, which is likely to be periodic dips, presumably due to azimuthal structure in the accretion disk. Both are consistent with this system being a normal low-mass X-ray binary harboring a neutron star, but at a great distance. We tentatively suggest that MS 1603.6+2600 is located in the outer halo of the Milky Way, perhaps associated with the globular cluster Palomar 14, 11 deg away from MS 1603.6+2600 on the sky at an estimated distance of 73.8 kpc.

Stellar wind measurements for Colliding Wind Binaries using X-ray observations

NASA Astrophysics Data System (ADS)

Sugawara, Yasuharu; Maeda, Yoshitomo; Tsuboi, Yohko

2017-11-01

We report the results of the stellar wind measurement for two colliding wind binaries. The X-ray spectrum is the best measurement tool for the hot postshock gas. By monitoring the changing of the the X-ray luminosity and column density along with the orbital phases, we derive the mass-loss rates of these stars.

Recognition of binary x-ray systems utilizing the doppler effect

NASA Technical Reports Server (NTRS)

Novak, B. L.

1980-01-01

The possibility of recognizing the duality of a single class of X-ray systems utilizing the Doppler effect is studied. The procedure is based on the presence of a period which coincides with the orbital period at the intensity of the radiation in a fixed energy interval of the X-ray component of a binary system.

A Chandra X-Ray Census of the Interacting Binaries in Old Open Clusters—Collinder 261

NASA Astrophysics Data System (ADS)

Vats, Smriti; van den Berg, Maureen

2017-03-01

We present the first X-ray study of Collinder 261 (Cr 261), which at an age of 7 Gyr is one of the oldest open clusters known in the Galaxy. Our observation with the Chandra X-Ray Observatory is aimed at uncovering the close interacting binaries in Cr 261, and reaches a limiting X-ray luminosity of {L}X≈ 4× {10}29 {erg} {{{s}}}-1 (0.3-7 keV) for stars in the cluster. We detect 107 sources within the cluster half-mass radius r h , and we estimate that among the sources with {L}X≳ {10}30 {erg} {{{s}}}-1, ˜26 are associated with the cluster. We identify a mix of active binaries and candidate active binaries, candidate cataclysmic variables, and stars that have “straggled” from the main locus of Cr 261 in the color-magnitude diagram. Based on a deep optical source catalog of the field, we estimate that Cr 261 has an approximate mass of 6500 M ⊙, roughly the same as the old open cluster NGC 6791. The X-ray emissivity of Cr 261 is similar to that of other old open clusters, supporting the trend that they are more luminous in X-rays per unit mass than old populations of higher (globular clusters) and lower (the local neighborhood) stellar density. This implies that the dynamical destruction of binaries in the densest environments is not solely responsible for the observed differences in X-ray emissivity.

Probing the Environment of Accreting Compact Objects

NASA Astrophysics Data System (ADS)

Hanke, Manfred

2011-04-01

X-ray binaries are the topic of this thesis. They consist of a compact object -- a black hole or a neutron star -- and an ordinary star, which loses matter to the compact object. The gravitational energy released through this process of mass accretion is largely converted into X-rays. The latter are used in the present work to screen the environment of the compact object. The main focus in the case of a massive star is on its wind, which is not homogeneous, but may display structures in form of temperature and density variations. Since great importance is, in multiple respects, attached to stellar winds in astrophysics, there is large interest in general to understand these structures more thoroughly. In particular for X-ray binaries, whose compact object obtains matter from the wind of its companion star, the state of the wind can decisively influence mass accretion and its related radiation processes. A detailed introduction to the fundamentals of stellar winds, compact objects, accretion and radiation processes in X-ray binaries, as well as to the employed instruments and analysis methods, is given in chapter 1. The focus of this investigation is on Cygnus X-1, a binary system with a black hole and a blue supergiant, which form a persistently very bright X-ray source because of accretion from the stellar wind. It had been known for a long time that this source -- when the black hole is seen through the dense stellar wind -- often displays abrupt absorption events whose origin is suspected to be in clumps in the wind. More detailed physical properties of these clumps and of the wind in general are explored in this work. Observations that were specifically acquired for this study, as well as archival data from different satellite observatories, are analyzed in view of signatures of the wind and its fine structures. These results are presented in chapter 2. In a first part of the analysis, the statistical distribution of the brightness of Cyg X-1, as measured since 1996 with the RXTE satellite's all-sky monitor, is investigated in the context of the binary system's orbital phase. The stellar wind is here noticed via absorption of the soft X-radiation. This analysis has not only shown that the mean column density in the wind is -- as already known -- larger along lines of sight passing close by the star, but also that the wind is more clumpy there. The evaluation of more than 2 000 spectra from RXTE's proportional counter, taken within 14.5 years and mostly in the framework of a monitoring campaign, has lead to the same result. Compared to previous studies, the accuracy of the measurements could be improved by a careful investigation of the quality of the low-energy spectrum, which was required to register the scatter due to the clumpiness. In the next part, several high-resolution X-ray sepectra were analyzed, which were recorded with the gratings spectrometer of the highly requested Chandra satellite. The modulation of the absorption could, for the first time, be ascribed to the highly ionized wind, which has consequences for its quantitative interpretation due to the reduced cross sections compared to neutral absorption. Moreover, the acceleration of the wind with increasing distance from the star could be demonstrated, which constitutes an important observational evidence in terms of the wind structure. A conjecture published in 2008, according to which no wind might develop in the ionized environment of the X-ray source, is therewith disproved. By means of spectroscopy of strong absorption events, it was for the first time unequivocally demonstrated that these can be ascribed to a shift of the ionization balance to less strongly ionized gas, due to the enhanced density of the clumps. The increase of the column density of lower ionization stages is also confirmed by the spectroscopic analysis of the contemporaneous observation with the XMM-Newton satellite. Since these simultaneous observations were, in the framework of the largest observational campaign to date, accompanied by all available X-ray satellites, the effect of the absorption events on hard X-rays could be investigated as well. A flux reduction was detected in light curves at high energies, not affected by absorption, which coincides with the time of the strongest absorption event. This effect could be confirmed by time resolved spectroscopy of the XMM data, and be interpreted as due to scattering on a fully ionized cloud. The evolution of the light curve constitutes therefore a tomography of this cloud, and reveals further structure in the stellar wind. The strong absorption event is caused by the cloud's core, which is sufficiently dense that its ionization balance is shifted. Results from the analysis of another source are briefly presented in chapter 3. For the X-ray binary system LMC X-1 in the Large Magellanic Cloud, six spectra have been analyzed in view of their absorption. A connection with the orbital phase was suggested, which indicates absorption by material within the system itself. Concluding this thesis, the detailed results are summarized and discussed in chapter 4, and an outlook on future research possibilities is given.

Wind accretion in the massive X-ray binary 4U 2206+54: abnormally slow wind and a moderately eccentric orbit

NASA Astrophysics Data System (ADS)

Ribó, M.; Negueruela, I.; Blay, P.; Torrejón, J. M.; Reig, P.

2006-04-01

Massive X-ray binaries are usually classified by the properties of the donor star in classical, supergiant and Be X-ray binaries, the main difference being the mass transfer mechanism between the two components. The massive X-ray binary 4U 2206+54 does not fit in any of these groups, and deserves a detailed study to understand how the transfer of matter and the accretion on to the compact object take place. To this end we study an IUE spectrum of the donor and obtain a wind terminal velocity (v_∞) of ~350 km s-1, which is abnormally slow for its spectral type. We also analyse here more than 9 years of available RXTE/ASM data. We study the long-term X-ray variability of the source and find it to be similar to that observed in the wind-fed supergiant system Vela X-1, reinforcing the idea that 4U 2206+54 is also a wind-fed system. We find a quasi-period decreasing from ~270 to ~130 d, noticed in previous works but never studied in detail. We discuss possible scenarios for its origin and conclude that long-term quasi-periodic variations in the mass-loss rate of the primary are probably driving such variability in the measured X-ray flux. We obtain an improved orbital period of P_orb=9.5591±0.0007 d with maximum X-ray flux at MJD 51856.6±0.1. Our study of the orbital X-ray variability in the context of wind accretion suggests a moderate eccentricity around 0.15 for this binary system. Moreover, the low value of v_∞ solves the long-standing problem of the relatively high X-ray luminosity for the unevolved nature of the donor, BD +53°2790, which is probably an O9.5 V star. We note that changes in v_∞ and/or the mass-loss rate of the primary alone cannot explain the different patterns displayed by the orbital X-ray variability. We finally emphasize that 4U 2206+54, together with LS 5039, could be part of a new population of wind-fed HMXBs with main sequence donors, the natural progenitors of supergiant X-ray binaries.

MS 1603.6 + 2600, an unusual X-ray selected binary system at high Galactic latitude

NASA Technical Reports Server (NTRS)

Morris, Simon L.; Liebert, James; Stocke, John T.; Gioia, Isabella M.; Schild, Rudy E.

1990-01-01

The discovery of an eclipsing binary system at Galactic latitude 47 deg, found as a serendipitous X-ray source in the Einstein Extended Medium Sensitivity Survey, is described. The object has X-ray flux 1.1 x 10 to the -12th ergs/sq cm s (0.3-3.5 keV) and mean magnitude R = 19.4. An orbital period of 111 minutes is found. The problem discussed is whether the system has a white dwarf or neutron star primary, in the end preferring the neutron star primary model. If the system has either optical or X-ray luminosities typical of low mass X-ray binaries (LMXB), it must be at a very large distance (30-80 kpc). Blueshifted He I absorption is seen, indicating cool outflowing material, similar to that seen in the LMXB AC 211 in the globular cluster M15.

Iron K lines from low-mass X-ray binaries

NASA Technical Reports Server (NTRS)

Kallman, T.; White, N. E.

1989-01-01

Models are presented for the 6-7 keV iron line emission from low-mass X-ray binaries. A simplified model for an accretion disk corona is used to examine the dependence of the observable line properties, line width and mean energy, on the radial distance of the emission region from the X-ray source, and on the fraction of the X-rays from the source which reach the disk surface. The effects of blending of multiple line components and of Comptonization of the line profile are included in numerical calculations of the emitted profile shape. The results of these calculations, when compared with the line properties observed from several low-mass X-ray binaries, suggest that the broadening is dominated either by rotation or by Compton scattering through a greater optical depth than is expected from an accretion disk corona.

Determination of the atmospheric structure of the BO star companion of SMC X-1 by analysis of Ginga observations

NASA Technical Reports Server (NTRS)

Clark, George W.

1994-01-01

The x-ray phenomena of the binary system SMC X-1/Sk 160, observed with the Ginga and ROSAT x-ray observatories, are compared with computed phenomena derived from a three dimensional hydrodynamical model of the stellar wind perturbed by x-ray heating and ionization which is described in the accompanying paper. In the model the BOI primary star has a line-driven stellar wind in the region of the x-ray shadow and a thermal wind in the region heated by x-rays. We find general agreement between the observed and predicted x-ray spectra throughout the binary orbit cycle, including the extended, variable, and asymmetric eclipse transitions and the period of deep eclipse.

Broad-Band Measurements of Cen X-3 With XTE and CGRO

NASA Technical Reports Server (NTRS)

Vestrand, W. Thomas

1999-01-01

Centaurus X-3 has played a key role in the development of our understanding of galactic x-ray binary sources. Timing analysis of the UHURU x-ray observations for the luminous Cen X-3 source (L approximately 10(exp 38) erg/s) revealed the first evidence for coherent x-ray pulsations from an object in a binary system (Giaconni 1971; Schreier 1972). It was quickly understood that the luminous pulsed x-ray emission could be generated by the accretion of matter from a companion star onto a rotating neutron star and led to the adoption of binary star models as the fundamental model for galactic x-ray sources (e.g. Pringle and Rees 1972; Lamb 1973). Based on modeling and refined observations since the original measurements, we now believe that Cen X-3 is a high mass x-ray binary system that contains a disk-fed pulsar with a period of 4.84 seconds that is in a 2.087 day orbit around an O-star companion. Since the pulsar discovery, its period has been intermittently monitored and those studies show a long term spin-up of the pulsar punctuated by short intervals of spin-down (e.g. Finger 1994). The implied torques are thought to originate from the interaction of an accretion disk with the magnetic field of a neutron star (Ghosh and Lamb 1979).

Optical spectroscopy of the Be/X-ray binary V850 Centauri/GX 304-1 during faint X-ray periodical activity

NASA Astrophysics Data System (ADS)

Malacaria, C.; Kollatschny, W.; Whelan, E.; Santangelo, A.; Klochkov, D.; McBride, V.; Ducci, L.

2017-07-01

Context. Be/X-ray binaries (BeXRBs) are the most populous class of high-mass X-ray binaries. Their X-ray duty cycle is tightly related to the optical companion wind activity, which in turn can be studied through dedicated optical spectroscopic observations. Aims: We study optical spectral features of the Be circumstellar disk to test their long-term variability and their relation with the X-ray activity. Special attention has been given to the Hα emission line, one of the best tracers of the disk conditions. Methods: We obtained optical broadband medium resolution spectra from a dedicated campaign with the Anglo-Australian Telescope and the Southern African Large Telescope in 2014-2015. Data span over one entire binary orbit, and cover both X-ray quiescent and moderately active periods. We used Balmer emission lines to follow the evolution of the circumstellar disk. Results: We observe prominent spectral features, like double-peaked Hα and Hβ emission lines. The HαV/R ratio significantly changes over a timescale of about one year. Our observations are consistent with a system observed at a large inclination angle (I ≳ 60°). The derived circumstellar disk size shows that the disk evolves from a configuration that prevents accretion onto the neutron star, to one that allows only moderate accretion. This is in agreement with the contemporary observed X-ray activity. Our results are interpreted within the context of inefficient tidal truncation of the circumstellar disk, as expected for this source's binary configuration. We derived the Hβ-emitting region size, which is equal to about half of the corresponding Hα-emitting disk, and constrain the luminosity class of V850 Cen as III-V, consistent with the previously proposed class.

A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, Delta Orionis Aa. II. X-Ray Variability

NASA Technical Reports Server (NTRS)

Nichols, J.; Huenemoerder, D. P.; Corcoran, M. F.; Waldron, W.; Naze, Y.; Pollock, A. M. T.; Moffat, A. F. J.; Lauer, J.; Shenar, T.; Russell, C. M. P.;

A Physical Parameterization of the Evolution of X-ray Binary Emission

NASA Astrophysics Data System (ADS)

Gilbertson, Woodrow; Lehmer, Bret; Eufrasio, Rafael

2018-01-01

The Chandra Deep Field-South (CDF-S) and North (CDF-N) surveys, 7 Ms and 2 Ms respectively, contain measurements spanning a large redshift range of z = 0 to 7. These data-rich fields provide a unique window into the cosmic history of X-ray emission from normal galaxies (i.e., not dominated by AGN). Scaling relations between normal-galaxy X-ray luminosity and quantities, such as star formation rate (SFR) and stellar mass (M*), have been used to constrain the redshift evolution of the formation rates of low-mass X-ray binaries (LMXB) and high-mass X-ray binaries (HMXB). However, these measurements do not directly reveal the driving forces behind the redshift evolution of X-ray binaries (XRBs). We hypothesize that changes in the mean stellar age and metallicity of the Universe drive the evolution of LMXB and HMXB emission, respectively. We use star-formation histories, derived through fitting broad-band UV-to-far-IR spectra, to estimate the masses of stellar populations in various age bins for each galaxy. We then divide our galaxy samples into bins of metallicity, and use our star-formation history information and measured X-ray luminosities to determine for each metallicity bin a best model LX/M*(tage). We show that this physical model provides a more useful parameterization of the evolution of X-ray binary emission, as it can be extrapolated out to high redshifts with more sensible predictions. This meaningful relation can be used to better estimate the emission of XRBs in the early Universe, where XRBs are predicted to play an important role in heating the intergalactic medium.

Radio-loudness in black hole transients: evidence for an inclination effect

NASA Astrophysics Data System (ADS)

Motta, S. E.; Casella, P.; Fender, R.

2018-06-01

Accreting stellar-mass black holes appear to populate two branches in a radio:X-ray luminosity plane. We have investigated the X-ray variability properties of a large number of black hole low-mass X-ray binaries, with the aim of unveiling the physical reasons underlying the radio-loud/radio-quiet nature of these sources, in the context of the known accretion-ejection connection. A reconsideration of the available radio and X-ray data from a sample of black hole X-ray binaries confirms that being radio-quiet is the more normal mode of behaviour for black hole binaries. In the light of this we chose to test, once more, the hypothesis that radio loudness could be a consequence of the inclination of the X-ray binary. We compared the slope of the `hard-line' (an approximately linear correlation between X-ray count rate and rms variability, visible in the hard states of active black holes), the orbital inclination, and the radio-nature of the sources of our sample. We found that high-inclination objects show steeper hard-lines than low-inclination objects, and tend to display a radio-quiet nature (with the only exception of V404 Cyg), as opposed to low-inclination objects, which appear to be radio-loud(er). While in need of further confirmation, our results suggest that - contrary to what has been believed for years - the radio-loud/quiet nature of black-hole low mass X-ray binaries might be an inclination effect, rather than an intrinsic source property. This would solve an important issue in the context of the inflow-outflow connection, thus providing significant constraints to the models for the launch of hard-state compact jets.

The physics of black hole x ray novae

NASA Technical Reports Server (NTRS)

Wheeler, J. C.; Kim, S.-W.; Moscoso, M. D.; Mineshige, S.

1994-01-01

X-ray transients that are established or plausible black hole candidates have been discovered at a rate of about one per year in the galaxy for the last five years. There are now well over a dozen black hole candidates, most being in the category of X-ray novae with low-mass companions. There may be hundreds of such transient systems in the galaxy yet to be discovered. Classic black hole candidates like Cygnus X-1 with massive companions are in the minority, and their census in the galaxy and magellanic clouds is likely to be complete. The black hole X-ray novae (BHXN) do not represent only the most common environment in which to discover black holes. Their time dependence gives a major new probe with which to study the physics of accretion into black holes. The BHXN show both a soft X-ray flux from an optically thick disk and a hard power law tail that is reminiscent of AGN spectra. The result may be new insight into the classical systems like Cyg X-1 and LMC X-1 that show similar power law tails, but also to accretion into supermassive black holes and AGN.

X-Ray Probes of Cosmic Star-Formation History

NASA Technical Reports Server (NTRS)

Ghosh, Pranab; White, Nicholas E.

2001-01-01

In a previous paper we point out that the X-ray luminosity L(sub x) of a galaxy is driven by the evolution of its X-ray binary population and that the profile of L(sub x) with redshift can both serve as a diagnostic probe of the Star Formation Rate (SFR) profile and constrain evolutionary models for X-ray binaries. We update our previous work using a suite of more recently developed SFR profiles that span the currently plausible range. The first Chandra deep imaging results on L(sub x)-evolution are beginning to probe the SFR profile of bright spirals and the early results are consistent with predictions based on current SFR models. Using these new SFR profiles the resolution of the "birthrate problem" of lowmass X-ray binaries (LMXBs) and recycled, millisecond pulsars in terms of an evolving global SFR is more complete. We also discuss the possible impact of the variations in the SFR profile of individual galaxies.

HST spectrum and timing of the ultracompact X-ray binary candidate 47 Tuc X9

NASA Astrophysics Data System (ADS)

Tudor, V.; Miller-Jones, J. C. A.; Knigge, C.; Maccarone, T. J.; Tauris, T. M.; Bahramian, A.; Chomiuk, L.; Heinke, C. O.; Sivakoff, G. R.; Strader, J.; Plotkin, R. M.; Soria, R.; Albrow, M. D.; Anderson, G. E.; van den Berg, M.; Bernardini, F.; Bogdanov, S.; Britt, C. T.; Russell, D. M.; Zurek, D. R.

2018-05-01

To confirm the nature of the donor star in the ultracompact X-ray binary candidate 47 Tuc X9, we obtained optical spectra (3000-10 000 Å) with the Hubble Space Telescope / Space Telescope Imaging Spectrograph. We find no strong emission or absorption features in the spectrum of X9. In particular, we place 3σ upper limits on the H α and He II λ4686 emission line equivalent widths - EWH α ≲ 14 Å and -EW_{He {II}} ≲ 9 Å, respectively. This is much lower than seen for typical X-ray binaries at a similar X-ray luminosity (which, for L_2-10 keV ≈ 10^{33}-10^{34} erg s-1 is typically - EWH α ˜ 50 Å). This supports our previous suggestion, by Bahramian et al., of an H-poor donor in X9. We perform timing analysis on archival far-ultraviolet, V- and I-band data to search for periodicities. In the optical bands, we recover the 7-d superorbital period initially discovered in X-rays, but we do not recover the orbital period. In the far-ultraviolet, we find evidence for a 27.2 min period (shorter than the 28.2 min period seen in X-rays). We find that either a neutron star or black hole could explain the observed properties of X9. We also perform binary evolution calculations, showing that the formation of an initial black hole/ He-star binary early in the life of a globular cluster could evolve into a present-day system such as X9 (should the compact object in this system indeed be a black hole) via mass-transfer driven by gravitational wave radiation.

Charge Exchange X-Ray Emission due to Highly Charged Ion Collisions with H, He, and H2: Line Ratios for Heliospheric and Interstellar Applications

NASA Astrophysics Data System (ADS)

Cumbee, R. S.; Mullen, P. D.; Lyons, D.; Shelton, R. L.; Fogle, M.; Schultz, D. R.; Stancil, P. C.

2018-01-01

The fundamental collisional process of charge exchange (CX) has been established as a primary source of X-ray emission from the heliosphere, planetary exospheres, and supernova remnants. In this process, X-ray emission results from the capture of an electron by a highly charged ion from a neutral atom or molecule, to form a highly excited, high-charge state ion. As the captured electron cascades down to the lowest energy level, photons are emitted, including X-rays. To provide reliable CX-induced X-ray spectral models to realistically simulate these environments, line ratios and spectra are computed using theoretical CX cross sections obtained with the multi-channel Landau-Zener, atomic-orbital close-coupling, molecular-orbital close-coupling, and classical trajectory Monte Carlo methods for various collisional velocities relevant to astrophysics. X-ray spectra were computed for collisions of bare and H-like C to Al ions with H, He, and H2 with results compared to available experimental data. Using these line ratios, XSPEC models of CX emission in the northeast rim of the Cygnus Loop supernova remnant and the heliosphere are shown as examples with ion velocity dependence.

Clumpy wind accretion in supergiant neutron star high mass X-ray binaries

NASA Astrophysics Data System (ADS)

Bozzo, E.; Oskinova, L.; Feldmeier, A.; Falanga, M.

2016-05-01

The accretion of the stellar wind material by a compact object represents the main mechanism powering the X-ray emission in classical supergiant high mass X-ray binaries and supergiant fast X-ray transients. In this work we present the first attempt to simulate the accretion process of a fast and dense massive star wind onto a neutron star, taking into account the effects of the centrifugal and magnetic inhibition of accretion ("gating") due to the spin and magnetic field of the compact object. We made use of a radiative hydrodynamical code to model the nonstationary radiatively driven wind of an O-B supergiant star and then place a neutron star characterized by a fixed magnetic field and spin period at a certain distance from the massive companion. Our calculations follow, as a function of time (on a total timescale of several hours), the transitions of the system through all different accretion regimes that are triggered by the intrinsic variations in the density and velocity of the nonstationary wind. The X-ray luminosity released by the system is computed at each time step by taking into account the relevant physical processes occurring in the different accretion regimes. Synthetic lightcurves are derived and qualitatively compared with those observed from classical supergiant high mass X-ray binaries and supergiant fast X-ray transients. Although a number of simplifications are assumed in these calculations, we show that taking into account the effects of the centrifugal and magnetic inhibition of accretion significantly reduces the average X-ray luminosity expected for any neutron star wind-fed binary. The present model calculations suggest that long spin periods and stronger magnetic fields are favored in order to reproduce the peculiar behavior of supergiant fast X-ray transients in the X-ray domain.

The Connection Between X-ray Binaries and Star Clusters in the Antennae

NASA Astrophysics Data System (ADS)

Rangelov, Blagoy; Chandar, R.; Prestwich, A.

2011-05-01

High Mass X-ray Binaries (HMXBs) are believed to form in massive, compact star clusters. However the correlation between these young binary star systems and properties of their parent clusters are still poorly known. We compare the locations of 82 X-ray binaries detected in the merging Antennae galaxies by Zezas et al. (2006) based on observations taken with the Chandra Space Telescope, with a catalog of optically selected star clusters presented recently by Whitmore et al. (2010) based on observations taken with the Hubble Space Telescope. We find 22 X-ray binaries coincident or nearly coincident with star clusters. The ages of the clusters were estimated by comparing their UBVIHα colors with predictions from stellar evolutionary models. We find that 14 of the 22 coincident sources (64%) are hosted by star clusters with ages of 6 Myr or less. At these very young ages, only stars initially more massive than M ≥ 30 Msun have evolved into compact remnants, almost certainly black holes. Therefore, these 14 sources are likely to be black hole binaries. Five of the XRBs are hosted by young clusters with ages τ 30-50 Myr, while three are hosted by intermediate age clusters with τ 100-300 Myr. We suggest that these older X-ray binaries likely have neutron stars as the compact object. We conclude that precision age-dating of star clusters, which are spatially coincident with XRBs in nearby star forming galaxies, is a powerful method of constraining the nature of the XRBs.

Testing the Merger Paradigm: X-ray Observations of Radio-Selected Sub-Galactic-Scale Binary AGNs

NASA Astrophysics Data System (ADS)

Fu, Hai

2016-09-01

Interactions play an important role in galaxy evolution. Strong gas inflows are expected in the process of gas-rich mergers, which may fuel intense black hole accretion and star formation. Sub-galactic-scale binary/dual AGNs thus offer elegant laboratories to study the merger-driven co-evolution phase. However, previous samples of kpc-scale binaries are small and heterogeneous. We have identified a flux-limited sample of kpc-scale binary AGNs uniformly from a wide-area high-resolution radio survey conducted by the VLA. Here we propose Chandra X-ray characterization of a subset of four radio-confirmed binary AGNs at z 0.1. Our goal is to compare their X-ray properties with those of matched control samples to test the merger-driven co-evolution paradigm.

VizieR Online Data Catalog: YSO jets from UWISH2. IV. Cygnus-X outflows (Makin+, 2018)

NASA Astrophysics Data System (ADS)

Makin, S. V.; Froebrich, D.

2018-03-01

We utilized data from the UKIRT Widefield Infrared Survey for H2 (UWISH2), specifically the extension toward the Cygnus-X region of the Galactic plane as described in Froebrich+, 2015, J/MNRAS/454/2586 Cygnus-X was observed between 2013 April 6 and December 11. The survey used the Wide Field Camera (WFCAM) to obtain images in the 1-0 S(1) narrowband filter at 2.122um (Δλ=0.021um), at the UK Infra-Red Telescope (UKIRT) in Hawaii. (1 data file).

High-mass X-ray binary populations. 1: Galactic modeling

NASA Technical Reports Server (NTRS)

Dalton, William W.; Sarazin, Craig L.

1995-01-01

Modern stellar evolutionary tracks are used to calculate the evolution of a very large number of massive binary star systems (M(sub tot) greater than or = 15 solar mass) which cover a wide range of total masses, mass ratios, and starting separations. Each binary is evolved accounting for mass and angular momentum loss through the supernova of the primary to the X-ray binary phase. Using the observed rate of star formation in our Galaxy and the properties of massive binaries, we calculate the expected high-mass X-ray binary (HMXRB) population in the Galaxy. We test various massive binary evolutionary scenarios by comparing the resulting HMXRB predictions with the X-ray observations. A major goal of this study is the determination of the fraction of matter lost from the system during the Roche lobe overflow phase. Curiously, we find that the total numbers of observable HMXRBs are nearly independent of this assumed mass-loss fraction, with any of the values tested here giving acceptable agreement between predicted and observed numbers. However, comparison of the period distribution of our HMXRB models with the observed period distribution does reveal a distinction among the various models. As a result of this comparison, we conclude that approximately 70% of the overflow matter is lost from a massive binary system during mass transfer in the Roche lobe overflow phase. We compare models constructed assuming that all X-ray emission is due to accretion onto the compact object from the donor star's wind with models that incorporate a simplified disk accretion scheme. By comparing the results of these models with observations, we conclude that the formation of disks in HMXRBs must be relatively common. We also calculate the rate of formation of double degenerate binaries, high velocity detached compact objects, and Thorne-Zytkow objects.

A POSSIBLE SIGNATURE OF LENSE-THIRRING PRECESSION IN DIPPING AND ECLIPSING NEUTRON-STAR LOW-MASS X-RAY BINARIES

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

Homan, Jeroen, E-mail: jeroen@space.mit.edu

2012-12-01

Relativistic Lense-Thirring precession of a tilted inner accretion disk around a compact object has been proposed as a mechanism for low-frequency ({approx}0.01-70 Hz) quasi-periodic oscillations (QPOs) in the light curves of X-ray binaries. A substantial misalignment angle ({approx}15 Degree-Sign -20 Degree-Sign ) between the inner-disk rotation axis and the compact-object spin axis is required for the effects of this precession to produce observable modulations in the X-ray light curve. A consequence of this misalignment is that in high-inclination X-ray binaries the precessing inner disk will quasi-periodically intercept our line of sight to the compact object. In the case of neutron-starmore » systems, this should have a significant observational effect, since a large fraction of the accretion energy is released on or near the neutron-star surface. In this Letter, I suggest that this specific effect of Lense-Thirring precession may already have been observed as {approx}1 Hz QPOs in several dipping/eclipsing neutron-star X-ray binaries.« less

A Search for Quiet Massive X-ray Binaries

NASA Astrophysics Data System (ADS)

McSwain, M. V.; Boyajian, T. S.; Grundstrom, E.; Gies, D. R.

2005-12-01

Wind accretion models of the X-ray luminosity in massive X-ray binaries (MXRBs) predict a class of "quiet" MXRBs in which the stellar wind is too weak to power a strong X-ray source. The first two candidates systems, HD 14633 and HD 15137, were recently detected. These O star + neutron star systems were ejected from the open cluster NGC 654, but although they both show evidence of a past supernova within the binary system, neither is a known X-ray emitter. These systems provide a new opportunity to examine the ejection mechanisms responsible for the OB runaway stars, and they can also provide key information about the evolution of spun-up, rejuvenated massive stars. We present here preliminary results from a search for other such quiet MXRBs. MVM is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0401460.

IGR J17329-2731: The birth of a symbiotic X-ray binary

NASA Astrophysics Data System (ADS)

Bozzo, E.; Bahramian, A.; Ferrigno, C.; Sanna, A.; Strader, J.; Lewis, F.; Russell, D. M.; di Salvo, T.; Burderi, L.; Riggio, A.; Papitto, A.; Gandhi, P.; Romano, P.

2018-05-01

We report on the results of the multiwavelength campaign carried out after the discovery of the INTEGRAL transient IGR J17329-2731. The optical data collected with the SOAR telescope allowed us to identify the donor star in this system as a late M giant at a distance of 2.7-1.2+3.4 kpc. The data collected quasi-simultaneously with XMM-Newton and NuSTAR showed the presence of a modulation with a period of 6680 ± 3 s in the X-ray light curves of the source. This unveils that the compact object hosted in this system is a slowly rotating neutron star. The broadband X-ray spectrum showed the presence of a strong absorption (≫1023 cm-2) and prominent emission lines at 6.4 keV, and 7.1 keV. These features are usually found in wind-fed systems, in which the emission lines result from the fluorescence of the X-rays from the accreting compact object on the surrounding stellar wind. The presence of a strong absorption line around 21 keV in the spectrum suggests a cyclotron origin, thus allowing us to estimate the neutron star magnetic field as 2.4 × 1012 G. All evidencethus suggests IGR J17329-2731 is a symbiotic X-ray binary. As no X-ray emission was ever observed from the location of IGR J17329-2731 by INTEGRAL (or other X-ray facilities) during the past 15 yr in orbit and considering that symbiotic X-ray binaries are known to be variable but persistent X-ray sources, we concluded that INTEGRAL caught the first detectable X-ray emission from IGR J17329-2731 when the source shined as a symbiotic X-ray binary. The Swift XRT monitoring performed up to 3 months after the discovery of the source, showed that it maintained a relatively stable X-ray flux and spectral properties.

Laboratory simulation of photoionized plasma among astronomical compact objects

NASA Astrophysics Data System (ADS)

Fujioka, Shinsuke; Yamamoto, Norimasa; Wang, Feilu; Salzmann, David; Li, Yutong; Rhee, Yong-Joo; Nishimura, Hiroaki; Takabe, Hideaki; Mima, Kunioki

2008-11-01

X-ray line emission with several-keV of photon energy was observed from photoionized accreting clouds, for example CYGNUS X-3 and VELA X-1, those are exposed by hard x-ray continuum from the compact objects, such as neutron stars, black holes, or white dwarfs, although accreting clouds are thermally cold. The x-ray continuum-induced line emission gives a good insight to the accreting clouds. We will present a novel laboratory simulation of the photoionized plasma under well-characterized conditions by using high-power laser facility. Blackbody radiator with 500-eV of temperature, as a miniature of a hot compact object, was created.Silicon (Si) plasma with 30-eV of electron temperature was produced in the vicinity of the 0.5-keV blackbody radiator. Line emissions of lithium- and helium-like Si ions was clearly observed around 2-keV of photon-energy from the thermally cold Si plasma, this result is hardly interpreted without consideration of the photoionization. Atomic kinetics code reveals importance of inner-shell ionization directly caused by incoming hard x-rays.

Radio emission from the X-ray pulsar Her X-1: a jet launched by a strong magnetic field neutron star?

NASA Astrophysics Data System (ADS)

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

2018-01-01

Her X-1 is an accreting neutron star (NS) in an intermediate-mass X-ray binary. Like low-mass X-ray binaries (LMXBs), it accretes via Roche lobe overflow, but similar to many high-mass X-ray binaries containing a NS; Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery of radio emission from Her X-1 with the Very Large Array. During the radio observation, the central X-ray source was partially obscured by a warped disc. We measure a radio flux density of 38.7 ± 4.8 μJy at 9 GHz but cannot constrain the spectral shape. We discuss possible origins of the radio emission, and conclude that coherent emission, a stellar wind, shocks and a propeller outflow are all unlikely explanations. A jet, as seen in LMXBs, is consistent with the observed radio properties. We consider the implications of the presence of a jet in Her X-1 on jet formation mechanisms and on the launching of jets by NSs with strong magnetic fields.

A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. II. X-Ray Variability

NASA Astrophysics Data System (ADS)

Nichols, J.; Huenemoerder, D. P.; Corcoran, M. F.; Waldron, W.; Nazé, Y.; Pollock, A. M. T.; Moffat, A. F. J.; Lauer, J.; Shenar, T.; Russell, C. M. P.; Richardson, N. D.; Pablo, H.; Evans, N. R.; Hamaguchi, K.; Gull, T.; Hamann, W.-R.; Oskinova, L.; Ignace, R.; Hoffman, Jennifer L.; Hole, K. T.; Lomax, J. R.

2015-08-01

We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution spectral data set of the δ Ori Aa binary system. The four observations, obtained with Chandra ACIS HETGS, have a total exposure time of ≈ 479 ks and provide nearly complete binary phase coverage. Variability of the total X-ray flux in the range of 5-25 Å is confirmed, with a maximum amplitude of about ±15% within a single ≈ 125 ks observation. Periods of 4.76 and 2.04 days are found in the total X-ray flux, as well as an apparent overall increase in the flux level throughout the nine-day observational campaign. Using 40 ks contiguous spectra derived from the original observations, we investigate the variability of emission line parameters and ratios. Several emission lines are shown to be variable, including S xv, Si xiii, and Ne ix. For the first time, variations of the X-ray emission line widths as a function of the binary phase are found in a binary system, with the smallest widths at ϕ = 0.0 when the secondary δ Ori Aa2 is at the inferior conjunction. Using 3D hydrodynamic modeling of the interacting winds, we relate the emission line width variability to the presence of a wind cavity created by a wind-wind collision, which is effectively void of embedded wind shocks and is carved out of the X-ray-producing primary wind, thus producing phase-locked X-ray variability. Based on data from the Chandra X-ray Observatory and the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia, with the assistance of the University of Vienna.

Fast transient X-rays from flare stars and RS CVn binaries

NASA Astrophysics Data System (ADS)

Rao, A. R.; Vahia, M. N.

1987-12-01

The authors have studied the fast transient X-ray (FTX) observations of the Ariel V satellite. They find that the FTX have characteristics very similar to the stellar flares detected in flare stars and RS CVn binaries by other satellites. It is found that, of the possible candidate objects, only the flare stars and RS CVn binaries can be associated with the Ariel V observations. 11 new flare stars and RS CVn binaries are associated with the FTX. This brings the total number of identifications with the flare stars and RS CVn binaries to 17. The authors further study the flare properties and correlate the peak X-ray luminosity of these Ariel V sources with the bolometric luminosity of the candidate stars. They discuss a solar flare model and show that the observed correlation can be explained under the assumption of constant temperature loops of binary sizes.

Smearing of mass accretion rate variation by viscous processes in accretion disks in compact binary systems

NASA Astrophysics Data System (ADS)

Ghosh, A.; Chakrabarti, Sandip K.

2016-09-01

Variation of mass supply rate from the companion can be smeared out by viscous processes inside an accretion disk. Hence, by the time the flow reaches the inner edge, the variation in X-rays need not reflect the true variation of the mass supply rate at the outer edge. However, if the viscosity fluctuates around a mean value, one would expect the viscous time scale t_{{visc}} also to spread around a mean value. In high mass X-ray binaries, which are thought to be primarily wind-fed, the size of the viscous Keplerian disk is smaller and thus such a spread could be lower as compared to the low mass X-ray binaries which are primarily fed by Roche lobe overflow. If there is an increasing or decreasing trend in viscosity, the interval between enhanced emission would be modified systematically. In the absence of a detailed knowledge about the variation of mass supply rates at the outer edge, we study ideal circumstances where modulation must take place exactly in orbital time scales, such as when there is an ellipticity in the orbit. We study a few compact binaries using long term All Sky monitor (ASM) data (1.5-12 keV) of Rossi X-ray Timing Explorer (RXTE) and all sky survey data (15-50 keV) of Swift satellites by different methods to look for such smearing effects and to infer what these results can tell us about the viscous processes inside the respective disks. We employ three different methods to seek imprints of periodicity on the X-ray variation and found that in all the cases, the location of the peak in the power density spectra is consistent with the orbital frequencies. Interestingly, in high mass X-ray binaries the peaks are sharp with high rms values, consistent with a small Keplerian disk in a wind fed system. However, in low mass X-ray binaries with larger Keplerian disk component, the peaks are spreaded out with much lower rms values. X-ray reflections, or superhump phenomena which may also cause such X-ray modulations would not be affected by the size of the Keplerian disk component. Our result thus confirms different sizes of Keplerian disks in these two important classes of binaries. If the orbital periods of any binary system is not known, they may be obtained with reasonable accuracy for HMXBs and with lesser accuracy for LMXBs by our method.

The Peculiar Galactic Center Neutron Star X-Ray Binary XMM J174457-2850.3

NASA Technical Reports Server (NTRS)

Degenaar, N.; Wijnands, R.; Reynolds, M. T.; Miller, J. M.; Altamirano, D.; Kennea, J.; Gehrels, N.; Haggard, D.; Ponti, G.

2014-01-01

The recent discovery of a milli-second radio pulsar experiencing an accretion outburst similar to those seen in low mass X-ray binaries, has opened up a new opportunity to investigate the evolutionary link between these two different neutron star manifestations. The remarkable X-ray variability and hard X-ray spectrum of this object can potentially serve as a template to search for other X-ray binary radio pulsar transitional objects. Here we demonstrate that the transient X-ray source XMM J174457-2850.3 near the Galactic center displays similar X-ray properties. We report on the detection of an energetic thermonuclear burst with an estimated duration of 2 hr and a radiated energy output of 5E40 erg, which unambiguously demonstrates that the source harbors an accreting neutron star. It has a quiescent X-ray luminosity of Lx5E32 ergs and exhibits occasional accretion outbursts during which it brightens to Lx1E35-1E36 ergs for a few weeks (2-10 keV). However, the source often lingers in between outburst and quiescence at Lx1E33-1E34 ergs. This unusual X-ray flux behavior and its relatively hard X-ray spectrum, a power law with an index of 1.4, could possibly be explained in terms of the interaction between the accretion flow and the magnetic field of the neutron star.

The X-Ray Luminosity Functions of Field Low-Mass X-Ray Binaries in Early-Type Galaxies: Evidence for a Stellar Age Dependence

NASA Technical Reports Server (NTRS)

Lehmer, B. D.; Berkeley, M.; Zezas, A.; Alexander, D. M.; Basu-Zych, A.; Bauer, F. E.; Brandt, W. N.; Fragos, T.; Hornschemeier, A. E.; Kalogera, V.;

Chandra enables study of x-ray jets

PubMed Central

Schwartz, Daniel

2010-01-01

The exquisite angular resolution of the Chandra x-ray telescope has enabled the detection and study of resolved x-ray jets in a wide variety of astronomical systems. Chandra has detected extended jets in our galaxy from protostars, symbiotic binaries, neutron star pulsars, black hole binaries, extragalactic jets in radio sources, and quasars. The x-ray data play an essential role in deducing the emission mechanism of the jets, in revealing the interaction of jets with the intergalactic or intracluster media, and in studying the energy generation budget of black holes. PMID:20378839

Modeling X-ray and gamma-ray emission in the intrabinary shock of pulsar binaries

NASA Astrophysics Data System (ADS)

An, H.

2017-10-01

We present broadband SED and light curve, and a wind interaction model for the gamma-ray binary 1FGL J1018.6-5856 (J1018) which exhibits double peaks in the X-ray light curve. Assuming that the X-ray to low-energy gamma-ray emission is produced by synchrotron radiation and high-energy gamma rays by inverse Compton scattering in the intrabinary shock (IBS), we model the broadband SED and light curve of J1018 using a two-component model having slow electrons in the shock and fast bulk-accelerated electrons at the skin of the shock. The model explains the broadband SED and light curve of J1018 qualitatively well. In particular, modeling the synchrotron emission constrains the orbital geometry. We discuss potential use of the model for other pulsar binaries.

Formation of Thorne-Żytkow objects in close binaries

NASA Astrophysics Data System (ADS)

Hutilukejiang, Bumareyamu; Zhu, Chunhua; Wang, Zhaojun; Lü, Guoliang

2018-04-01

Thorne-Żytkow objects (TŻOs), originally proposed by Thorne and Żytkow, may form as a result of unstable mass transfer in a massive X-ray binary after a neutron star (NS) is engulfed in the envelope of its companion star. Using a rapid binary evolution program and the Monte Carlo method, we simulated the formation of TŻOs in close binary stars. The Galactic birth rate of TŻOs is about 1.5× 10^{-4} yr^{-1}. Their progenitors may be composed of a NS and a main-sequence star, a star in the Hertzsprung gap or a core-helium burning, or a naked helium star. The birth rates of TŻOs via the above different progenitors are 1.7× 10^{-5}, 1.2× 10^{-4}, 0.7× 10^{-5}, 0.6× 10^{-5} yr^{-1}, respectively. These progenitors may be massive X-ray binaries. We found that the observational properties of three massive X-ray binaries (SMC X-1, Cen X-3 and LMC X-4) in which the companions of NSs may fill their Roche robes were consistent with those of their progenitors.

Theory of magnetic cataclysmic binary X-ray sources

NASA Technical Reports Server (NTRS)

Lamb, Don Q.

1988-01-01

The theory of magnetic cataclysmic binary X-ray sources is reviewed. The physics of the accretion torque for disk and for stream accretion is described, and the magnetic field strengths of DQ Her stars inferred from their spin behavior and of AM Her stars from direct measurement are discussed. The implications of disk and stream accretion for the geometry of the emission region and for the X-ray pulse profiles are considered. The physicl properties of the X-ray emission region and the expected infrared, optical, soft X-ray, and hard X-ray spectra are described. The orientations of the magnetic moment in AM Her stars inferred from the circular and linear polarization of the optical light and the optical light curve are commented on.

A Comparison Between Spectral Properties of ULXs and Luminous X-ray Binaries

NASA Astrophysics Data System (ADS)

Berghea, C. T.; Colbert, E. J. M.; Roberts, T. P.

2004-05-01

What is special about the 1039 erg s-1 limit that is used to define the ULX class? We investigate this question by analyzing Chandra X-ray spectra of 71 X-ray bright point sources from nearby galaxies. Fifty-one of these sources are ULXs (LX(0.3-8.0 keV) ≥ 1039 erg s-1), and 20 sources (our comparison sample) are less-luminous X-ray binaries with LX(0.3-8.0 keV) = 1038-39 erg s-1. Our sample objects were selected from the Chandra archive to have ≥1000 counts and thus represent the highest quality spectra in the Chandra archives for extragalactic X-ray binaries and ULXs. We fit the spectra with one-component models (e.g., cold absorption with power-law, or cold absorption with multi-colored disk blackbody) and two-component models (e.g. absorption with both a power-law and a multi colored disk blackbody). A crude measure of the spectral states of the sources are determined observationally by calibrating the strength of the disk (blackbody) and coronal (power-law) components. These results are then use to determine if spectral properties of the ULXs are statistically distinct from those of the comparison objects, which are assumed to be ``normal'' black-hole X-ray binaries.

The dust scattering halo of Cygnus X-3

NASA Astrophysics Data System (ADS)

Corrales, L. R.; Paerels, F.

2015-10-01

Dust grains scatter X-ray light through small angles, producing a diffuse halo image around bright X-ray point sources situated behind a large amount of interstellar material. We present analytic solutions to the integral for the dust scattering intensity, which allow for a Bayesian analysis of the scattering halo around Cygnus X-3. Fitting the optically thin 4-6 keV halo surface brightness profile yields the dust grain size and spatial distribution. We assume a power-law distribution of grain sizes (n ∝ a-p) and fit for p, the grain radius cut-off amax, and dust mass column. We find that a p ≈ 3.5 dust grain size distribution with amax ≈ 0.2 μm fits the halo profile relatively well, whether the dust is distributed uniformly along the line of sight or in clumps. We find that a model consisting of two dust screens, representative of foreground spiral arms, requires the foreground Perseus arm to contain 80 per cent of the total dust mass. The remaining 20 per cent of the dust, which may be associated with the outer spiral arm of the Milky Way, is located within 1 kpc of Cyg X-3. Regardless of which model was used, we found τ_sca ˜ 2 E_keV^{-2}. We examine the energy resolved haloes of Cyg X-3 from 1 to 6 keV and find that there is a sharp drop in scattering halo intensity when E < 2-3 keV, which cannot be explained with multiple scattering effects. We hypothesize that this may be caused by large dust grains or material with unique dielectric properties, causing the scattering cross-section to depart from the Rayleigh-Gans approximation that is used most often in X-ray scattering studies. The foreground Cyg OB2 association, which contains several evolved stars with large extinction values, is a likely culprit for grains of unique size or composition.

A Coordinated X-Ray and Optical Campaign of the Nearby Massive Binary Sigma Orionis Aa. II; X-Ray Variability

NASA Technical Reports Server (NTRS)

Nichols, J.; Huenemoerder, D. P.; Corcoran, M. F.; Waldron, W.; Naze, Y; Pollock, A. M. T.; Moffat, A. F. J.; Lauer, J.; Shenar, T.; Russell, C. M. P.;

Spectroscopic classification of X-ray sources in the Galactic Bulge Survey

NASA Astrophysics Data System (ADS)

Wevers, T.; Torres, M. A. P.; Jonker, P. G.; Nelemans, G.; Heinke, C.; Mata Sánchez, D.; Johnson, C. B.; Gazer, R.; Steeghs, D. T. H.; Maccarone, T. J.; Hynes, R. I.; Casares, J.; Udalski, A.; Wetuski, J.; Britt, C. T.; Kostrzewa-Rutkowska, Z.; Wyrzykowski, Ł.

2017-10-01

We present the classification of 26 optical counterparts to X-ray sources discovered in the Galactic Bulge Survey. We use (time-resolved) photometric and spectroscopic observations to classify the X-ray sources based on their multiwavelength properties. We find a variety of source classes, spanning different phases of stellar/binary evolution. We classify CX21 as a quiescent cataclysmic variable (CV) below the period gap, and CX118 as a high accretion rate (nova-like) CV. CXB12 displays excess UV emission, and could contain a compact object with a giant star companion, making it a candidate symbiotic binary or quiescent low-mass X-ray binary (although other scenarios cannot be ruled out). CXB34 is a magnetic CV (polar) that shows photometric evidence for a change in accretion state. The magnetic classification is based on the detection of X-ray pulsations with a period of 81 ± 2 min. CXB42 is identified as a young stellar object, namely a weak-lined T Tauri star exhibiting (to date unexplained) UX Ori-like photometric variability. The optical spectrum of CXB43 contains two (resolved) unidentified double-peaked emission lines. No known scenario, such as an active galactic nucleus or symbiotic binary, can easily explain its characteristics. We additionally classify 20 objects as likely active stars based on optical spectroscopy, their X-ray to optical flux ratios and photometric variability. In four cases we identify the sources as binary stars.

FIRST LIGHT: MeV ASTROPHYSICS FROM THE MOON

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

Miller, Richard S.; Lawrence, David J., E-mail: richard.s.miller@uah.edu

We report evidence of the first astrophysical source detected from the Moon at MeV energies. Our detection of Cygnus X-1 is a validation of a new investigative paradigm in which the lunar environment is intrinsic to the detection approach: the Lunar Occultation Technique (LOT). NASA’s Lunar Prospector mission served as a proxy for a dedicated LOT-based mission. The characteristic signature of temporal modulation, generated by repeated lunar occultations and encoded within acquired gamma-ray data (0.5–9 MeV), is consistent with an unambiguous detection of Cygnus X-1 at 5.4 σ significance. Source localization and long-term monitoring capabilities of the LOT are alsomore » demonstrated. This “first light” detection verifies the basic tenets of the LOT methodology, reinforces its feasibility as an alternative astronomical detection paradigm for nuclear astrophysics investigations, and is an illustration of the fundamental benefits of the Moon as a platform for science.« less

Dark jets in the soft X-ray state of black hole binaries?

NASA Astrophysics Data System (ADS)

Drappeau, S.; Malzac, J.; Coriat, M.; Rodriguez, J.; Belloni, T. M.; Belmont, R.; Clavel, M.; Chakravorty, S.; Corbel, S.; Ferreira, J.; Gandhi, P.; Henri, G.; Petrucci, P.-O.

2017-04-01

X-ray binary observations led to the interpretation that powerful compact jets, produced in the hard state, are quenched when the source transitions to its soft state. The aim of this paper is to discuss the possibility that a powerful dark jet is still present in the soft state. Using the black hole X-ray binaries GX339-4 and H1743-322 as test cases, we feed observed X-ray power density spectra in the soft state of these two sources to an internal shock jet model. Remarkably, the predicted radio emission is consistent with current upper limits. Our results show that for these two sources, a compact dark jet could persist in the soft state with no major modification of its kinetic power compared to the hard state.

A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy

NASA Astrophysics Data System (ADS)

Hailey, Charles J.; Mori, Kaya; Bauer, Franz E.; Berkowitz, Michael E.; Hong, Jaesub; Hord, Benjamin J.

2018-04-01

The existence of a ‘density cusp’—a localized increase in number—of stellar-mass black holes near a supermassive black hole is a fundamental prediction of galactic stellar dynamics. The best place to detect such a cusp is in the Galactic Centre, where the nearest supermassive black hole, Sagittarius A*, resides. As many as 20,000 black holes are predicted to settle into the central parsec of the Galaxy as a result of dynamical friction; however, so far no density cusp of black holes has been detected. Low-mass X-ray binary systems that contain a stellar-mass black hole are natural tracers of isolated black holes. Here we report observations of a dozen quiescent X-ray binaries in a density cusp within one parsec of Sagittarius A*. The lower-energy emission spectra that we observed in these binaries is distinct from the higher-energy spectra associated with the population of accreting white dwarfs that dominates the central eight parsecs of the Galaxy. The properties of these X-ray binaries, in particular their spatial distribution and luminosity function, suggest the existence of hundreds of binary systems in the central parsec of the Galaxy and many more isolated black holes. We cannot rule out a contribution to the observed emission from a population (of up to about one-half the number of X-ray binaries) of rotationally powered, millisecond pulsars. The spatial distribution of the binary systems is a relic of their formation history, either in the stellar disk around Sagittarius A* (ref. 7) or through in-fall from globular clusters, and constrains the number density of sources in the modelling of gravitational waves from massive stellar remnants, such as neutron stars and black holes.

A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy.

PubMed

Hailey, Charles J; Mori, Kaya; Bauer, Franz E; Berkowitz, Michael E; Hong, Jaesub; Hord, Benjamin J

2018-04-04

The existence of a 'density cusp'-a localized increase in number-of stellar-mass black holes near a supermassive black hole is a fundamental prediction of galactic stellar dynamics. The best place to detect such a cusp is in the Galactic Centre, where the nearest supermassive black hole, Sagittarius A*, resides. As many as 20,000 black holes are predicted to settle into the central parsec of the Galaxy as a result of dynamical friction; however, so far no density cusp of black holes has been detected. Low-mass X-ray binary systems that contain a stellar-mass black hole are natural tracers of isolated black holes. Here we report observations of a dozen quiescent X-ray binaries in a density cusp within one parsec of Sagittarius A*. The lower-energy emission spectra that we observed in these binaries is distinct from the higher-energy spectra associated with the population of accreting white dwarfs that dominates the central eight parsecs of the Galaxy. The properties of these X-ray binaries, in particular their spatial distribution and luminosity function, suggest the existence of hundreds of binary systems in the central parsec of the Galaxy and many more isolated black holes. We cannot rule out a contribution to the observed emission from a population (of up to about one-half the number of X-ray binaries) of rotationally powered, millisecond pulsars. The spatial distribution of the binary systems is a relic of their formation history, either in the stellar disk around Sagittarius A* (ref. 7) or through in-fall from globular clusters, and constrains the number density of sources in the modelling of gravitational waves from massive stellar remnants, such as neutron stars and black holes.

A Search for Black Holes and Neutron Stars in the Kepler Field

NASA Astrophysics Data System (ADS)

Orosz, Jerome; Short, Donald; Welsh, William; Windmiller, Gur; Dabney, David

2018-01-01

Black holes and neutron stars represent the final evolutionary stages of the most massive stars. In addition to their use as probes into the evolution of massive stars, black holes and neutron stars are ideal laboratories to test General Relativity in the strong field limit. The number of neutron stars and black holes in the Milky Way is not precisely known, but there are an estimated one billion neutron stars in the galaxy based on the observed numbers of radio pulsars. The number of black holes is about 100 million, based on the behavior of the Initial Mass Function at high stellar masses.All of the known steller-mass black holes (and a fair number of neutron stars) are in ``X-ray binaries'' that were discovered because of their luminous X-ray emission. The requirement to be in an X-ray-emitting binary places a strong observational bias on the discovery of stellar-mass black holes. Thus the 21 known black hole binaries represent only the very uppermost tip of the population iceberg.We have conducted an optical survey using Kepler data designed to uncover black holes and neutron stars in both ``quiescent'' X-ray binaries and ``pre-contact'' X-ray binaries. We discuss how the search was conducted, including how potentially interesting light curves were classified and the how variability types were identified. Although we did not find any convincing candidate neutron star or black hole systems, we did find a few noteworthy binary systems, including two binaries that contain low-mass stars with unusually low albedos.

Chandra Observations of the Eclipsing Wolf-Rayet Binary CQ CepOver a Full Orbital Cycle

NASA Astrophysics Data System (ADS)

Skinner, Steve L.; Guedel, Manuel; Schmutz, Werner; Zhekov, Svetozar

2018-06-01

We present results of Chandra X-ray observations and simultaneous optical light curves of the short-period (1.64 d) eclipsing WN6+O9 binary system CQ Cep obtained in 2013 and 2017 covering a full binary orbit. Our primary objective was to compare the observed X-ray properties with colliding wind shock theory, which predicts that the hottest shock plasma (T > 20 MK) will form on or near the line-of-centers between the stars. Thus, X-ray variability is expected during eclipses when the hottest plasma is occulted. The X-ray spectrum is strikingly similar to apparently single WN6 stars such as WR 134 and spectral lines reveal plasma over a broad range of temperatures T ~ 4 - 40 MK. Both primary and secondary optical eclipses were clearly detected and provide an accurate orbital period determination (P = 1.6412 d). The X-ray emission remained remarkably steady throughout the orbit and statistical tests give a low probability of variability. The lack of significant X-ray variabililty during eclipses indicates that the X-ray emission is not confined along the line-of-centers but is extended on larger spatial scales, contrary to colliding wind predictions.

Unusual Black Hole Binary LMC X-3: A Transient High-Mass X-Ray Binary That Is Almost Always On?

NASA Technical Reports Server (NTRS)

Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A.

2017-01-01

We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi- Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with Gamma = 1.41‚+/- 0.65 and a luminosity of 7.97 x 10(exp 33) erg/s (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of approx. 8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of approx. 4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always "on."

More surprises from the violent gamma-ray binary LS 2883 /B1259-63.

NASA Astrophysics Data System (ADS)

Kargaltsev, Oleg; Hare, Jeremy; Pavlov, George G.

2018-01-01

We report the results of a Chandra X-ray Observatory (CXO) monitoring campaign of the high-mass gamma-ray binary LS 2883, which hosts the young pulsar B1259-63. The monitoring now covers two binary cycles (6.8 years) and allows us to conclude that ejections of high-velocity X-ray emitting material are common for this binary. In the first cycle we observed an extended feature which detached and moved away from the binary. The observed changes in position were consistent with a steady motion with v=(0.07+/-0.01)c and a slight hint of acceleration. Tracing the motion back in time suggested that the X-ray emitting matter was ejected close to periastron passage. In the last orbital cycle, accelerated motion (reaching (0.13+/-0.02)c) is strongly preferred over a steady motion (the latter would imply that the ejected material was launched ~400 days after the periastron passage). The moving feature is also more luminous, compared to the previous binary cycle, larger in its apparent extent, and exhibits a puzzling morphology. We will show the CXO movies from both binary cycles and discuss physical interpretation of the resolved outflow dynamics in this remarkable system, which provides unique insight into the properties of the pulsar and stellar winds and their interaction.

The X-ray eclipse of the LMC binary CAL 87

NASA Technical Reports Server (NTRS)

Schmidtke, P. C.; Mcgrath, T. K.; Cowley, A. P.; Frattare, L. M.

1993-01-01

ROSAT-PSPC observations of the LMC eclipsing binary CAL 87 show a short-duration, shallow X-ray eclipse which coincides in phase with the primary optical minimum. Characteristics of the eclipse suggest the X-ray emitting region is only partially occulted. Similarities with the eclipse of the accretion-disk corona in X 1822-37 are discussed. However, no temperature variation through eclipse is found for CAL 87. A revised orbital period, combining published data and recent optical photometry, is given.

A SPITZER VIEW OF STAR FORMATION IN THE CYGNUS X NORTH COMPLEX

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

Beerer, I. M.; Koenig, X. P.; Hora, J. L.

2010-09-01

We present new images and photometry of the massive star-forming complex Cygnus X obtained with the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS) on board the Spitzer Space Telescope. A combination of IRAC, MIPS, UKIRT Deep Infrared Sky Survey, and Two Micron All Sky Survey data are used to identify and classify young stellar objects (YSOs). Of the 8231 sources detected exhibiting infrared excess in Cygnus X North, 670 are classified as class I and 7249 are classified as class II. Using spectra from the FAST Spectrograph at the Fred L. Whipple Observatory and Hectospecmore » on the MMT, we spectrally typed 536 sources in the Cygnus X complex to identify the massive stars. We find that YSOs tend to be grouped in the neighborhoods of massive B stars (spectral types B0 to B9). We present a minimal spanning tree analysis of clusters in two regions in Cygnus X North. The fraction of infrared excess sources that belong to clusters with {>=}10 members is found to be 50%-70%. Most class II objects lie in dense clusters within blown out H II regions, while class I sources tend to reside in more filamentary structures along the bright-rimmed clouds, indicating possible triggered star formation.« less

Spectral and Timing Nature of the Symbiotic X-Ray Binary 4U 1954+319: The Slowest Rotating Neutron Star in AN X-Ray Binary System

NASA Technical Reports Server (NTRS)

Enoto, Teruaki; Sasano, Makoto; Yamada, Shin'Ya; Tamagawa, Toru; Makishima, Kazuo; Pottschmidt, Katja; Marcu, Diana; Corbet, Robin H. D.; Fuerst, Felix; Wilms, Jorn

2014-01-01

The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its approx. 5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (is approx. 7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-K alpha line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (approx. 60%-80%), and the location in the Corbet diagram favor high B-field (approx. greater than 10(exp12) G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10(exp33)-10(exp35) erg s(exp-1)), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a approx. 10(exp13) G NS, this scheme can explain the approx. 5.4 hr equilibrium rotation without employing the magnetar-like field (approx. 10(exp16) G) required in the disk accretion case. The timescales of multiple irregular flares (approx. 50 s) can also be attributed to the free-fall time from the Alfv´en shell for a approx. 10(exp13) G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

Unusual Black Hole Binary LMC X-3: A Transient High-mass X-Ray Binary That Is Almost Always On?

NASA Astrophysics Data System (ADS)

Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A.

2017-11-01

We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi-Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with {{Γ }}=1.41+/- 0.65 and a luminosity of 7.97× {10}33 erg s-1 (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of ˜8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of ˜4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always “on.”

The infrared counterpart of the eclipsing X-ray binary HO253 + 193

NASA Technical Reports Server (NTRS)

Zuckerman, B.; Becklin, E. E.; Mclean, I. S.; Patterson, Joseph

1992-01-01

We report the identification of the infrared counterpart of the pulsating X-ray source HO253 + 193. It is a highly reddened star varying in K light with a period near 3 hr, but an apparent even-odd effect in the light curve implies that the true period is 6.06 hr. Together with the recent report of X-ray eclipses at the latter period, this establishes the close binary nature of the source. Infrared minimum occurs at X-ray minimum, certifying that the infrared variability arises from the tidal distortion of the lobe-filling secondary. The absence of a point source at radio wavelengths, plus the distance derived from the infrared data, suggests that the binary system is accidentally located behind the dense core of the molecular cloud Lynds 1457. The eclipses and pulsations in the X-ray light curve, coupled with the hard X-ray spectrum and low luminosity, demonstrate that HO253 + 193 contains an accreting magnetic white dwarf, and hence belongs to the 'DQ Herculis' class of cataclysmic variables.

Chandra X-ray spectroscopy of focused wind in the Cygnus X-1 system: II. The non-dip spectrum in the low/hard state – modulations with orbital phase

DOE PAGES

Miskovicova, Ivica; Hell, Natalie; Hanke, Manfred; ...

2016-05-25

Accretion onto the black hole in the system HDE 226868/Cygnus X-1 is powered by the strong line-driven stellar wind of the O-type donor star. We study the X-ray properties of the stellar wind in the hard state of Cyg X-1, as determined using data from the Chandra High Energy Transmission Gratings. Large density and temperature inhomogeneities are present in the wind, with a fraction of the wind consisting of clumps of matter with higher density and lower temperature embedded in a photoionized gas. Absorption dips observed in the light curve are believed to be caused by these clumps. This workmore » concentrates on the non-dip spectra as a function of orbital phase. The spectra show lines of H-like and He-like ions of S, Si, Na, Mg, Al, and highly ionized Fe (Fe xvii–Fe xxiv). We measure velocity shifts, column densities, and thermal broadening of the line series. The excellent quality of these five observations allows us to investigate the orbital phase-dependence of these parameters. We show that the absorber is located close to the black hole. Doppler shifted lines point at a complex wind structure in this region, while emission lines seen in some observations are from a denser medium than the absorber. Here, the observed line profiles are phase-dependent. Their shapes vary from pure, symmetric absorption at the superior conjunction to P Cygni profiles at the inferior conjunction of the black hole.« less

The coupling of a disk corona and a jet for the radio/X-ray correlation in black hole X-ray binaries

NASA Astrophysics Data System (ADS)

Qiao, Erlin

2016-02-01

We interpret the radio/X-ray correlation of L R ~ L X ~1.4 for L X/L Edd >~ 10-3 with a detailed disk corona-jet model, in which the accretion flow and the jet are connected by a parameter, η, describing the fraction of the matter in the accretion flow ejected outward to form the jet. We calculate L R and L X at different Ṁ, adjusting η to fit the observed radio/X-ray correlation of the black hole X-ray transient H1743-322 for L X/L Edd > 10-3. It is found that the value of η for this radio/X-ray correlation for L X/L Edd > 10-3, is systematically less than that of the case for L X/L Edd < 10-3, which is consistent with the general idea that the jet is often relatively suppressed at the high luminosity phase in black hole X-ray binaries.

X-ray observations of the colliding wind binary WR 25

NASA Astrophysics Data System (ADS)

Arora, Bharti; Pandey, Jeewan Chandra

2018-04-01

Using the archival data obtained from Chandra and Suzaku spanning over '8 years, we present an analysis of a WN6h+O4f Wolf-Rayet binary, WR 25. The X-ray light curves folded over a period of '208 d in the 0.3 - 10.0 keV energy band showed phase-locked variability where the count rates were found to be maximum near the periastron passage. The X-ray spectra of WR 25 were well explained by a two-temperature plasma model with temperatures of 0.64 ± 0.01 and 2.96 ± 0.05 keV and are consistent with previous results. The orbital phase dependent local hydrogen column density was found to be maximum just after the periastron passage, when the WN type star is in front of the O star. The hard (2.0 - 10.0 keV) X-ray luminosity was linearly dependent on the inverse of binary separation which confirms that WR 25 is a colliding wind binary.

Close Encounters of the Stellar Kind

NASA Astrophysics Data System (ADS)

2003-07-01

NASA's Chandra X-ray Observatory has confirmed that close encounters between stars form X-ray emitting, double-star systems in dense globular star clusters. These X-ray binaries have a different birth process than their cousins outside globular clusters, and should have a profound influence on the cluster's evolution. A team of scientists led by David Pooley of the Massachusetts Institute of Technology in Cambridge took advantage of Chandra's unique ability to precisely locate and resolve individual sources to determine the number of X-ray sources in 12 globular clusters in our Galaxy. Most of the sources are binary systems containing a collapsed star such as a neutron star or a white dwarf star that is pulling matter off a normal, Sun-like companion star. "We found that the number of X-ray binaries is closely correlated with the rate of encounters between stars in the clusters," said Pooley. "Our conclusion is that the binaries are formed as a consequence of these encounters. It is a case of nurture not nature." A similar study led by Craig Heinke of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. confirmed this conclusion, and showed that roughly 10 percent of these X-ray binary systems contain neutron stars. Most of these neutron stars are usually quiet, spending less than 10% of their time actively feeding from their companion. NGC 7099 NGC 7099 A globular cluster is a spherical collection of hundreds of thousands or even millions of stars buzzing around each other in a gravitationally-bound stellar beehive that is about a hundred light years in diameter. The stars in a globular cluster are often only about a tenth of a light year apart. For comparison, the nearest star to the Sun, Proxima Centauri, is 4.2 light years away. With so many stars moving so close together, interactions between stars occur frequently in globular clusters. The stars, while rarely colliding, do get close enough to form binary star systems or cause binary stars to exchange partners in intricate dances. The data suggest that X-ray binary systems are formed in dense clusters known as globular clusters about once a day somewhere in the universe. Observations by NASA's Uhuru X-ray satellite in the 1970's showed that globular clusters seemed to contain a disproportionately large number of X-ray binary sources compared to the Galaxy as a whole. Normally only one in a billion stars is a member of an X-ray binary system containing a neutron star, whereas in globular clusters, the fraction is more like one in a million. The present research confirms earlier suggestions that the chance of forming an X-ray binary system is dramatically increased by the congestion in a globular cluster. Under these conditions two processes, known as three-star exchange collisions, and tidal captures, can lead to a thousandfold increase in the number of X-ray sources in globular clusters. 47 Tucanae 47 Tucanae In an exchange collision, a lone neutron star encounters a pair of ordinary stars. The intense gravity of the neutron star can induce the most massive ordinary star to "change partners," and pair up with the neutron star while ejecting the lighter star. A neutron star could also make a grazing collision with a single normal star, and the intense gravity of the neutron star could distort the gravity of the normal star in the process. The energy lost in the distortion, could prevent the normal star from escaping from the neutron star, leading to what is called tidal capture. "In addition to solving a long-standing mystery, Chandra data offer an opportunity for a deeper understanding of globular cluster evolution," said Heinke. "For example, the energy released in the formation of close binary systems could keep the central parts of the cluster from collapsing to form a massive black hole." NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the Office of Space Science, NASA Headquarters, Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW, Inc., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. The image and additional information are available at: http://chandra.harvard.edu and http://chandra.nasa.gov

The super-orbital modulation of supergiant high-mass X-ray binaries

NASA Astrophysics Data System (ADS)

Bozzo, E.; Oskinova, L.; Lobel, A.; Hamann, W.-R.

2017-10-01

The long-term X-ray light curves of classical supergiant X-ray binaries and supergiant fast X-ray transients show relatively similar super-orbital modulations, which are still lacking a sound interpretation. We propose that these modulations are related to the presence of corotating interaction regions (CIRs) known to thread the winds of OB supergiants. To test this hypothesis, we couple the outcomes of three-dimensional (3D) hydrodynamic models for the formation of CIRs in stellar winds with a simplified recipe for the accretion onto a neutron star. The results show that the synthetic X-ray light curves are indeed modulated by the presence of the CIRs. The exact period and amplitude of these modulations depend on a number of parameters governing the hydrodynamic wind models and on the binary orbital configuration. To compare our model predictions with the observations, we apply the 3D wind structure previously shown to well explain the appearance of discrete absorption components in the UV time series of a prototypical B0.5I-type supergiant. Using the orbital parameters of IGRJ 16493-4348, which has the same B0.5I donor spectral type, the period and modulations in the simulated X-ray light curve are similar to the observed ones, thus providing support to our scenario. We propose that the presence of CIRs in donor star winds should be considered in future theoretical and simulation efforts of wind-fed X-ray binaries.

P-23 Highlights 6/10/12: Cygnus Dual Beam Radiographic Facility Refurbishment completed at U1A tunnel in Nevada NNSS meeting Level 2 milestone

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

Deyoung, Anemarie; Smith, John R.

2012-05-03

A moratorium was placed on U.S. underground nuclear testing in 1992. In response, the Stockpile Stewardship Program was created to maintain readiness of the existing nuclear inventory through several efforts such as computer modeling, material analysis, and subcritical nuclear experiments (SCEs). As in the underground test era, the Nevada National Security Site (NNSS), formerly the Nevada Test Site, provides a safe and secure environment for SCEs by the nature of its isolated and secure facilities. A major tool for SCE diagnosis installed in the 05 drift laboratory is a high energy x-ray source used for time resolved imaging. This toolmore » consists of two identical sources (Cygnus 1 and Cygnus 2) and is called the Cygnus Dual Beam Radiographic Facility (Figs. 2-6). Each Cygnus machine has 5 major elements: Marx Generator, Pulse Forming Line (PFL), Coaxial Transmission Line (CTL), 3-cell Inductive Voltage Adder (IVA), and Rod Pinch Diode. Each machine is independently triggered and may be fired in separate tests (staggered mode), or in a single test where there is submicrosecond separation between the pulses (dual mode). Cygnus must operate as a single shot machine since on each pulse the diode electrodes are destroyed. The diode is vented to atmosphere, cleaned, and new electrodes are inserted for each shot. There is normally two shots per day on each machine. Since its installation in 2003, Cygnus has participated in: 4 Subcritical Experiments (Armando, Bacchus, Barolo A, and Barolo B), a 12 shot plutonium physics series (Thermos), and 2 plutonium step wedge calibration series (2005, 2011), resulting in well over 1000 shots. Currently the Facility is in preparation for 2 SCEs scheduled for this calendar year - Castor and Pollux. Cygnus has performed well during 8 years of operations at NNSS. Many improvements in operations and performance have been implemented during this time. Throughout its service at U1a, major maintenance and replacement of many hardware items were delayed due to programmatic requirements. It is anticipated that Cygnus will be in service at U1a for another 5 years. With this assumption, it was realized that significant resources and effort should be allotted to bring the hardware back to its original condition, or even to improve elements when appropriate. The Cygnus Refurbishment and Enhancement Project started in April, 2011 with the intent to encompass a major overhaul of Cygnus.« less

Simulating the X-ray luminosity of Be X-ray binaries: the case for black holes versus neutron stars

NASA Astrophysics Data System (ADS)

Brown, R. O.; Ho, W. C. G.; Coe, M. J.; Okazaki, A. T.

2018-04-01

There are over 100 Be stars that are known to have neutron star companions but only one such system with a black hole. Previous theoretical work suggests this is not due to their formation but due to differences in X-ray luminosity. It has also been proposed that the truncation of the Be star's circumstellar disc is dependent on the mass of the compact object. Hence, Be star discs in black hole binaries are smaller. Since accretion onto the compact object from the Be star's disc is what powers the X-ray luminosity, a smaller disc in black hole systems leads to a lower luminosity. In this paper, simulations are performed with a range of eccentricities and compact object mass. The disc's size and density are shown to be dependent on both quantities. Mass capture and, in turn, X-ray luminosity are heavily dependent on the size and density of the disc. Be/black hole binaries are expected to be up to ˜10 times fainter than Be/neutron star binaries when both systems have the same eccentricity and can be 100 times fainter when comparing systems with different eccentricity.

Hot-spot model for accretion disc variability as random process. II. Mathematics of the power-spectrum break frequency

NASA Astrophysics Data System (ADS)

Pecháček, T.; Goosmann, R. W.; Karas, V.; Czerny, B.; Dovčiak, M.

2013-08-01

Context. We study some general properties of accretion disc variability in the context of stationary random processes. In particular, we are interested in mathematical constraints that can be imposed on the functional form of the Fourier power-spectrum density (PSD) that exhibits a multiply broken shape and several local maxima. Aims: We develop a methodology for determining the regions of the model parameter space that can in principle reproduce a PSD shape with a given number and position of local peaks and breaks of the PSD slope. Given the vast space of possible parameters, it is an important requirement that the method is fast in estimating the PSD shape for a given parameter set of the model. Methods: We generated and discuss the theoretical PSD profiles of a shot-noise-type random process with exponentially decaying flares. Then we determined conditions under which one, two, or more breaks or local maxima occur in the PSD. We calculated positions of these features and determined the changing slope of the model PSD. Furthermore, we considered the influence of the modulation by the orbital motion for a variability pattern assumed to result from an orbiting-spot model. Results: We suggest that our general methodology can be useful for describing non-monotonic PSD profiles (such as the trend seen, on different scales, in exemplary cases of the high-mass X-ray binary Cygnus X-1 and the narrow-line Seyfert galaxy Ark 564). We adopt a model where these power spectra are reproduced as a superposition of several Lorentzians with varying amplitudes in the X-ray-band light curve. Our general approach can help in constraining the model parameters and in determining which parts of the parameter space are accessible under various circumstances.

Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

NASA Astrophysics Data System (ADS)

Madau, Piero; Fragos, Tassos

2017-05-01

We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior to and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z ≲ 4. Together with an updated empirical determination of the cosmic history of star formation, recent modeling of the stellar mass-metallicity relation, and a scheme for absorption by the IGM that accounts for the presence of ionized H II bubbles during the epoch of reionization, our detailed calculations provide refined predictions of the X-ray volume emissivity and filtered radiation background from “normal” galaxies at z ≳ 6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. Because of the energy dependence of photoabsorption, soft X-ray photons are produced by local sources, while more energetic radiation arrives unattenuated from larger cosmological volumes. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct He I photoionizations are the main source of IGM heating, and the temperature of the largely neutral medium in between H II cavities increases above the temperature of the cosmic microwave background (CMB) only at z ≲ 10, when the volume filling factor of H II bubbles is already ≳0.1. Therefore, in this scenario, it is only at relatively late epochs that neutral intergalactic hydrogen may be observable in 21 cm emission against the CMB.

Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

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

Madau, Piero; Fragos, Tassos

We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior to and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z ≲ 4. Together with an updated empirical determination of the cosmic history of star formation, recent modeling of the stellar mass–metallicity relation, and a scheme for absorption by the IGM that accounts for the presencemore » of ionized H ii bubbles during the epoch of reionization, our detailed calculations provide refined predictions of the X-ray volume emissivity and filtered radiation background from “normal” galaxies at z ≳ 6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. Because of the energy dependence of photoabsorption, soft X-ray photons are produced by local sources, while more energetic radiation arrives unattenuated from larger cosmological volumes. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct He i photoionizations are the main source of IGM heating, and the temperature of the largely neutral medium in between H ii cavities increases above the temperature of the cosmic microwave background (CMB) only at z ≲ 10, when the volume filling factor of H ii bubbles is already ≳0.1. Therefore, in this scenario, it is only at relatively late epochs that neutral intergalactic hydrogen may be observable in 21 cm emission against the CMB.« less

Problems for the standard black hole/accretion disk models in Cygnus X-1?

NASA Technical Reports Server (NTRS)

Done, C.; Mulchaey, J. S.; Mushotzky, R. F.; Arnaud, K. A.

1992-01-01

Archival EXOSAT and HEAO1-A2 data from Cyg X-1 show the 'high energy excess' above 10 keV seen in X-ray observations of AGN. Using a likelihood ratio test, we are for the first time able to distinguish conclusively in favor of Compton reflection rather than partial covering as the origin of the high energy excess. This supports the idea of an X-ray illuminated accretion disk in Cyg X-1, but the line equivalent width is smaller by a factor of 2-3 than that expected from such a disk. While the larger optical depth required for reflection as opposed to line emission admit the possibility of seeing line without reflection, the converse is not possible. To see a reflection spectrum, including the strong iron absorption edge, implies that strong iron emission must be observed as the line and edge are causally linked.

Soft X-ray production by photon scattering in pulsating binary neutron star sources

NASA Technical Reports Server (NTRS)

Bussard, R. W.; Meszaros, P.; Alexander, S.

1985-01-01

A new mechanism is proposed as a source of soft (less than 1 keV) radiation in binary pulsating X-ray sources, in the form of photon scattering which leaves the electron in an excited Landau level. In a plasma with parameters typical of such sources, the low-energy X-ray emissivity of this mechanism far exceeds that of bremsstrahlung. This copious source of soft photons is quite adequate to provide the seed photons needed to explain the power-law hard X-ray spectrum by inverse Comptonization on the hot electrons at the base of the accretion column.

Recycling Matter in the Universe. X-Ray observations of SBS1150+599A (PN 6135.9+55.9)

NASA Technical Reports Server (NTRS)

Tovmassian, Gagik; Tomsick, John; Napiwotzki, Ralf; Yungelson, Lev; Stasinska, Grazyna; Pena, Miriam; Richer, Michael

2008-01-01

We present X-ray observations of the close binary nucleus of the planetary nebula SBS 1150+599A obtained with the XMM-Newton satellite. Only one component of the binary can be observed in optical-UV. New X-ray observations show that the previously invisible component is a very hot compact star. This finding allows us to deduce rough values for the basic parameters of the binary. With a high probability the total mass of the system exceeds Chandrasekhar limit and makes the SBS1150+599A one of the best candidate for a supernova type Ia progenitor.

Physics of Accretion in X-Ray Binaries

NASA Technical Reports Server (NTRS)

Vrtilek, Saeqa D.

2004-01-01

This project consists of several related investigations directed to the study of mass transfer processes in X-ray binaries. Models developed over several years incorporating highly detailed physics will be tested on a balanced mix of existing data and planned observations with both ground and space-based observatories. The extended time coverage of the observations and the existence of {\\it simultaneous} X-ray, ultraviolet, and optical observations will be particularly beneficial for studying the accretion flows. These investigations, which take as detailed a look at the accretion process in X-ray binaries as is now possible, test current models to their limits, and force us to extend them. We now have the ability to do simultaneous ultraviolet/X-ray/optical spectroscopy with HST, Chandra, XMM, and ground-based observatories. The rich spectroscopy that these Observations give us must be interpreted principally by reference to detailed models, the development of which is already well underway; tests of these essential interpretive tools are an important product of the proposed investigations.

The Physics of Accretion in X-Ray Binaries

NASA Technical Reports Server (NTRS)

Vrtilek, S.; Oliversen, Ronald (Technical Monitor)

2001-01-01

This project consists of several related investigations directed to the study of mass transfer processes in X-ray binaries. Models developed over several years incorporating highly detailed physics will be tested on a balanced mix of existing data and planned observations with both ground and space-based observatories. The extended time coverage of the observations and the existence of simultaneous X-ray, ultraviolet, and optical observations will be particularly beneficial for studying the accretion flows. These investigations, which take as detailed a look at the accretion process in X-ray binaries as is now possible, test current models to their limits, and force us to extend them. We now have the ability to do simultaneous ultraviolet/X-ray/optical spectroscopy with HST, Chandra, XMM, and ground-based observatories. The rich spectroscopy that these observations give us must be interpreted principally by reference to detailed models, the development of which is already well underway; tests of these essential interpretive tools are an important product of the proposed investigations.

X1908+075: An X-Ray Binary with a 4.4 Day Period

NASA Astrophysics Data System (ADS)

Wen, Linqing; Remillard, Ronald A.; Bradt, Hale V.

2000-04-01

X1908+075 is an optically unidentified and highly absorbed X-ray source that appeared in early surveys such as Uhuru, OSO 7, Ariel 5, HEAO-1, and the EXOSAT Galactic Plane Survey. These surveys measured a source intensity in the range 2-12 mcrab at 2-10 keV, and the position was localized to ~0.5d. We use the Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor (ASM) to confirm our expectation that a particular Einstein/IPC detection (1E 1908.4+0730) provides the correct position for X1908+075. The analysis of the coded mask shadows from the ASM for the position of 1E 1908.4+0730 yields a persistent intensity ~8 mcrab (1.5-12 keV) over a 3 yr interval beginning in 1996 February. Furthermore, we detect a period of 4.400+/-0.001 days with a false-alarm probability less than 10-7. The folded light curve is roughly sinusoidal, with an amplitude that is 26% of the mean flux. The X-ray period may be attributed to the scattering and absorption of X-rays through a stellar wind combined with the orbital motion in a binary system. We suggest that X1908+075 is an X-ray binary with a high-mass companion star.

Time correlations between low and high energy gamma rays from discrete sources

NASA Technical Reports Server (NTRS)

Ellsworth, R. W.

1995-01-01

Activities covered the following areas: (1) continuing analysis of the Cygnus Experiment data on the shadowing of cosmic rays by the moon and sun, which led to a direct confirmation of the angular resolution of the CYGNUS EAS array; and (2) development of analysis methods for the daily search overlapping with EGRET targets. To date, no steady emission of ultrahigh energy (UHE) gamma rays from any source has been detected by the Cygnus Experiment, but some evidence for sporadic emission had been found. Upper limits on steady fluxes from 49 sources in the northern hemisphere have been published. In addition, a daily search of 51 possible sources over the interval April 1986 to June 1992 found no evidence for emission. From these source lists, four candidates were selected for comparison with EGRET data.

A1540-53, an eclipsing X-ray binary pulsator

NASA Technical Reports Server (NTRS)

Becker, R. H.; Swank, J. H.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.; Pravdo, S. H.; Saba, J. R.

1977-01-01

An eclipsing X-ray binary pulsator consistent with the location of A1540-53 has been observed. The source pulse period was 528.93 + or - 0.10 s. The binary nature is confirmed by a Doppler curve for the pulsation period. The eclipse angle of 30.5 + or - 3 deg and the 4-hour transition to and from eclipse suggest an early-type giant or supergiant primary star.

VLA HI Zeeman Observations of the Cygnus X Region: DR 22 And ON 2

NASA Astrophysics Data System (ADS)

Mayo, Elizabeth A.; Troland, T. H.

2010-01-01

The Very Large Array in Socorro, New Mexico has been used to study the Zeeman Effect in the 21cm HI line seen in absorption against radio sources in the Cygnus X region. Cygnus X is geometrically favorable for Zeeman effect observations as the region lies along the mean field direction of the diffuse interstellar medium (ISM) of the galaxy. We present observations of two compact HII regions within Cygnus X, DR 22 and ON 2. The data show magnetic field strengths of the order -80 μG toward DR 22 alone with no significant detections toward ON 2. This information is used to estimate the magnetic energy of the DR 22 star-forming cloud, and allows for a complete analysis of the energetics of the region revealing the role of the magnetic field. Support for this work was provided by the NSF PAARE program to South Carolina State University under award AST-0750814.

An unidentified TeV source in the vicinity of Cygnus OB2

NASA Astrophysics Data System (ADS)

Aharonian, F.; Akhperjanian, A.; Beilicke, M.; Bernlöhr, K.; Börst, H.; Bojahr, H.; Bolz, O.; Coarasa, T.; Contreras, J.; Cortina, J.; Denninghoff, S.; Fonseca, V.; Girma, M.; Götting, N.; Heinzelmann, G.; Hermann, G.; Heusler, A.; Hofmann, W.; Horns, D.; Jung, I.; Kankanyan, R.; Kestel, M.; Kettler, J.; Kohnle, A.; Konopelko, A.; Kornmeyer, H.; Kranich, D.; Krawczynski, H.; Lampeitl, H.; Lopez, M.; Lorenz, E.; Lucarelli, F.; Magnussen, N.; Mang, O.; Meyer, H.; Milite, M.; Mirzoyan, R.; Moralejo, A.; Ona, E.; Panter, M.; Plyasheshnikov, A.; Prahl, J.; Pühlhofer, G.; Rauterberg, G.; Reyes, R.; Rhode, W.; Ripken, J.; Röhring, A.; Rowell, G. P.; Sahakian, V.; Samorski, M.; Schilling, M.; Schröder, F.; Siems, M.; Sobzynska, D.; Stamm, W.; Tluczykont, M.; Völk, H. J.; Wiedner, C. A.; Wittek, W.; Uchiyama, Y.; Takahashi, T.; HEGRA Collaboration

2002-10-01

Deep observation ( ~ 113 hrs) of the Cygnus region at TeV energies using the HEGRA stereoscopic system of air Čerenkov telescopes has serendipitously revealed a signal positionally inside the core of the OB association Cygnus OB2, at the edge of the 95% error circle of the EGRET source 3EG J2033+4118, and ~ 0.5o north of Cyg X-3. The source centre of gravity is RA alphaJ2000: 20h 32m 07s+/- 9.2sstat +/-2.2ssys, Dec deltaJ2000: +41o 30' 30''+/- 2.0'stat +/- 0.4'sys. The source is steady, has a post-trial significance of +4.6sigma , indication for extension with radius 5.6' at the ~ 3sigma level, and has a differential power-law flux with hard photon index of -1.9 +/-0.3stat +/-0.3sys. The integral flux above 1 TeV amounts ~ 3% that of the Crab. No counterpart for the TeV source at other wavelengths is presently identified, and its extension would disfavour an exclusive pulsar or AGN origin. If associated with Cygnus OB2, this dense concentration of young, massive stars provides an environment conducive to multi-TeV particle acceleration and likely subsequent interaction with a nearby gas cloud. Alternatively, one could envisage gamma -ray production via a jet-driven termination shock.

X-ray characteristics of the Lupus Loop and SN 1006 supernova remnants

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

Toor, A.

1980-01-01

The spatial extent of the Lupus Loop and spectra for the Lupus Loop and SN1006 supernova remnants have been determined with a rocket-borne payload. The Lupus Loop is an extended source of soft X-rays (approx. 300' diam) that shows a correlation between its brightest x-ray and radio-emission regions. Its spectrum is characterized by a temperature of 350 eV. Thus, the Lupus Loop appears similar to Vela X and Cygnus Loop, although much weaker. Emission from SN1006 is spatially unresolved and exhibits a harder spectrum than that of the Lupus Loop. All spectral data (0.2 to 10 keV) from our observationmore » and previous observations are satisfactorily fit with a power law (index = 2.15). This spectral dependence suggests the possibility that a rotating neutron star is the underlying source of the radiated energy although such an interpretation appears inconsistent with the remnant's morphology.« less

A disc corona-jet model for the radio/X-ray correlation in black hole X-ray binaries

NASA Astrophysics Data System (ADS)

Qiao, Erlin; Liu, B. F.

2015-04-01

The observed tight radio/X-ray correlation in the low spectral state of some black hole X-ray binaries implies the strong coupling of the accretion and jet. The correlation of L_R ∝ L_X^{˜ 0.5-0.7} was well explained by the coupling of a radiatively inefficient accretion flow and a jet. Recently, however, a growing number of sources show more complicated radio/X-ray correlations, e.g. L_R ∝ L_X^{˜ 1.4} for LX/LEdd ≳ 10-3, which is suggested to be explained by the coupling of a radiatively efficient accretion flow and a jet. In this work, we interpret the deviation from the initial radio/X-ray correlation for LX/LEdd ≳ 10-3 with a detailed disc corona-jet model. In this model, the disc and corona are radiatively and dynamically coupled. Assuming a fraction of the matter in the accretion flow, η ≡ dot{M}_jet/dot{M}, is ejected to form the jet, we can calculate the emergent spectrum of the disc corona-jet system. We calculate LR and LX at different dot{M}, adjusting η to fit the observed radio/X-ray correlation of the black hole X-ray transient H1743-322 for LX/LEdd > 10-3. It is found that always the X-ray emission is dominated by the disc corona and the radio emission is dominated by the jet. We noted that the value of η for the deviated radio/X-ray correlation for LX/LEdd > 10-3 is systematically less than that of the case for LX/LEdd < 10-3, which is consistent with the general idea that the jet is often relatively suppressed at the high-luminosity phase in black hole X-ray binaries.

Luminous Binary Supersoft X-Ray Sources

NASA Technical Reports Server (NTRS)

DiStefano, Rosanne; Oliversen, Ronald J. (Technical Monitor)

2002-01-01

This grant was for the study of Luminous Supersoft X-Ray Sources (SSSs). During the first year a number of projects were completed and new projects were started. The projects include: 1) Time variability of SSSs 2) SSSs in M31; 3) Binary evolution scenarios; and 4) Acquiring new data.

X-ray Binaries and the Galaxy Structure in Hard X-rays

NASA Astrophysics Data System (ADS)

Lutovinov, Alexander

The Galaxy structure in the hard X-ray energy band (¿20 keV) was studied using data of the INTEGRAL observatory. A deep and nearly uniform coverage of the galactic plane allowed to increase significantly the sensitivity of the survey and discover several dozens new galac-tic sources. The follow-up observations with XMM-Newton and CHANDRA observatories in X-rays and ground-based telescopes in optical and infrared wavebands gave us a possibility to determine optical counterparts and distances for number of new and already known faint sources. That, in turn, allowed us to build the spatial distribution of different classes of galactic X-ray binaries and obtain preliminary results of the structure of the further part of the Galaxy.

News on the X-ray emission from hot subdwarf stars

NASA Astrophysics Data System (ADS)

Palombara, Nicola La; Mereghetti, Sandro

2017-12-01

In latest years, the high sensitivity of the instruments on-board the XMM-Newton and Chandra satellites allowed us to explore the properties of the X-ray emission from hot subdwarf stars. The small but growing sample of X-ray detected hot subdwarfs includes binary systems, in which the X-ray emission is due to wind accretion onto a compact companion (white dwarf or neutron star), as well as isolated sdO stars, in which X-rays are probably due to shock instabilities in the wind. X-ray observations of these low-mass stars provide information which can be useful for our understanding of the weak winds of this type of stars and can lead to the discovery of particularly interesting binary systems. Here we report the most recent results we have recently obtained in this research area.

Long-term optical and X-ray variability of the Be/X-ray binary H 1145-619: Discovery of an ongoing retrograde density wave

NASA Astrophysics Data System (ADS)

Alfonso-Garzón, J.; Fabregat, J.; Reig, P.; Kajava, J. J. E.; Sánchez-Fernández, C.; Townsend, L. J.; Mas-Hesse, J. M.; Crawford, S. M.; Kretschmar, P.; Coe, M. J.

2017-11-01

Context. Multiwavelength monitoring of Be/X-ray binaries is crucial to understand the mechanisms producing their outbursts. H 1145-619 is one of these systems, which has recently displayed X-ray activity. Aims: We investigate the correlation between the optical emission and X-ray activity to predict the occurrence of new X-ray outbursts from the inferred state of the circumstellar disc. Methods: We have performed a multiwavelength study of H 1145-619 from 1973 to 2017 and present here a global analysis of its variability over the last 40 yr. We used optical spectra from the SAAO, SMARTS, and SALT telescopes and optical photometry from the Optical Monitoring Camera (OMC) onboard INTEGRAL and from the All Sky Automated Survey (ASAS). We also used X-ray observations from INTEGRAL/JEM-X, and IBIS to generate the light curves and combined them with Swift/XRT to extract the X-ray spectra. In addition, we compiled archival observations and measurements from the literature to complement these data. Results: Comparing the evolution of the optical continuum emission with the Hα line variability, we identified three different patterns of optical variability: first, global increases and decreases of the optical brightness, observed from 1982 to 1994 and from 2009 to 2017, which can be explained by the dissipation and replenishment of the circumstellar disc; second, superorbital variations with a period of Psuperorb ≈ 590 days, observed in 2002-2009, which seems to be related to the circumstellar disc; and third, optical outbursts, observed in 1998-1999 and 2002-2005, which we interpret as mass ejections from the Be star. We discovered the presence of a retrograde one-armed density wave, which appeared in 2016 and is still present in the circumstellar disc. Conclusions: We carried out the most complete long-term optical study of the Be/X-ray binary H 1145-619 in correlation with its X-ray activity. For the first time, we found the presence of a retrograde density perturbation in the circumstellar disc of a Be/X-ray binary.

A Search for Ultra--High-Energy Gamma-Ray Emission from Five Supernova Remnants

NASA Astrophysics Data System (ADS)

Allen, G. E.; Berley, D.; Biller, S.; Burman, R. L.; Cavalli-Sforza, M.; Chang, C. Y.; Chen, M. L.; Chumney, P.; Coyne, D.; Dion, C. L.; Dorfan, D.; Ellsworth, R. W.; Goodman, J. A.; Haines, T. J.; Hoffman, C. M.; Kelley, L.; Klein, S.; Schmidt, D. M.; Schnee, R.; Shoup, A.; Sinnis, C.; Stark, M. J.; Williams, D. A.; Wu, J.-P.; Yang, T.; Yodh, G. B.

1995-07-01

The majority of the cosmic rays in our Galaxy with energies in the range of ~1010--1014 eV are thought to be accelerated in supernova remnants (SNRs). Measurements of SNR gamma-ray spectra in this energy region could support or contradict this concept. The Energetic Gamma-Ray Experiment Telescope (EGRET) collaboration has reported six sources of gamma rays above 108 eV whose coordinates are coincident with SNRs. Five of these sources are within the field of view of the CYGNUS extensive air shower detector. A search of the CYGNUS data set reveals no evidence of gamma-ray emission at energies ~1014 eV for these five SNRs. The flux upper limits from the CYGNUS data are compared to the lower energy fluxes measured with the EGRET detector using Drury, Aharonian, & Volk's recent model of gamma-ray production in the shocks of SNRs. The results suggest one or more of the following: (1) the gamma-ray spectra for these five SNRs soften by about 1014 eV, (2) the integral gamma-ray spectra of the SNRs are steeper than about E-1.3, or (3) most of the gamma rays detected with the EGRET instrument for each SNR are not produced in the SNR's shock but are produced at some other site (such as a pulsar).

Simultaneous observation of the gamma-ray binary LS I+61 303 with GLAST and Suzaku

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

Tanaka, Takuya; Fukazawa, Yasushi; Mizuno, Tsunefumi

2007-07-12

The gamma-ray binary LS I+61 303 is a bright gamma-ray source, and thus an attracting object for GLAST. We proposed to observe this object with the X-ray satellite Suzaku (AO-2), simultaneously with GLAST, radio wave, and optical spectro-polarimetry, in order to probe the geometrical state of the binary system emitting the gamma-ray radiation, as a function of the binary orbital phase for the first time. This is essential to understand the mechanism of jet production and gamma-ray emission. The idea is not only to measure the multi-band overall continuum shape, but also to make use of continuous monitoring capability ofmore » GLAST, wide X-ray band of Suzaku, and good accessibility of the Kanata optical/NIR telescope (Hiroshima University) with the sensitive optical spectro-polarimetry. Further collaboration with TeV gamma-ray telescopes is also hoped to constrain the jet constitution.« less

Opening the CHOCBOX: clumpy stellar winds in Cyg X-1

NASA Astrophysics Data System (ADS)

Grinberg, V.; Uttley, P.; Wilms, J.; Miller-Jones, J.; Pottschmidt, K.; Niu, S.; Hirsch, M.; Chocbox Collaboration

2017-10-01

Winds of O/B-stars are key drivers of enrichment and star formation and evolution. Yet, our understanding of their clumpy structure is limited. Luckily, high mass X-ray binaries, where the compact object accretes from the stellar wind of the companion, are perfect laboratories to study such winds: the X-ray radiation from the vicinity of the compact object is quasi-pointlike and effectively X-rays the clumps crossing the line of sight. We observed the high mass X-ray binary Cyg X-1 with XMM for 7 consecutive days with simultaneous coverage with NuSTAR, INTEGRAL and VLBA. One of our main aims was to probe the wind of the O-type companion in an unprecedented uninterrupted campaign, spanning more than an orbital period and including two superior conjunctions where we expect the densest wind. Here, we present first results from the CHOCBOX (Cyg X-1 Hard state Observations of a Complete Binary Orbit in X-rays) campaign and compare them to previous work, in particular multi-year studies of absorption variability and high resolution snapshots with Chandra-HETG. We argue that the clumps have a complex structure with hotter outer and colder inner layers and are not symmetrical.

Consolidated RXTE Observing Grants on Observation of Neutron Stars and Black Holes in Binaries

NASA Technical Reports Server (NTRS)

Prince, Thomas A.; Vaughan, Brian A.

1998-01-01

This final report is a study of neutron stars and black holes in binaries. The activities focused on observation made with the Rossi X-ray Timing Explorer. The following areas were covered: long term observations of accreting binary pulsars with the All-Sky Monitor (ASM); observations of Centaurus X-3 with the Proportional Counter Array (PCA) and the High-Energy X-ray Timing Experiment (HEXTE); observations of accreting pulsars with the PCA and HEXTE; studies of quasi-periodic oscillations (QPO); and investigations of accreting black-hole candidates.

A1540-53, an eclipsing X-ray binary pulsator

NASA Technical Reports Server (NTRS)

Becker, R. H.; Swank, J. H.; Boldt, E. A.; Holt, S. S.; Pravdo, S. H.; Saba, J. R.; Serlemitsos, P. J.

1977-01-01

An eclipsing X-ray binary pulsator consistent with the location of A1540-53 was observed. The source pulse period was 528.93 plus or minus 0.10 seconds. The binary nature is confirmed by a Doppler curve for the pulsation period. The eclipse angle of 30.5 deg plus or minus 3 deg and the 4 h transition to and from eclipse suggest an early type, giant or supergiant, primary star.

A luminous gamma-ray binary in the large magellanic cloud

DOE PAGES

Corbet, R. H. D.; Chomiuk, L.; Coe, M. J.; ...

2016-09-27

Gamma-ray binaries consist of a neutron star or a black hole interacting with a normal star to produce gamma-ray emission that dominates the radiative output of the system. Previously, only a handful of such systems have been discovered, all within our Galaxy. We report the discovery of a luminous gamma-ray binary in the Large Magellanic Cloud, found with the Fermi Large Area Telescope (LAT), from a search for periodic modulation in all sources in the third Fermi LAT catalog. This is the first such system to be found outside the Milky Way. Furthermore, the system has an orbital period ofmore » 10.3 days, and is associated with a massive O5III star located in the supernova remnant DEM L241, previously identified as the candidate high-mass X-ray binary (HMXB) CXOU J053600.0–673507. X-ray and radio emission are also modulated on the 10.3 day period, but are in anti-phase with the gamma-ray modulation. Optical radial velocity measurements suggest that the system contains a neutron star. The source is significantly more luminous than similar sources in the Milky Way, at radio, optical, X-ray, and gamma-ray wavelengths. The detection of this extra-galactic system, but no new Galactic systems, raises the possibility that the predicted number of gamma-ray binaries in our Galaxy has been overestimated, and that HMXBs may be born containing relatively slowly rotating neutron stars.« less

Up and Down the Black Hole Radio/X-Ray Correlation: The 2017 Mini-outbursts from Swift J1753.5-0127

NASA Astrophysics Data System (ADS)

Plotkin, R. M.; Bright, J.; Miller-Jones, J. C. A.; Shaw, A. W.; Tomsick, J. A.; Russell, T. D.; Zhang, G.-B.; Russell, D. M.; Fender, R. P.; Homan, J.; Atri, P.; Bernardini, F.; Gelfand, J. D.; Lewis, F.; Cantwell, T. M.; Carey, S. H.; Grainge, K. J. B.; Hickish, J.; Perrott, Y. C.; Razavi-Ghods, N.; Scaife, A. M. M.; Scott, P. F.; Titterington, D. J.

2017-10-01

The candidate black hole X-ray binary Swift J1753.5-0127 faded to quiescence in 2016 November after a prolonged outburst that was discovered in 2005. Nearly three months later, the system displayed renewed activity that lasted through 2017 July. Here, we present radio and X-ray monitoring over ≈ 3 months of the renewed activity to study the coupling between the jet and the inner regions of the disk/jet system. Our observations cover low X-ray luminosities that have not historically been well-sampled ({L}{{X}}≈ 2× {10}33{--}{10}36 {erg} {{{s}}}-1; 1-10 keV), including time periods when the system was both brightening and fading. At these low luminosities, Swift J1753.5-0127 occupies a parameter space in the radio/X-ray luminosity plane that is comparable to “canonical” systems (e.g., GX 339-4), regardless of whether the system was brightening or fading, even though during its ≳11 year outburst, Swift J1753.5-0127 emitted less radio emission from its jet than expected. We discuss implications for the existence of a single radio/X-ray luminosity correlation for black hole X-ray binaries at the lowest luminosities ({L}{{X}}≲ {10}35 {erg} {{{s}}}-1), and we compare to supermassive black holes. Our campaign includes the lowest luminosity quasi-simultaneous radio/X-ray detection to date for a black hole X-ray binary during its rise out of quiescence, thanks to early notification from optical monitoring combined with fast responses from sensitive multiwavelength facilities.

Characterizing X-ray Sources in the Rich Open Cluster NGC 7789 Using XMM-Newton

NASA Astrophysics Data System (ADS)

Farner, William; Pooley, David

2018-01-01

It is well established that globular clusters exhibit a correlation between their population of exotic binaries and their rate of stellar encounters, but little work has been done to characterize this relationship in rich open clusters. X-ray observations are the most efficient means to find various types of close binaries, and optical (and radio) identifications can provide secure source classifications. We report on an observation of the rich open cluster NGC 7789 using the XMM-Newton observatory. We present the X-ray and optical imaging data, source lists, and preliminary characterization of the sources based on their X-ray and multiwavelength properties.

X-ray and Optical Explorations of Spiders

NASA Astrophysics Data System (ADS)

Roberts, M.; Al Noori, H.; Torres, R.; Russell, D.; Mclaughlin, M.; Gentile, P.

2017-10-01

Black widows and redbacks are binary systems consisting of a millisecond pulsar in a close binary with a companion which is having matter driven off of its surface by the pulsar wind. X-rays due to an intrabinary shock have been observed from many of these systems, as well as orbital variations in the optical emission from the companion due to heating and tidal distortion. We have been systematically studying these systems in radio, optical and X-rays. Here we will present an overview of X-ray and optical studies of these systems, including new XMM-Newton data obtained from several of these systems, along with new optical photometry.

Using HMXBs to Probe Massive Binary Evolution

NASA Astrophysics Data System (ADS)

Garofali, Kristen

2017-09-01

We propose using deep archival Chandra data of M33 to characterize the distribution of physical parameters for the high-mass X-ray binary (HMXB) population from X-ray spectra, X-ray lightcurves, and identified optical counterparts coupled with ground-based spectroscopy. Our analysis will provide the largest clean sample of HMXBs in M33, including hardness, short- and long-term variability, luminosity, and ages. These measurements will be compared across M33 and to HMXB studies in other nearby galaxies to test correlations between HMXB population and host properties such as metallicity and star formation rate. Furthermore, our measurements will yield empirical constraints on prescriptions for models of the formation and evolution of massive stars in binaries.

X-Ray Probes of Cosmic Star Formation History

NASA Technical Reports Server (NTRS)

Ghosh, Pranab; White, Nicholas E.

2001-01-01

We discuss the imprints left by a cosmological evolution of the star formation rate (SFR) on the evolution of X-ray luminosities Lx of normal galaxies, using the scheme earlier proposed by us, wherein the evolution of LX of a galaxy is driven by the evolution of its X-ray binary population. As indicated in our earlier work, the profile of Lx with redshift can both serve as a diagnostic probe of the SFR profile and constrain evolutionary models for X-ray binaries. We report here the first calculation of the expected evolution of X-ray luminosities of galaxies, updating our work by using a suite of more recently developed SFR profiles that span the currently plausible range. The first Chandra deep imaging results on Lx evolution are beginning to probe the SFR profile of bright spiral galaxies; the early results are consistent with predictions based on current SFR models. Using these new SFR profiles, the resolution of the "birthrate problem" of low-mass X-ray binaries and recycled, millisecond pulsars in terms of an evolving global SFR is more complete. We discuss the possible impact of the variations in the SFR profile of individual galaxies and galaxy types.

Evolution of the X-ray luminosity in young HII galaxies

NASA Astrophysics Data System (ADS)

Rosa González, D.; Terlevich, E.; Jiménez Bailón, E.; Terlevich, R.; Ranalli, P.; Comastri, A.; Laird, E.; Nandra, K.

2009-10-01

In an effort to understand the correlation between X-ray emission and present star formation rate, we obtained XMM-Newton data to estimate the X-ray luminosities of a sample of actively star-forming HII galaxies. The obtained X-ray luminosities are compared to other well-known tracers of star formation activity such as the far-infrared and the ultraviolet luminosities. We also compare the obtained results with empirical laws from the literature and with recently published analysis applying synthesis models. We use the time delay between the formation of the stellar cluster and that of the first X-ray binaries, in order to put limits on the age of a given stellar burst. We conclude that the generation of soft X-rays, as well as the Hα or infrared luminosities is instantaneous. The relation between the observed radio and hard X-ray luminosities, on the other hand, points to the existence of a time delay between the formation of the stellar cluster and the explosion of the first massive stars and the consequent formation of supernova (SN) remnants and high-mass X-ray binaries, which originate the radio and hard X-ray fluxes, respectively. When comparing hard X-rays with a star formation indicator that traces the first million years of evolution (e.g. Hα luminosities), we found a deficit in the expected X-ray luminosity. This deficit is not found when the X-ray luminosities are compared with infrared luminosities, a star formation tracer that represents an average over the last 108yr. The results support the hypothesis that hard X-rays are originated in X-ray binaries which, as SN remnants, have a formation time delay of a few mega years after the star-forming burst. Partially based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. E-mail: danrosa@inaoep.mx ‡ Visiting Fellow, IoA, Cambridge, UK.

Compact Objects In Binary Systems: Formation and Evolution of X-ray Binaries and Tides in Double White Dwarfs

NASA Astrophysics Data System (ADS)

Valsecchi, Francesca

Binary star systems hosting black holes, neutron stars, and white dwarfs are unique laboratories for investigating both extreme physical conditions, and stellar and binary evolution. Black holes and neutron stars are observed in X-ray binaries, where mass accretion from a stellar companion renders them X-ray bright. Although instruments like Chandra have revolutionized the field of X-ray binaries, our theoretical understanding of their origin and formation lags behind. Progress can be made by unravelling the evolutionary history of observed systems. As part of my thesis work, I have developed an analysis method that uses detailed stellar models and all the observational constraints of a system to reconstruct its evolutionary path. This analysis models the orbital evolution from compact-object formation to the present time, the binary orbital dynamics due to explosive mass loss and a possible kick at core collapse, and the evolution from the progenitor's Zero Age Main Sequence to compact-object formation. This method led to a theoretical model for M33 X-7, one of the most massive X-ray binaries known and originally marked as an evolutionary challenge. Compact objects are also expected gravitational wave (GW) sources. In particular, double white dwarfs are both guaranteed GW sources and observed electromagnetically. Although known systems show evidence of tidal deformation and a successful GW astronomy requires realistic models of the sources, detached double white dwarfs are generally approximated to point masses. For the first time, I used realistic models to study tidally-driven periastron precession in eccentric binaries. I demonstrated that its imprint on the GW signal yields constrains on the components' masses and that the source would be misclassified if tides are neglected. Beyond this adiabatic precession, tidal dissipation creates a sink of orbital angular momentum. Its efficiency is strongest when tides are dynamic and excite the components' free oscillation modes. Accounting for this effect will determine whether our interpretation of current and future observations will constrain the sources' true physical properties. To investigate dynamic tides I have developed CAFein, a novel code that calculates forced non-adiabatic stellar oscillations using a highly stable and efficient numerical method.

Finding a 24 Day Orbital Period for the X-Ray Binary 1A 1118-616

NASA Technical Reports Server (NTRS)

Staubert, R.; Pottschmidt, K.; Doroshenko, V.; Wilms, J.; Suchy, S.; Rothschild, R.; Santangelo, A.

2010-01-01

We report the first determination of the binary period and the orbital ephemeris of the Be X-ray binary containing the pulsar IA 1118-616 (35 years after the discovery of the source). The orbital period is found to be P(sub orb) = 24.0+/-0.4 days. The source was observed by RXTE during its last big X-ray outburst in January 2009, peaking at MJD 54845.4. This outburst was sampled by taking short observations every few days, covering an elapsed time comparable to the orbital period. Using the phase connection technique, pulse arrival time delays could be measured and an orbital solution determined. The data are consistent with a circular orbit, the time of 90 degrees longitude was found to be T,/2 = MJD 54845.37(10), coincident with the peak X-ray flux.

HESS J1844-030: A New Gamma-Ray Binary?

NASA Astrophysics Data System (ADS)

McCall, Hannah; Errando, Manel

2018-01-01

Gamma-ray binaries are comprised of a massive, main-sequence star orbiting a neutron star or black hole that generates bright gamma-ray emission. Only six of these systems have been discovered. Here we report on a candidate stellar-binary system associated with the unidentified gamma-ray source HESS J1844-030, whose detection was revealed in the H.E.S.S. galactic plane survey. Analysis of 60 ks of archival Chandra data and over 100 ks of XMM-Newton data reveal a spatially associated X-ray counterpart to this TeV-emitting source (E>1012 eV), CXO J1845-031. The X-ray spectra derived from these exposures yields column density absorption in the range nH = (0.4 - 0.7) x 1022 cm-2, which is below the total galactic value for that part of the sky, indicating that the source is galactic. The flux from CXO J1845-031 increases with a factor of up to 2.5 in a 60 day timescale, providing solid evidence for flux variability at a confidence level exceeding 7 standard deviations. The point-like nature of the source, the flux variability of the nearby X-ray counterpart, and the low column density absorption are all indicative of a binary system. Once confirmed, HESS J1844-030 would represent only the seventh known gamma-ray binary, providing valuable data to advance our understanding of the physics of pulsars and stellar winds and testing high-energy astrophysical processes at timescales not present in other classes of objects.

All sky Northern Hemisphere 10(15) EV gamma-ray survey

NASA Technical Reports Server (NTRS)

Baltrusaitis, R. M.; Cassiday, G. L.; Cooper, R.; Elbert, J. W.; Gerhardy, P. R.; Loh, E. C.; Mizumoto, Y.; Sokolsky, P.; Sommers, P.; Steck, D.

1985-01-01

Flux limits in the range 10 to the minus 13th power-10 to the minus 12 power/sq cm/s have been obtained by observing Cerenkov flashes from small air showers. During 1983, a 3.5 sigma excess of showers was observed during the phase interval 0.2 to 0.3 of the 4.8h period of Cygnus X-3, but no excess was found in 1984 observations.

Quasi-spherical accretion in High Mass X-ray Binaries

NASA Astrophysics Data System (ADS)

Postnov, Konstantin

2016-07-01

Quasi-spherical accreion onto magnetized neutron stars from stellar winds in high-mass X-ray binaries is discussed. Depending on the X-ray luminosity of the neutron star, the accretion can proceed in two regimes (modes): at L_x ≳ 4× 10^{36} erg/s, Compton cooling of accreting matter near magnetosphere leads to a supersonic (Bondi) accretion, while at smaller X-ray luminosity the Compton cooling is ineffective, and subsonic settling accretion regime sets in. In this regime, a hot convective shell is formed around the magnetosphere, and the plasma entry rate into magnetosphere is controlled by less effective radiative plasma cooling. The shell mediates the angular momentum transfer from/to the neutron star magnetosphere. Observational evidences for the different accretion regimes in slowly rotating X-ray pulsars with moderate and low X-ray luminosity, as well as possible manifestations of non-stationary quasi-spherical settling accretion due to the magnetospheric shell instability in Supergiant Fast X-ray Transients will be presented.

Swings between rotation and accretion power in a binary millisecond pulsar.

PubMed

Papitto, A; Ferrigno, C; Bozzo, E; Rea, N; Pavan, L; Burderi, L; Burgay, M; Campana, S; Di Salvo, T; Falanga, M; Filipović, M D; Freire, P C C; Hessels, J W T; Possenti, A; Ransom, S M; Riggio, A; Romano, P; Sarkissian, J M; Stairs, I H; Stella, L; Torres, D F; Wieringa, M H; Wong, G F

2013-09-26

It is thought that neutron stars in low-mass binary systems can accrete matter and angular momentum from the companion star and be spun-up to millisecond rotational periods. During the accretion stage, the system is called a low-mass X-ray binary, and bright X-ray emission is observed. When the rate of mass transfer decreases in the later evolutionary stages, these binaries host a radio millisecond pulsar whose emission is powered by the neutron star's rotating magnetic field. This evolutionary model is supported by the detection of millisecond X-ray pulsations from several accreting neutron stars and also by the evidence for a past accretion disc in a rotation-powered millisecond pulsar. It has been proposed that a rotation-powered pulsar may temporarily switch on during periods of low mass inflow in some such systems. Only indirect evidence for this transition has hitherto been observed. Here we report observations of accretion-powered, millisecond X-ray pulsations from a neutron star previously seen as a rotation-powered radio pulsar. Within a few days after a month-long X-ray outburst, radio pulses were again detected. This not only shows the evolutionary link between accretion and rotation-powered millisecond pulsars, but also that some systems can swing between the two states on very short timescales.

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

NASA Astrophysics Data System (ADS)

Bogdanov, Slavko; Halpern, Jules P.

2015-04-01

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

Shot model parameters for Cygnus X-1 through phase portrait fitting

NASA Technical Reports Server (NTRS)

Lochner, James C.; Swank, J. H.; Szymkowiak, A. E.

1991-01-01

Shot models for systems having about 1/f power density spectrum are developed by utilizing a distribution of shot durations. Parameters of the distribution are determined by fitting the power spectrum either with analytic forms for the spectrum of a shot model with a given shot profile, or with the spectrum derived from numerical realizations of trial shot models. The shot fraction is specified by fitting the phase portrait, which is a plot of intensity at a given time versus intensity at a delayed time and in principle is sensitive to different shot profiles. These techniques have been extensively applied to the X-ray variability of Cygnus X-1, using HEAO 1 A-2 and an Exosat ME observation. The power spectra suggest models having characteristic shot durations lasting from milliseconds to a few seconds, while the phase portrait fits give shot fractions of about 50 percent. Best fits to the portraits are obtained if the amplitude of the shot is a power-law function of the duration of the shot. These fits prefer shots having a symmetric exponential rise and decay. Results are interpreted in terms of a distribution of magnetic flares in the accretion disk.

AN EXTENDED AND MORE SENSITIVE SEARCH FOR PERIODICITIES IN ROSSI X-RAY TIMING EXPLORER/ALL-SKY MONITOR X-RAY LIGHT CURVES

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

Levine, Alan M.; Bradt, Hale V.; Chakrabarty, Deepto

2011-09-01

We present the results of a systematic search in {approx}14 years of Rossi X-ray Timing Explorer All-Sky Monitor (ASM) data for evidence of periodicities. Two variations of the commonly used Fourier analysis search method have been employed to significantly improve upon the sensitivity achieved by Wen et al. in 2006, who also searched for periodicities in ASM data. In addition, the present search is comprehensive in terms of sources studied and frequency range covered, and has yielded the detection of the signatures of the orbital periods of eight low-mass X-ray binary systems and of ten high-mass X-ray binaries not listedmore » in the tables of Wen et al. Orbital periods, epochs, signal amplitudes, modulation fractions, and folded light curves are given for each of these systems. Seven of the orbital periods are the most precise reported to date. In the course of this work, the 18.545 day orbital period of IGR J18483-0311 was co-discovered, and the first detections in X-rays were made of the {approx}3.9 day orbital period of LMC X-1 and the {approx}3.79 hr orbital period of 4U 1636-536. The results inform future searches for orbital and other periodicities in X-ray binaries.« less

Soft X-ray Absorption Edges in LMXBs

NASA Technical Reports Server (NTRS)

2004-01-01

The XMM observation of LMC X-2 is part of our program to study X-ray absorption in the interstellar medium (ISM). This program includes a variety of bright X-ray binaries in the Galaxy as well as the Magellanic Clouds (LMC and SMC). LMC X-2 is located near the heart of the LMC. Its very soft X-ray spectrum is used to determine abundance and ionization fractions of neutral and lowly ionized oxygen of the ISM in the LMC. The RGS spectrum so far allowed us to determine the O-edge value to be for atomic O, the EW of O-I in the ls-2p resonance absorption line, and the same for O-II. The current study is still ongoing in conjunction with other low absorption sources like Sco X-1 and the recently observed X-ray binary 4U 1957+11.

Massive binary stars as a probe of massive star formation

NASA Astrophysics Data System (ADS)

Kiminki, Daniel C.

2010-10-01

Massive stars are among the largest and most influential objects we know of on a sub-galactic scale. Binary systems, composed of at least one of these stars, may be responsible for several types of phenomena, including type Ib/c supernovae, short and long gamma ray bursts, high-velocity runaway O and B-type stars, and the density of the parent star clusters. Our understanding of these stars has met with limited success, especially in the area of their formation. Current formation theories rely on the accumulated statistics of massive binary systems that are limited because of their sample size or the inhomogeneous environments from which the statistics are collected. The purpose of this work is to provide a higher-level analysis of close massive binary characteristics using the radial velocity information of 113 massive stars (B3 and earlier) and binary orbital properties for the 19 known close massive binaries in the Cygnus OB2 Association. This work provides an analysis using the largest amount of massive star and binary information ever compiled for an O-star rich cluster like Cygnus OB2, and compliments other O-star binary studies such as NGC 6231, NGC 2244, and NGC 6611. I first report the discovery of 73 new O or B-type stars and 13 new massive binaries by this survey. This work involved the use of 75 successful nights of spectroscopic observation at the Wyoming Infrared Observatory in addition to observations obtained using the Hydra multi-object spectrograph at WIYN, the HIRES echelle spectrograph at KECK, and the Hamilton spectrograph at LICK. I use these data to estimate the spectrophotometric distance to the cluster and to measure the mean systemic velocity and the one-sided velocity dispersion of the cluster. Finally, I compare these data to a series of Monte Carlo models, the results of which indicate that the binary fraction of the cluster is 57 +/- 5% and that the indices for the power law distributions, describing the log of the periods, mass-ratios, and eccentricities, are --0.2 +/- 0.3, 0.3 +/- 0.3, and --0.8 +/- 0.3 respectively (or not consistent with a simple power law distribution). The observed distributions indicate a preference for short period systems with nearly circular orbits and companions that are not likely drawn from a standard initial mass function, as would be expected from random pairing. An interesting and unexpected result is that the period distribution is inconsistent with a standard power-law slope stemming mainly from an excess of periods between 3 and 5 days and an absence of periods between 7 and 14 days. One possible explanation of this phenomenon is that the binary systems with periods from 7--14 days are migrating to periods of 3--5 days. In addition, the binary distribution here is not consistent with previous suggestions in the literature that 45% of OB binaries are members of twin systems (mass ratio near 1).

X-ray binary formation in low-metallicity blue compact dwarf galaxies

NASA Astrophysics Data System (ADS)

Brorby, M.; Kaaret, P.; Prestwich, A.

2014-07-01

X-rays from binaries in small, metal-deficient galaxies may have contributed significantly to the heating and reionization of the early Universe. We investigate this claim by studying blue compact dwarfs (BCDs) as local analogues to these early galaxies. We constrain the relation of the X-ray luminosity function (XLF) to the star formation rate (SFR) using a Bayesian approach applied to a sample of 25 BCDs. The functional form of the XLF is fixed to that found for near-solar metallicity galaxies and is used to find the probability distribution of the normalization that relates X-ray luminosity to SFR. Our results suggest that the XLF normalization for low-metallicity BCDs (12+log(O/H) < 7.7) is not consistent with the XLF normalization for galaxies with near-solar metallicities, at a confidence level 1-5 × 10- 6. The XLF normalization for the BCDs is found to be 14.5± 4.8 ({M}_{⊙}^{-1} yr), a factor of 9.7 ± 3.2 higher than for near-solar metallicity galaxies. Simultaneous determination of the XLF normalization and power-law index result in estimates of q = 21.2^{+12.2}_{-8.8} ({M}_{⊙}^{-1} yr) and α = 1.89^{+0.41}_{-0.30}, respectively. Our results suggest a significant enhancement in the population of high-mass X-ray binaries in BCDs compared to the near-solar metallicity galaxies. This suggests that X-ray binaries could have been a significant source of heating in the early Universe.

Bayesian performance metrics of binary sensors in homeland security applications

NASA Astrophysics Data System (ADS)

Jannson, Tomasz P.; Forrester, Thomas C.

2008-04-01

Bayesian performance metrics, based on such parameters, as: prior probability, probability of detection (or, accuracy), false alarm rate, and positive predictive value, characterizes the performance of binary sensors; i.e., sensors that have only binary response: true target/false target. Such binary sensors, very common in Homeland Security, produce an alarm that can be true, or false. They include: X-ray airport inspection, IED inspections, product quality control, cancer medical diagnosis, part of ATR, and many others. In this paper, we analyze direct and inverse conditional probabilities in the context of Bayesian inference and binary sensors, using X-ray luggage inspection statistical results as a guideline.

A Study of Cen X-3 as Seen by INTEGRAL

NASA Astrophysics Data System (ADS)

La Barbera, A.; Baushev, A.; Ferrigno, C.; Piraino, S.; Santangelo, A.; Segreto, A.; Orlandini, M.; Kretschmar, P.; Kreykenbohm, I.; Wilms, J.; Staubert, R.; Coburn, W.; Heindl, W. A.

2004-10-01

We present a preliminary analysis of 14 observa- tions (Science Windows SCW) of the eclipsing High Mass X ray Binary Pulsar Cen X 3 taken during the Galactic Plane Scan (GPS) with INTEGRAL. The source was detected in 4 SCWs by JEM-X for a total exposure time of 8.7 ksec and in 11 SCWs by ISGRI for a total exposure time of 23.8 ksec. The study of the pulse profile is reported. The 10 70 keV spec- trum is also described. The results are compared with those from previous X ray missions. Key words: pulsars, individual: Cen X 3; stars: neu- tron stars; X rays: binaries.

Low-Luminosity AGN As Analogues of Galactic Black Holes in the Low/Hard State: Evidence from X-Ray Timing of NGC 4258

NASA Technical Reports Server (NTRS)

Markowitz, A.; Uttley, P.

2005-01-01

We present a broadband power spectral density function (PSD) measured from extensive RXTE monitoring data of the low-luminosity AGN NGC 4258, which has an accurate, maser-determined black hole mass of (3.9 plus or minus 0.1) x 10(exp 7) solar mass. We constrain the PSD break time scale to be greater than 4.5 d at greater than 90% confidence, which appears to rule out the possibility that NGC 4258 is an analogue of black hole X-ray binaries (BHXRBs) in the high/soft state. In this sense, the PSD of NGC 4258 is different to that of some more-luminous Seyferts, which appear similar to the PSDs of high/soft state X-ray binaries. This result supports previous analogies between LLAGN and X-ray binaries in the low/hard state based on spectral energy distributions, indicating that the AGN/BHXRB analogy is valid across a broad range of accretion rates.

X-ray mapping of the stellar wind in the binary PSR J2032+4127/MT91 213

NASA Astrophysics Data System (ADS)

Petropoulou, M.; Vasilopoulos, G.; Christie, I. M.; Giannios, D.; Coe, M. J.

2018-02-01

PSR J2032+4127 is a young and rapidly rotating pulsar on a highly eccentric orbit around the high-mass Be star MT91 213. X-ray monitoring of the binary system over an ˜4000 d period with Swift has revealed an increase of the X-ray luminosity which we attribute to the synchrotron emission of the shocked pulsar wind. We use Swift X-ray observations to infer a clumpy stellar wind with r-2 density profile and constrain the Lorentz factor of the pulsar wind to 105 < γw < 106. We investigate the effects of an axisymmetric stellar wind with polar gradient on the X-ray emission. Comparison of the X-ray light curve hundreds of days before and after the periastron can be used to explore the polar structure of the wind.

X-Rays from Galaxies Teeming with Black Holes and Neutron Stars

NASA Technical Reports Server (NTRS)

Hornschemeier, Ann

2010-01-01

Thanks to more than forty years of investment in space-based technology capable of observing the Universe in the x-ray band (0.5 - 100 keV), we have learned quite a bit about the X-ray universe. It has become clear that most of the glow of the X-ray sky is attributed to accretion onto supermassive black holes. However, as we push ever fainter in our detection methods, we find an interesting population of very faint sources arising. These are normal "Milky-way-type" galaxies that also glow in X-rays. The X-ray emission from these galaxies arises from populations of accreting black holes and neutron stars contained in binary systems. This talk will describe our understanding of this population, including some strange regularity in the production of such accreting binary systems. The future, including new technology planned for the next 5-10 years and anticipated theoretical advancements, will also be discussed.

1E 1048.5 + 5421 - A new 114 minute AM Herculis binary

NASA Technical Reports Server (NTRS)

Morris, Simon L.; Schmidt, Gary D.; Liebert, James; Gioia, Isabella M.; Maccacaro, Tommaso

1987-01-01

The discovery of a new AM Herculis binary system, found as a serendipitous Einstein X-ray source, is described. Like the previously discovered mass-transfer binaries involving synchronously rotating magnetic white-dwarf primaries, the system exhibits strong circular polarization, X-ray and optical continuum variations, and optical emission lines, all of which seem to be modulated with these binary periods of 114.5 + or - 0.2 minutes. Although all data are not concurrent, the new system appears to possess the highest ratio of F(x)/F(opt) yet found for an AM Her system. The surprising accumulation of AM Her variables with periods near 114 minute is commented on.

RXTE Observation of Cygnus X-1. Report 2; TIming Analysis

NASA Technical Reports Server (NTRS)

Nowak, Michael A.; Vaughan, Brian A.; Wilms, Joern; Dove, James B.; Begelman, Mitchell C.

1998-01-01

We present timing analysis for a Rossi X-ray Timing Explorer (RXTE) observation of Cygnus X-1 in its hard/low state. This was the first RXTE observation of Cyg X-1 taken after it transited back to this state from its soft/high state. RXTE's large effective area, superior timing capabilities, and ability to obtain long, uninterrupted observations have allowed us to obtain measurements of the power spectral density (PSD), coherence function, and Fourier time lags to a decade lower in frequency and half a decade higher in frequency than typically was achieved with previous instruments. Notable aspects of our observations include a weak 0.005 Hz feature in the PSD coincident with a coherence recovery; a 'hardening' of the high-frequency PSD with increasing energy; a broad frequency range measurement of the coherence function, revealing rollovers from unity coherence at both low and high frequency; and an accurate determination of the Fourier time lags over two and a half decades in frequency. As has been noted in previous similar observations, the time delay is approximately proportional to f(exp -0.7), and at a fixed Fourier frequency the time delay of the hard X-rays compared to the softest energy channel tends to increase logarithmically with energy. Curiously, the 0.01-0.2 Hz coherence between the highest and lowest energy bands is actually slightly greater than the coherence between the second highest and lowest energy bands. We carefully describe all of the analysis techniques used in this paper, and we make comparisons of the data to general theoretical expectations. In a companion paper, we make specific comparisons to a Compton corona model that we have successfully used to describe the energy spectral data from this observation.

An interacting O + O supergiant close binary system: Cygnus OB2-5 (V729 Cyg)

NASA Astrophysics Data System (ADS)

Yaşarsoy, B.; Yakut, K.

2014-08-01

The massive interacting close binary system V729 Cyg (OIa + O/WN9), plausibly progenitor of a Wolf-Rayet system, is studied using new observations gathered over 65 nights and earlier published data. Radial velocity and five color light curves are analysed simultaneously. Estimated physical parameters of the components are M1=36±3 M, M2=10±1 M, R1=27±1 R, R2=15±0.6 R, log(L1/L⊙)=5.59±0.06, and log(L2/L⊙)=4.65±0.07. We give only the formal 1σ scatter, but we believe systematic errors in the luminosities, of uncertain origin as discussed in the text, are likely to be much bigger. The distance of the Cygnus OB2 association is estimated as 967±48 pc by using our newly obtained parameters.

Periodic Emission from the Gamma-ray Binary 1FGL J1018.6-5856

NASA Technical Reports Server (NTRS)

Celic, O.; Corbet, R. H. D.; Donato, D.; Ferrara, E. C.; Gehrels, N.; Harding, A. K.; Hays, E.; McEnery, J. E.; Thompson, D. J.; Troja, E.

2012-01-01

Gamma-ray binaries are stellar systems containing a neutron star or black hole with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that IFGL JI018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable X-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an 06V f) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. IFGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

Periodic emission from the gamma-ray binary 1FGL J1018.6-5856.

PubMed

Fermi LAT Collaboration; Ackermann, M; Ajello, M; Ballet, J; Barbiellini, G; Bastieri, D; Belfiore, A; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Cavazzuti, E; Cecchi, C; Çelik, Ö; Charles, E; Chaty, S; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Corbel, S; Corbet, R H D; Cutini, S; de Luca, A; den Hartog, P R; de Palma, F; Dermer, C D; Digel, S W; do Couto e Silva, E; Donato, D; Drell, P S; Drlica-Wagner, A; Dubois, R; Dubus, G; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Fortin, P; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hill, A B; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, T J; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ozaki, M; Paneque, D; Parent, D; Pesce-Rollins, M; Pierbattista, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Ritz, S; Romani, R W; Roth, M; Saz Parkinson, P M; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Suson, D J; Takahashi, H; Tanaka, T; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vianello, G; Vitale, V; Waite, A P; Winer, B L; Wood, K S; Wood, M; Yang, Z; Zimmer, S; Coe, M J; Di Mille, F; Edwards, P G; Filipović, M D; Payne, J L; Stevens, J; Torres, M A P

2012-01-13

Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6-day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

Periodic Emission from the Gamma-Ray Binary 1FGL J1018.6-5856

NASA Technical Reports Server (NTRS)

2012-01-01

Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy, A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL ]1018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL ]1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

Stellar X-Ray Polarimetry

NASA Technical Reports Server (NTRS)

Swank, J.

2011-01-01

Most of the stellar end-state black holes, pulsars, and white dwarfs that are X-ray sources should have polarized X-ray fluxes. The degree will depend on the relative contributions of the unresolved structures. Fluxes from accretion disks and accretion disk corona may be polarized by scattering. Beams and jets may have contributions of polarized emission in strong magnetic fields. The Gravity and Extreme Magnetism Small Explorer (GEMS) will study the effects on polarization of strong gravity of black holes and strong magnetism of neutron stars. Some part of the flux from compact stars accreting from companion stars has been reflected from the companion, its wind, or accretion streams. Polarization of this component is a potential tool for studying the structure of the gas in these binary systems. Polarization due to scattering can also be present in X-ray emission from white dwarf binaries and binary normal stars such as RS CVn stars and colliding wind sources like Eta Car. Normal late type stars may have polarized flux from coronal flares. But X-ray polarization sensitivity is not at the level needed for single early type stars.

A search for X-ray polarization in cosmic X-ray sources. [binary X-ray sources and supernovae remnants

NASA Technical Reports Server (NTRS)

Hughes, J. P.; Long, K. S.; Novick, R.

1983-01-01

Fifteen strong X-ray sources were observed by the X-ray polarimeters on board the OSO-8 satellite from 1975 to 1978. The final results of this search for X-ray polarization in cosmic sources are presented in the form of upper limits for the ten sources which are discussed elsewhere. These limits in all cases are consistent with a thermal origin for the X-ray emission.

Formation of Black Hole X-Ray Binaries with Non-degenerate Donors in Globular Clusters

NASA Astrophysics Data System (ADS)

Ivanova, Natalia; da Rocha, Cassio A.; Van, Kenny X.; Nandez, Jose L. A.

2017-07-01

In this Letter, we propose a formation channel for low-mass X-ray binaries with black hole accretors and non-degenerate donors via grazing tidal encounters with subgiants. We estimate that in a typically dense globular cluster with a core density of 105 stars pc-3, the formation rates are about one binary per Gyr per 50-100 retained black holes. The donors—stripped subgiants—will be strongly underluminous when compared to subgiant or giant branch stars of the same colors. The products of tidal stripping are underluminous by at least one magnitude for several hundred million years when compared to normal stars of the same color, and differ from underluminous red stars that could be produced by non-catastrophic mass transfer in an ordinary binary. The dynamically formed binaries become quiescent LMXBs, with lifetimes of about a Gyr. The expected number of X-ray binaries is one per 50-200 retained black holes, while the expected number of strongly underluminous subsubgiant is about half this. The presence of strongly underluminous stars in a GC may be indicative of the presence of black holes.

X-Ray Timing Analysis of Cyg X-3 Using AstroSat/LAXPC: Detection of Milli-hertz Quasi-periodic Oscillations during the Flaring Hard X-Ray State

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

Pahari, Mayukh; Misra, Ranjeev; Antia, H M

We present here results from the X-ray timing and spectral analysis of the X-ray binary Cyg X-3 using observations from the Large Area X-ray proportional Counter on board AstroSat . Consecutive light curves observed over a period of one year show the binary orbital period of 17253.56 ± 0.19 s. Another low-amplitude, slow periodicity of the order of 35.8 ± 1.4 days is observed, which may be due to the orbital precession as suggested earlier by Molteni et al. During the rising binary phase, power density spectra from different observations during the flaring hard X-ray state show quasi-periodic oscillations (QPOs)more » at ∼5–8 mHz, ∼12–14 mHz, and ∼18–24 mHz frequencies at the minimum confidence of 99%. However, during the consecutive binary decay phase, no QPO is detected up to 2 σ significance. Energy-dependent time-lag spectra show soft lag (soft photons lag hard photons) at the mHz QPO frequency and the fractional rms of the QPO increases with the photon energy. During the binary motion, the observation of mHz QPOs during the rising phase of the flaring hard state may be linked to the increase in the supply of the accreting material in the disk and corona via stellar wind from the companion star. During the decay phase, the compact source moves in the outer wind region causing the decrease in supply of material for accretion. This may cause weakening of the mHz QPOs below the detection limit. This is also consistent with the preliminary analysis of the orbital phase-resolved energy spectra presented in this paper.« less

Low-mass X-ray binaries and gamma-ray bursts

NASA Technical Reports Server (NTRS)

Lasota, J. P.; Frank, J.; King, A. R.

1992-01-01

More than twenty years after their discovery, the nature of gamma-ray burst sources (GRBs) remains mysterious. The results from BATSE experiment aboard the Compton Observatory show however that most of the sources of gamma-ray bursts cannot be distributed in the galactic disc. The possibility that a small fraction of sites of gamma-ray bursts is of galactic disc origin cannot however be excluded. We point out that large numbers of neutron-star binaries with orbital periods of 10 hr and M dwarf companions of mass 0.2-0.3 solar mass are a natural result of the evolution of low-mass X-ray binaries (LMXBs). The numbers and physical properties of these systems suggest that some gamma-ray burst sources may be identified with this endpoint of LMXB evolution. We suggest an observational test of this hypothesis.

Wind-jet interaction in high-mass X-ray binaries

NASA Astrophysics Data System (ADS)

Zdziarski, Andrzej

2016-07-01

Jets in high-mass X-ray binaries can strongly interact with the stellar wind from the donor. The interaction leads, in particular, to formation of recollimation shocks. The shocks can then accelerate electrons in the jet and lead to enhanced emission, observable in the radio and gamma-ray bands. DooSoo, Zdziarski & Heinz (2016) have formulated a condition on the maximum jet power (as a function of the jet velocity and wind rate and velocity) at which such shocks form. This criterion can explain the large difference in the radio and gamma-ray loudness between Cyg X-1 and Cyg X-3. The orbital modulation of radio emission observed in Cyg X-1 and Cyg X-3 allows a measurement of the location of the height along the jet where the bulk of emission at a given frequency occurs. Strong absorption of X-rays in the wind of Cyg X-3 is required to account for properties of the correlation of the radio emission with soft and hard X-rays. That absorption can also account for the unusual spectral and timing X-ray properties of this source.

Globular cluster x-ray sources

PubMed Central

Pooley, David

2010-01-01

Globular clusters and x-ray astronomy have a long and fruitful history. Uhuru and OSO-7 revealed highly luminous (> 1036 ergs-1) x-ray sources in globular clusters, and Einstein and ROSAT revealed a larger population of low-luminosity (< 1033 ergs-1) x-ray sources. It was realized early on that the high-luminosity sources were low-mass x-ray binaries in outburst and that they were orders of magnitude more abundant per unit mass in globular clusters than in the rest of the galaxy. However, the low-luminosity sources proved difficult to classify. Many ideas were put forth—low-mass x-ray binaries in quiescence (qLMXBs), cataclysmic variables (CVs), active main-sequence binaries (ABs), and millisecond pulsars (MSPs)—but secure identifications were scarce. In ROSAT observations of 55 clusters, about 25 low-luminosity sources were found. Chandra has now observed over 80 Galactic globular clusters, and these observations have revealed over 1,500 x-ray sources. The superb angular resolution has allowed for many counterpart identifications, providing clues to the nature of this population. It is a heterogeneous mix of qLMXBs, CVs, ABs, and MSPs, and it has been shown that the qLMXBs and CVs are both, in part, overabundant like the luminous LMXBs. The number of x-ray sources in a cluster correlates very well with its encounter frequency. This points to dynamical formation scenarios for the x-ray sources and shows them to be excellent tracers of the complicated internal dynamics. The relation between the encounter frequency and the number of x-ray sources has been used to suggest that we have misunderstood the dynamical states of globular clusters. PMID:20404204

Low-mass X-ray binary MAXI J1421-613 observed by MAXI GSC and Swift XRT

NASA Astrophysics Data System (ADS)

Serino, Motoko; Shidatsu, Megumi; Ueda, Yoshihiro; Matsuoka, Masaru; Negoro, Hitoshi; Yamaoka, Kazutaka; Kennea, Jamie A.; Fukushima, Kosuke; Nagayama, Takahiro

2015-04-01

Monitor of All sky X-ray Image (MAXI) discovered a new outburst of an X-ray transient source named MAXI J1421-613. Because of the detection of three X-ray bursts from the source, it was identified as a neutron star low-mass X-ray binary. The results of data analyses of the MAXI GSC (Gas Slit Camera) and the Swift XRT (X-Ray Telescope) follow-up observations suggest that the spectral hardness remained unchanged during the first two weeks of the outburst. All the XRT spectra in the 0.5-10 keV band can be well explained by thermal Comptonization of multi-color disk blackbody emission. The photon index of the Comptonized component is ≈ 2, which is typical of low-mass X-ray binaries in the low/hard state. Since X-ray bursts have a maximum peak luminosity, it is possible to estimate the (maximum) distance from its observed peak flux. The peak flux of the second X-ray burst, which was observed by the GSC, is about 5 photons cm-2 s-1. By assuming a blackbody spectrum of 2.5 keV, the maximum distance to the source is estimated as 7 kpc. The position of this source is contained by the large error regions of two bright X-ray sources detected with Orbiting Solar Observatory-7 (OSO-7) in the 1970s. Besides this, no past activities at the XRT position are reported in the literature. If MAXI J1421-613 is the same source as (one of) these, the outburst observed with MAXI may have occurred after a quiescence of 30-40 years.

X Persei - correlation between H-alpha and X-ray variability

NASA Astrophysics Data System (ADS)

Zamanov, R.; Stoyanov, K. A.; Petrov, N.; Nikolov, Y.; Marchev, D.; Wolter, U.

2018-03-01

We performed H-alpha spectroscopic observations of the Be/X-ray binary X Per, optical counterpart of the slow X-ray pulsar 4U 0352+30, using the 2.0m telescope of the Rozhen National Astronomical Observatory, Bulgaria and the 1.2m TIGRE telescope located in Mexico.

Ginga observations of dipping low mass X ray binaries

NASA Technical Reports Server (NTRS)

Smale, Alan P.; Mukai, Koji; Williams, O. Rees; Jones, Mark H.; Parmar, Arvind N.; Corbet, Robin H. D.

1989-01-01

Ginga observations of several low mass X ray binaries displaying pronounced dips of variable depth and duration in their X ray light curves are analyzed. The periodic occultation of the central X ray source by azimuthal accretion disk structure is considered. A series of spectra selected by intensity from the dip data from XB1916-053, are presented. The effects of a rapidly changing column density upon the spectral fitting results are modeled. EXO0748-676 was observed in March 1989 for three days. The source was found to be in a bright state with a 1 to 20 keV flux of 8.8 x 10 (exp -10) erg/sqcms. The data include two eclipses, observed with high time resolution.

The binary millisecond pulsar PSR J1023+0038 during its accretion state - I. Optical variability

NASA Astrophysics Data System (ADS)

Shahbaz, T.; Linares, M.; Nevado, S. P.; Rodríguez-Gil, P.; Casares, J.; Dhillon, V. S.; Marsh, T. R.; Littlefair, S.; Leckngam, A.; Poshyachinda, S.

2015-11-01

We present time-resolved optical photometry of the binary millisecond `redback' pulsar PSR J1023+0038 (=AY Sex) during its low-mass X-ray binary phase. The light curves taken between 2014 January and April show an underlying sinusoidal modulation due to the irradiated secondary star and accretion disc. We also observe superimposed rapid flaring on time-scales as short as ˜20 s with amplitudes of ˜0.1-0.5 mag and additional large flare events on time-scales of ˜5-60 min with amplitudes of ˜0.5-1.0 mag. The power density spectrum of the optical flare light curves is dominated by a red-noise component, typical of aperiodic activity in X-ray binaries. Simultaneous X-ray and UV observations by the Swift satellite reveal strong correlations that are consistent with X-ray reprocessing of the UV light, most likely in the outer regions of the accretion disc. On some nights we also observe sharp-edged, rectangular, flat-bottomed dips randomly distributed in orbital phase, with a median duration of ˜250 s and a median ingress/egress time of ˜20 s. These rectangular dips are similar to the mode-switching behaviour between disc `active' and `passive' luminosity states, observed in the X-ray light curves of other redback millisecond pulsars. This is the first time that the optical analogue of the X-ray mode-switching has been observed. The properties of the passive- and active-state light curves can be explained in terms of clumpy accretion from a trapped inner accretion disc near the corotation radius, resulting in rectangular, flat-bottomed optical and X-ray light curves.

Contrasting Behaviour from Two Be/X-ray Binary Pulsars: Insights into Differing Neutron Star Accretion Modes

NASA Technical Reports Server (NTRS)

Townsend, L. J.; Drave, S. P.; Hill, A. B.; Coe, M. J.; Corbet, R. H. D.; Bird, A. J.

2013-01-01

In this paper we present the identification of two periodic X-ray signals coming from the direction of the Small Magellanic Cloud (SMC). On detection with the Rossi X-ray Timing Explorer (RXTE), the 175.4 s and 85.4 s pulsations were considered to originate from new Be/X-ray binary (BeXRB) pulsars with unknown locations. Using rapid follow-up INTEGRAL and XMM-Newton observations, we show the first pulsar (designated SXP175) to be coincident with a candidate high-mass X-ray binary (HMXB) in the northern bar region of the SMC undergoing a small Type II outburst. The orbital period (87d) and spectral class (B0-B0.5IIIe) of this system are determined and presented here for the first time. The second pulsar is shown not to be new at all, but is consistent with being SXP91.1 - a pulsar discovered at the very beginning of the 13 year long RXTE key monitoring programme of the SMC. Whilst it is theoretically possible for accreting neutron stars to change spin period so dramatically over such a short time, the X-ray and optical data available for this source suggest this spin-up is continuous during long phases of X-ray quiescence, where accretion driven spin-up of the neutron star should be minimal.

X-Ray Emissions from Accreting White Dwarfs: A Review

NASA Technical Reports Server (NTRS)

Mukai, K.

2017-01-01

Interacting binaries in which a white dwarf accretes material from a companion-cataclysmic variables (CVs) in which the mass donor is a Roche-lobe filling star on or near the main sequence, and symbiotic stars in which the mass donor is a late type giant-are relatively commonplace. They display a wide range of behaviors in the optical, X-rays, and other wavelengths, which still often baffle observers and theorists alike. Here I review the existing body of research on X-ray emissions from these objects for the benefits of both experts and newcomers to the field. I provide introductions to the past and current X-ray observatories, the types of known X-ray emissions from these objects, and the data analysis techniques relevant to this field. I then summarize of our knowledge regarding the X-ray emissions from magnetic CVs, non-magnetic CVs and symbiotic stars, and novae in eruption. I also discuss space density and the X-ray luminosity functions of these binaries and their contribution to the integrated X-ray emission from the Galaxy. I then discuss open questions and future prospects.

Millisecond Oscillations in X-ray Binaries

NASA Astrophysics Data System (ADS)

van der Klis, M.

The first millisecond X-ray variability phenomena from accreting compact objects have recently been discovered with the Rossi X-ray Timing Explorer. Three new phenomena are observed from low-mass X-ray binaries containing low-magnetic-field neutron stars: millisecond pulsations, burst oscillations, and kilohertz quasi-periodic oscillations. Models for these new phenomena involve the neutron star spin and orbital motion close around the neutron star, and rely explicitly on our understanding of strong gravity and dense matter. I review the observations of these new neutron-star phenomena and some possibly related phenomena in black-hole candidates, and describe the attempts to use these observations to perform measurements of fundamental physical interest in these systems.

A State Change In The Missing Link Binary Pulsar System Psr J1023+0038

DOE PAGES

Stappers, B. W.; Archibald, A. M.; Hessels, J. W. T.; ...

2014-07-01

We present radio, X-ray, and γ-ray observations which reveal that the binary millisecond pulsar / low-mass X-ray binary transition system PSR J1023+0038 has undergone a transformation in state. Whereas until recently the system harbored a bright millisecond radio pulsar, the radio pulsations at frequencies between 300 to 5000MHz have now become undetectable. Concurrent with this radio disappearance, the γ-ray flux of the system has quintupled. We conclude that, though the radio pulsar is currently not detectable, the pulsar mechanism is still active and the pulsar wind, as well as a newly formed accretion disk, are together providing the necessary conditionsmore » to create the γ-ray increase. The system is the first example of a transient, compact, low-mass γ-ray binary and will continue to provide an exceptional test bed for better understanding the formation of millisecond pulsars as well as accretion onto neutron stars in general.« less

A Chandra X-ray Mosaic of the Onsala 2 Star-Forming Region

NASA Astrophysics Data System (ADS)

Skinner, Steve L.; Sokal, Kimberly; Guedel, Manuel

2018-01-01

Multiple lines of evidence for active high-mass star-formation in the Onsala 2 (ON2) complex in Cygnus include masers, compact HII (cHII) regions, and massive outflows. ON2 is thought to be physically associated with the young stellar cluster Berkeley 87 which contains several optically-identified OB stars and the rare oxygen-type (WO) Wolf-Rayet star WR 142. WO stars are undergoing advanced nuclear core burning as they approach the end of their lives as supernovae, and only a few are known in the Galaxy. We present results of a sensitive 70 ks Chandra ACIS-I observation of the northern half of ON2 obtained in 2016. This new observation, when combined with our previous 70 ks ACIS-I observation of the southern half in 2009, provides a complete X-ray mosaic of ON2 at arcsecond spatial resolution and reveals several hundred X-ray sources. We will summarize key results emerging from our ongoing analysis including the detection of an embedded population of young stars revealed as a tight grouping of X-ray sources surrounding the cHII region G75.77+0.34, possible diffuse X-ray emission (or unresolved faint point sources) near the cHII region G75.84+0.40, and confirmation of hard heavily-absorbed X-ray emission from WR 142 that was seen in the previous 2009 Chandra observation.

Hydrodynamical and Spectral Simulations of HMXB Winds

NASA Astrophysics Data System (ADS)

Mauche, Christopher W.; Liedahl, D. A.; Plewa, T.

2006-09-01

We describe the results of a research program to develop improved models of the X-ray spectra of cosmic sources such as X-ray binaries, CVs, and AGN in which UV line-driven mass flows are photoionized by an X-ray source. Work to date has focused on high-mass X-ray binaries (HMXBs) and on Vela X-1 in particular, for which there are high-quality Chandra HETG spectra in the archive. Our research program combines FLASH hydrodynamic calculations, XSTAR photoionization calculations, HULLAC atomic data, improved calculations of the line force multiplier, X-ray emission models appropriate to X-ray photoionized plasmas, and Monte Carlo radiation transport. We will present movies of the relevant physical quantities (density, temperature, ionization parameter, velocity) from a FLASH two-dimensional time-dependent simulation of Vela X-1, maps showing the emissivity distributions of the X-ray emission lines, and a preliminary comparison of the resulting synthetic spectra to the Chandra HETG spectra. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

THE NuSTAR Hard X-Ray Survey of the Norma Arm Region

NASA Technical Reports Server (NTRS)

Fornasini, Francesca M.; Tomsick, John A.; Hong, Jaesub; Gotthelf, Eric V.; Bauer, Franz; Rahoui, Farid; Stern, Daniel K.; Bodaghee, Arash; Chiu, Jeng-Lun; Clavel, Maïca;

The NuSTAR Hard X-Ray Survey of the Norma Arm Region

DOE PAGES

Fornasini, Francesca M.; Tomsick, John A.; Hong, JaeSub; ...

2017-04-06

We present a catalog of hard X-ray sources in a square-degree region surveyed by NuSTAR in the direction of the Norma spiral arm. This survey has a total exposure time of 1.7 Ms, and typical and maximum exposure depths of 50 ks and 1 Ms, respectively. In the area of deepest coverage, sensitivity limits of 5 x 10 -14 and 4 x 10-14 erg s -1 cm -2 in the 3–10 and 10–20 keV bands, respectively, are reached. Twenty-eight sources are firmly detected and ten are detected with low significance; eight of the 38 sources are expected to be activemore » galactic nuclei. The three brightest sources were previously identified as a low-mass X-ray binary, high-mass X-ray binary, and pulsar wind nebula. Based on their X-ray properties and multi-wavelength counterparts, we identify the likely nature of the other sources as two colliding wind binaries, three pulsar wind nebulae, a black hole binary, and a plurality of cataclysmic variables (CVs). The CV candidates in the Norma region have plasma temperatures of ≈10–20 keV, consistent with the Galactic Ridge X-ray emission spectrum but lower than temperatures of CVs near the Galactic Center. This temperature difference may indicate that the Norma region has a lower fraction of intermediate polars relative to other types of CVs compared to the Galactic Center. The NuSTAR logN-logS distribution in the 10–20 keV band is consistent with the distribution measured by Chandra at 2–10 keV if the average source spectrum is assumed to be a thermal model with kT ≈ 15 keV, as observed for the CV candidates.« less

Periodic Emission from the Gamma-Ray Binary 1FGL J1018.6-5856

DOE PAGES

Ackermann, M.

2012-01-12

Gamma-ray binaries are stellar systems containing a neutron star or black hole with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable X-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGLmore » J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.« less

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

McCollough, M. L.; Dunham, M. M.; Corrales, L., E-mail: mmccollough@cfa.harvard.edu

Chandra observations have revealed a feature within 16″ of Cygnus X-3 that varied in phase with Cygnus X-3. This feature was shown to be a Bok globule that is along the line of sight to Cygnus X-3. We report on observations made with the Submillimeter Array to search for molecular emission from this globule, also known as Cygnus X-3's “Little Friend.” We have found a counterpart in both {sup 12}CO (2-1) and {sup 13}CO (2-1) emission. From the velocity shift of the molecular lines we are able to find two probable distances based on the Bayesian model of Milky Waymore » kinematics of Reid et al. For the LF velocity of −47.5 km s{sup −1}, we find distances of 6.1 ± 0.6 kpc (62% probability) and 7.8 ± 0.6 kpc (38% probability). This yields distances to Cyg X-3 of 7.4 ± 1.1 kpc and 10.2 ± 1.2 kpc, respectively. Based on the probabilities entailed, we take 7.4 ± 1.1 kpc as the preferred distance to Cyg X-3. We also report the discovery of bipolar molecular outflow, suggesting that there is active star formation occurring within the Little Friend.« less

Formation Constraints Indicate a Black Hole Accretor in 47 Tuc X9

NASA Astrophysics Data System (ADS)

Church, Ross P.; Strader, Jay; Davies, Melvyn B.; Bobrick, Alexey

2017-12-01

The luminous X-ray binary 47 Tuc X9 shows radio and X-ray emission consistent with a stellar-mass black hole (BH) accreting from a carbon-oxygen white dwarf. Its location, in the core of the massive globular cluster 47 Tuc, hints at a dynamical origin. We assess the stability of mass transfer from a carbon-oxygen white dwarf onto compact objects of various masses, and conclude that for mass transfer to proceed stably, the accretor must, in fact, be a BH. Such systems can form dynamically by the collision of a stellar-mass BH with a giant star. Tidal dissipation of energy in the giant’s envelope leads to a bound binary with a pericenter separation less than the radius of the giant. An episode of common-envelope evolution follows, which ejects the giant’s envelope. We find that the most likely target is a horizontal-branch star, and that a realistic quantity of subsequent dynamical hardening is required for the resulting binary to merge via gravitational wave emission. Observing one binary like 47 Tuc X9 in the Milky Way globular cluster system is consistent with the expected formation rate. The observed 6.8-day periodicity in the X-ray emission may be driven by eccentricity induced in the ultra-compact X-ray binary’s orbit by a perturbing companion.

Superorbital Periodic Modulation in Wind-Accretion High-Mass X-Ray Binaries from Swift Burst Alert Telescope Observations

NASA Technical Reports Server (NTRS)

Corbet, Robin H. D.; Krimm, Hans A.

2013-01-01

We report the discovery using data from the Swift-Burst Alert Telescope (BAT) of superorbital modulation in the wind-accretion supergiant high-mass X-ray binaries 4U 1909+07 (= X 1908+075), IGR J16418-4532, and IGR J16479-4514. Together with already known superorbital periodicities in 2S 0114+650 and IGR J16493-4348, the systems exhibit a monotonic relationship between superorbital and orbital periods. These systems include both supergiant fast X-ray transients and classical supergiant systems, and have a range of inclination angles. This suggests an underlying physical mechanism which is connected to the orbital period. In addition to these sources with clear detections of superorbital periods, IGR J16393-4643 (= AX J16390.4-4642) is identified as a system that may have superorbital modulation due to the coincidence of low-amplitude peaks in power spectra derived from BAT, Rossi X-Ray Timing Explorer Proportional Counter Array, and International Gamma-Ray Astrophysics Laboratory light curves. 1E 1145.1-6141 may also be worthy of further attention due to the amount of low-frequency modulation of its light curve. However, we find that the presence of superorbital modulation is not a universal feature of wind-accretion supergiant X-ray binaries.

A Deep Chandra ACIS Survey of M51

NASA Astrophysics Data System (ADS)

Kuntz, K. D.; Long, Knox S.; Kilgard, Roy E.

2016-08-01

We have obtained a deep X-ray image of the nearby galaxy M51 using Chandra. Here we present the catalog of X-ray sources detected in these observations and provide an overview of the properties of the point-source population. We find 298 sources within the D 25 radii of NGC 5194/5, of which 20% are variable, a dozen are classical transients, and another half dozen are transient-like sources. The typical number of active ultraluminous X-ray sources in any given observation is ˜5, and only two of those sources persist in an ultraluminous state over the 12 yr of observations. Given reasonable assumptions about the supernova remnant population, the luminosity function is well described by a power law with an index between 1.55 and 1.7, only slightly shallower than that found for populations dominated by high-mass X-ray binaries (HMXBs), which suggests that the binary population in NGC 5194 is also dominated by HMXBs. The luminosity function of NGC 5195 is more consistent with a low-mass X-ray binary dominated population. Based on observations made with NASA's Chandra X-ray Observatory, which is operated by the Smithsonian Astrophysical Observatory under contract #NAS83060, and the data were obtained through program GO1-12115.

High Energy Studies of Astrophysical Dust

NASA Astrophysics Data System (ADS)

Corrales, Lia Racquel

Astrophysical dust---any condensed matter ranging from tens of atoms to micron sized grains---accounts for about one third of the heavy elements produced in stars and disseminated into space. These tiny pollutants are responsible for producing the mottled appearance in the spray of light we call the "Milky Way." However these seemingly inert particles play a strong role in the physics of the interstellar medium, aiding star and planet formation, and perhaps helping to guide galaxy evolution. Most dust grains are transparent to X-ray light, leaving a signature of atomic absorption, but also scattering the light over small angles. Bright X-ray objects serendipitously situated behind large columns of dust and gas provide a unique opportunity to study the dust along the line of sight. I focus primarily on X-ray scattering through dust, which produces a diffuse halo image around a central point source. Such objects have been observed around X-ray bright Galactic binaries and extragalactic objects that happen to shine through the plane of the Milky Way. I use the Chandra X-ray Observatory, a space-based laboratory operated by NASA, which has imaging resolution ideal for studying X-ray scattering halos. I examine several bright X-ray objects with dust-free sight lines to test their viability as templates and develop a parametric model for the Chandra HETG point spread function (PSF). The PSF describes the instrument's imaging response to a point source, an understanding of which is necessary for properly measuring the surface brightness of X-ray scattering halos. I use an HETG observation of Cygnus X-3, one of the brightest objects available in the Chandra archive, to derive a dust grain size distribution. There exist degenerate solutions for the dust scattering halo, but with the aid of Bayesian analytics I am able to apply prior knowledge about the Cyg X-3 sight line to measure the relative abundance of dust in intervening Milky Way spiral arms. I also demonstrate how information from a single scattering halo can be used in conjunction with X-ray spectroscopy to directly measure the dust-to-gas mass ratio, laying the groundwork for future scattering halo surveys. Distant quasars also produce X-rays that pierce the intergalactic medium. These sources invite the unique opportunity to search for extragalactic dust, whether distributed diffusely throughout intergalactic space, surrounding other galaxies, or occupying reservoirs of cool intergalactic gas. I review X-ray scattering in a cosmological context, examining the range and sensitivity of Chandra to detect the low surface brightness levels of intergalactic scattering. Of particular interest is large "grey" dust, which would cause systematic errors in precision cosmology experiments at a level comparable to the size of the error bars sought. This requires using the more exact Mie scattering treatment, which reduces the scattering cross-section for soft X-rays by a factor of about ten, compared to the Rayleigh-Gans approximation used for interstellar X-ray scattering studies. This allows me to relax the limit on intergalactic dust imposed by previous X-ray imaging of a z=4.3 quasar, QSO 1508+5714, which overestimated the scattering intensity. After implementing the Mie solution with the cosmological integral for scattering halo intensity, I found that intergalactic dust will scatter 1-3% of soft X-ray light. Unfortunately the wings of the Chandra PSF are brighter than the surface brightness expected for these intergalactic scattering halos. The X-ray signatures of intergalactic dust may only be visible if a distant quasar suddenly dimmed by a factor of 1000 or more, leaving behind an X-ray scattering echo, or "ghost" halo.

High-energy variability of the Pulsar binary PSR J1311-3430

NASA Astrophysics Data System (ADS)

An, Hongjun; Fermi-LAT Collaboration

2018-01-01

We present analysis results of high-energy observations of the extreme mass-ratio black-widow millisecond pulsar binary PSR J1311-3430. Our studies in the UV, X-ray, and gamma-ray bands confirm the orbital modulation in the gamma-ray band as suggested previously. In addition, we find that the modulation is stronger in the high-energy band. In the lower-energy UV and X-ray bands, we detect flares which were observed previously and attributed to magnetic activities. We find that the optical flares are associated with the X-ray flares, suggesting common origin. We explore possible connections of the variabilities with the intrabinary shock (IBS) and magnetic activity on the low mass companion.

RXTE Observation of Cygnus X-1. 1; Spectral Analysis

NASA Technical Reports Server (NTRS)

Dove, James B.; Wilms, Joern; Nowak, Michael A.; Vaughan, Brian A.; Begelman, Mitchell C.

1998-01-01

We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200 keV, using data from a 10 ksec observation by the Rossi X-ray Timing Explorer. The spectrum can be well described phenomenologically by an exponentially cut-off power law with a photon index Gamma = 1.45(+0.01 -0.02) (a value considerably harder 0.02 than typically found), e-folding energy E(sub f) = 162(+9 -8) keV, plus a deviation from a power law that formally can be modeled as a thermal blackbody with temperature kT(sub bb) = 1.2(+0.0 -0.1) keV. Although the 3-30 keV portion of the spectrum can be fit with a reflected power law with Gamma = 1.81 + or - 0.01 and covering fraction f = 0.35 + or - 0.02, the quality of the fit is significantly reduced when the HEXTE data in the 30-100 keV range is included, as there is no observed hardening in the power law within this energy range. As a physical description of this system, we apply the accretion disc corona models of Dove, Wilms & Begelman (1997a) - where the temperature of the corona is determined self-consistently. A spherical corona with a total optical depth pi = 1.6 + or - 0.1 and an average temperature kT(sub c) = 87 + or - 5 keV, surrounded by an exterior cold disc, does provide a good description of the data (X(exp 2 sub red) = 1.55). These models deviate from red the data by up to 7% in the 5 - 10 keV range, and we discuss possible reasons for these discrepancies. However, considering bow successfully the spherical corona reproduces the 10 - 200 keV data, such "pboton-starved" coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

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

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

Bogdanov, Slavko; Halpern, Jules P.

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

INTERFERENCE AS AN ORIGIN OF THE PEAKED NOISE IN ACCRETING X-RAY BINARIES

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

Veledina, Alexandra, E-mail: alexandra.veledina@gmail.com

2016-12-01

We propose a physical model for the peaked noise in the X-ray power density spectra of accreting X-ray binaries. We interpret its appearance as an interference of two Comptonization continua: one coming from the upscattering of seed photons from the cold thin disk and the other fed by the synchrotron emission of the hot flow. Variations of both X-ray components are caused by fluctuations in mass accretion rate, but there is a delay between them corresponding to the propagation timescale from the disk Comptonization radius to the region of synchrotron Comptonization. If the disk and synchrotron Comptonization are correlated, themore » humps in the power spectra are harmonically related and the dips between them appear at frequencies related as odd numbers 1:3:5. If they are anti-correlated, the humps are related as 1:3:5, but the dips are harmonically related. Similar structures are expected to be observed in accreting neutron star binaries and supermassive black holes. The delay can be easily recovered from the frequency of peaked noise and further used to constrain the combination of the viscosity parameter and disk height-to-radius ratio α ( H / R ){sup 2} of the accretion flow. We model multi-peak power spectra of black hole X-ray binaries GX 339–4 and XTE J1748–288 to constrain these parameters.« less

Binaries, cluster dynamics and population studies of stars and stellar phenomena

NASA Astrophysics Data System (ADS)

Vanbeveren, Dany

2005-10-01

The effects of binaries on population studies of stars and stellar phenomena have been investigated over the past 3 decades by many research groups. Here we will focus mainly on the work that has been done recently in Brussels and we will consider the following topics: the effect of binaries on overall galactic chemical evolutionary models and on the rates of different types of supernova, the population of point-like X-ray sources where we distinguish the standard high mass X-ray binaries and the ULXs, a UFO-scenario for the formation of WR+OB binaries in dense star systems. Finally we critically discuss the possible effect of rotation on population studies.

Chandra-SDSS Normal and Star-Forming Galaxies. I. X-Ray Source Properties of Galaxies Detected by the Chandra X-Ray Observatory in SDSS DR2

NASA Astrophysics Data System (ADS)

Hornschemeier, A. E.; Heckman, T. M.; Ptak, A. F.; Tremonti, C. A.; Colbert, E. J. M.

2005-01-01

We have cross-correlated X-ray catalogs derived from archival Chandra X-Ray Observatory ACIS observations with a Sloan Digital Sky Survey Data Release 2 (DR2) galaxy catalog to form a sample of 42 serendipitously X-ray-detected galaxies over the redshift interval 0.03

INTEGRAL and XMM-Newton observations of the puzzling binary system LSI +61 303

NASA Astrophysics Data System (ADS)

Chernyakova, Masha; Neronov, A.; Walter, R.

LSI +61° 303 is one of the few X-ray binaries with Be star companion from which both radio and high-energy gamma-ray emission have been observed. We present XMM-Newton and INTE- GRAL observations which reveal variability of the X-ray spectral index of the system. The X-ray spectrum is hard (photon index Γ ≃ 1.5) during the orbital phases of both high and low X-ray flux. However, the spectrum softens at the moment of transition from high to low X-ray state. The spectrum of the system in the hard X-ray band does not reveal the presence of a cut-off (or, at least a spectral break) at 10-60 keV energies, expected if the compact object is an accreting neu- tron star. The observed spectrum and spectral variability can be explained if the compact object in the system is a rotation powered pulsar. In this case the recently found X-ray spectral variability of the system on the several kiloseconds time scale can be explained by the clumpy structure of the Be star disk.

Forming short-period Wolf-Rayet X-ray binaries and double black holes through stable mass transfer

NASA Astrophysics Data System (ADS)

van den Heuvel, E. P. J.; Portegies Zwart, S. F.; de Mink, S. E.

2017-11-01

We show that black hole high-mass X-ray binaries (HMXBs) with O- or B-type donor stars and relatively short orbital periods, of order one week to several months may survive spiral-in, to then form Wolf-Rayet (WR) X-ray binaries with orbital periods of order a day to a few days; while in systems where the compact star is a neutron star, HMXBs with these orbital periods never survive spiral-in. We therefore predict that WR X-ray binaries can only harbour black holes. The reason why black hole HMXBs with these orbital periods may survive spiral-in is: the combination of a radiative envelope of the donor star and a high mass of the compact star. In this case, when the donor begins to overflow its Roche lobe, the systems are able to spiral in slowly with stable Roche lobe overflow, as is shown by the system SS433. In this case, the transferred mass is ejected from the vicinity of the compact star (so-called isotropic re-emission mass-loss mode, or SS433-like mass-loss), leading to gradual spiral-in. If the mass ratio of donor and black hole is ≳3.5, these systems will go into common-envelope evolution and are less likely to survive. If they survive, they produce WR X-ray binaries with orbital periods of a few hours to one day. Several of the well-known WR+O binaries in our Galaxy and the Magellanic Clouds, with orbital periods in the range between a week and several months, are expected to evolve into close WR-black hole binaries, which may later produce close double black holes. The galactic formation rate of double black holes resulting from such systems is still uncertain, as it depends on several poorly known factors in this evolutionary picture. It might possibly be as high as ˜10-5 yr-1.

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

Corbet, R. H. D.; Chomiuk, L.; Strader, J.

Gamma-ray binaries consist of a neutron star or a black hole interacting with a normal star to produce gamma-ray emission that dominates the radiative output of the system. Only a handful of such systems have been previously discovered, all within our Galaxy. Here, we report the discovery of a luminous gamma-ray binary in the Large Magellanic Cloud, found with the Fermi Large Area Telescope (LAT), from a search for periodic modulation in all sources in the third Fermi LAT catalog. This is the first such system to be found outside the Milky Way. The system has an orbital period ofmore » 10.3 days, and is associated with a massive O5III star located in the supernova remnant DEM L241, previously identified as the candidate high-mass X-ray binary (HMXB) CXOU J053600.0–673507. X-ray and radio emission are also modulated on the 10.3 day period, but are in anti-phase with the gamma-ray modulation. Optical radial velocity measurements suggest that the system contains a neutron star. The source is significantly more luminous than similar sources in the Milky Way, at radio, optical, X-ray, and gamma-ray wavelengths. The detection of this extra-galactic system, but no new Galactic systems, raises the possibility that the predicted number of gamma-ray binaries in our Galaxy has been overestimated, and that HMXBs may be born containing relatively slowly rotating neutron stars.« less

The MAVERIC Survey: A Red Straggler Binary with an Invisible Companion in the Galactic Globular Cluster M10

NASA Astrophysics Data System (ADS)

Shishkovsky, Laura; Strader, Jay; Chomiuk, Laura; Bahramian, Arash; Tremou, Evangelia; Li, Kwan-Lok; Salinas, Ricardo; Tudor, Vlad; Miller-Jones, James C. A.; Maccarone, Thomas J.; Heinke, Craig O.; Sivakoff, Gregory R.

2018-03-01

We present the discovery and characterization of a radio-bright binary in the Galactic globular cluster M10. First identified in deep radio continuum data from the Karl G. Jansky Very Large Array, M10-VLA1 has a flux density of 27 ± 4 μJy at 7.4 GHz and a flat-to-inverted radio spectrum. Chandra imaging shows an X-ray source with L X ≈ 1031 erg s‑1 matching the location of the radio source. This places M10-VLA1 within the scatter of the radio-X-ray luminosity correlation for quiescent stellar-mass black holes, and a black hole X-ray binary is a viable explanation for this system. The radio and X-ray properties of the source disfavor, but do not rule out, identification as an accreting neutron star or white dwarf system. Optical imaging from the Hubble Space Telescope and spectroscopy from the SOAR telescope show that the system has an orbital period of 3.339 days and an unusual “red straggler” component: an evolved star found redward of the M10 red giant branch. These data also show UV/optical variability and double-peaked Hα emission characteristic of an accretion disk. However, SOAR spectroscopic monitoring reveals that the velocity semi-amplitude of the red straggler is low. We conclude that M10-VLA1 is most likely either a quiescent black hole X-ray binary with a rather face-on (i < 4°) orientation or an unusual flaring RS Canum Venaticorum variable-type active binary, and discuss future observations that could distinguish between these possibilities.

CHANDRA X-RAY AND HUBBLE SPACE TELESCOPE IMAGING OF OPTICALLY SELECTED KILOPARSEC-SCALE BINARY ACTIVE GALACTIC NUCLEI. II. HOST GALAXY MORPHOLOGY AND AGN ACTIVITY

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

Shangguan, Jinyi; Ho, Luis C.; Liu, Xin

Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W ( U -band) and F105W ( Y -band) images taken by the Wide Fieldmore » Camera 3 on board the Hubble Space Telescope . Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U − Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers.« less

Probing the X-ray Emission from the Massive Star Cluster Westerlund 2

NASA Astrophysics Data System (ADS)

Lopez, Laura

2017-09-01

We propose a 300 ks Chandra ACIS-I observation of the massive star cluster Westerlund 2 (Wd2). This region is teeming with high-energy emission from a variety of sources: colliding wind binaries, OB and Wolf-Rayet stars, two young pulsars, and an unidentified source of very high-energy (VHE) gamma-rays. Our Chandra program is designed to achieve several goals: 1) to take a complete census of Wd2 X-ray point sources and monitor variability; 2) to probe the conditions of the colliding winds in the binary WR 20a; 3) to search for an X-ray counterpart of the VHE gamma-rays; 4) to identify diffuse X-ray emission; 5) to compare results to other massive star clusters observed by Chandra. Only Chandra has the spatial resolution and sensitivity necessary for our proposed analyses.

REVIEWS OF TOPICAL PROBLEMS: Masses of black holes in binary stellar systems

NASA Astrophysics Data System (ADS)

Cherepashchuk, Anatolii M.

1996-08-01

Mass determination methods and their results for ten black holes in X-ray binary systems are summarised. A unified interpretation of the radial velocity and optical light curves allows one to reliably justify the close binary system model and to prove the correctness of determination of the optical star mass function fv(m).The orbit plane inclination i can be estimated from an analysis of optical light curve of the system, which is due mainly to the ellipsoidal shape of the optical star (the so-called ellipticity effect). The component mass ratio q = mx/mv is obtained from information about the distance to the binary system as well as from data about rotational broadening of absorption lines in the spectrum of the optical star. These data allow one to obtain from the value of fv(m) a reliable value of the black hole mass mx or its low limit, as well as the optical star mass mv. An independent estimate of the optical star mass mv obtained from information about its spectral class and luminosity gives us test results. Additional test comes from information about the absence or presence of X-ray eclipses in the system. Effects of the non-zero dimension of the optical star, its pear-like shape, and X-ray heating on the absorption line profiles and the radial velocity curve are investigated. It is very significant that none of ten known massive (mx > 3M\\odot) X-ray sources considered as black hole candidates is an X-ray pulsar or an X-ray burster of the first kind.

X-ray variability of Cygnus X-1 in its soft state

NASA Technical Reports Server (NTRS)

Cui, W.; Zhang, S. N.; Jahoda, K.; Focke, W.; Swank, J.; Heindl, W. A.; Rothschild, R. E.

1997-01-01

Observations from the Rossi X-ray Timing Explorer (RXTE) of Cyg X-1 in the soft state and during the soft to hard transition are examined. The results of this analysis confirm previous conclusions that for this source there is a settling period (following the transition from the hard to soft state during which the low energy spectrum varies significantly, while the high energy portion changes little) during which the source reaches nominal soft state brightness. This behavior can be characterized by a soft low energy spectrum and significant low frequency 1/f noise and white noise on the power density spectrum, which becomes softer upon reaching the true soft state. The low frequency 1/f noise is not observed when Cyg X-1 is in the hard state, and therefore appears to be positively correlated with the disk mass accretion rate. The difference in the observed spectral and timing properties between the hard and soft states is qualitatively consistent with a fluctuating corona model.

A View through a Bamboo Screen: From Moire Patterns to Black Holes.

ERIC Educational Resources Information Center

Oda, Minoru

1992-01-01

Describes the genesis, the early experiments, and the limitations of X-ray astronomy. Discusses original methods for searching and locating the first interstellar X-ray source, modern attempts to identify a massive black hole as part of a binary system X-ray source, and the effort to generate X-ray images of solar flares. (JJK)

Relativistic Astrophysics in Black Hole and Low-Mass Neutron Star X-ray Binaries

NASA Technical Reports Server (NTRS)

2000-01-01

During the five-year period, our study of "Relativistic Astrophysics in Black Hole and Low-Mass Neutron Star X-ray Binaries" has been focused on the following aspects: observations, data analysis, Monte-Carlo simulations, numerical calculations, and theoretical modeling. Most of the results of our study have been published in refereed journals and conference presentations.

GBM Observations of Be X-Ray Binary Outbursts

NASA Technical Reports Server (NTRS)

Wilson-Hodge, Colleen A.; Finger, M. H.; Jenke, P. A.

2014-01-01

Since 2008 we have been monitoring accreting pulsars using the Gamma ray Burst Monitor (GBM) on Fermi. This monitoring program includes daily blind full sky searches for previously unknown or previously quiescent pulsars and source specific analysis to track the frequency evolution of all detected pulsars. To date we have detected outbursts from 23 transient accreting pulsars, including 21 confirmed or likely Be/X-ray binaries. I will describe our techniques and highlight results for selected pulsars.

Supergiant X-Ray Binaries Observed by Suzaku

NASA Technical Reports Server (NTRS)

Bodaghee, A.; Tomsick, J. A.; Rodriquez, J.; Chaty, S.; Pottschmidt, K.; Walter, R.; Romano, P.

2011-01-01

Suzaku observations are presented for the high-mass X-ray binaries IGR 116207-5129 and IGR 117391-3021. For IGR 116207-5129, we provide the first X-ray broadband (0.5-60 keV) spectrum from which we confirm a large intrinsic column density (N(sub H) = 1.6 x 10(exp 23)/sq cm), and we constrain the cutoff energy for the first time (E(sub cut) = 19 keV). A prolonged (> 30 ks) attenuation of the X-ray flux was observed which we tentatively attribute to an eclipse of the probable neutron star by its massive companion, in a binary system with an orbital period between 4 and 9 days, and inclination angles> 50 degrees. For IGRJ17391-3021, we witnessed a transition from quiescence to a low-activity phase punctuated by weak flares whose peak luminosities in the 0.5-10keV band are only a factor of 5 times that of the pre-flare emission. These micro flares are accompanied by an increase in NH which suggests the accretion of obscuring clumps of wind. We now recognize that these low-activity epochs constitute the most common emission phase for this system, and perhaps in other supergiant fast X-ray transients (SFXTs) as well. We close with an overview of our upcoming program in which Suzaku will provide the first ever observation of an SFXT (IGRJ16479-4514) during a binary orbit enabling us to probe the accretion wind at every phase.

The X-ray monitoring of the long-period colliding wind binaries

NASA Astrophysics Data System (ADS)

Sugawara, Y.; Maeda, Y.; Tsuboi, Y.

2017-10-01

We present the first results from XMM-Newton and Swift observations of two long-period colliding wind binaries WR19 and WR125 around periastron passages. Mass-loss is one of the most important and uncertain parameters in the evolution of a massive star. The X-ray spectrum off the colliding wind binary is the best measure of conditions in the hot postshock gas. By monitoring the changing of the X-ray luminosity and column density along with the orbital phases, we derive the mass-loss rates of these stars. It is known that WR19 (WC5+O9; P=10.1 yr) and WR125 (WC7+O9; P> 24.3 yr) are the dust-making binaries. Each periastron is expected to come in 2016-2017. Since 2016, we carry out on-going monitoring campaigns of WR19 and WR125 with XMM-Newton and Swift. On these observations, the X-rays from WR19 and WR125 were detected for the first time. In the case of WR19, as periastron approached, the column density increased, which indicates that the emission from the wind-wind collision plasma was absorbed by the dense Wolf-Rayet wind.

Colliding winds from early-type stars in binary systems

NASA Technical Reports Server (NTRS)

Stevens, Ian R.; Blondin, John M.; Pollock, A. M. T.

1992-01-01

The dynamics of the wind and shock structure formed by the wind collision in early-type binary systems is examined by means of a 2D hydrodynamics code, which self-consistently accounts for radiative cooling, and represents a significant improvement over previous attempts to model these systems. The X-ray luminosity and spectra of the shock-heated region, accounting for wind attenuation and the influence of different abundances on the resultant level and spectra of X-ray emission are calculated. A variety of dynamical instabilities that are found to dominate the intershock region is examined. These instabilities are found to be particularly important when postshock material is able to cool. These instabilities disrupt the postshock flow and add a time variability of order 10 percent to the X-ray luminosity. The X-ray spectrum of these systems is found to vary with the nuclear abundances of winds. These theoretical models are used to study several massive binary systems, in particular V444 Cyg and HD 193793.

RE 1016-053 - A pre-cataclysmic binary, and the first extreme ultraviolet and X-ray detections of a DAO white dwarf

NASA Technical Reports Server (NTRS)

Tweedy, R. W.; Holberg, J. B.; Barstow, M. A.; Bergeron, P.; Grauer, A. D.; Liebert, James; Fleming, T. A.

1993-01-01

Photometric observations and analysis of the optical, UV, EUV, and X-ray spectra are presented for the EUV/X-ray source RE 1016-53. Multiwavelength observations of RE 1016-53 point out that it is a precataclysmic binary. Optical spectra exhibit the steep blue continuum and Balmer absorption typical of a hot white dwarf, but there are bright, narrow emission lines of H I, He I, and Ca II superimposed on this. The white dwarf component, with T (eff) = 55,800 +/- 1000 K and log g = 7.81 +/- 0.007, dominates the spectrum from the optical to the EUV/X-ray. An He II 4686 A absorption line suggests that the white dwarf is a hydrogen-helium (DAO) hybrid star. Four of the five precataclysmic binaries with white dwarfs with T(eff) greater than 40,000 K appear to be DAOs. A mass of 0.57 +/- 0.003 solar mass has been derived.

X-RAY EMISSION FROM THE DOUBLE-BINARY OB-STAR SYSTEM QZ CAR (HD 93206)

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

Parkin, E. R.; Naze, Y.; Rauw, G.

X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The respective orbits of systems A (O9.7 I+b2 v, P{sub A} = 21 days) and B (O8 III+o9 v, P{sub B} = 6 days) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three-temperature thermal plasma model, characterized by cool, moderate, and hot plasma components at kT {approx_equal} 0.2, 0.7, and 2 keV, respectively,more » and a circumstellar absorption of {approx_equal}0.2 x 10{sup 22} cm{sup -2}. Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of {approx_equal}7 x 10{sup -13} erg s{sup -1} cm{sup -2}, do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. Yet, despite this, system B is expected to produce an observed X-ray flux well in excess of the observations. If one considers the wind of the O8 III star to be disrupted by mass transfer, the model and observations are in far better agreement, which lends support to the previous suggestion of mass transfer in the O8 III + o9 v binary. We conclude that the X-ray emission from QZ Car can be reasonably well accounted for by a combination of contributions mainly from the single stars and the mutual wind-wind collision between systems A and B.« less

CXOGBS J173620.2-293338: A candidate symbiotic X-ray binary associated with a bulge carbon star

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

Hynes, Robert I.; Britt, C. T.; Johnson, C. B.

2014-01-01

The Galactic Bulge Survey (GBS) is a wide but shallow X-ray survey of regions above and below the Plane in the Galactic Bulge. It was performed using the Chandra X-ray Observatory's ACIS camera. The survey is primarily designed to find and classify low luminosity X-ray binaries. The combination of the X-ray depth of the survey and the accessibility of optical and infrared counterparts makes this survey ideally suited to identification of new symbiotic X-ray binaries (SyXBs) in the Bulge. We consider the specific case of the X-ray source CXOGBS J173620.2-293338. It is coincident to within 1 arcsec with a verymore » red star, showing a carbon star spectrum and irregular variability in the Optical Gravitational Lensing Experiment data. We classify the star as a late C-R type carbon star based on its spectral features, photometric properties, and variability characteristics, although a low-luminosity C-N type cannot be ruled out. The brightness of the star implies it is located in the Bulge, and its photometric properties are overall consistent with the Bulge carbon star population. Given the rarity of carbon stars in the Bulge, we estimate the probability of such a close chance alignment of any GBS source with a carbon star to be ≲ 10{sup –3}, suggesting that this is likely to be a real match. If the X-ray source is indeed associated with the carbon star, then the X-ray luminosity is around 9 × 10{sup 32} erg s{sup –1}. Its characteristics are consistent with a low luminosity SyXB, or possibly a low accretion rate white dwarf symbiotic.« less

Rapid X-ray variability properties during the unusual very hard state in neutron-star low-mass X-ray binaries

NASA Astrophysics Data System (ADS)

Wijnands, R.; Parikh, A. S.; Altamirano, D.; Homan, J.; Degenaar, N.

2017-11-01

Here, we study the rapid X-ray variability (using XMM-Newton observations) of three neutron-star low-mass X-ray binaries (1RXS J180408.9-342058, EXO 1745-248 and IGR J18245-2452) during their recently proposed very hard spectral state. All our systems exhibit a strong to very strong noise component in their power density spectra (rms amplitudes ranging from 34 per cent to 102 per cent) with very low characteristic frequencies (as low as 0.01 Hz). These properties are more extreme than what is commonly observed in the canonical hard state of neutron-star low-mass X-ray binaries observed at X-ray luminosities similar to those we observe from our sources. This suggests that indeed the very hard state is a spectral-timing state distinct from the hard state, although we argue that the variability behaviour of IGR J18245-2452 is very extreme and possibly this source was in a very unusual state. We also compare our results with the rapid X-ray variability of the accreting millisecond X-ray pulsars IGR J00291+5934 and Swift J0911.9-6452 (also using XMM-Newton data) for which previously similar variability phenomena were observed. Although their energy spectra (as observed using the Swift X-ray telescope) were not necessarily as hard (i.e. for Swift J0911.9-6452) as for our other three sources, we conclude that likely both sources were also in very similar state during their XMM-Newton observations. This suggests that different sources that are found in this new state might exhibit different spectral hardness and one has to study both the spectral and the rapid variability to identify this unusual state.

The X-ray Spectral Evolution of eta Carinae as Seen by ASCA

NASA Technical Reports Server (NTRS)

Corcoran, M. F.; Fredericks, A. C.; Petre, R.; Swank, J. H.; Drake, S. A.; White, Nicholas E. (Technical Monitor)

2000-01-01

Using data from the ASCA X-ray observatory, we examine the variations in the X-ray spectrum of the supermassive star nu Carinae with an unprecedented combination of spatial and spectral resolution. We include data taken during the recent X-ray eclipse in 1997-1998, after recovery from the eclipse, and during and after an X-ray flare. We show that the eclipse variation in the X-ray spectrum is apparently confined to a decrease in the emission measure of the source. We compare our results with a simple colliding wind binary model and find that the observed spectral variations are only consistent, with the binary model if there is significant high-temperature emission far from the star and/or a substantial change in the temperature distribution of the hot plasma. If contamination in the 2-10 keV band is important, the observed eclipse spectrum requires an absorbing column in excess of 10(exp 24)/sq cm for consistency with the binary model, which may indicate an increase in the first derivative of M from nu Carinae near the time of periastron passage. The flare spectra are consistent with the variability seen in nearly simultaneous RXTE observations and thus confirm that nu Carinae itself is the source of the flare emission. The variation in the spectrum during the flare seems confined to a change in the source emission measure. By comparing 2 observations obtained at the same phase in different X-ray cycles, we find that the current, X-ray brightness of the source is slightly higher than the brightness of the source during the last cycle perhaps indicative of a long-term increase in the first derivative of M, not associated with the X-ray cycle.

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. V. Rising X-Ray Emission from an Off-axis Jet

NASA Astrophysics Data System (ADS)

Margutti, R.; Berger, E.; Fong, W.; Guidorzi, C.; Alexander, K. D.; Metzger, B. D.; Blanchard, P. K.; Cowperthwaite, P. S.; Chornock, R.; Eftekhari, T.; Nicholl, M.; Villar, V. A.; Williams, P. K. G.; Annis, J.; Brown, D. A.; Chen, H.; Doctor, Z.; Frieman, J. A.; Holz, D. E.; Sako, M.; Soares-Santos, M.

2017-10-01

We report the discovery of rising X-ray emission from the binary neutron star merger event GW170817. This is the first detection of X-ray emission from a gravitational-wave (GW) source. Observations acquired with the Chandra X-ray Observatory (CXO) at t≈ 2.3 days post-merger reveal no significant emission, with {L}x≲ 3.2× {10}38 {erg} {{{s}}}-1 (isotropic-equivalent). Continued monitoring revealed the presence of an X-ray source that brightened with time, reaching {L}x≈ 9× {10}38 {erg} {{{s}}}-1 at ≈ 15.1 days post-merger. We interpret these findings in the context of isotropic and collimated relativistic outflows (both on- and off-axis). We find that the broadband X-ray to radio observations are consistent with emission from a relativistic jet with kinetic energy {E}k˜ {10}49-50 {erg}, viewed off-axis with {θ }{obs}˜ 20^\\circ {--}40^\\circ . Our models favor a circumbinary density n˜ {10}-4{--}{10}-2 {{cm}}-3, depending on the value of the microphysical parameter {ɛ }B={10}-4{--}{10}-2. A central-engine origin of the X-ray emission is unlikely. Future X-ray observations at t≳ 100 days, when the target will be observable again with the CXO, will provide additional constraints to solve the model degeneracies and test our predictions. Our inferences on {θ }{obs} are testable with GW information on GW170817 from advanced LIGO/Virgo on the binary inclination.

A transient radio jet in an erupting dwarf nova.

PubMed

Körding, Elmar; Rupen, Michael; Knigge, Christian; Fender, Rob; Dhawan, Vivek; Templeton, Matthew; Muxlow, Tom

2008-06-06

Astrophysical jets seem to occur in nearly all types of accreting objects, from supermassive black holes to young stellar objects. On the basis of x-ray binaries, a unified scenario describing the disc/jet coupling has evolved and been extended to many accreting objects. The only major exceptions are thought to be cataclysmic variables: Dwarf novae, weakly accreting white dwarfs, show similar outburst behavior to x-ray binaries, but no jet has yet been detected. Here we present radio observations of a dwarf nova in outburst showing variable flat-spectrum radio emission that is best explained as synchrotron emission originating in a transient jet. Both the inferred jet power and the relation to the outburst cycle are analogous to those seen in x-ray binaries, suggesting that the disc/jet coupling mechanism is ubiquitous.

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

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

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

2016-09-10

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

X-Ray and UV Orbital Phase Dependence in LMC X-3

NASA Technical Reports Server (NTRS)

Dolan, Joseph F.; Boyd, P. T.; Smale, A. P.

2001-01-01

The black-hole binary LMC X-3 is known to be variable on time scales of days to years. We investigated X-ray and ultraviolet variability in the system as a function of the 1.7 d binary orbit using a 6.4 day observation with the Rossi X-ray Timing Explorer (RXTE) in 1998 December. An abrupt 14 % flux decrease lasting nearly an entire orbit was followed by a return to previous flux levels. This behavior occurred twice at nearly the same binary phase, but is not present in consecutive orbits. When the X-ray flux is at lower intensity, a periodic amplitude modulation of 7 % is evident in data folded modulo the orbital period. The higher intensity data show weaker correlation with phase. This is the first report of X-ray variability at the orbital period of LMC X-3. Archival RXTE observations of LMC X-3 during a high flux state in 1996 December show similar phase dependence. An ultraviolet light curve obtained with the High Speed Photometer (HSP) on the Hubble Space Telescope (HST) shows a phase dependent variability consistent with that observed in the visible, ascribed to the ellipsoidal variation of the visible star. The X-ray spectrum of LMC X-3 is acceptably represented by a phenomenological disk black-body plus a power law. Changes in the spectrum of LMX X-3 during our observations are compatible with earlier observations during which variations in the 2-10 keV flux are closely correlated with the disk geometry spectral model parameter.

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. V. Rising X-Ray Emission from an Off-axis Jet

DOE PAGES

Margutti, Raffaella; Berger, E.; Fong, W.; ...

2017-10-16

Here, we report the discovery of rising X-ray emission from the binary neutron star merger event GW170817. This is the first detection of X-ray emission from a gravitational-wave (GW) source. Observations acquired with the Chandra X-ray Observatory ( CXO) atmore » $$t\\approx 2.3$$ days post-merger reveal no significant emission, with $${L}_{x}\\lesssim 3.2\\times {10}^{38}\\,\\mathrm{erg}\\,{{\\rm{s}}}^{-1}$$ (isotropic-equivalent). Continued monitoring revealed the presence of an X-ray source that brightened with time, reaching $${L}_{x}\\approx 9\\times {10}^{38}\\,\\mathrm{erg}\\,{{\\rm{s}}}^{-1}$$ at $$\\approx 15.1$$ days post-merger. We interpret these findings in the context of isotropic and collimated relativistic outflows (both on- and off-axis). We find that the broadband X-ray to radio observations are consistent with emission from a relativistic jet with kinetic energy $${E}_{k}\\sim {10}^{49-50}\\,\\mathrm{erg}$$, viewed off-axis with $${\\theta }_{\\mathrm{obs}}\\sim 20^\\circ \\mbox{--}40^\\circ $$. Our models favor a circumbinary density $$n\\sim {10}^{-4}\\mbox{--}{10}^{-2}\\,{\\mathrm{cm}}^{-3}$$, depending on the value of the microphysical parameter $${\\epsilon }_{B}={10}^{-4}\\mbox{--}{10}^{-2}$$. A central-engine origin of the X-ray emission is unlikely. Future X-ray observations at $$t\\gtrsim 100$$ days, when the target will be observable again with the CXO, will provide additional constraints to solve the model degeneracies and test our predictions. Our inferences on $${\\theta }_{\\mathrm{obs}}$$ are testable with GW information on GW170817 from advanced LIGO/Virgo on the binary inclination.« less

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. V. Rising X-Ray Emission from an Off-axis Jet

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

Margutti, Raffaella; Berger, E.; Fong, W.

Here, we report the discovery of rising X-ray emission from the binary neutron star merger event GW170817. This is the first detection of X-ray emission from a gravitational-wave (GW) source. Observations acquired with the Chandra X-ray Observatory ( CXO) atmore » $$t\\approx 2.3$$ days post-merger reveal no significant emission, with $${L}_{x}\\lesssim 3.2\\times {10}^{38}\\,\\mathrm{erg}\\,{{\\rm{s}}}^{-1}$$ (isotropic-equivalent). Continued monitoring revealed the presence of an X-ray source that brightened with time, reaching $${L}_{x}\\approx 9\\times {10}^{38}\\,\\mathrm{erg}\\,{{\\rm{s}}}^{-1}$$ at $$\\approx 15.1$$ days post-merger. We interpret these findings in the context of isotropic and collimated relativistic outflows (both on- and off-axis). We find that the broadband X-ray to radio observations are consistent with emission from a relativistic jet with kinetic energy $${E}_{k}\\sim {10}^{49-50}\\,\\mathrm{erg}$$, viewed off-axis with $${\\theta }_{\\mathrm{obs}}\\sim 20^\\circ \\mbox{--}40^\\circ $$. Our models favor a circumbinary density $$n\\sim {10}^{-4}\\mbox{--}{10}^{-2}\\,{\\mathrm{cm}}^{-3}$$, depending on the value of the microphysical parameter $${\\epsilon }_{B}={10}^{-4}\\mbox{--}{10}^{-2}$$. A central-engine origin of the X-ray emission is unlikely. Future X-ray observations at $$t\\gtrsim 100$$ days, when the target will be observable again with the CXO, will provide additional constraints to solve the model degeneracies and test our predictions. Our inferences on $${\\theta }_{\\mathrm{obs}}$$ are testable with GW information on GW170817 from advanced LIGO/Virgo on the binary inclination.« less

Characterizing the X-ray Emission in Small Magellanic Cloud Supernova Remnants

NASA Astrophysics Data System (ADS)

Man, Nicole; Auchettl, Katie; Lopez, Laura

2018-01-01

The Small Magellanic Cloud is a close, metal-poor galaxy with active star formation, and it has a diverse population of 24 supernova remnants (SNRs) that have been identified at several wavelengths. Past work has characterized the X-ray emission in these sources separately and aimed to constrain their explosive origins from observations with Chandra and XMM-Newton. Three SNRs have possible evidence for Type Ia explosions based on strong Fe-L emission in their X-ray spectra, although the environments and intermediate-mass element abundances are more consistent with those of core-collapse SNe. In this poster, we analyze the archival Chandra and XMM-Newton observations of the SMC SNR sample, and we model the sources' X-ray spectra in a systematic way to derive the plasma properties and to constrain the nature of the explosions. In one SNR, we note the presence of an X-ray binary near the source's geometric center, suggesting the compact object was produced in the SN explosion. As one of only three SNRs known in the Local Group to host a binary system, this source is worthy of follow-up investigations to probe explosions of massive stars in binary systems.

A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, Delta Orionis Aa. I. Overview of the X-Ray Spectrum

NASA Technical Reports Server (NTRS)

Corcoran, M. F.; Nicholas, J. S.; Pablo, H.; Shenar, T.; Pollock, A. M. T.; Waldron, W. L.; Moffat, A. F. J.; Richardson, N. D.; Russell, C. M. P.; Hamaguchi, K.;

A COORDINATED X-RAY AND OPTICAL CAMPAIGN OF THE NEAREST MASSIVE ECLIPSING BINARY, δ ORIONIS Aa. I. OVERVIEW OF THE X-RAY SPECTRUM

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

Corcoran, M. F.; Hamaguchi, K.; Nichols, J. S.

2015-08-20

We present an overview of four deep phase-constrained Chandra HETGS X-ray observations of δ Ori A. Delta Ori A is actually a triple system that includes the nearest massive eclipsing spectroscopic binary, δ Ori Aa, the only such object that can be observed with little phase-smearing with the Chandra gratings. Since the fainter star, δ Ori Aa2, has a much lower X-ray luminosity than the brighter primary (δ Ori Aa1), δ Ori Aa provides a unique system with which to test the spatial distribution of the X-ray emitting gas around δ Ori Aa1 via occultation by the photosphere of, andmore » wind cavity around, the X-ray dark secondary. Here we discuss the X-ray spectrum and X-ray line profiles for the combined observation, having an exposure time of nearly 500 ks and covering nearly the entire binary orbit. The companion papers discuss the X-ray variability seen in the Chandra spectra, present new space-based photometry and ground-based radial velocities obtained simultaneously with the X-ray data to better constrain the system parameters, and model the effects of X-rays on the optical and UV spectra. We find that the X-ray emission is dominated by embedded wind shock emission from star Aa1, with little contribution from the tertiary star Ab or the shocked gas produced by the collision of the wind of Aa1 against the surface of Aa2. We find a similar temperature distribution to previous X-ray spectrum analyses. We also show that the line half-widths are about 0.3−0.5 times the terminal velocity of the wind of star Aa1. We find a strong anti-correlation between line widths and the line excitation energy, which suggests that longer-wavelength, lower-temperature lines form farther out in the wind. Our analysis also indicates that the ratio of the intensities of the strong and weak lines of Fe xvii and Ne x are inconsistent with model predictions, which may be an effect of resonance scattering.« less

Infrared outbursts as potential tracers of common-envelope events in high-mass X-ray binary formation

NASA Astrophysics Data System (ADS)

Oskinova, Lidia M.; Bulik, Tomasz; Gómez-Morán, Ada Nebot

2018-06-01

Context. Classic massive binary evolutionary scenarios predict that a transitional common-envelope (CE) phase could be preceded as well as succeeded by the evolutionary stage when a binary consists of a compact object and a massive star, that is, a high-mass X-ray binary (HMXB). The observational manifestations of common envelope are poorly constrained. We speculate that its ejection might be observed in some cases as a transient event at mid-infrared (IR) wavelengths. Aims: We estimate the expected numbers of CE ejection events and HMXBs per star formation unit rate, and compare these theoretical estimates with observations. Methods: We compiled a list of 85 mid-IR transients of uncertain nature detected by the Spitzer Infrared Intensive Transients Survey and searched for their associations with X-ray, optical, and UV sources. Results: Confirming our theoretical estimates, we find that only one potential HMXB may be plausibly associated with an IR-transient and tentatively propose that X-ray source NGC 4490-X40 could be a precursor to the SPIRITS 16az event. Among other interesting sources, we suggest that the supernova remnant candidate [BWL2012] 063 might be associated with SPIRITS 16ajc. We also find that two SPIRITS events are likely associated with novae, and seven have potential optical counterparts. Conclusions: The massive binary evolutionary scenarios that involve CE events do not contradict currently available observations of IR transients and HMXBs in star-forming galaxies.

Identification and properties of the M giant/X-ray system HD 154791 = 2A 1704+241

NASA Technical Reports Server (NTRS)

Garcia, M.; Baliunas, S. L.; Elvis, M.; Fabbiano, G.; Patterson, J.; Schwartz, D.; Doxsey, R.; Koenigsberger, G.; Swank, J.; Watson, M. G.

1983-01-01

The Aerial V X-ray source 2A 1704+241 (= 4U 1700+24 = 3A 1703+241) is identified with the M3 II star HD 154791. The identification is based on a precise X-ray position determined by the HEAO 1 scanning modulation collimator and the Einstein Observatory imaging proportional counter, together with a spectrum measured by the International Ultraviolet Explorer. The ultraviolet spectrum shows strong emission of C IV 1550 A, N v 1238 A, and Mg II 2800 A, which is very unusual among M giants. This is the first X-ray detection of an M giant which has a completely normal optical spectrum. The X-ray luminosity reaches three orders of magnitude above the mean upper limit for the coronal X-ray flux from M giants. Although there is no direct evidence for a binary system, since radial velocity variations have not been observed, it is shown that a plausible neutron star binary model can be constructed.

Formation of black hole x-ray binaries in globular clusters

NASA Astrophysics Data System (ADS)

Kremer, Kyle; Chatterjee, Sourav; Rodriguez, Carl; Rasio, Frederic

2018-01-01

We explore the formation of mass-transferring binary systems containing black holes within globular clusters. We show that it is possible to form mass-transferring binaries with main sequence, giant, and white dwarf companions with a variety of orbital parameters in globular clusters spanning a large range in present-day properties. We show that the presence of mass-transferring black hole systems has little correlation with the total number of black holes within the cluster at any time. In addition to mass-transferring binaries retained within their host clusters at late times, we also examine the black hole and neutron star binaries that are ejected from their host clusters. These ejected systems may contribute to the low-mass x-ray binary population in the galactic field.

Studying Dust Scattering Halos with Galactic X-ray Binaries

NASA Astrophysics Data System (ADS)

Beeler, Doreen; Corrales, Lia; Heinz, Sebastian

2018-01-01

Dust is an important part of the interstellar medium (ISM) and contributes to the formation of stars and planets. Since the advent of modern X-ray telescopes, Galactic X-ray point sources have permitted a closer look at all phases of the ISM. Interstellar metals from oxygen to iron — in both gas and dust form — are responsible for absorption and scattering of X-ray light. Dust scatters the light in a forward direction and creates a diffuse halo image surrounding many bright Galactic X-ray binaries. We use all the bright X-ray point sources available in the Chandra HETG archive to study dust scattering halos from the local ISM. We have described a data analysis pipeline using a combination of the data reduction software CIAO and Python. We compare our results from Chandra HETG and ACIS-I observations of a well studied dust scattering halo around GX 13+1, in order to characterize any systematic errors associated with the HETG data set. We describe how our data products will be used to measure ISM scaling relations for X-ray extinction, dust abundance, and dust-to-metal ratios.

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

Parkin, E. R.; Sim, S. A., E-mail: parkin@mso.anu.edu.au, E-mail: s.sim@qub.ac.uk

In an early-type, massive star binary system, X-ray bright shocks result from the powerful collision of stellar winds driven by radiation pressure on spectral line transitions. We examine the influence of the X-rays from the wind-wind collision shocks on the radiative driving of the stellar winds using steady-state models that include a parameterized line force with X-ray ionization dependence. Our primary result is that X-ray radiation from the shocks inhibits wind acceleration and can lead to a lower pre-shock velocity, and a correspondingly lower shocked plasma temperature, yet the intrinsic X-ray luminosity of the shocks, L{sub X}, remains largely unaltered,more » with the exception of a modest increase at small binary separations. Due to the feedback loop between the ionizing X-rays from the shocks and the wind driving, we term this scenario as self-regulated shocks. This effect is found to greatly increase the range of binary separations at which a wind-photosphere collision is likely to occur in systems where the momenta of the two winds are significantly different. Furthermore, the excessive levels of X-ray ionization close to the shocks completely suppress the line force, and we suggest that this may render radiative braking less effective. Comparisons of model results against observations reveal reasonable agreement in terms of log (L{sub X}/L{sub bol}). The inclusion of self-regulated shocks improves the match for kT values in roughly equal wind momenta systems, but there is a systematic offset for systems with unequal wind momenta (if considered to be a wind-photosphere collision).« less

Formation of Black Hole X-Ray Binaries with Non-degenerate Donors in Globular Clusters

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

Ivanova, Natalia; Rocha, Cassio A. da; Van, Kenny X.

In this Letter, we propose a formation channel for low-mass X-ray binaries with black hole accretors and non-degenerate donors via grazing tidal encounters with subgiants. We estimate that in a typically dense globular cluster with a core density of 10{sup 5} stars pc{sup −3}, the formation rates are about one binary per Gyr per 50–100 retained black holes. The donors—stripped subgiants—will be strongly underluminous when compared to subgiant or giant branch stars of the same colors. The products of tidal stripping are underluminous by at least one magnitude for several hundred million years when compared to normal stars of themore » same color, and differ from underluminous red stars that could be produced by non-catastrophic mass transfer in an ordinary binary. The dynamically formed binaries become quiescent LMXBs, with lifetimes of about a Gyr. The expected number of X-ray binaries is one per 50–200 retained black holes, while the expected number of strongly underluminous subsubgiant is about half this. The presence of strongly underluminous stars in a GC may be indicative of the presence of black holes.« less

A First Estimate of the X-Ray Binary Frequency as a Function of Star Cluster Mass in a Single Galactic System

NASA Astrophysics Data System (ADS)

Clark, D. M.; Eikenberry, S. S.; Brandl, B. R.; Wilson, J. C.; Carson, J. C.; Henderson, C. P.; Hayward, T. L.; Barry, D. J.; Ptak, A. F.; Colbert, E. J. M.

2008-05-01

We use the previously identified 15 infrared star cluster counterparts to X-ray point sources in the interacting galaxies NGC 4038/4039 (the Antennae) to study the relationship between total cluster mass and X-ray binary number. This significant population of X-Ray/IR associations allows us to perform, for the first time, a statistical study of X-ray point sources and their environments. We define a quantity, η, relating the fraction of X-ray sources per unit mass as a function of cluster mass in the Antennae. We compute cluster mass by fitting spectral evolutionary models to Ks luminosity. Considering that this method depends on cluster age, we use four different age distributions to explore the effects of cluster age on the value of η and find it varies by less than a factor of 4. We find a mean value of η for these different distributions of η = 1.7 × 10-8 M-1⊙ with ση = 1.2 × 10-8 M-1⊙. Performing a χ2 test, we demonstrate η could exhibit a positive slope, but that it depends on the assumed distribution in cluster ages. While the estimated uncertainties in η are factors of a few, we believe this is the first estimate made of this quantity to "order of magnitude" accuracy. We also compare our findings to theoretical models of open and globular cluster evolution, incorporating the X-ray binary fraction per cluster.

GSFC Contributions to the NATO X-ray Astronomy Institute, Erice, July 1979. [X-ray spectra of supernova remants, galactic X-ray sources, active galactic nuclei, and clusters of galaxies

NASA Technical Reports Server (NTRS)

Holt, S. S.; Mushotzky, R. F.

1979-01-01

An overview of X-ray astronomical spectroscopy in general is presented and results obtained by HEAO 1 and 2 as well as earlier spacecraft are examined. Particular emphasis is given to the spectra of supernova remnants; galactic binary X-ray sources, cataclysmic variables, bulges, pulsars, and stars; the active nuclei of Seyfert 1 galaxy, BL Lac, and quasars; the diffuse X-ray background; and galactic clusters.

A NuSTAR Observation of the Gamma-Ray Emitting Millisecond Pulsar PSR J1723–2837

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

Kong, A. K. H.; Hui, C. Y.; Takata, J.

We report on the first NuSTAR observation of the gamma-ray emitting millisecond pulsar binary PSR J1723–2837. X-ray radiation up to 79 keV is clearly detected, and the simultaneous NuSTAR and Swift spectrum is well described by an absorbed power law with a photon index of ∼1.3. We also find X-ray modulations in the 3–10, 10–20, 20–79, and 3–79 keV bands at the 14.8 hr binary orbital period. All of these are entirely consistent with previous X-ray observations below 10 keV. This new hard X-ray observation of PSR J1723–2837 provides strong evidence that the X-rays are from the intrabinary shock viamore » an interaction between the pulsar wind and the outflow from the companion star. We discuss how the NuSTAR observation constrains the physical parameters of the intrabinary shock model.« less

Spectroscopic observations of X-ray selected late type stars

NASA Technical Reports Server (NTRS)

Takalo, L. O.

1988-01-01

A spectroscopic survey of nine X-ray selected late type stars was conducted. These stars are serendipitously discovered EINSTEIN X-ray sources, selected from two large x-ray surveys: the Columbia Astrophysical Laboratory survey (five stars) and the CFA Medium Sensitivity survey (four stars). Four of the Columbia survey stars were found to be short period binaries. The fifth was found to be an active single G dwarf. None of the Medium Sensitivity survey stars were found to be either binaries or active stars. Activity was measured by comparing the H-alpha and the CaII infrared triplet (8498, 8542) lines in these stars to the lines in inactive stars of similar spectral type. A correlation was found between the excess H-alpha lime emission and V sin(i) and between the excess H-alpha line emission and X-ray luminosity. No correlation was found between the infrared line emission and any other measured quantity.

X-rays from the colliding wind binary WR 146

NASA Astrophysics Data System (ADS)

Zhekov, Svetozar A.

2017-12-01

The X-ray emission from the massive Wolf-Rayet binary (WR 146 ) is analysed in the framework of the colliding stellar wind (CSW) picture. The theoretical CSW model spectra match well the shape of the observed X-ray spectrum of WR 146, but they overestimate considerably the observed X-ray flux (emission measure). This is valid in the case of both complete temperature equalization and partial electron heating at the shock fronts (different electron and ion temperatures), but there are indications for a better correspondence between model predictions and observations for the latter. To reconcile the model predictions and observations, the mass-loss rate of WR 146 must be reduced by a factor of 8-10 compared to the currently accepted value for this object (the latter already takes clumping into account). No excess X-ray absorption is derived from the CSW modelling.

Recurrent X-ray Emission Variations of Eta Carinae and the Binary Hypothesis

NASA Technical Reports Server (NTRS)

Ishibashi, K.; Corcoran, M. F.; Davidson, K.; Swank, J. H.; Petre, R.; Drake, S. A.; Damineki, A.; White, S.

1998-01-01

Recent studies suggest that, the super-massive star eta Carinae may have a massive stellar companion (Damineli, Conti, and Lopes 1997), although the dense ejecta surrounding the star make this claim hard to test using conventional methods. Settling this question is critical for determining the current evolutionary state and future evolution of the star. We address this problem by an unconventional method: If eta Carinae is a binary, X-ray emission should be produced in shock waves generated by wind-wind collisions in the region between eta Carinae and its companion. Detailed X-ray monitoring of eta Carinae for more that) 2 years shows that the observed emission generally resembles colliding-wind X-ray emission, but with some significant discrepancies. Furthermore, periodic X-ray "flaring" may provide an additional clue to determine the presence of a companion star and for atmospheric pulsation in eta Carinae.

Swift/BAT Detects Increase in Hard X-ray Emission from the Ultra-compact X-ray Binary 4U 1543-624

NASA Astrophysics Data System (ADS)

Ludlam, Renee; Miller, Jon M.; Miller-Jones, James; Reynolds, Mark

2017-08-01

The Swift/BAT detected an increase in hard X-ray emission (15-50 keV) coming from the ultra-compact X-ray binary 4U 1543-624 around 2017 August 9. The MAXI daily monitoring also shows a gradual increase in 2.0-20.0 keV X-ray intensity as of 2017 August 19. Swift/XRT ToO monitoring of the source was triggered and shows an increase in unabsorbed flux to 1.06E-9 ergs/cm2/s in the 0.3-10.0 keV energy band as of 2017 August 26. ATCA performed ToO observations for approximately 4 hours in the 5.5 GHz and 9.0 GHz bands while the antennas were in the 1.5A array configuration from 11:25-16:09 UTC on 2017 August 23. The source was not detected in either band.

Retrograde Accretion Discs in High-Mass Be/X-Ray Binaries

NASA Technical Reports Server (NTRS)

Christodoulou, D. M.; Laycock, S. G. T.; Kazanas, D.

2017-01-01

We have compiled a comprehensive library of all X-ray observations of Magellanic pulsars carried out by XMM-Newton, Chandra and RXTE in the period 1997-2014. In this work, we use the data from 53 high-mass Be/X-ray binaries in the Small Magellanic Cloud to demonstrate that the distribution of spin-period derivatives versus spin periods of spinning-down pulsars is not at all different from that of the accreting spinning-up pulsars. The inescapable conclusion is that the up and down samples were drawn from the same continuous parent population; therefore, Be/X-ray pulsars that are spinning down over periods spanning 18 yr are, in fact, accreting from retrograde discs. The presence of prograde and retrograde discs in roughly equal numbers supports a new evolutionary scenario for Be/X-ray pulsars in their spin period-period derivative diagram.

Anti-correlated X-ray and Radio Variability in the Transitional Millisecond Pulsar PSR J1023+0038

NASA Astrophysics Data System (ADS)

Bogdanov, Slavko; Deller, Adam; Miller-Jones, James; Archibald, Anne; Hessels, Jason W. T.; Jaodand, Amruta; Patruno, Alessandro; Bassa, Cees; D'Angelo, Caroline

2018-01-01

The PSR J1023+0038 binary system hosts a 1.69-ms neutron star and a low-mass, main-sequence-like star. The system underwent a transformation from a rotation-powered to a low-luminosity accreting state in 2013 June, in which it has remained since. We present an unprecedented set of strictly simultaneous Chandra X-ray Observatory and Karl G. Jansky Very Large Array observations, which for the first time reveal a highly reproducible, anti-correlated variability pattern. Rapid declines in X-ray flux are always accompanied by a radio brightening with duration that closely matches the low X-ray flux mode intervals. We discuss these findings in the context of accretion and jet outflow physics and their implications for using the radio/X-ray luminosity plane to distinguish low-luminosity candidate black hole binary systems from accreting transitional millisecond pulsars.

A Deep Pulse Search in 11 Low Mass X-Ray Binaries

NASA Astrophysics Data System (ADS)

Patruno, A.; Wette, K.; Messenger, C.

2018-06-01

We present a systematic coherent X-ray pulsation search in 11 low mass X-ray binaries (LMXBs). We select a relatively broad variety of LMXBs, including persistent and transient sources, spanning orbital periods between 0.3 and 17 hr. We use about 3.6 Ms of data collected by the Rossi X-Ray Timing Explorer and XMM-Newton and apply a semi-coherent search strategy to look for weak and persistent pulses in a wide spin frequency range. We find no evidence for X-ray pulsations in these systems and consequently set upper limits on the pulsed sinusoidal semi-amplitude below 1.6% for ten outbursting/persistent LMXBs and 6% for a quiescent system; the upper limits are further refined, by searching a narrower parameter space around the outliers, down to 0.14%–0.78% and 2.9%, respectively. These results suggest that weak pulsations might not form in (most) non pulsating LMXBs.

CHANDRA CHARACTERIZATION OF X-RAY EMISSION IN THE YOUNG F-STAR BINARY SYSTEM HD 113766

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

Lisse, C. M.; Christian, D. J.; Wolk, S. J.

Using Chandra , we have obtained imaging X-ray spectroscopy of the 10–16 Myr old F-star binary HD 113766. We individually resolve the 1.″4 separation binary components for the first time in the X-ray and find a total 0.3–2.0 keV luminosity of 2.2 × 10{sup 29} erg s{sup −1}, consistent with previous RASS estimates. We find emission from the easternmost, infrared-bright, dusty member HD 113766A to be only ∼10% that of the western, infrared-faint member HD 113766B. There is no evidence for a 3rd late-type stellar or substellar member of HD 113766 with L {sub x} > 6 × 10{sup 25} erg s{sup −1} within 2′ ofmore » the binary pair. The ratio of the two stars’ X-ray luminosity is consistent with their assignments as F2V and F6V by Pecaut et al. The emission is soft for both stars, kT {sub Apec} = 0.30–0.50 keV, suggesting X-rays produced by stellar rotation and/or convection in young dynamos, but not accretion or outflow shocks, which we rule out. A possible 2.8 ± 0.15 (2 σ ) hr modulation in the HD 113766B X-ray emission is seen, but at very low confidence and of unknown provenance. Stellar wind drag models corresponding to L {sub x} ∼ 2 × 10{sup 29} erg s{sup −1} argue for a 1 mm dust particle lifetime around HD 113766B of only ∼90,0000 years, suggesting that dust around HD 113766B is quickly removed, whereas 1 mm sized dust around HD 113766A can survive for >1.5 × 10{sup 6} years. At 10{sup 28}–10{sup 29} erg s{sup −1} X-ray luminosity, astrobiologically important effects, like dust warming and X-ray photolytic organic synthesis, are likely for any circumstellar material in the HD 113766 systems.« less

Carbon Observatory’s First Data on This Week @NASA - August 15, 2014

NASA Image and Video Library

2014-08-15

A month after its launch, the Orbiting Carbon Observatory-2, NASA’s first spacecraft dedicated to studying atmospheric carbon dioxide – has reached its final operating orbit and returned its first science data. “First light” test data were collected on August 6 as OCO-2 flew over central New Guinea, confirming the health of the spacecraft’s science instrument’s. Also, ATV-5 Delivers Cargo, Cygnus Departs Station, Super Celestial Show, Black Hole Blurs X-ray Light, Million Pound Move and more!

Searches for millisecond pulsations in low-mass X-ray binaries, 2

NASA Technical Reports Server (NTRS)

Vaughan, B. A.; Van Der Klis, M.; Wood, K. S.; Norris, J. P.; Hertz, P.; Michelson, P. F.; Paradijs, J. Van; Lewin, W. H. G.; Mitsuda, K.; Penninx, W.

1994-01-01

Coherent millisecond X-ray pulsations are expected from low-mass X-ray binaries (LMXBs), but remain undetected. Using the single-parameter Quadratic Coherence Recovery Technique (QCRT) to correct for unknown binary orbit motion, we have performed Fourier transform searches for coherent oscillations in all long, continuous segments of data obtained at 1 ms time resolution during Ginga observations of LMXB. We have searched the six known Z sources (GX 5-1, Cyg X-2, Sco X-1, GX 17+2, GX 340+0, and GX 349+2), seven of the 14 known atoll sources (GX 3+1. GX 9+1, GX 9+9, 1728-33. 1820-30, 1636-53 and 1608-52), the 'peculiar' source Cir X-1, and the high-mass binary Cyg X-3. We find no evidence for coherent pulsations in any of these sources, with 99% confidence limits on the pulsed fraction between 0.3% and 5.0% at frequencies below the Nyquist frequency of 512 Hz. A key assumption made in determining upper limits in previous searches is shown to be incorrect. We provide a recipe for correctly setting upper limits and detection thresholds. Finally we discuss and apply two strategies to improve sensitivity by utilizing multiple, independent, continuous segments of data with comparable count rates.

Detection of potential periodicities in the unique hard X-ray source Swift J0042.6+4112, dominating the hard X-ray emission in M31

NASA Astrophysics Data System (ADS)

Yukita, Mihoko; Tzanavaris, Panayiotis; Corbet, Robin; Ptak, Andrew; Hornschemeier, Ann; Pottschmidt, Katja; Ballhausen, Ralf; Enoto, Teruaki; Antoniou, Vallia; Lehmer, Bret; Maccarone, Thomas J.; Wik, Daniel; Williams, Ben; Zezas, Andreas

2018-01-01

Recent NuSTAR-Swift observations revealed that a single resolved X-ray source, Swift J0042.6+4112, with Lx of a few times 1038 erg/s dominates the hard X-ray emission from the Andromeda galaxy. HST-based stellar population synthesis modeling combined with the 0.5-50 keV spectral shape suggests that this might be an X-ray pulsar with an intermediate- (or low-) mass donor. Here we further explore the alternative scenario of a symbiotic or ultracompact X-ray binary, based on long-term variability from Swift observations between 2005 and 2016. We find that the soft (0.3-8.0 keV) X-ray flux varies within a factor of 4 but does not exhibit transient behavior. Its power spectrum suggests a 6.1-day period. Additionally, we find a strong 3s-period candidate from both NuSTAR and XMM observations taken in 2017. If interpreted as an orbital and spin period respectively, the source's temporal behavior would not support either the symbiotic or the ultracompact X-ray binary scenario. Rather, it is more consistent with an accreting pulsar with a higher mass donor.

Spectral and Timing Investigations of Dwarf Novae Selected in Hard X-Rays

NASA Technical Reports Server (NTRS)

Thorstensen, John; Remillard, Ronald A.

2000-01-01

There are 9 dwarf novae (DN) among the 43 cataclysmic variables (accreting white dwarfs in close binary systems) that were detected during the HEAO-1 all-sky X-ray survey (1977-1979). On the other hand, there are roughly one hundred dwarf novae that are closer and/or optically brighter and yet they were not detected as hard X-ray sources. Two of the HEAO-1 DN show evidence for X-ray pulsations that imply strong magnetic fields on the white dwarf surface, and magnetic CVs are known to be strong X-ray sources. However, substantial flux in hard X-rays may be caused by non-magnetic effects, such as an optically thin boundary layer near a massive white dwarf. We proposed RXTE observations to measure plasma temperatures and to search for X-ray pulsations. The observations would distinguish whether these DN belong to one of (rare) magnetic subclasses. For those that do not show pulsations, the observations support efforts to define empirical relations between X-ray temperature, the accretion rate, and the mass of the white dwarf. The latter is determined via optical studies of the dynamics of the binary constituents.

The formation efficiency of different generations of HMXBs in the low metallicity environment of the SMC

NASA Astrophysics Data System (ADS)

Antoniou, Vallia; Zezas, Andreas; Drake, Jeremy J.; Badenes, Carles; Hong, Jaesub; SMC XVP Collaboration

2018-01-01

Nearby star-forming galaxies offer a unique environment to study the populations of young (<100 Myr) X-ray binaries, which consist of a compact object - typically a neutron star or a black hole - powered by accretion from a companion star. These systems are tracers of past populations of massive stars that heavily affect their immediate environment and parent galaxies. The Small Magellanic Cloud (SMC) is the ideal environment for population studies of young X-ray binaries by providing us with what the Milky Way cannot: A complete sample of X-ray sources within a galaxy. Using a Chandra X-ray Visionary program, we investigate the young neutron-star binary population in this low-metallicity, nearby, star-forming galaxy by reaching quiescent X-ray luminosity levels (~few times 1032 erg/s). In this talk, I will present the first measurement of the formation efficiency of high-mass X-ray binaries (HMXBs) as a function of the age of their parent stellar populations. We use three indicators of the formation efficiency of young accreting binaries in the low SMC metallicity: the number ratio of the HMXBs, N(HMXBs), to the number of OB stars, to the star-formation rate (SFR), and to the stellar mass produced during the specific star-formation burst they are associated with, all as a function of the age of their parent stellar populations. In all cases, we find that the HMXB formation efficiency increases as a function of time up to ~40—60 Myr, and then gradually decreases. The peak formation efficiency N(HMXB)/SFR is in good agreement with previous estimates of the average formation efficiency in the broad ~20—60 Myr age range, and a factor of at least ~8 and ~4 higher than the formation efficiency in earlier (~10 Myr) and later (~260 Myr) epochs. I will also present the deepest luminosity function ever recorded for a galaxy, and discuss the X-ray properties of the largest sample of extragalactic accreting pulsars as well.

Quasiperiodic Oscillations in X-ray Binaries

NASA Astrophysics Data System (ADS)

van der Klis, M.; Murdin, P.

2000-11-01

The term quasiperiodic oscillation (QPO) is used in high-energy astrophysics for any type of non-periodic variability that is constrained to a relatively narrow range of variability frequencies. X-RAY BINARIES are systems in which a `compact object', either a BLACK HOLE or a NEUTRON STAR, orbits a normal star and captures matter from it. The matter spirals down to the compact object and heats up ...

A DEEP CHANDRA OBSERVATION OF THE WOLF-RAYET + BLACK HOLE BINARY NGC 300 X-1

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

Binder, B.; Williams, B. F.; Anderson, S. F.

We have obtained a 63 ks Chandra ACIS-I observation of the Wolf-Rayet + black hole binary NGC 300 X-1. We measure rapid low-amplitude variability in the 0.35-8 keV light curve. The power density spectrum has a power-law index {gamma} = 1.02 {+-} 0.15 consistent with an accreting black hole in a steep power-law state. When compared to previous studies of NGC 300 X-1 performed with XMM-Newton, we find the source at the low end of the previously measured 0.3-10 keV luminosity. The spectrum of NGC 300 X-1 is dominated by a power law ({Gamma} = 2.0 {+-} 0.3) with amore » contribution at low energies by a thermal component. We estimate the 0.3-10 keV luminosity to be 2.6{sup +0.8}{sub -1.0} Multiplication-Sign 10{sup 38} erg s{sup -1}. The timing and spectroscopic properties of NGC 300 X-1 are consistent with being in a steep power-law state, similar to earlier observations performed with XMM-Newton. We additionally compare our observations to known high-mass X-ray binaries and ultraluminous X-ray sources, and find the properties of NGC 300 X-1 are most consistent with black hole high-mass X-ray binaries.« less

Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active Nuclei in Massive Mergers

NASA Technical Reports Server (NTRS)

Teng, Stacy H.; Schwainski, Kevin; Urry, C. Megan; Darg, Dan W.; Kaviraj, Sugata; Oh, Kyuseok; Bonning, Erin W.; Cardamone, Carolin N.; Keel, William C.; Lintott, Chris J.;

Searches for Periodic Neutrino Emission from Binary Systems with 22 and 40 Strings of IceCube

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brown, A. M.; Buitink, S.; Caballero-Mora, K. S.; Carson, M.; Chirkin, D.; Christy, B.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; Cruz Silva, A. H.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; Degner, T.; Demirörs, L.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Dunkman, M.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Góra, D.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, B.; Homeier, A.; Hoshina, K.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kroll, G.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lünemann, J.; Madsen, J.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Panknin, S.; Paul, L.; Pérez de los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Richman, M.; Rodrigues, J. P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schönwald, A.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Stüer, M.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Zoll, M.; IceCube Collaboration

2012-04-01

In this paper, we present the results of searches for periodic neutrino emission from a catalog of binary systems. Such modulation, observed in the photon flux, would be caused by the geometry of these systems. In the analysis, the period is fixed by these photon observations, while the phase and duration of the neutrino emission are treated as free parameters to be fit with the data. If the emission occurs during ~20% or less of the total period, this analysis achieves better sensitivity than a time-integrated analysis. We use the IceCube data taken from 2007 May 31 to 2008 April 5 with its 22 string configuration and from 2008 April 5 to 2009 May 20 with its 40 string configuration. No evidence for neutrino emission is found, with the strongest excess occurring for Cygnus X-3 at 2.1σ significance after accounting for trials. Neutrino flux upper limits for both periodic and time-integrated emission are provided.

Stellar winds in binary X-ray systems

NASA Technical Reports Server (NTRS)

Macgregor, K. B.; Vitello, P. A. J.

1982-01-01

It is thought that accretion from a strong stellar wind by a compact object may be responsible for the X-ray emission from binary systems containing a massive early-type primary. To investigate the effect of X-ray heating and ionization on the mass transfer process in systems of this type, an idealized model is constructed for the flow of a radiation-driven wind in the presence of an X-ray source of specified luminosity, L sub x. It is noted that for low values of L sub x, X-ray photoionization gives rise to additional ions having spectral lines with wavelengths situated near the peak of the primary continuum flux distribution. As a consequence, the radiation force acting on the gas increases in relation to its value in the absence of X-rays, and the wind is accelerated to higher velocities. As L sub x is increased, the degree of ionization of the wind increases, and the magnitude of the radiation force is diminished in comparison with the case in which L sub x = 0. This reduction leads at first to a decrease in the wind velocity and ultimately (for L sub x sufficiently large) to the termination of radiatively driven mass loss.

Evidence from Quasi-Periodic Oscillations for a Millisecond Pulsar in the Low Mass X-Ray Binary 4U 0614+091

NASA Technical Reports Server (NTRS)

Ford, E.; Kaaret, P.; Tavani, M.; Barret, D.; Bloser, P.; Grindlay, J.; Harmon, B. A.; Paciesas, W. S.; Zhang, S. N.

1997-01-01

We have detected quasi-periodic oscillations (QPOs) near 1 kHz from the low mass X-ray binary 4U 0614+091 in observations with RXTE. The observations span several months and sample the source over a large range of X-ray luminosity. In every interval QPOs are present above 400 Hz with fractional RMS amplitudes from 3 to 12% over the full PCA band. At high count rates, two high frequency QPOs are detected simultaneously. The difference of their frequency centroids is consistent with a constant value of 323 Hz in all observations. During one interval a third signal is detected at 328 +/- 2 Hz. This suggests the system has a stable 'clock' which is most likely the neutron star with spin period 3.1 msec. Thus, our observations of 4U 0614+091 and those of 4U 1728-34 provide the first evidence for millisecond pulsars within low-mass X-ray binary systems and reveal the 'missing-link' between millisecond radiopulsars and the late stages of binary evolution in low mass X-ray binaries. The constant difference of the high frequency QPOs sug,,ests a beat-frequency interpretation. In this model, the high frequency QPO is associated with the Keplerian frequency of the inner accretion disk and the lower frequency QPO is a 'beat' between the differential rotation frequency of the inner disk and the spinning neutron star. Assuming the high frequency QPO is a Keplerian orbital frequency for the accretion disk, we find a maximum mass of 1.9 solar mass and a maximum radius of 17 km for the neutron star.

CONSTRAINING RELATIVISTIC BOW SHOCK PROPERTIES IN ROTATION-POWERED MILLISECOND PULSAR BINARIES.

PubMed

Wadiasingh, Zorawar; Harding, Alice K; Venter, Christo; Böttcher, Markus; Baring, Matthew G

2017-04-20

Multiwavelength followup of unidentified Fermi sources has vastly expanded the number of known galactic-field "black widow" and "redback" millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase-centering of the double-peaked X-ray orbital modulation originating from mildly-relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock stand-off R 0 . We develop synthetic X-ray synchrotron orbital light curves and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the stand-off is R 0 ~ 0.15-0.3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R 0 ≲ 0.4 while X-ray light curves suggest 0.1 ≲ R 0 ≲ 0.3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy-dependence in the shape of light curves motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein.

CONSTRAINING RELATIVISTIC BOW SHOCK PROPERTIES IN ROTATION-POWERED MILLISECOND PULSAR BINARIES

PubMed Central

Wadiasingh, Zorawar; Harding, Alice K.; Venter, Christo; Böttcher, Markus; Baring, Matthew G.

2018-01-01

Multiwavelength followup of unidentified Fermi sources has vastly expanded the number of known galactic-field “black widow” and “redback” millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase-centering of the double-peaked X-ray orbital modulation originating from mildly-relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock stand-off R0. We develop synthetic X-ray synchrotron orbital light curves and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the stand-off is R0 ~ 0.15–0.3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R0 ≲ 0.4 while X-ray light curves suggest 0.1 ≲ R0 ≲ 0.3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy-dependence in the shape of light curves motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein. PMID:29651167

Constraining Relativistic Bow Shock Properties in Rotation-Powered Millisecond Pulsar Binaries

NASA Technical Reports Server (NTRS)

Wadiasingh, Zorawar; Harding, Alice K.; Venter, Christo; Bottcher, Markus; Baring, Matthew G.

2017-01-01

Multiwavelength follow-up of unidentified Fermi sources has vastly expanded the number of known galactic-field "black widow" and "redback" millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase-centering of the double-peaked X-ray orbital modulation originating from mildly-relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock stand-off R(sub 0). We develop synthetic X-ray synchrotron orbital light curves and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the stand-off is R(sub 0) approximately 0:15 - 0:3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R(sub 0) is approximately less than 0:4 while X-ray light curves suggest 0:1 is approximately less than R(sub 0) is approximately less than 0:3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy-dependence in the shape of light curves motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein.

Constraining Relativistic Bow Shock Properties in Rotation-powered Millisecond Pulsar Binaries

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

Wadiasingh, Zorawar; Venter, Christo; Böttcher, Markus

2017-04-20

Multiwavelength follow-up of unidentified Fermi sources has vastly expanded the number of known galactic-field “black widow” and “redback” millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase centering of the double-peaked X-ray orbital modulation originating from mildly relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock standoff R {sub 0}. We develop synthetic X-ray synchrotron orbital light curvesmore » and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the standoff is R {sub 0} ∼ 0.15–0.3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R {sub 0} ≲ 0.4, while X-ray light curves suggest 0.1 ≲ R {sub 0} ≲ 0.3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy dependence in the shape of light curves, motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein.« less

Longterm lightcurves of X-ray binaries

NASA Astrophysics Data System (ADS)

Clarkson, William

The X-ray Binaries (XRB) consist of a compact object and a stellar companion, which undergoes large-scale mass-loss to the compact object by virtue of the tight ( P orb usually hours-days) orbit, producing an accretion disk surrounding the compact object. The liberation of gravitational potential energy powers exotic high-energy phenomena, indeed the resulting accretion/ outflow process is among the most efficient energy-conversion machines in the universe. The Burst And Transient Source Experiment (BATSE) and RXTE All Sky Monitor (ASM) have provided remarkable X-ray lightcurves above 1.3keV for the entire sky, at near-continuous coverage, for intervals of 9 and 7 years respectively (with ~3 years' overlap). With an order of magnitude increase in sensitivity compared to previous survey instruments, these instruments have provided new insight into the high-energy behaviour of XRBs on timescales of tens to thousands of binary orbits. This thesis describes detailed examination of the long-term X-ray lightcurves of the neutron star XRB X2127+119, SMC X-1, Her X- 1, LMC X-4, Cyg X-2 and the as yet unclassified Circinus X-1, and for Cir X-1, complementary observations in the IR band. Chapters 1 & 2 introduce X-ray Binaries in general and longterm periodicities in particular. Chapter 3 introduces the longterm datasets around which this work is based, and the chosen methods of analysis of these datasets. Chapter 4 examines the burst history of the XRB X2127+119, suggesting three possible interpretations of the apparently contradictory X-ray emission from this system, including a possible confusion of two spatially distinct sources (which was later vindicated by high-resolution imaging). Chapters 5 and 6 describe the characterisation of accretion disk warping, providing observational verification of the prevailing theoretical framework for such disk-warps. Chapters 7 & 8 examine the enigmatic XRB Circinus X-1 with high-resolution IR spectroscopy (chapter 7) and the RXTE/ASM (chapter 8), establishing an improved orbital ephemeris and suggesting the system may be in a state of rapid post- supernova evolution. In chapter 8 we follow this up with a direct search for the X-ray supernova remnant expected from such a system, concluding that with present observations the diffuse emission from Cir X-1 is indistinguishable from scattering by dust-grains in the interstellar medium.

X-ray Binaries in the Central Region of M31

NASA Astrophysics Data System (ADS)

Trudolyubov, Sergey P.; Priedhorsky, W. C.; Cordova, F. A.

2006-09-01

We present the results of the systematic survey of X-ray sources in the central region of M31 using the data of XMM-Newton observations. The spectral properties and variability of 124 bright X-ray sources were studied in detail. We found that more than 80% of sources observed in two or more observations show significant variability on the time scales of days to years. At least 50% of the sources in our sample are spectrally variable. The fraction of variable sources in our survey is much higher than previously reported from Chandra survey of M31, and is remarkably close to the fraction of variable sources found in M31 globular cluster X-ray source population. We present spectral distribution of M31 X-ray sources, based on the spectral fitting with a power law model. The distribution of spectral photon index has two main peaks at 1.8 and 2.3, and shows clear evolution with source luminosity. Based on the similarity of the properties of M31 X-ray sources and their Galactic counterparts, we expect most of X-ray sources in our sample to be accreting binary systems with neutron star and black hole primaries. Combining the results of X-ray analysis (X-ray spectra, hardness-luminosity diagrams and variability) with available data at other wavelengths, we explore the possibility of distinguishing between bright neutron star and black hole binary systems, and identify 7% and 25% of sources in our sample as a probable black hole and neutron star candidates. Finally, we compare the M31 X-ray source population to the source populations of normal galaxies of different morphological type. Support for this work was provided through NASA Grant NAG5-12390. Part of this work was done during a summer workshop ``Revealing Black Holes'' at the Aspen Center for Physics, S. T. is grateful to the Center for their hospitality.

Late-time X-ray signatures of compact binary mergers: potential counterparts of gravitational wave events

NASA Astrophysics Data System (ADS)

Tanvir, Nial

2017-09-01

Merging compact binaries (NS-NS or NS-BH) offer the best prospects for detection of EM signals accompanying gravitational wave (GW) events. They may be seen as bright short-GRBs (SGRBs), but this is likely to be rare due to beaming. Alternatively, more isotropic near-IR emission is predicted to result from the 'kilonova' produced by radioactive decay of neutron star ejecta. However, recent XMM observations have shown unexplained excess X-ray emission several days post-burst in two low-z SGRBs. This may indicate ongoing engine activity which both enhances the nIR emission, and crucially provides a potential new isotropic X-ray signature of compact binary mergers. We propose a detailed study of a further z<0.35 SGRB, to explore this phenomenon and inform future searches for GW counterparts.

VLA Observations of the AGILE Cygnus Region Source Field Following its May 2008 Re-brightening in Gamma-rays, II: An Update

NASA Astrophysics Data System (ADS)

Cheung, C. C.

2008-06-01

The AGILE team (Chen et al. ATel #1585) has detected a new flare (occurring on June 20/21, 2008) from AGL2021+4029, the variable gamma-ray source in the Cygnus region. The error circles of this new June flare and that of the newly reported position of the persistent source, both unfortunately, lie outside of the r~0.5 deg field we targeted with the VLA (ATel #1584) following the May 2008 rebrightening (Giuliani et al.

NASA's Kepler Mission Discovers Multiple Planets Orbiting Twin Suns (Reporter Pkg)

NASA Image and Video Library

2012-08-28

NASA's Kepler mission has discovered the first transiting circumbinary system -- multiple planets orbiting two suns -- 4,900 light-years from Earth, in the constellation Cygnus, proving that more than one planets can form and survive in orbit around a binary star.

Neutrino flux from cosmic ray accelerators in the Cygnus spiral arm of the Galaxy

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

Anchordoqui, Luis; Halzen, Francis; O'Murchadha, Aongus

2007-09-15

Intriguing evidence has been accumulating for the production of cosmic rays in the Cygnus region of the galactic plane. We here show that the IceCube experiment can produce incontrovertible evidence for cosmic ray acceleration by observing the neutrinos from the decay of charged pions accompanying the TeV photon flux observed in the HEGRA, Whipple, Tibet, and Milagro experiments. Our assumption is that the TeV photons observed are the decay products of neutral pions produced by cosmic ray accelerators in the nearby spiral arm of the galaxy. Because of the proximity of the sources, IceCube will obtain evidence at the 5{sigma}more » level in 15 years of observation.« less

Eclipse timings of the low-mass X-ray binary EXO 0748-676: Statistical arguments against orbital period changes

NASA Technical Reports Server (NTRS)

Hertz, Paul; Wood, Kent S.; Cominsky, Lynn

1995-01-01

EXO 0748-676, an eclipsing low-mass X-ray binary, is one of only about four or five low-mass X-ray binaries for which orbital period evolution has been reported. We observed a single eclipse egress with ROSAT . The time of this egress is consistent with the apparent increase in P(sub orb) previously reported on the basis of EXOSAT and Ginga observations. Standard analysis, in which O-C (observed minus calculated) timing residuals are examined for deviations from a constant period, implicitly assume that the only uncertainty in each residual is measurement error and that these errors are independent. We argue that the variable eclipse durations and profiles observed in EXO 0748-676 imply that there is an additional source of uncertainty in timing measurements, that this uncertainty is intrinsic to the binary system, and that it is correlated from observation to observation with a variance which increases as a function of the number of binary cycles between observations. This intrinsic variability gives rise to spurious trends in O-C residuals which are misinterpreted as changes in the orbital period. We describe several statistics tests which can be used to test for the presence of intrinsic variability. We apply those statistical tests which are suitable to the EXO 0748-676 observations. The apparent changes in the orbital period of EXO 0748-676 can be completely accounted for by intrinsic variability with an rms variability of approximately 0.35 s per orbital cycle. The variability appears to be correlated from cycle-to-cycle on timescales of less than 1 yr. We suggest that the intrinsic variability is related to slow changes in either the source's X-ray luminosity or the structure of the companion star's atmosphere. We note that several other X-ray binaries and cataclysmic variables have previously reported orbital period changes which may also be due to intrinsic variability rather than orbital period evolution.

Probing the X-Ray Binary Populations of the Ring Galaxy NGC 1291

NASA Technical Reports Server (NTRS)

Luo, B.; Fabbiano, G.; Fragos, T.; Kim, D. W.; Belczynski, K.; Brassington, N. J.; Pellegrini, S.; Tzanavaris, P.; Wang, J.; Zezas, A.

2012-01-01

We present Chandra studies of the X-ray binary (XRB) populations in the bulge and ring regions of the ring galaxy NGC 1291. We detect 169 X-ray point sources in the galaxy, 75 in the bulge and 71 in the ring, utilizing the four available Chandra observations totaling an effective exposure of 179 ks. We report photometric properties of these sources in a point-source catalog. There are approx. 40% of the bulge sources and approx. 25% of the ring sources showing > 3(sigma) long-term variability in their X-ray count rate. The X-ray colors suggest that a significant fraction of the bulge (approx. 75%) and ring (approx. 65%) sources are likely low-mass X-ray binaries (LMXBs). The spectra of the nuclear source indicate that it is a low-luminosity AGN with moderate obscuration; spectral variability is observed between individual observations. We construct 0.3-8.0 keV X-ray luminosity functions (XLFs) for the bulge and ring XRB populations, taking into account the detection incompleteness and background AGN contamination. We reach 90% completeness limits of approx.1.5 x 10(exp 37) and approx. 2.2 x 10(exp 37) erg/s for the bulge and ring populations, respectively. Both XLFs can be fit with a broken power-law model, and the shapes are consistent with those expected for populations dominated by LMXBs. We perform detailed population synthesis modeling of the XRB populations in NGC 1291 , which suggests that the observed combined XLF is dominated by aD old LMXB population. We compare the bulge and ring XRB populations, and argue that the ring XRBs are associated with a younger stellar population than the bulge sources, based on the relative over-density of X-ray sources in the ring, the generally harder X-ray color of the ring sources, the overabundance of luminous sources in the combined XLF, and the flatter shape of the ring XLF.

First Detection of the Hatchett-McCray Effect in the High-Mass X-ray Binary

NASA Technical Reports Server (NTRS)

Sonneborn, G.; Iping, R. C.; Kaper, L.; Hammerschiag-Hensberge, G.; Hutchings, J. B.

2004-01-01

The orbital modulation of stellar wind UV resonance line profiles as a result of ionization of the wind by the X-ray source has been observed in the high-mass X-ray binary 4U1700-37/HD 153919 for the first time. Far-UV observations (905-1180 Angstrom, resolution 0.05 Angstroms) were made at the four quadrature points of the binary orbit with the Far Ultraviolet Spectroscopic Explorer (FUSE) in 2003 April and August. The O6.5 laf primary eclipses the X-ray source (neutron star or black hole) with a 3.41-day period. Orbital modulation of the UV resonance lines, resulting from X-ray photoionization of the dense stellar wind, the so-called Hatchett-McCray (HM) effect, was predicted for 4U1700-37/HD153919 (Hatchett 8 McCray 1977, ApJ, 211, 522) but was not seen in N V 1240, Si IV 1400, or C IV 1550 in IUE and HST spectra. The FUSE spectra show that the P V 1118-1128 and S IV 1063-1073 P-Cygni lines appear to vary as expected for the HM effect, weakest at phase 0.5 (X-ray source conjunction) and strongest at phase 0.0 (X-ray source eclipse). The phase modulation of the O VI 1032-1037 lines, however, is opposite to P V and S IV, implying that O VI may be a byproduct of the wind's ionization by the X-ray source. Such variations were not observed in N V, Si IV, and C IV because of their high optical depth. Due to their lower cosmic abundance, the P V and S IV wind lines are unsaturated, making them excellent tracers of the ionization conditions in the O star's wind.

X-RAY SOURCES IN THE DWARF SPHEROIDAL GALAXY DRACO

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

Sonbas, E.; Rangelov, B.; Kargaltsev, O.

2016-04-10

We present the spectral analysis of an 87 ks XMM-Newton observation of Draco, a nearby dwarf spheroidal galaxy. Of the approximately 35 robust X-ray source detections, we focus our attention on the brightest of these sources, for which we report X-ray and multiwavelength parameters. While most of the sources exhibit properties consistent with active galactic nuclei, few of them possess the characteristics of low-mass X-ray binaries (LMXBs) and cataclysmic variable (CVs). Our analysis places constraints on the population of X-ray sources with L{sub X} > 3 × 10{sup 33} erg s{sup −1} in Draco, suggesting that there are no actively accreting black hole andmore » neutron star binaries. However, we find four sources that could be quiescent state LMXBs/CVs associated with Draco. We also place constraints on the central black hole luminosity and on a dark matter decay signal around 3.5 keV.« less

The Discovery of a Second Luminous Low Mass X-Ray Binary System in the Globular Cluster M15

NASA Technical Reports Server (NTRS)

White, Nicholas E.; Angelini, Lorella

2001-01-01

Using the Chandra X-ray Observatory we have discovered a second bright X-ray source in the globular cluster M15 that is 2.7" to the west of AC211, the previously known low mass X-ray binary (LMXB) in this system. Prior to the 0.5" imaging capability of Chandra this second source could not have been resolved from AC211. The luminosity and spectrum of this new source, which we call M15-X2, are consistent with it also being a LMXB system. This is the first time that two LMXBs have been seen to be simultaneously active in a globular cluster. The new source, M15-X2, is coincident with a 18th U magnitude very blue star. The discovery of a second LMXB in M15 clears up a long standing puzzle where the X-ray and optical properties of AC211 appear consistent with the central source being hidden behind an accretion disk corona, and yet also showed a luminous X-ray burst suggesting the neutron star is directly visible. This discovery suggests instead that the X-ray burst did not come from AC211, but rather from the newly discovered X-ray source. We discuss the implications of this discovery for X-ray observations of globular clusters in nearby galaxies.

An X-ray Investigation of the NGC 346 Field. 1; The LBV HD 5980 and the NGC 346 Cluster

NASA Technical Reports Server (NTRS)

Naze, Y.; Hartwell, J. M.; Stevens, I. R.; Corcoran, M. F.; Chu, Y.-H.; Koenigsberger, G.; Moffat, A. F. J.; Niemela, V. S.

2002-01-01

We present results from a Chandra observation of the NGC 346 star formation region, which contains numerous massive stars, and is related to N66, the largest H(II) region of the SMC (Small Magellanic Cloud). In this first paper, we will focus on the characteristics of the main objects of the field. The NGC 346 cluster itself shows only relatively faint X-ray emission (with L((sub X)(sup unabs)) is approximately 1.5 x 10(exp 34) erg s(exp -1), tightly correlated with the core of the cluster. In the field also lies HD 5980, a LBV (Luminous Blue Variable) star in a binary (or triple system) that is detected for the first time at X-ray energies. The star is X-ray bright, with an unabsorbed luminosity of L((sub X)(sup unabs)) is approximately 1.7 x 10(exp 34) erg s(exp -1), but needs to be monitored further to investigate its X-ray variability over a complete orbital cycle. The high X-ray luminosity may be associated either with colliding winds in the binary system or with the 1994 eruption. HD 5980 is surrounded by a region of diffuse X-ray emission, which may be a superimposed supernova remnant.

First Search for an X-Ray-Optical Reverberation Signal in an Ultraluminous X-Ray Source

NASA Technical Reports Server (NTRS)

Pasham, Dheeraj R.; Strohmayer, Tod E.; Cenko, S. Bradley; Trippe, Margaret L.; Mushotzky, Richard F.; Gandhi, Poshak

2016-01-01

Using simultaneous optical (VLT/FORS2) and X-ray (XMM-Newton) data of NGC 5408, we present the first ever attempt to search for a reverberation signal in an ultraluminous X-ray source (NGC 5408 X-1). The idea is similar to active galactic nucleus broad line reverberation mapping where a lag measurement between the X-ray and the optical flux combined with a Keplerian velocity estimate should enable us to weigh the central compact object. We find that although NGC 5408 X-1's X-rays are variable on a timescale of a few hundred seconds (rms of 9.0 +/- 0.5%), the optical emission does not show any statistically significant variations. We set a 3s upper limit on the rms optical variability of 3.3%. The ratio of the X-ray to the optical variability is an indicator of X-ray reprocessing efficiency. In X-ray binaries, this ratio is roughly 5. Assuming a similar ratio for NGC 5408 X-1, the expected rms optical variability is approximately equal to 2%, which is still a factor of roughly two lower than what was possible with the VLT observations in this study. We find marginal evidence (3 sigma) for optical variability on an approximately 24 hr timescale. Our results demonstrate that such measurements can be made, but photometric conditions, low sky background levels, and longer simultaneous observations will be required to reach optical variability levels similar to those of X-ray binaries.

Phase lags of quasi-periodic oscillations across source states in the low-mass X-ray binary 4U 1636-53

NASA Astrophysics Data System (ADS)

de Avellar, Marcio G. B.

2017-06-01

The majority of attempts to explain the origin and phenomenology of the quasi-periodic oscillations (QPOs) detected in low-mass X-ray binaries invoke dynamical models, and it was just in recent years that renewed attention has been given on how radiative processes occurring in these extreme environments gives rise to the variability features observed in the X-ray light curves of these systems. The study of the dependence of the phase lags upon the energy and frequency of the QPOs is a step towards this end. The methodology we developed here allowed us to study for the first time these dependencies for all QPOs detected in the range of 1 to 1300 Hz in the low-mass X-ray binary 4U 1636-53 as the source changes its state during its cycle in the colour-colour diagram. Our results suggest that within the context of models of up-scattering Comptonization, the phase lags dependencies upon frequency and energy can be used to extract size scales and physical conditions of the medium that produces the lags.

A periodicity of approximately 1 hour in X-ray emission from the active galaxy RE J1034+396.

PubMed

Gierliński, Marek; Middleton, Matthew; Ward, Martin; Done, Chris

2008-09-18

Active galactic nuclei and quasars are thought to be scaled-up versions of Galactic black hole binaries, powered by accretion onto supermassive black holes with masses of 10(6)-10(9) M[symbol: see text], as opposed to the approximately 10 M [symbol: see text] in binaries (here M [symbol: see text] is the solar mass). One example of the similarities between these two types of systems is the characteristic rapid X-ray variability seen from the accretion flow. The power spectrum of this variability in black hole binaries consists of a broad noise with multiple quasi-periodic oscillations superimposed on it. Although the broad noise component has been observed in many active galactic nuclei, there have hitherto been no significant detections of quasi-periodic oscillations. Here we report the discovery of an approximately 1-hour X-ray periodicity in a bright active galaxy, RE J1034+396. The signal is highly statistically significant (at the 5.6 sigma level) and very coherent, with quality factor Q > 16. The X-ray modulation arises from the direct vicinity of the black hole.

The Chandra Delta Ori Large Project: Occultation Measurements of the Shocked Gas tn the Nearest Eclipsing O-Star Binary

NASA Technical Reports Server (NTRS)

Corcoran, Michael F.; Nichols, Joy; Naze, Yael; Rauw, Gregor; Pollock, Andrew; Moffat, Anthony; Richardson, Noel; Evans, Nancy; Hamaguchi, Kenji; Oskinova, Lida;

Discovery of 105 Hz coherent pulsations in the ultracompact binary IGR J16597-3704

NASA Astrophysics Data System (ADS)

Sanna, A.; Bahramian, A.; Bozzo, E.; Heinke, C.; Altamirano, D.; Wijnands, R.; Degenaar, N.; Maccarone, T.; Riggio, A.; Di Salvo, T.; Iaria, R.; Burgay, M.; Possenti, A.; Ferrigno, C.; Papitto, A.; Sivakoff, G. R.; D'Amico, N.; Burderi, L.

2018-02-01

We report the discovery of X-ray pulsations at 105.2 Hz (9.5 ms) from the transient X-ray binary IGR J16597-3704 using NuSTAR and Swift. The source was discovered by INTEGRAL in the globular cluster NGC 6256 at a distance of 9.1 kpc. The X-ray pulsations show a clear Doppler modulation that implies an orbital period of 46 min and a projected semi-major axis of 5 lt-ms, which makes IGR J16597-3704 an ultracompact X-ray binary system. We estimated a minimum companion mass of 6.5 × 10-10 M⊙, assuming a neutron star mass of 1.4 M⊙, and an inclination angle of <75° (suggested by the absence of eclipses or dips in its light curve). The broad-band energy spectrum of the source is well described by a disk blackbody component (kT 1.4 keV) plus a comptonised power-law with photon index 2.3 and an electron temperature of 30 keV. Radio pulsations from the source were unsuccessfully searched for with the Parkes Observatory.

Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active Nuclei in Massive Mergers

NASA Technical Reports Server (NTRS)

Teng, Stacy H.; Schawinski, Kevin; Urry, C. Megan; Darg, Dan W.; Kaviraj, Sugata; Oh, Kyuseok; Bonning, Erin W.; Cardamone, Carolin N.; Keel, William C.; Lintott, Chris J.;

A TRANSIENT SUB-EDDINGTON BLACK HOLE X-RAY BINARY CANDIDATE IN THE DUST LANES OF CENTAURUS A

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

Burke, Mark J.; Raychaudhury, Somak; Kraft, Ralph P.

2012-04-20

We report the discovery of a bright X-ray transient CXOU J132527.6-430023 in the nearby early-type galaxy NGC 5128. The source was first detected over the course of five Chandra observations in 2007, reaching an unabsorbed outburst luminosity of (1-2) Multiplication-Sign 10{sup 38} erg s{sup -1} in the 0.5-7.0 keV band before returning to quiescence. Such luminosities are possible for both stellar-mass black hole and neutron star (NS) X-ray binary transients. Here, we attempt to characterize the nature of the compact object. No counterpart has been detected in the optical or radio sky, but the proximity of the source to themore » dust lanes allows for the possibility of an obscured companion. The brightness of the source after a >100-fold increase in X-ray flux makes it either the first confirmed transient non-ultraluminous X-ray black hole system in outburst to be subject to detailed spectral modeling outside the Local Group, or a bright (>10{sup 38} erg s{sup -1}) transient NS X-ray binary, which are very rare. Such a large increase in flux would appear to lend weight to the view that this is a black hole transient. X-ray spectral fitting of an absorbed power law yielded unphysical photon indices, while the parameters of the best-fit absorbed disk blackbody model are typical of an accreting {approx}10 M{sub Sun} black hole in the thermally dominant state.« less

The Orbital Parameters and Nature of the X-ray Pulsar IGR J16393-4643 Using Pulse Timing Analysis

NASA Astrophysics Data System (ADS)

Pearlman, Aaron B.; Corbet, R. H. D.; Pottschmidt, K.; Skinner, G. K.

2011-09-01

A 3.7 day orbital period was previously suggested for the 910 s X-ray pulsar IGR J16393-4643 from a pulse timing study of widely separated X-ray observations (Thompson et al., 2006), placing the system in the supergiant wind-fed region of the Ppulse-Porb diagram. However, orbital periods of 50.2 and 8.1 days could not be excluded. Nespoli et al. (2010) refute this wind-accreting high-mass X-ray binary classification and suggest a symbiotic X-ray binary (SyXB) designation based on infrared spectroscopy of the proposed counterpart and the potential 50.2 day orbital solution. SyXBs are low-mass X-ray binaries in which a neutron star accretes from the inhomogeneous medium around an M-type giant companion. We find that two statistically independent light curves of IGR J16393-4643, from the Swift Burst Alert Telescope (15-50 keV) and the Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) Galactic bulge scans (2-10 keV), show highly significant orbital modulation near 4.24 days. Making use of this precise orbital period, we present the results from pulse arrival time analysis on IGR J16393-4643 using RXTE PCA observations. We provide significantly improved phase-connected pulse timing results using archival observations presented in Thompson et al. (2006) and additional pulse timing data not included in their study to determine the orbital parameters of the system. The derived 7.5 M⊙ mass function is inconsistent with a SyXB identification.

Multiwavength Observations of the Black Hole X-Ray Binary A0620-00 in Quiescence

NASA Astrophysics Data System (ADS)

Dinçer, Tolga; Bailyn, Charles D.; Miller-Jones, James C. A.; Buxton, Michelle; MacDonald, Rachel K. D.

2018-01-01

We present results from simultaneous multiwavelength X-ray, radio, and optical/near-infrared observations of the quiescent black hole X-ray binary A0620-00 performed in 2013 December. We find that the Chandra flux has brightened by a factor of 2 since 2005, and by a factor of 7 since 2000. The spectrum has not changed significantly over this time, being consistent with a power law of {{Γ }}=2.07+/- 0.13 and a hydrogen column of {N}H=(3.0+/- 0.5)× {10}21 {{cm}}-2. Very Large Array observations of A0620-00 at three frequencies, over the interval of 5.25–22.0 GHz, have provided us with the first broadband radio spectrum of a quiescent stellar mass black hole system at X-ray luminosities as low as 10‑8 times the Eddington luminosity. Compared to previous observations, the source has moved to lower radio and higher X-ray luminosity, shifting it perpendicular to the standard track of the radio/X-ray correlation for X-ray binaries. The radio spectrum is inverted with a spectral index α =0.74+/- 0.19 ({S}ν \\propto {ν }α ). This suggests that the peak of the spectral energy distribution is likely to be between 1012 and 1014 Hz, and that the near-IR and optical flux contain significant contributions from the star, the accretion flow, and from the outflow. Decomposing these components may be difficult, but holds the promise of revealing the interplay between accretion and jet in low luminosity systems.

Discovery of two eclipsing X-ray binaries in M 51

NASA Astrophysics Data System (ADS)

Wang, Song; Soria, Roberto; Urquhart, Ryan; Liu, Jifeng

2018-04-01

We discovered eclipses and dips in two luminous (and highly variable) X-ray sources in M 51. One (CXOM51 J132943.3+471135) is an ultraluminous supersoft source, with a thermal spectrum at a temperature of about 0.1 keV and characteristic blackbody radius of about 104 km. The other (CXOM51 J132946.1+471042) has a two-component spectrum with additional thermal-plasma emission; it approached an X-ray luminosity of 1039erg s-1 during outbursts in 2005 and 2012. From the timing of three eclipses in a series of Chandra observations, we determine the binary period (52.75 ± 0.63 hr) and eclipse fraction (22% ± 0.1%) of CXOM51 J132946.1+471042. We also identify a blue optical counterpart in archival Hubble Space Telescope images, consistent with a massive donor star (mass of ˜20-35M⊙). By combining the X-ray lightcurve parameters with the optical constraints on the donor star, we show that the mass ratio in the system must be M_2/M_1 ≳ 18, and therefore the compact object is most likely a neutron star (exceeding its Eddington limit in outburst). The general significance of our result is that we illustrate one method (applicable to high-inclination sources) of identifying luminous neutron star X-ray binaries, in the absence of X-ray pulsations or phase-resolved optical spectroscopy. Finally, we discuss the different X-ray spectral appearance expected from super-Eddington neutron stars and black holes at high viewing angles.

Discovery of two eclipsing X-ray binaries in M 51

NASA Astrophysics Data System (ADS)

Wang, Song; Soria, Roberto; Urquhart, Ryan; Liu, Jifeng

2018-07-01

We discovered eclipses and dips in two luminous (and highly variable) X-ray sources in M 51. One (CXOM51 J132943.3+471135) is an ultraluminous supersoft source, with a thermal spectrum at a temperature of about 0.1 keV and characteristic blackbody radius of about 104 km. The other (CXOM51 J132946.1+471042) has a two-component spectrum with additional thermal-plasma emission; it approached an X-ray luminosity of 1039 erg s-1 during outbursts in 2005 and 2012. From the timing of three eclipses in a series of Chandra observations, we determine the binary period (52.75 ± 0.63 h) and eclipse fraction (22 ± 0.1 per cent) of CXOM51 J132946.1+471042. We also identify a blue optical counterpart in archival Hubble Space Telescope images, consistent with a massive donor star (mass of ˜20-35 M⊙). By combining the X-ray light-curve parameters with the optical constraints on the donor star, we show that the mass ratio in the system must be M_2/M_1 ≳ 18 and therefore the compact object is most likely a neutron star (exceeding its Eddington limit in outburst). The general significance of our result is that we illustrate one method (applicable to high-inclination sources) of identifying luminous neutron star X-ray binaries, in the absence of X-ray pulsations or phase-resolved optical spectroscopy. Finally, we discuss the different X-ray spectral appearance expected from super-Eddington neutron stars and black holes at high viewing angles.

High energy gamma ray astronomy

NASA Technical Reports Server (NTRS)

Fichtel, Carl E.

1987-01-01

High energy gamma ray astronomy has evolved with the space age. Nonexistent twenty-five years ago, there is now a general sketch of the gamma ray sky which should develop into a detailed picture with the results expected to be forthcoming over the next decade. The galactic plane is the dominant feature of the gamma ray sky, the longitude and latitude distribution being generally correlated with galactic structural features including the spiral arms. Two molecular clouds were already seen. Two of the three strongest gamma ray sources are pulsars. The highly variable X-ray source Cygnus X-3 was seen at one time, but not another in the 100 MeV region, and it was also observed at very high energies. Beyond the Milky Way Galaxy, there is seen a diffuse radiation, whose origin remains uncertain, as well as at least one quasar, 3C 273. Looking to the future, the satellite opportunities for high energy gamma ray astronomy in the near term are the GAMMA-I planned to be launched in late 1987 and the Gamma Ray Observatory, scheduled for launch in 1990. The Gamma Ray Observatory will carry a total of four instruments covering the entire energy range from 30,000 eV to 3 x 10 to the 10th eV with over an order of magnitude increase in sensitivity relative to previous satellite instruments.

General Relativistic Effects and QPOs in X-Ray Binaries

NASA Astrophysics Data System (ADS)

Markovic, D.; Lamb, F. K.

We have investigated whether general relativistic effects may be responsible for some of the quasi-periodic X-ray brightness oscillations (QPOs) observed in low-mass binary systems containing accreting neutron stars and black hole candidates. In particular, we have computed the motions of accreting gas in the strong gravitational fields near such objects and have explored possible mechanisms for producing X-ray flux oscillations. We have discovered a family of weakly damped global gravitomagnetic (Lense-Thirring) warping modes of the inner (viscous) accretion disk that have precession frequencies ranging up to the single-particle gravitomagnetic precession frequency at the inner edge of the disk, which is about 30 Hz if the disk extends inward to the innermost stable circular orbit around a compact object of solar mass with dimensionless angular momentum cJ/GM2 ~ 0.2. Precession of regions of enhanced viscous dissipation or modulation of the accretion flow by the precession may produce observable periodic variation of the X-ray flux. Detectable effects might also be produced if the gas in the inner disk breaks up into a collection of distinct clumps. We have analyzed the dynamics of such clumps as well as the conditions required for their formation and survival on time scales long enough to produce QPOs with the coherence observed in low-mass X-ray binaries.

IGR J19294+1816: a new Be-X-ray binary revealed through infrared spectroscopy

NASA Astrophysics Data System (ADS)

Rodes-Roca, J. J.; Bernabeu, G.; Magazzù, A.; Torrejón, J. M.; Solano, E.

2018-05-01

The aim of this work is to characterize the counterpart to the INTErnational Gamma-Ray Astrophysics Laboratory high-mass X-ray binary candidate IGR J19294+1816 so as to establish its true nature. We obtained H-band spectra of the selected counterpart acquired with the Near Infrared Camera and Spectrograph instrument mounted on the Telescopio Nazionale Galileo 3.5-m telescope which represents the first infrared spectrum ever taken of this source. We complement the spectral analysis with infrared photometry from UKIDSS, 2MASS, WISE, and NEOWISE data bases. We classify the mass donor as a Be star. Subsequently, we compute its distance by properly taking into account the contamination produced by the circumstellar envelope. The findings indicate that IGR J19294+1816 is a transient source with a B1Ve donor at a distance of d = 11 ± 1 kpc, and luminosities of the order of 1036-37 erg s-1, displaying the typical behaviour of a Be-X-ray binary.

Cyclotron Line and Wind studies of Galactic High Mass X-ray Binaries

NASA Astrophysics Data System (ADS)

Suchy, Slawomir

High mass X-ray binaries are rotating neutron stars with very strong magnetic fields that channel accreting matter from their companion star onto the magnetic poles with subsequent collimated X-ray emission. The stars are fed either by a strong stellar wind of the optical companion or by an accretion disk, where material follows the magnetic field lines, emitting X-rays throughout this process either in the accretion column or directly from the neutron star surface. The fast rotation and the narrow collimation of the X-ray emission creates an observed pulsation, forming the concept of a pulsar. Some of the key questions of these thesis are the emission processes above the magnetic pole, including the influence of the magnetic field, the formation of the X-ray beam, and the structure of the stellar wind. An important process is the effect of the teraGauss magnetic field. Cyclotron resonance scattering creates spectral features similar to broad absorption lines (CRSFs or cyclotron lines) that are directly related to the magnetic field. The discovery of cyclotron lines ˜ 35 years ago allows for the only direct method to measure the magnetic field strength in neutron star systems. Variations in the line parameters throughout the pulse phase, and a dependence in the observed luminosity can also aid in the understanding of these processes. In this thesis I present the results of phase averaged and phase resolved analysis of the three high mass X-ray binaries CenX-3, 1A 1118--61, and GX301--2. The data used for this work were obtained with NASA's Rossi X-ray Timing Explorer and the Japanese Suzaku mission. Both satellites are ideal to cover the broad energy band, where CRSFs occur and are necessary for understanding the continuum as a whole. In the process of investigating the 3 sources, I discovered a CRSF at ˜ 55 keV in the transient binary 1A 1118--61, which indicates one of the strongest magnetic fields known in these objects. I used the variations of the CRSF in GX 301--2 throughout its pulse phase to develop a simple dipole model of the relationship between the magnetic moment vector and the spin axis of the neutron star. In Cen X-3 I use a similar model to demonstrate that the magnetic field most likely includes higher orders than just the simple dipole. The use of a wind model in high mass X-ray binaries can give information about the type of accretion, disk or wind, and the structure of the wind by measuring the amount of the material in the line of sight versus orbital phase. In Cen X-3, I used a simple spherical wind model throughout the two binary orbits and found that the observed absorption column densities are not consistent with pure wind accretion, and that either an accretion wake or a disk are needed to be consistent with the data. Similar results were observed in GX 301--2, where the neutron star may have passed through an accretion stream, increasing the observed amount of absorbed material.

Nobeyama 45 m Cygnus-X CO Survey. I. Photodissociation of Molecules Revealed by the Unbiased Large-scale CN and C18O Maps

NASA Astrophysics Data System (ADS)

Yamagishi, M.; Nishimura, A.; Fujita, S.; Takekoshi, T.; Matsuo, M.; Minamidani, T.; Taniguchi, K.; Tokuda, K.; Shimajiri, Y.

2018-03-01

We present an unbiased large-scale (9 deg2) CN (N = 1–0) and C18O (J = 1–0) survey of Cygnus-X conducted with the Nobeyama 45 m Cygnus-X CO survey. CN and C18O are detected in various objects toward the Cygnus-X North and South (e.g., DR17, DR18, DR21, DR22, DR23, and W75N). We find that CN/C18O integrated intensity ratios are systematically different from region to region, and are especially enhanced in DR17 and DR18, which are irradiated by the nearby OB stars. This result suggests that CN/C18O ratios are enhanced via photodissociation reactions. We investigate the relation between the CN/C18O ratio and strength of the UV radiation field. As a result, we find that CN/C18O ratios correlate with the far-UV intensities, G 0. We also find that CN/C18O ratios decrease inside molecular clouds, where the interstellar UV radiation is reduced due to the interstellar dust extinction. We conclude that the CN/C18O ratio is controlled by the UV radiation, and is a good probe of photon-dominated regions.

Chandra X-Ray and Hubble Space Telescope Imaging of Optically Selected Kiloparsec-scale Binary Active Galactic Nuclei. II. Host Galaxy Morphology and AGN Activity

NASA Astrophysics Data System (ADS)

Shangguan, Jinyi; Liu, Xin; Ho, Luis C.; Shen, Yue; Peng, Chien Y.; Greene, Jenny E.; Strauss, Michael A.

2016-05-01

Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W (U-band) and F105W (Y-band) images taken by the Wide Field Camera 3 on board the Hubble Space Telescope. Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U - Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers. 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 number GO 12363.

Rapid Jet Precession During the 2015 Outburst of the Black Hole X-ray Binary V404 Cygni

NASA Astrophysics Data System (ADS)

Sivakoff, Gregory R.; Miller-Jones, James; Tetarenko, Alex J.

2017-08-01

In stellar-mass black holes that are orbited by lower-mass companions (black hole low-mass X-ray binaries), the accretion process can undergo dramatic outbursts that can be accompanied by the launching of powerful relativistic jets. We still do not know the exact mechanism responsible for launching these jets, despite decades of research and the importance of determining this mechanism given the clear analogue of accreting super-massive black holes and their jets. The two main models for launching jets involve the extraction of the rotational energy of a spinning black hole (Blandford-Znajek) and the centrifugal acceleration of particles by open magnetic field lines rotating with the accretion flow (Blandford-Payne). Since some relativistic jets are not fully aligned with the angular momentum of the binary's orbit, the inner accretion flow of some black hole X-ray binaries may precess due to frame-dragging by a spinning black hole (Lense-Thirring precession). This precession has been previously observed close to the black hole as second-timescale quasi-periodic (X-ray) variability. In this talk we will present radio-through-sub-mm timing and high-angular resolution radio imaging (including a high-timing resolution movie) of the black hole X-ray binary V404 Cygni during its 2015 outburst. These data show that at the peak of the outburst the relativistic jets in this system were precessing on timescales of hours. We will discuss how rapid precession can be explained by Lense-Thirring precession of a vertically-extended slim disc that is maintained out to a radius of 6 X 1010 cm by a highly super-Eddington accretion rate. This would imply that the jet axis of V404 Cyg is not aligned with the black hole spin. More importantly, this places a key requirement on any model for launching jets, and may favour launching the jet from the rotating magnetic fields threading the disc.

Restablished Accretion in Post-outburst Classical Novae Revealed by X-rays

NASA Astrophysics Data System (ADS)

Hernanz, Margarita; Ferri, Carlo; Sala, Glòria

2009-05-01

Classical novae are explosions on accreting white dwarfs (hereinafter WDs) in cataclysmic variables (hereinafter CVs) a hydrogen thermonuclear runaway on top of the WD is responsible for the outburst. X-rays provide a unique way to study the turn-off of H-burning, because super soft X-rays reveal the hot WD photosphere, but also to understand how accretion is established again in the binary system. Observations with XMM-Newton of some post-outburst novae have revealed such a process, but a coverage up to larger energies -as Simbol-X will provide- is fundamental to well understand the characteristics of the binary system and of the nova ejecta. We present a brief summary of our results up to now and prospects for the Simbol-X mission.

X-Ray Emission from Massive Stars in Cyg OB2

NASA Astrophysics Data System (ADS)

Rauw, G.; Nazé, Y.; Wright, N. J.; Drake, J. J.; Guarcello, M. G.; Prinja, R. K.; Peck, L. W.; Albacete Colombo, J. F.; Herrero, A.; Kobulnicky, H. A.; Sciortino, S.; Vink, J. S.

2015-11-01

We report on the analysis of the Chandra-ACIS data of O, B, and WR stars in the young association Cyg OB2. X-ray spectra of 49 O-stars, 54 B-stars, and 3 WR-stars are analyzed and for the brighter sources, the epoch dependence of the X-ray fluxes is investigated. The O-stars in Cyg OB2 follow a well-defined scaling relation between their X-ray and bolometric luminosities: {log}\\\\frac{{L}{{X}}}{{L}{bol}}=-7.2+/- 0.2. This relation is in excellent agreement with the one previously derived for the Carina OB1 association. Except for the brightest O-star binaries, there is no general X-ray overluminosity due to colliding winds in O-star binaries. Roughly half of the known B-stars in the surveyed field are detected, but they fail to display a clear relationship between LX and Lbol. Out of the three WR stars in Cyg OB2, probably only WR 144 is itself responsible for the observed level of X-ray emission, at a very low {log}\\\\frac{{L}{{X}}}{{L}{bol}}=-8.8+/- 0.2. The X-ray emission of the other two WR-stars (WR 145 and 146) is most probably due to their O-type companion along with a moderate contribution from a wind-wind interaction zone.

Inclination Angles of Black Hole X-Ray Binaries Manifest Strong Gravity around Black Holes

NASA Technical Reports Server (NTRS)

Zhang, S. N.; Zhang, Xiao-Ling; Yao, Yangsen

2002-01-01

System inclination angles have been determined for about 15 X-ray binaries, in which stellar mass black holes are considered to exist. These inclination angles range between 25 degrees and 80 degrees, but peaked between 60-70 degrees. This peak is not explained in the frame work of Newtonian gravity. However, this peak is reproduced naturally if we model the observed X-ray radiations as being produced in the accretion disks very close to the black hole horizons, where the extremely strong general and special relativistic effects, caused by the extremely strong gravity near the black hole horizons, modify the local radiation significantly as the X-rays propagate to the remote observer. Therefore the peak of the inclination angle distribution provides evidence or strong gravity around stellar mass black holes.

Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi

NASA Astrophysics Data System (ADS)

Hitomi Collaboration; Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra; Cackett, Edward M.; Chernyakova, Maria; Chiao, Meng P.; Coppi, Paolo S.; Costantini, Elisa; de Plaa, Jelle; de Vries, Cor P.; den Herder, Jan-Willem; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C.; Ferrigno, Carlo; Foster, Adam R.; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C.; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana M.; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko S.; Hornschemeier, Ann; Hoshino, Akio; Hughes, John P.; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iwai, Masachika; Kaastra, Jelle; Kallman, Tim; Kamae, Tsuneyoshi; Kataoka, Jun; Katsuda, Satoru; Kawai, Nobuyuki; Kelley, Richard L.; Kilbourne, Caroline A.; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Katsuji; Koyama, Shu; Kretschmar, Peter; Krimm, Hans A.; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lee, Shiu-Hang; Leutenegger, Maurice A.; Limousin, Olivier O.; Loewenstein, Michael; Long, Knox S.; Lumb, David; Madejski, Greg; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R.; Mehdipour, Missagh; Miller, Eric D.; Miller, Jon M.; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard F.; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stéphane; Petre, Robert; Pinto, Ciro; Porter, Frederick S.; Pottschmidt, Katja; Reynolds, Christopher S.; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemtsos, Peter J.; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K.; Soong, Yang; Stawarz, Łukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shiníchiro; Takei, Yoh; Tamagawa, Toru; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki T.; Tashiro, Makoto S.; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi Go; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Uno, Shiníchiro; Urry, C. Megan; Ursino, Eugenio; Watanabe, Shin; Werner, Norbert; Wilkins, Dan R.; Williams, Brian J.; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Zhuravleva, Irina; Zoghbi, Abderahmen; Nakaniwa, Nozomi

2018-03-01

We report on a Hitomi observation of IGR J16318-4848, a high-mass X-ray binary system with an extremely strong absorption of NH ˜ 1024 cm-2. Previous X-ray studies revealed that its spectrum is dominated by strong fluorescence lines of Fe as well as continuum emission lines. For physical and geometrical insight into the nature of the reprocessing material, we utilized the high spectroscopic resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer: SXS) and the wide-band sensitivity by the soft and hard X-ray imagers (SXI and HXI) aboard Hitomi. Even though the photon counts are limited due to unintended off-axis pointing, the SXS spectrum resolves Fe Kα1 and Kα2 lines and puts strong constraints on the line centroid and line width. The line width corresponds to a velocity of 160^{+300}_{-70} km s-1. This represents the most accurate, and smallest, width measurement of this line made so far from the any X-ray binary, much less than the Doppler broadening and Doppler shift expected from speeds that are characteristic of similar systems. Combined with the K-shell edge energy measured by the SXI and HXI spectra, the ionization state of Fe is estimated to be in the range of Fe I-IV. Considering the estimated ionization parameter and the distance between the X-ray source and the absorber, the density and thickness of the materials are estimated. The extraordinarily strong absorption and the absence of a Compton shoulder component have been confirmed. These characteristics suggest reprocessing materials that are distributed in a narrow solid angle or scattering, primarily by warm free electrons or neutral hydrogen. This measurement was achieved using the SXS detection of 19 photons. It provides strong motivation for follow-up observations of this and other X-ray binaries using the X-ray Astrophysics Recovery Mission and other comparable future instruments.

Physics of the Merging Clusters Cygnus A, A3667, and A2065

NASA Astrophysics Data System (ADS)

Markevitch, Maxim; Sarazin, Craig L.; Vikhlinin, Alexey

1999-08-01

We present ASCA gas temperature maps of the nearby merging galaxy clusters Cygnus A, A3667, and A2065. Cygnus A appears to have a particularly simple merger geometry that allows an estimate of the subcluster collision velocity from the observed temperature variations. We estimate it to be ~2000 km s-1. Interestingly, this is similar to the free-fall velocity that the two Cygnus A subclusters should have achieved at the observed separation, suggesting that the merger has been effective in dissipating the kinetic energy of gas halos into thermal energy, without channeling its major fraction elsewhere (e.g., into turbulence). In A3667 we may be observing a spatial lag between the shock front seen in the X-ray image and the corresponding rise of the electron temperature. A lag of the order of hundreds of kiloparsecs is possible because of the combination of thermal conduction and a finite electron-ion equilibration time. Forthcoming better spatial resolution data will allow a direct measurement of these phenomena in the cluster gas using such lags. A2065 has gas density peaks coincident with two central galaxies. A merger with the collision velocity estimated from the temperature map should have swept away such peaks if the subcluster total mass distributions had flat cores in the centers. The fact that the peaks have survived (or quickly reemerged) suggests that the gravitational potential is also strongly peaked. Finally, the observed specific entropy variations in A3667 and Cygnus A indicate that energy injection from a single major merger may be of the order of the full thermal energy of the gas. We hope that these order-of-magnitude estimates will encourage further work on hydrodynamic simulations, as well as a more quantitative representation of the simulation results, in anticipation of the Chandra and XMM data.

Searching for Intermediate Mass Black Holes in Ultraluminous X-ray Binaries

NASA Astrophysics Data System (ADS)

Fritze, Hannah; Wright, Simon; Kilgard, Roy

2018-01-01

X-ray observations of nearby galaxies provide one of the best laboratories in the universe for studying two exotic classes of object: black holes and neutron stars. These observations allow us to study the dramatic effect such objects have on their surroundings, as well as the high-energy physics involved in their emission. We conduct a volume-limited archival survey of X-ray sources in all galaxies observed with the Chandra X-ray observatory within 15 Mpc, and identify a set of ultraluminous X-ray sources for detailed spectral analysis. We perform this analysis with the aim of searching for signatures of spectral state transitions and super-Eddington accretion that could indicate the presence of an Intermediate Mass Black Hole (IMBH) binary system. Here, we identify 43 potential IMBH sources that have signatures of super-Eddington accretion. We plan to follow up this initial selection with a multiwavelength analysis of these sources, in order to place further constraints on their nature and surrounding environment.

H-alpha images of the Cygnus Loop - A new look at shock-wave dynamics in an old supernova remnant

NASA Technical Reports Server (NTRS)

Fesen, Robert A.; Kwitter, Karen B.; Downes, Ronald A.

1992-01-01

Attention is given to deep H-alpha images of portions of the east, west, and southwest limbs of the Cygnus Loop which illustrate several aspects of shock dynamics in a multiphase interstellar medium. An H-alpha image of the isolated eastern shocked cloud reveals cloud deformation and gas stripping along the cloud's edges, shock front diffraction and reflection around the rear of the cloud, and interior remnant emission due to upstream shock reflection. A faint Balmer-dominated filament is identified 30 arcmin further west of the remnant's bright line of western radiative filaments. This detection indicates a far more westerly intercloud shock front position than previously realized, and resolves the nature of the weak X-ray, optical, and nonthermal radio emission observed west of NGC 6960. Strongly curved Balmer-dominated filaments along the remnant's west and southwest edge may indicate shock diffraction caused by shock wave passage in between clouds.

An X-ray excited wind in Centaurus X-3

NASA Technical Reports Server (NTRS)

Day, C. S. R.; Stevens, Ian R.

1993-01-01

We propose a new interpretation of the behavior of the notable X-ray binary source Centaurus X-3. Based on both theoretical and observational arguments (using EXOSAT data), we suggest that an X-ray excited wind emanating from the O star is present in this system. Further, we suggest that this wind is responsible for the mass transfer in the system rather than Roche-lobe overflow or a normal radiatively driven stellar wind. We show that the ionization conditions in Cen X-3 are too extreme to permit a normal radiatively driven wind to emanate from portions of the stellar surface facing toward the neutron star. In addition, the flux of X-rays from the neutron star is strong enough to drive a thermal wind from the O star with sufficient mass-flux to power the X-ray source. We find that this model can reasonably account for the long duration of the eclipse transitions and other observed features of Cen X-3. If confirmed, this will be the first example of an X-ray excited wind in a massive binary. We also discuss the relationship between the excited wind in Cen X-3 to the situation in eclipsing millisecond pulsars, where an excited wind is also believed to be present.

The 5 Hour Pulse Period and Broadband Spectrum of the Symbiotic X-Ray Binary 3A 1954+319

NASA Technical Reports Server (NTRS)

Marcu, Diana M.; Fuerst, Felix; Pottschmidt, Katja; Grinberg, Victoria; Miller, Sebstian; Wilms, Joern; Postnov, Konstantin A.; Corbet, Robin H. D.; Markwardt, Craig B.; Cadolle Bel, Marion

2011-01-01

We present an analysis of the highly variable accreting X-ray pulsar 3A 1954+319 using 2005-2009 monitoring data obtained with INTEGRAL and Swift. This considerably extends the pulse period history and covers flaring episodes in 2005 and 2008. In 2006 the source was identified as one of only a few known symbiotic X-ray binaries, Le" systems composed of a neutron star accreting from the inhomogeneous medium around an M-giant star. The extremely long pulse period of approximately 5.3 h is directly visible in the 2008 INTEGRAL-ISGRI outburst light curve. The pulse profile is double peaked and not significantly energy dependent. During the outburst a strong spin-up of -1.8 x 10(exp -4) h h(exp -1) occurred. Between 2005 and 2008 a long term spin-down trend of 2.1 x 10(exp -5) h h(exp -1) was observed for the first time for this source. The 3-80 keV pulse peak spectrum of 3A 1954+319 during the 2008 flare could be well described by a thermal Comptonization model. We interpret the results within the framework of a recently developed quasi-spherical accretion model for symbiotic X-ray binaries.

Structure of thermal pair clouds around gamma-ray-emitting black holes

NASA Technical Reports Server (NTRS)

Liang, Edison P.

1991-01-01

Using certain simplifying assumptions, the general structure of a quasi-spherical thermal pair-balanced cloud surrounding an accreting black hole is derived from first principles. Pair-dominated hot solutions exist only for a restricted range of the viscosity parameter. These results are applied as examples to the 1979 HEAO 3 gamma-ray data of Cygnus X-1 and the Galactic center. Values are obtained for the viscosity parameter lying in the range of about 0.1-0.01. Since the lack of synchrotron soft photons requires the magnetic field to be typically less than 1 percent of the equipartition value, a magnetic field cannot be the main contributor to the viscous stress of the inner accretion flow, at least during the high gamma-ray states.

1FGL J1417.7-4407: A Likely Gamma-Ray Bright Binary with A Massive Neutron Star and A Giant Secondary

NASA Technical Reports Server (NTRS)

Strader, Jay; Chomiuk, Laura; Cheung, C. C.; Sand, David J.; Donato, Davide; Corbet, Robin H. D.; Koeppe, Dana; Edwards, Philip G.; Stevens, Jamie; Petrov, Leonid

2015-01-01

We present multiwavelength observations of the persistent Fermi-Large Area Telescope unidentified gamma-ray source 1FGL J1417.7-4407, showing it is likely to be associated with a newly discovered X-ray binary containing a massive neutron star (nearly 2 solar mass) and a approximately 0.35 solar mass giant secondary with a 5.4 day period. SOAR optical spectroscopy at a range of orbital phases reveals variable double-peaked H alpha emission, consistent with the presence of an accretion disk. The lack of radio emission and evidence for a disk suggests the gamma-ray emission is unlikely to originate in a pulsar magnetosphere, but could instead be associated with a pulsar wind, relativistic jet, or could be due to synchrotron self-Compton at the disk-magnetosphere boundary. Assuming a wind or jet, the high ratio of gamma- ray to X-ray luminosity (approximately 20) suggests efficient production of gamma-rays, perhaps due to the giant companion. The system appears to be a low-mass X-ray binary that has not yet completed the pulsar recycling process. This system is a good candidate to monitor for a future transition between accretion-powered and rotational-powered states, but in the context of a giant secondary.

The Universe, Two by Two.

ERIC Educational Resources Information Center

Metz, William

1983-01-01

Discusses the nature of and current research related to binary stars, indicating that the knowledge that most stars come in pairs is critical to the understanding of stellar phenomena. Subjects addressed include aberrant stellar behavior, x-ray binaries, lobes/disks, close binaries, planetary nebulas, and formation/evolution of binaries. (JN)

Precision X-ray Timing of RX J0806.3+1527 with CHANDRA: Evidence for Gravitational Radiation from an Ultracompact Binary

NASA Technical Reports Server (NTRS)

Strohymayer, Tod E.

2004-01-01

RX J0806.3+1527 is a candidate double degenerate binary with possibly the shortest known orbital period. The source shows an approximately equal to 100% X-ray intensity modulation at the putative orbital frequency of 3.11 mHz (321.5 s). If the system is a detached, ultracompact binary gravitational radiation should drive spin-up with a magnitude of nu(sup dot) approximately 10(exp -16) Hz per second. Efforts to constrain the X-ray frequency evolution to date have met with mixed success, principally due to the sparseness of earlier observations. Here we describe the results of the first phase coherent X-ray monitoring campaign on RX J0806.3+1527 with Chandra. We obtained a total of 70 ksec of exposure in 6 epochs logarithmically spaced over 320 days. With these data we conclusively show that the X-ray frequency is increasing at a rate of 3.77 plus or minus 0.8 x 10(exp -16) Hz per second. Using the ephemeris derived from the new data we are able to phase up all the earlier Chandra and ROSAT data and show they are consistent with a constant nu(sup dot) = 3.63 plus or minus 0.06 x 10(exp -16) Hz per second over the past decade. This value appears consistent with that recently derived by Israel et al. largely from monitoring of the optical modulation, and is in rough agreement with the solutions reported initially by Hakala et al., based on ground-based optical observations. The large and stable nu(sup dot) over a decade is consistent with gravitational radiation losses driving the evolution. An intermediate polar (IP) scenario where the observed X-ray period is the spin period of an accreting white dwarf appears less tenable because the observed nu(sup dot) requires an m(sup dot) approximately equal to 4 x 10 (exp -8) solar mass yr(sup -l), that is much larger than that inferred from the observed X-ray luminosity (although this depends on the uncertain distance and bolometric corrections), and it is difficult to drive such a high m(sup dot) in a binary system with parameters consistent with all the multiwavelength data. If the ultracompact scenario is correct, then the X-ray flux cannot be powered by stable accretion which would drive the components apart, suggesting a new type of energy source (perhaps electromagnetic) may power the X-ray flux.

Evidence for a massive stellar black hole in x ray Nova Muscae

NASA Technical Reports Server (NTRS)

Chen, Wan; Gehrels, Neil; Cheng, F. H.

1992-01-01

We present evidence that the X-ray Nova Muscae system contains a massive, greater than 10 M solarmass, black hole. A recently measured photometric binary mass function gives the black hole mass for this system as a function of orbital inclination angle. From the spectral redshift and width of the positron annihilation gamma-ray line observed by GRANAT/SIGMA, we find the accretion disk inclination angle to be 22 deg plus or minus 18 deg. Assuming the accretion disk lies in the orbital plane of the system, the black hole mass is found to have a lower limit of 14 M solar mass although statistics are poor. This is supported by spectral modeling of combined optical/UV/x-ray/gamma-ray data and by a new Nova Muscae distance limit we derive of greater than 3 kpc. The large mass for this black hole and the high binary mass ratio it implies (greater than 20) raise a serious challenge to theoretical models of the formation and evolution of massive binaries. The gamma-ray line technique introduced here can give tight constraints on orbital parameters when high-sensitivity line measurements are made by such missions as GRO.

Black Hole Binaries in Quiescence

NASA Astrophysics Data System (ADS)

Bailyn, Charles D.

I discuss some of what is known and unknown about the behavior of black hole binary systems in the quiescent accretion state. Quiescence is important for several reasons: 1) the dominance of the companion star in optical and IR wavelengths allows the binary parameters to be robustly determined - as an example, we argue that the longer proposed distance to the X-ray source GRO J1655-40 is correct; 2) quiescence represents the limiting case of an extremely low accretion rate, in which both accretion and jets can be observed; 3) understanding the evolution and duration of the quiescent state is a key factor in determining the overall demographics of X-ray binaries, which has taken on a new importance in the era of gravitational wave astronomy.

Binary interaction dominates the evolution of massive stars.

PubMed

Sana, H; de Mink, S E; de Koter, A; Langer, N; Evans, C J; Gieles, M; Gosset, E; Izzard, R G; Le Bouquin, J-B; Schneider, F R N

2012-07-27

The presence of a nearby companion alters the evolution of massive stars in binary systems, leading to phenomena such as stellar mergers, x-ray binaries, and gamma-ray bursts. Unambiguous constraints on the fraction of massive stars affected by binary interaction were lacking. We simultaneously measured all relevant binary characteristics in a sample of Galactic massive O stars and quantified the frequency and nature of binary interactions. More than 70% of all massive stars will exchange mass with a companion, leading to a binary merger in one-third of the cases. These numbers greatly exceed previous estimates and imply that binary interaction dominates the evolution of massive stars, with implications for populations of massive stars and their supernovae.

X ray spectra of X Per. [oso-8 observations

NASA Technical Reports Server (NTRS)

Becker, R. H.; Boldt, E. A.; Holt, S. S.; Pravdo, S. H.; Robinson-Saba, J.; Serlemitsos, P. J.; Swank, J. H.

1978-01-01

The cosmic X-ray spectroscopy experiment on OSO-8 observed X Per for twenty days during two observations in Feb. 1976 and Feb. 1977. The spectrum of X Per varies in phase with its 13.9 min period, hardening significantly at X-ray minimum. Unlike other X-ray binary pulsar spectra, X Per's spectra do not exhibit iron line emission or strong absorption features. The data show no evidence for a 22 hour periodicity in the X-ray intensity of X Per. These results indicate that the X-ray emission from X Per may be originating from a neutron star in a low density region far from the optically identified Be star.

First Detection of Phase-dependent Colliding Wind X-ray Emission outside the Milky Way

NASA Technical Reports Server (NTRS)

Naze, Yael; Koenigsberger, Gloria; Moffat, Anthony F. J.

2007-01-01

After having reported the detection of X-rays emitted by the peculiar system HD 5980, we assess here the origin of this high-energy emission from additional X-ray observations obtained with XMM-Newton. This research provides the first detection of apparently periodic X-ray emission from hot gas produced by the collision of winds in an evolved massive binary outside the Milky Way. It also provides the first X-ray monitoring of a Luminous Blue Variable only years after its eruption and shows that the source of the X-rays is not associated with the ejecta.

Study of muons from the direction of Cygnus X-3 using an underground proportional-tube array

NASA Astrophysics Data System (ADS)

Kochocki, J. A.; Allison, W. W.; Alner, G. J.; Ambats, I.; Ayres, D. S.; Balka, L. J.; Barr, G. D.; Barrett, W. L.; Benjamin, D.; Border, P.; Brooks, C. B.; Cobb, J. H.; Cockerill, D. J.; Coover, K.; Courant, H.; Dahlin, B.; Dasgupta, U.; Dawson, J. W.; Edwards, V. W.; Fields, T. H.; Kirby-Gallagher, L. M.; Garcia-Garcia, C.; Giles, R. H.; Goodman, M. C.; Heller, K.; Heppelman, S.; Hill, N.; Hoftiezer, J. H.; Jankowski, D. J.; Johns, K.; Joyce, T.; Kafka, T.; Litchfield, P. J.; Lopez, F. V.; Lowe, M.; Mann, W. A.; Marshak, M. L.; May, E. N.; McMaster, L.; Milburn, R. H.; Miller, W.; Napier, A.; Oliver, W. P.; Pearce, G. F.; Perkins, D. H.; Peterson, E. A.; Price, L. E.; Roback, D.; Rosen, D. B.; Ruddick, K.; Saitta, B.; Schlereth, J. L.; Schmid, D.; Schneps, J.; Shield, P. D.; Shupe, M.; Sundaralingam, N.; Thomson, M. A.; Thron, J. L.; Werkema, S.; West, N.

1990-11-01

From July 1987 through March 1988 an array of proportional wire modules was operated as a muon detector at a depth of 2090 meters water equivalent in the Soudan mine in northern Minnesota. A spatial angular resolution of 1.2° was achieved for muon tracking. A clean sample of 1.02×105 muon trajectories recorded underground is used to search for an excess flux of muons from the direction of Cygnus X-3. For muons within the phase interval [0.6, 0.9] of the source's 4.8-h period, 90%-C.L. upper limits for fluxes arriving within 3° and 1.5° half-angle cones centered on the Cygnus X-3 direction are 8.5×10-11 cm-2s-1 and 3.1×10-11 cm-2s-1, respectively.

High Energy Astronomy Observatory (HEAO)

NASA Image and Video Library

1980-01-01

This image of the suspected Black Hole, Cygnus X-1, was the first object seen by the High Energy Astronomy Observatory (HEAO)-2/Einstein Observatory. According to the theories to date, one concept of a black hole is a star, perhaps 10 times more massive than the Sun, that has entered the last stages of stelar evolution. There is an explosion triggered by nuclear reactions after which the star's outer shell of lighter elements and gases is blown away into space and the heavier elements in the stellar core begin to collapse upon themselves. Once this collapse begins, the inexorable force of gravity continues to compact the material until it becomes so dense it is squeezed into a mere point and nothing can escape from its extreme gravitational field, not even light. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy.

Galaxies in the X-Ray Band

NASA Technical Reports Server (NTRS)

Hornschemeier, Ann

2008-01-01

This talk will provide a brief review of progress an X-ray emission from normal (non-AGN) galaxy populations, including important constraints on the evolution of accreting binary populations over important cosmological timescales. We will also look to the future, anticipating constraints from near-term imaging hard X-ray missions such as NuSTAR, Simbol-X and NeXT and then the longer-term prospects for studying galaxies with the Generation-X mission,