WorldWideScience

Sample records for adc x-ray binary

  1. Broadband X-ray Spectroscopy of the ADC Source 4U 1822-37 with Suzaku

    Cottam, J.; White, N.

    2006-01-01

    We will present the broadband spectra of the low mass x-ray binary 4U 1822-37, recently observed with Suzaku. 4U 1822-37 is the canonical accretion disk corona (ADC) source where the compact object is obscured by an extended corona that intercepts and scatters the central continuum emission, some of which is then reprocessed in the outer regions of the accretion disk. 4U 1822-37 therefore serves as an important link between x-ray binaries and AGN. The broadband x-ray spectra from the Suzaku XIS and HXD provide a unique opportunity to probe the physical conditions in the corona and the accretion disk for this important accretion geometry.

  2. X-ray Pulsations in the Supersoft X-ray Binary CAL 83

    Schmidtke, P. C.; Cowley, A. P.

    2005-01-01

    X-ray data reveal that the supersoft X-ray binary CAL 83 exhibits 38.4 minute pulsations at some epochs. These X-ray variations are similar to those found in some novae and are likely to be caused by nonradial pulsations the white dwarf. This is the first detection of pulsations in a classical supersoft X-ray binary.

  3. Outbursts in ultracompact X-ray binaries

    Hameury, J -M

    2016-01-01

    Very faint X-ray binaries appear to be transient in many cases with peak luminosities much fainter than that of usual soft X-ray transients, but their nature still remains elusive. We investigate the possibility that this transient behaviour is due to the same thermal/viscous instability which is responsible for outbursts of bright soft X-ray transients, occurring in ultracompact binaries for adequately low mass-transfer rates. More generally, we investigate the observational consequences of this instability when it occurs in ultracompact binaries. We use our code for modelling the thermal-viscous instability of the accretion disc, assumed here to be hydrogen poor. We also take into account the effects of disc X-ray irradiation, and consider the impact of the mass-transfer rate on the outburst brightness. We find that one can reproduce the observed properties of both the very faint and the brighter short transients (peak luminosity, duration, recurrence times), provided that the viscosity parameter in quiesce...

  4. X-ray binaries, part 1

    Optical observations of X-ray binaries and their interpretation are described. A number of early-type stars which are identified as companions of X-ray sources are photometrically and spectroscopically observed. The spectra were obtained with the coude spectrograph attached to the 1.5 m telescope of the European Southern Observatory, La Silla, Chile. Registrations of the spectra were made with the Faul-Coradi microphotometer of the Observatory at Utrecht. To study radial velocity variations, the positions of the spectral lines were measured with the Grant comparator of the University of Groningen

  5. Polarisation modulation in X-ray binaries

    Ingram, Adam; Maccarone, Thomas

    2016-07-01

    X-ray polarimetry promises to provide a powerful new lever arm for studying accretion onto black holes with the next generation of X-ray telescopes. I will discuss how polarisation can be used to help constrain the physical origin of quasi-periodic oscillations (QPOs) observed in the X-ray light curves of accreting black holes. QPOs may be signatures of the frame dragging effect: in General Relativity, a spinning black hole twists up the surrounding space-time, causing vertical precession of nearby orbits. In the truncated disc / precessing inner flow model, the entire inner accretion flow precesses as a solid body causing a modulation in the X-ray flux through solid angle and Doppler effects. This model also predicts the observed polarisation of the X-ray signal to vary quasi-periodically. I will summarise our work to model the polarisation signal from a precessing accretion flow, starting with simple assumptions about the emission mechanism but taking General Relativity fully into account. We find that it should be possible to measure the predicted modulation in polarisation degree for a reasonable region of parameter space with a polarimeter capable of detecting ~60 counts per second from a bright black hole binary. I will also show that sensitivity can be greatly improved by correlating the signal with a high count rate reference band signal.

  6. Transient High Mass X-ray Binaries

    Paul, Biswajit

    2011-01-01

    High Mass X-ray Binaries (HMXBs) are interesting objects that provide a wide range of observational probes to the nature of the two stellar components, accretion process, stellar wind and orbital parameters of the systems. A large fraction of the transient HMXBs are found to be Be/X-ray binaries in which the companion Be star with its circumstellar disk governs the outburst. These outbursts are understood to be due to the sudden enhanced mass accretion to the neutron star and is likely to be associated with changes in the circumstellar disk of the companion. In the recent years, another class of transient HMXBs have been found which have supergiant companions and show shorter bursts. X-ray, infrared and optical observations of these objects provide vital information regarding these systems. Here we review some key observational properties of the transient HMXBs and also discuss some important recent developments from studies of this class of sources. The X-ray properties of these objects are discussed in some...

  7. Formation and evolution of X-ray binaries

    2010-01-01

    We review recent progress in theoretical understanding of X-ray binaries,which has largely been driven by new observations.We select several topics including formation of compact low-mass X-ray binaries,the evolutionary connection between low-mass X-ray binaries and binary and millisecond radio pulsars,and ultraluminous X-ray sources,to illustrate the interplay between theories and observations.

  8. On the universal X-ray luminosity function of binary X-ray sources in galaxies

    Postnov, K. A.

    2002-01-01

    The empirically determined universal power-law shape of X-ray luminosity function of high mass X-ray binaries in galaxies is explained by fundamental mass-luminosity and mass-radius relations for massive stars.

  9. X-ray spectroscopy of the ADC source X1822-371 with Chandra and XMM-Newton

    Iaria, R.; T. Di Salvo; D'Aì, A.; Burderi, L.; Mineo, T.; Riggio, A.; Papitto, A.; Robba, N.

    2012-01-01

    The eclipsing low-mass X-ray binary X1822-371 is the prototype of the accretion disc corona (ADC) sources. We analyse two Chandra observations and one XMM-Newton observation to study the discrete features and their variation as a function of the orbital phase, deriving constraints on the temperature, density, and location of the plasma responsible for emission lines. The HETGS and XMM/Epic-pn observed X1822-371 for 140 and 50 ks, respectively. We extracted an averaged spectrum and five spectr...

  10. QPO-jet relation in X-ray binaries

    Belloni, Tomaso M

    2010-01-01

    In the past years, a clear picture of the evolution of outbursts of black-hole X-ray binaries has emerged. While the X-ray properties can be classified into our distinct states, based on spectral and timing properties, the observations in the radio band have shown strong links between accretion and ejection properties. Here I briefly outline the association between X-ray timing and jet properties.

  11. Linking Jet Emission, X-Ray States, and Hard X-Ray Tails in the Neutron Star X-Ray Binary GX 17+2

    S. Migliari; J.C.A. Miller-Jones; R.P. Fender; J. Homan; T. di Salvo; R.E. Rothschild; M.P. Rupen; J.A. Tomsick; R. Wijnands; M. van der Klis

    2007-01-01

    We present the results of simultaneous radio (VLA) and X-ray (RXTE) observations of the Z-type neutron star X-ray binary GX 17+2. The aim is to assess the coupling between X-ray and radio properties throughout its three rapidly variable X-ray states and during the time-resolved transitions. These ob

  12. On the X-ray properties of V Sge and its relation to the supersoft X-ray binaries

    Greiner, Jochen; van Teeseling, Andre

    1998-01-01

    We investigate the ROSAT X-ray properties of V Sge, which has been proposed to be related to supersoft X-ray binaries. During optical bright states, V Sge is a faint hard X-ray source, while during optical faint states (V >=12 mag), V Sge is a `supersoft' X-ray source. Spectral fitting confirms that V~Sge's X-ray properties during its soft X-ray state may be similar to those of supersoft X-ray binaries, although a much lower luminosity cannot be excluded. It is possible to explain the differe...

  13. An X-ray and optical study of the ultracompact X-ray binary A 1246-58

    in 't Zand, J. J. M.; Bassa, C. G.; Keek, L.; Verbunt, F.; Mendez, M.; Markwardt, C. B.; Jonker, P.G.

    2008-01-01

    Results are discussed of an X-ray and optical observation campaign of the low-mass X-ray binary A 1246-58 performed with instruments on Satellite per Astronomia X ("BeppoSAX"), the Rossi X-ray Timing Explorer (RXTE), the X-ray Multi-mirror Mission ("XMM-Newton"), the Swift mission, and the Very Larg

  14. An X-ray and optical study of the ultracompact X-ray binary A1246-58

    Zand, J. J. M. in 't

    2008-01-01

    Results are discussed of an X-ray and optical observation campaign of the low-mass X-ray binary A 1246-58 performed with instruments on Satellite per Astronomia X (’BeppoSAX’), the Rossi X-ray Timing Explorer (RXTE), the X-ray Multi-mirror Mission (’XMM-Newton’), the Swift mission, and the Very Larg

  15. X-ray binary systems - Ariel V SSI observations

    The basis of our current theoretical understanding of galactic x-ray sources is reviewed. Models are outlined involving close binary systems containing a compact object accreting mass which has been lost from the nondegenerate star by a variety of mechanisms. The present status of galactic x-ray astronomy is discussed, with emphasis on the links between established observational categories and the characteristics of the proposed models. Observational results, consisting primarily of extended x-ray light curves derived from analysis of Ariel V SSI data are presented for two main classes of galactic x-ray source: (i) high-mass x-ray binaries containing an early-type giant or supergiant star; (ii) low-mass x-ray binaries in which the nondegenerate star is a late-type dwarf. For the high-mass binaries emphasis is placed on the determination and improvement of the orbital parameters; for the low-mass binaries, where a less complete picture is available, the discussion centres on the type of system involved, taking into account the optical observations of the source. Finally, the properties of two further categories - the sources in the galactic bulge and those associated with dwarf novae - are discussed as examples of rather different types of galactic x-ray emitter. In the case of the galactic bulge sources current observations have not led so far to a clear picture of the nature of the systems involved, indeed their binary membership is not established. X-ray emission from dwarf novae and related objects is a relatively recent discovery and represents the opening up of a new field of galactic x-ray astronomy. (author)

  16. Spectroscopic Studies of X-Ray Binary Pulsars

    F. Nagase

    2002-03-01

    Several new features of X-ray binary pulsars are revealed from recent observations with ASCA, RXTE, BeppoSAX and other X-ray observatories. Among these, I will review in this paper some recent progress in spectroscopic studies of accreting X-ray pulsars in binary systems (XBPs). First, I will discuss soft excess features observed in the energy spectra of XBPs and propose that it is a common feature for various subclasses of XBPs. Next I will present some recent results of high resolution spectroscopy with ASCA and Chandra.

  17. Exploring subluminous X-ray binaries

    N.D. Degenaar

    2010-01-01

    Halfway the twentieth century, technological developments made it possible to carry detection instruments outside the absorbing layers of the Earth’s atmosphere onboard rockets and satellites. This opened up the opportunity to detect the emission from celestial objects at X-ray wavelengths, thereby

  18. THE X-RAY SPECTRAL EVOLUTION OF GALACTIC BLACK HOLE X-RAY BINARIES TOWARD QUIESCENCE

    Most transient black hole X-ray binaries (BHXBs) spend the bulk of their time in a quiescent state, where they accrete matter from their companion star at highly sub-Eddington luminosities (we define quiescence here as a normalized Eddington ratio lx = L0.5-10keV/LEdd –5). Here, we present Chandra X-ray imaging spectroscopy for three BHXB systems (H 1743–322, MAXI J1659–152, and XTE J1752–223) as they fade into quiescence following an outburst. Multiple X-ray observations were taken within one month of each other, allowing us to track each individual system's X-ray spectral evolution during its decay. We compare these three systems to other BHXB systems. We confirm that quiescent BHXBs have softer X-ray spectra than low-hard-state BHXBs, and that quiescent BHXB spectral properties show no dependence on the binary system's orbital parameters. However, the observed anti-correlation between X-ray photon index (Γ) and lx in the low-hard state does not continue once a BHXB enters quiescence. Instead, Γ plateaus to an average (Γ) = 2.08 ± 0.07 by the time lx reaches ∼10–5. lx ∼ 10–5 is thus an observationally motivated upper limit for the beginning of the quiescent spectral state. Our results are discussed in the context of different accretion flow models and across the black hole mass scale

  19. Optical studies of massive X-ray binaries

    Photometric and spectroscopic studies of several optical counterparts of massive X-ray binaries are presented. Subjects of study were the binary systems:HD77581/4U0900-40 (Vela X-1), HD153919/4U1700-37, Wray 977/4U1223-62 and Sk160/4U0115-74 (=SMC X-1). (Auth.)

  20. Applications of Indirect Imaging techniques in X-ray binaries

    Harlaftis, E T

    2000-01-01

    A review is given on aspects of indirect imaging techniques in X-ray binaries which are used as diagnostics tools for probing the X-ray dominated accretion disc physics. These techniques utilize observed properties such as the emission line profile variability, the time delays between simultaneous optical/X-ray light curves curves, the light curves of eclipsing systems and the pulsed emission from the compact object in order to reconstruct the accretion disc's line emissivity (Doppler tomography), the irradiated disc and heated secondary (echo mapping), the outer disc structure (modified eclipse mapping) and the accreting regions onto the compact object, respectively.

  1. Simultaneous radio and X-ray observations of Galactic Centre low mass X-ray binaries

    Berendsen, S.G.H.; Fender, R.; Kuulkers, E; Heise, J.; M. van der Klis(Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands)

    2000-01-01

    We have performed simultaneous X-ray and radio observations of thirteen Galactic centre low-mass X-ray binaries in 1998 April using the Wide-Field Cameras onboard BeppoSAX and the Australia Telescope Compact Array, the latter simultaneously at 4.8 and 8.64 GHz. We detect two Z sources, GX 17+2 and GX 5-1, and the unusual `hybrid' source GX 13+1. Upper limits, which are significantly deeper than previous non-detections, are placed on the radio emission from two more Z sources and seven atoll s...

  2. Linking burst-only X-ray binary sources to faint X-ray transients

    Campana, S.

    2009-01-01

    Burst-only sources are X-ray sources showing up only during short bursts but with no persistent emission (at least with the monitoring instrument which led to their discovery). These bursts have spectral characteristics consistent with thermonuclear (type I) burst from the neutron star surface, linking burst-only sources to neutron star X-ray binary transients. We have carried out a series of snapshot observations of the entire sample of burst-only sources with the Swift satellite. We found a...

  3. Linking Jet Emission, X-ray States and Hard X-ray Tails in the Neutron Star X-ray Binary GX 17+2

    Migliari, S.; Miller-Jones, J. C. A.; Fender, R. P.; Homan, J.; T. Di Salvo; Rothschild, R. E.; Rupen, M P; Tomsick, J. A.; Wijnands, R.; van der Klis, M.

    2007-01-01

    We present the results from simultaneous radio (Very Large Array) and X-ray (Rossi-X-ray Timing Explorer) observations of the Z-type neutron star X-ray binary GX~17+2. The aim is to assess the coupling between X-ray and radio properties throughout its three rapidly variable X-ray states and during the time-resolved transitions. These observations allow us, for the first time, to investigate quantitatively the possible relations between the radio emission and the presence of the hard X-ray tai...

  4. Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni During Quiescence

    Rana, Vikram; Loh, Alan; Corbel, Stephane;

    2016-01-01

    We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broadband (0...

  5. Echo Tomography of Reprocessing Sites in X-Ray Binaries

    Patterson, Joseph; Haswell, Carole

    1998-01-01

    We discovered correlated rapid variability between the optical/UV and X-ray emission for the first time in a soft X-ray transient, GRO J1655-40. Hubble Space Telescope light curves show features similar to those seen by the Rossi X-ray Timing Explorer, but with a mean delay of up to 10 - 20 s. We interpret the correlation as the result of reprocessing of X-rays into optical and UV emission, with a delay owing to finite light travel time; this assumption enables us to perform echo mapping of the system. The time-delay distribution has a mean of 14.6 +/-1.4 s and a dispersion of 10.5+/-1.9 s at binary phase 0.4. This establishes that the reprocessing region is the accretion disk around the compact star, rather than the mass-donating secondary. These results have been published.

  6. Accretion disk dynamics in X-ray binaries

    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

  7. Very faint X-ray binaries with XMM-Newton

    Armas Padilla, M.

    2016-06-01

    A population of very faint X-ray binaries has been discovered in the last years thanks to the improvement in sensitivity and resolution of the new generations of X-ray missions. These systems show anomalously low luminosities, below 10^{36} ergs/sec, challenging our understanding of accretion physics and binary evolution models, and thereby opening new windows for both observational and theoretical work on accretion onto compact objects. XMM-Newton is playing a crucial role in the study of this dim family of objects thanks to its incomparable spectral capabilities at low luminosities. I will review the state-of-the-art of the field and present our XMM results in both black hole and neutron star objects. Finally, I will discuss the possibilities that the new generation of X-ray telescopes offer for this research line.

  8. An optical & X-ray study of the counterpart to the SMC X-ray binary pulsar system SXP327

    Coe, M J; Corbet, R H D; Galache, J; McBride, V A; Townsend, L J; Udalski, A

    2008-01-01

    Optical and X-ray observations are presented here of a newly reported X-ray transient system in the Small Magellanic Cloud. The data reveal many previously unknown X-ray detections of this system and clear evidence for a 49.995d binary period. In addition, the optical photometry show recurring outburst features at the binary period which may well be indicative of the neutron star interacting with a circumstellar disk around a Be star.

  9. Jet spectral breaks in black hole X-ray binaries

    D.M. Russell; S. Markoff; P. Casella; A.G. Cantrell; R. Chatterjee; R.P. Fender; E. Gallo; P. Gandhi; J. Homan; D. Maitra; J.C.A. Miller Jones; K. O'Brien; T. Shahbaz

    2013-01-01

    In X-ray binaries, compact jets are known to commonly radiate at radio to infrared frequencies, whereas at optical to γ-ray energies, the contribution of the jet is debated. The total luminosity, and hence power of the jet, is critically dependent on the position of the break in its spectrum, betwee

  10. X-ray spectroscopy of the ADC source X1822-371 with Chandra and XMM-Newton

    Iaria, R; D'Aì, A; Burderi, L; Mineo, T; Riggio, A; Papitto, A; Robba, N R

    2012-01-01

    The eclipsing low-mass X-ray binary X1822-371 is the prototype of the accretion disc corona (ADC) sources. We analyse two Chandra observations and one XMM-Newton observation to study the discrete features and their variation as a function of the orbital phase, deriving constraints on the temperature, density, and location of the plasma responsible for emission lines. The HETGS and XMM/Epic-pn observed X1822-371 for 140 and 50 ks, respectively. We extracted an averaged spectrum and five spectra from five selected orbital-phase intervals that are 0.04-0.25, 0.25-0.50, 0.50-0.75, 0.75-0.95, and, finally, 0.95-1.04; the orbital phase zero corresponds to the eclipse time. All spectra cover the energy band between 0.35 and 12 keV. We confirm the presence of local neutral matter that partially covers the X-ray emitting region; the equivalent hydrogen column is $5 \\times 10^{22}$ cm$ ^{-2}$ and the covered fraction is about 60-65%. We identify emission lines from highly ionised elements, and a prominent fluorescence ...

  11. Classifying X-ray Binaries: A Probabilistic Approach

    Gopalan, Giri; Bornn, Luke

    2015-01-01

    In X-ray binary star systems consisting of a compact object that accretes material from an orbiting secondary star, there is no straightforward means to decide if the compact object is a black hole or a neutron star. To assist this process we develop a Bayesian statistical model which makes use of the fact that X-ray binary systems appear to cluster based on their compact object type when viewed from a 3-dimensional coordinate system derived from X-ray spectral data, where the first coordinate is the ratio of counts in mid to low energy band (color 1), the second coordinate is the ratio of counts in high to low energy band (color 2), and the third coordinate is the sum of counts in all three bands. Precisely, we use this model to estimate the probabilities that an X-ray binary system contains a black hole, non-pulsing neutron star or pulsing neutron star. In particular we utilize a latent variable model in which the latent variables follow a Gaussian process prior distribution, and hence we are able to induce...

  12. The Be X-ray Binary Outburst Zoo II

    Kuehnel, M.; Kretschmar, P.; Nespoli, E.; Okazaki, A. T.; Schoenherr, G.; Wilson-Hodge, C. A.; Falkner, S.; Brand, T.; Anders, F.; Schwarm, F.-W.; Kreykenbohm, I.; Mueller, S.; Pottschmidt, K.; Fuerst, F.; Grinberg, V.; Wilms, J.

    2015-03-01

    We have continued our recently started systematic study of Be X-ray binary (BeXRB) outbursts. Specifically, we are developing a catalogue of outbursts including their basic properties based on nearly all available X-ray all-sky-monitors. These properties are derived by fitting asymmetric Gaussians to the outburst lightcurves. This model describes most of the outbursts covered by our preliminary catalogue well; only 13% of all datasets show more complex outburst shapes. Analyzing the basic properties, we reveal a strong correlation between the outburst length and the reached peak flux. As an example, we discuss possible models describing the observed correlation in EXO 2030+375.

  13. Observational studies of X-ray binary systems

    The subject of Chapter 1 is theoretical. The other chapters, Ch. 2 to 6, contain original observational data and efforts towards their interpretation. Of these, Ch. 3, 4 and 5 deal with massive X-ray binaries, Ch. 6 with low-mass systems and Ch. 2 with Cygnus X-3, which we have not yet been able to assign to any of these two classes. The X-ray observations described were made with the COS-B satellite. Work based on UV and optical observations is described in Ch. 5. The UV observations were made with the IUE satellite, the optical observations at several ground-based observatories. (Auth.)

  14. Power colours: simple X-ray binary variability comparison

    Heil, L. M.; Uttley, P.; Klein-Wolt, M.

    2015-04-01

    We demonstrate a new method of variability classification using observations of black hole X-ray binaries. Using `power colours' - ratios of integrated power in different Fourier frequency bands - we can clearly differentiate different canonical black hole states as the objects evolve during outburst. We analyse (˜2400) Rossi X-ray Timing Explorer observations of 12 transient low-mass black hole X-ray binaries and find that the path taken around the power colour-colour diagram as the sources evolve is highly consistent from object to object. We discuss how the consistency observed in the power colour-colour diagram between different objects allows for easy state classification based on only a few observations, and show how the power-spectral shapes can be simply classified using a single parameter, the power-spectral `hue'. To illustrate the benefits of our simple model-independent approach, we show that the persistent high-mass X-ray binary Cyg X-1 shows very similar power-spectral evolution to the transient black hole sources, with the main difference being caused by a combination of a lack of quasi-periodic oscillations and an excess of low-frequency power-law noise in the Cyg X-1 power spectra during the transitional state. We also compare the transient objects to the neutron star atoll source Aquila X-1, demonstrating that it traces a different path in the power colour-colour plot. Thus, power colours could be an effective method to classify newly discovered X-ray binaries.

  15. X-Ray Line Spectroscopy of Massive X-Ray Binaries

    Liedahl, D. A.; Sako, M.; Wojdowski, P. S.; Paerels, F.; Kahn, S. M.

    2000-01-01

    Spectra from ASCA have provided the most, detailed view to date of the X-ray spectral properties of stellar winds in massive X-ray binaries. Using detailed atomic models that account for recombination cascade kinetics, we have reexamined archival data from Vela X-1 and Cen X-3 in the context of simple models of their wind geometries and velocity distributions. Our approach emphasizes apparent differential emission measure (DEM) distributions, and their dependence on orbital phase and wind parameters. A grid of theoretical DEM distributions is used to generate model spectra, which are compared to the data. We obtain good fits, and derive constraints oil the stellar wind parameters. We provide a summary of the method, and show that, even though the companion stars in Vela X-1 and Cen X-3 have comparable mass-loss rates, the winds in these two systems are dramatically different, in character.

  16. X-ray spectroscopy of the ADC source X1822-371 with Chandra and XMM-Newton

    Iaria, R.; Di Salvo, T.; D'Aì, A.; Burderi, L.; Mineo, T.; Riggio, A.; Papitto, A.; Robba, N. R.

    2013-01-01

    Context. The eclipsing low-mass X-ray binary X1822-371 is the prototype of the accretion disc corona (ADC) sources. Its inclination angle (≃82.5°) is high enough that flux from the neutron star is blocked by the edge-on accretion disc. Because the neutron star's direct emission is hidden, its ADC emission is visible. The physical properties of the ADC in X1822-371 have been widely studied, but are still debated in literature. In light of the recent literature and of the results reported in this work we show that the ADC is optically thin. Aims: We analyse two Chandra observations and one XMM-Newton observation to study the discrete features in this source and their variation as a function of the orbital phase, deriving constraints on the temperature, density, and location of the plasma responsible for emission lines. Methods: The HETGS and XMM/Epic-pn observed X1822-371 for 140 and 50 ks, respectively. We extracted an averaged spectrum and five spectra from five selected orbital-phase intervals that are 0.04-0.25, 0.25-0.50, 0.50-0.75, 0.75-0.95, and, finally, 0.95-1.04; the orbital phase zero corresponds to the eclipse time. All spectra cover the energy band between 0.35 and 12 keV. Results: We confirm the presence of local neutral matter that partially covers the X-ray emitting region; the equivalent hydrogen column is 5 × 1022 cm-2 and the covered fraction is about 60-65%. We identify several emission lines of He-like and H-like ions, and a prominent fluorescence iron line associated with a blending of Fe i-Fe xv resonant transitions. The transitions of He-like ions show that the intercombination dominates over the forbidden and resonance lines. The line fluxes are the highest during the orbital phases between 0.04 and 0.75. Conclusions: We discuss the presence of an extended, optically thin corona with optical depth of about 0.01 that scatters the X-ray photons from the innermost region into the line of sight. The photoionised plasma producing the O viii

  17. Transient Low-Mass X-Ray Binaries in Quiescence

    Bildsten, L

    2000-01-01

    We summarize the quiescent X-ray observations of transient low-mass X-ray binaries. These observations show that, in quiescence, binaries containing black holes are fainter than those containing neutron stars. This has triggered a number of theoretical ideas about what causes the quiescent X-ray emission. For black hole binaries, the options are accretion onto the black hole or coronal emission from the rapidly rotating stellar companion. There are more possibilities for the neutron stars: accretion, thermal emission from the surface or non-thermal emission from a ``turned-on'' radio pulsar. We review recent theoretical work on these mechanisms and note where current observations can distinguish between them. We highlight the re-analysis of the quiescent neutron star emission by Rutledge and collaborators that showed thermal emission to be a predominant contributor in many of these systems. Our knowledge of these binaries is bound to dramatically improve now that the Chandra and XMM satellites are operating s...

  18. Classifying X-Ray Binaries: A Probabilistic Approach

    Gopalan, Giri; Dil Vrtilek, Saeqa; Bornn, Luke

    2015-08-01

    In X-ray binary star systems consisting of a compact object that accretes material from an orbiting secondary star, there is no straightforward means to decide whether the compact object is a black hole or a neutron star. To assist in this process, we develop a Bayesian statistical model that makes use of the fact that X-ray binary systems appear to cluster based on their compact object type when viewed from a three-dimensional coordinate system derived from X-ray spectral data where the first coordinate is the ratio of counts in the mid- to low-energy band (color 1), the second coordinate is the ratio of counts in the high- to low-energy band (color 2), and the third coordinate is the sum of counts in all three bands. We use this model to estimate the probabilities of an X-ray binary system containing a black hole, non-pulsing neutron star, or pulsing neutron star. In particular, we utilize a latent variable model in which the latent variables follow a Gaussian process prior distribution, and hence we are able to induce the spatial correlation which we believe exists between systems of the same type. The utility of this approach is demonstrated by the accurate prediction of system types using Rossi X-ray Timing Explorer All Sky Monitor data, but it is not flawless. In particular, non-pulsing neutron systems containing “bursters” that are close to the boundary demarcating systems containing black holes tend to be classified as black hole systems. As a byproduct of our analyses, we provide the astronomer with the public R code which can be used to predict the compact object type of XRBs given training data.

  19. In-pixel conversion with a 10 bit SAR ADC for next generation X-ray FELs

    Lodola, L.; Batignani, G.; Benkechkache, M. A.; Bettarini, S.; Casarosa, G.; Comotti, D.; Dalla Betta, G. F.; Fabris, L.; Forti, F.; Grassi, M.; Latreche, S.; Malcovati, P.; Manghisoni, M.; Mendicino, R.; Morsani, F.; Paladino, A.; Pancheri, L.; Paoloni, E.; Ratti, L.; Re, V.; Rizzo, G.; Traversi, G.; Vacchi, C.; Verzellesi, G.; Xu, H.

    2016-07-01

    This work presents the design of an interleaved Successive Approximation Register (SAR) ADC, part of the readout channel for the PixFEL detector. The PixFEL project aims at substantially advancing the state-of-the-art in the field of 2D X-ray imaging for applications at the next generation Free Electron Laser (FEL) facilities. For this purpose, the collaboration is developing the fundamental microelectronic building blocks for the readout channel. This work focuses on the design of the ADC carried out in a 65 nm CMOS technology. To obtain a good tradeoff between power consumption, conversion speed and area occupation, an interleaved SAR ADC architecture was adopted.

  20. GBM Observations of Be X-Ray Binary Outbursts

    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.

  1. GALACTIC ULTRACOMPACT X-RAY BINARIES: EMPIRICAL LUMINOSITIES

    Ultracompact X-ray binaries (UCXBs) are thought to have relatively simple binary evolution post-contact, leading to clear predictions of their luminosity function. We test these predictions by studying the long-term behavior of known UCXBs in our Galaxy, principally using data from the MAXI All-Sky Survey and the Galactic bulge scans with RXTE's Proportional Counter Array instrument. Strong luminosity variations are common (and well documented) among persistent UCXBs, which requires an explanation other than the disk instability mechanism. We measure the luminosity function of known UCXBs in the Milky Way, which extends to lower luminosities than some proposed theoretical luminosity functions of UCXBs. The difference between field and globular cluster (GC) X-ray luminosity functions in other galaxies cannot be explained by an increased fraction of UCXBs in GCs. Instead, our measured luminosity function suggests that UCXBs only make up a small fraction of the X-ray binaries above a few × 1036 erg s–1 in both old field populations and GCs.

  2. Population synthesis of high mass X-ray binaries

    Guo-Liang Lü; Chun-Hua Zhu; Zhao-Jun Wang

    2011-01-01

    By simulating the evolution of spin periods of magnetized neutron stars which interact with their environment in binary systems, we investigate the Galactic population of high mass X-ray binaries (HMXBs). The number of HMXBs in the Galaxy is between 190 and 240, and their birthrate is from 5.9 × 10-5 yr-1 to 6.3 ×10-5 yr-1. Comparing the Corbet diagram (the positions of the spin periods vs. the orbital periods of HMXBs ) in our model with the associated observations, we find that the stellar wind structure and the process of matter transfer are very important for understanding HMXBs.

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

    Islam, Nazma

    2016-01-01

    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 10^{36} - 10^{39} 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 r...

  4. Low Mass X-ray Binaries As the Source of the Very Soft X-ray Emission in the X-ray Faintest Early-Type Galaxies

    Irwin, Jimmy A.; Sarazin, Craig L.

    1997-01-01

    The X-ray emission from the faintest X-ray elliptical and S0 galaxies is characterized by a hard ~5 keV component, and a very soft ~0.2 keV component. The hard component has generally been regarded as the integrated emission from low mass X-ray binaries (LMXBs), but the origin of the soft component is unknown. We present evidence which suggests that LMXBs also exhibit a soft component, which is responsible for the very soft X-ray emission in the faintest early-type galaxies. This soft compone...

  5. The Correlation between Hard X-Ray Peak Flux and Soft X-Ray Peak Flux in the Outburst Rise of Low-Mass X-Ray Binaries

    Yu, W.; Klis, van der, M.; Fender, R. P.

    2004-01-01

    We have analyzed Rossi X-Ray Timing Explorer pointed observations of the outbursts of black hole and neutron star soft X-ray transients in which an initial low/hard state, or ``island'' state, followed by a transition to a softer state was observed. In three sources-the black hole transient XTE J1550-564, the neutron star transient Aquila X-1, and the quasi-persistent neutron star low-mass X-ray binary 4U 1705-44-two such outbursts were found. We find that the flux of the soft X-ray peak, whi...

  6. Is CGCS 5926 a symbiotic X-ray binary?

    Masetti, N; Henden, A A; Page, K L; Osborne, J P; Starrfield, S

    2011-01-01

    We here report on multiwavelength (X-ray to optical) followup observations of carbon star CGCS 5926. These were motivated by the fact that this star is positionally coincident with a faint X-ray emitting object belonging to the ROSAT catalog of sources, thus suggesting a possible symbiotic X-ray binary (SyXB) nature for it. Our spectrophotometric optical data confirm the giant carbon star nature of the object and allow us to classify its spectral type as C(6,2). This classification places CGCS 5926 at a distance of about 5 kpc from Earth. BVRcIc photometry of the star shows that it displays a variability of about 0.3 mag on timescales of months, with the star getting bluer when its brightness increases. Our photometric data indicate a periodicity of 151 days, which we explain as due to radial pulsations of CGCS 5926 on the basis of its global characteristics. The source is not detected at X-rays with Swift/XRT down to a 0.3-10 keV band luminosity of around 3e32 erg/s. This nondetection is apparently in contra...

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

    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

  8. Jet spectral breaks in black hole X-ray binaries

    Russell, D M; Casella, P; Cantrell, A G; Chatterjee, R; Fender, R P; Gallo, E; Gandhi, P; Homan, J; Maitra, D; Miller-Jones, J C A; O'Brien, K; Shahbaz, T

    2012-01-01

    In X-ray binaries, compact jets are known to commonly radiate at radio to infrared frequencies, whereas at optical to gamma-ray energies, the contribution of the jet is debated. The total luminosity, and hence power of the jet is critically dependent on the position of the break in its spectrum, between optically thick (self-absorbed) and optically thin synchrotron emission. This break, or turnover, has been reported in just one black hole X-ray binary (BHXB) thus far, GX 339-4, and inferred via spectral fitting in two others, A0620-00 and Cyg X-1. Here, we collect a wealth of multiwavelength data from the outbursts of BHXBs during hard X-ray states, in order to search for jet breaks as yet unidentified in their spectral energy distributions. In particular, we report the direct detection of the jet break in the spectrum of V404 Cyg during its 1989 outburst, at nu_b = (1.8 +- 0.3) x 10^14 Hz (1.7 +- 0.2 microns). We increase the number of BHXBs with measured jet breaks from three to eight. Jet breaks are found...

  9. Bimodality of Wind-fed Accretion in High Mass X-ray Binaries

    Karino, S.

    2014-01-01

    We study an influence of X-ray photo-ionization from an accreting neutron star in a high mass X-ray binary. Our aim is to unveil a new principle governing X-ray luminosities of X-ray binaries, with a simple analysis of fluid equations simulating line-driven wind flow under influence of X-ray irradiation. In this study, we solve equation of motion of the accretion flow taking into account the line-driven acceleration and X-ray photo-ionization. Under the influence of X-ray irradiation, we find...

  10. A complementary dual-slope ADC with high frame rate and wide input range for fast X-ray imaging

    Lee, Daehee; Cho, Minsik; Kang, Dong-Uk; Kim, Myung Soo; Kim, Hyunduk; Cho, Gyuseong

    2014-02-01

    The single-slope analog-to-digital converter (SS-ADC) is the most commonly used column-level ADC for high-speed industrial, complementary metal-oxide semiconductor (CMOS)-based X-ray image sensors because of its small chip area (the width of a pixel), its simple circuit structure, and its low power consumption. However, it generally has a long conversion time, so we propose an innovative design: a complimentary dual-slope ADC (CDS-ADC) that uses two opposite ramp signals instead of a single ramp to double the conversion speed. This CDS-ADC occupies only 15% more area than the original SS-ADC. A prototype 12-bit CDS-ADC and a 12-bit SS-ADC were fabricated using a 0.35-µm 1P 4M CMOS process. During comparison of the two, the measured maximum differential non-linearity (DNL) of the CDS-ADC was a 0.49 least significant bit (LSB), the maximum integral non-linearity (INL) was a 0.43 LSB, the effective number of bits (ENOB) was 9.18 bits, and the figure of merit (FOM) was 0.03 pJ/conversion. The total power consumption was 0.031 uW. The conversion time of the new CDS-ADC was half that of the SS-ADC. The proposed dual-slope concept can be extended to further multiply the conversion speed by using multiple pairs of dual-slope ramps.

  11. Population Synthesis for Symbiotic X-ray Binaries

    Lu, G -L; Postnov, K A; Yungelson, L R; Kuranov, A G; Wang, N

    2012-01-01

    Symbiotic X-ray binaries (SyXBs) comprise a rare class of low-mass X-ray binaries. We study the Galactic SyXBs, which we consider as detached binaries composed of low-mass giants and wind-fed neutron star companions, by simulation of the interaction of a magnetized neutron star (NS) with its environment and utilizing a population synthesis code. We focus mainly on the parameters that influence observational appearance of the SyXB: the donor wind velocity (vw) and the angular momentum distribution in the shell of matter settling onto NS. We estimate the birthrate of SyXB as $\\sim 4.1\\times 10^{-5}$ yr$^{-1}$ to $ \\sim 6.6\\times 10^{-6}$ yr$^{-1}$ and their number in the Galaxy as $\\sim$(100 -- 1000). Assumed stellar wind velocity from cool giants is the input parameter that influences the model SyXBs population most. Among known SyXBs or candidate systems, 4U 1954+31 and IGR J16358-4724 in which NS have very long spin periods may host quasi-spherically accreting NSs. GX 1+4 has a peculiar long-term spin behavi...

  12. Broad Iron Lines in AGN and X-ray Binaries

    Fabian, A.C.

    2004-01-01

    Several AGN and black hole X-ray binaries show a clear very broad iron line which is strong evidence that the black holes are rapidly spinning. Detailed analysis of these objects shows that the emission line is not significantly affected by absorption and that the source variability is principally due to variation in amplitude of a power-law. Underlying this is a much less variable, relativistically-smeared, reflection-dominated, component which carries the imprint of strong gravity at a few ...

  13. The Be X-ray Binary Outburst Zoo

    Kretschmar, Peter; Reig, Pablo; Anders, Friedrich

    2013-01-01

    Be X-ray binaries are among the best known transient high-energy sources. Their outbursts are commonly classified into a simple scheme of 'normal' and 'giant' outbursts, but a closer look shows that actual outbursts do not always follow this simple scheme. Recent data show a variety of properties, like pre-flares, shifts of the outburst peaks with respect to the periastron, multi-peaked outbursts etc. We present results from a systematic study of a large number of outbursts monitored by various space missions, comparing outburst properties and their relation to system parameters and current theoretical understanding.

  14. On the origin of the hard X-ray tail in neutron-star X-ray binaries

    Reig, P.; Kylafis, N.

    2016-01-01

    Neutron star X-ray binaries emit a compact, optically thick, relativistic radio jet during low-luminosity, usually hard states, as Galactic black-hole X-ray binaries do. When radio emission is bright, a hard power-law tail without evidence for an exponential cutoff is observed in most systems. We have developed a jet model that explains many spectral and timing properties of black-hole binaries in the states where a jet is present. Our goal is to investigate whether our jet model can reproduc...

  15. Correlation between Hard X-ray Peak Flux and Soft X-ray Peak Flux in the Outburst Rise of Low Mass X-ray Binaries

    Yu, Wenfei; van der Klis, Michiel; Fender, Rob

    2004-01-01

    We have analyzed {\\it Rossi} X-ray timing explorer (RXTE) pointed observations of the outbursts of black hole and neutron star soft X-ray transients in which an initial low/hard state or `island' state, followed by a transition to a softer state, was observed. In three sources, the black hole transient XTE J1550-564, the neutron star transient Aquila X-1 and a quasi-persistent neutron star low mass X-ray binary (LMXB) 4U 1705-44, two such outbursts were found. We find that the flux of the sof...

  16. X-ray-binary spectra in the lamp post model

    Vincent, F H; Zdziarski, A A; Madej, J

    2016-01-01

    [Abridged] Context. The high-energy radiation from black-hole binaries may be due to the reprocessing of a lamp located on the black hole axis, emitting X-rays. The observed spectrum is made of 3 components: the direct spectrum; the thermal bump; and the reflected spectrum made of the Compton hump and the iron-line complex. Aims. We aim at computing accurately the complete reprocessed spectrum (thermal bump + reflected) of black-hole binaries over the entire X-ray band. We also determine the strength of the direct component. Our choice of parameters is adapted to a source showing an important thermal component. Methods. We compute in full GR the illumination of a thin disk by a lamp along the rotation axis. We use the ATM21 radiative transfer code to compute the spectrum emitted along the disk. We ray trace this local spectrum to determine the reprocessed spectrum as observed at infinity. We discuss the dependence of the local and ray-traced spectra on the emission angle and spin. Results. We show the importa...

  17. Powerful jets from black hole X-ray binaries in Low/Hard X-ray states

    Fender, R. P.

    2000-01-01

    Four persistent (Cygnus X-1, GX 339-4, GRS 1758-258 and 1E 1740.7-2942) and three transient (GS 2023+38, GRO J0422+32 and GS 1354-64) black hole X-ray binary systems have been extensively observed at radio wavelengths during extended periods in the Low/Hard X-ray state, which is characterised in X-rays by a hard power-law spectrum and strong variability. All seven systems show a persistent flat or inverted (in the sense that spectral index alpha >= 0) radio spectrum in this state, markedly di...

  18. A Strong X-Ray Burst from the Low Mass X-Ray Binary EXO0748-676

    Wolff, Michael T.; Becker, Peter A.; Ray, Paul S.; Wood, Kent S.

    2005-01-01

    We have observed an unusually strong X-ray burst as a part of our regular eclipse timing observations of the low mass binary system EXO0748-676. The burst peak flux was 5.2x10^-8 ergs cm^-2 s^-1, approximately five times the normal peak X-ray burst flux observed from this source by RXTE. Spectral fits to the data strongly suggest that photospheric radius expansion occurred during the burst. In this Letter we examine the properties of this X-ray burst, which is the first example of a radius ex...

  19. Accretion in supergiant High Mass X-ray Binaries

    Manousakis, A; Blondin, J

    2013-01-01

    Supergiant High Mass X-ray Binary systems (sgHMXBs) consist of a massive, late type, star and a neutron star. The massive stars exhibits strong, radiatively driven, stellar winds. Wind accretion onto compact object triggers X-ray emission, which alters the stellar wind significantly. Hydrodynamic simulation has been used to study the neutron star - stellar wind interaction it two sgHMXBs: i) A heavily obscured sgHMXB (IGR J17252-3616) discovered by INTEGRAL. To account for observable quantities (i.e., absorbing column density) we have to assume a very slow wind terminal velocity of about 500 km/s and a rather massive neutron star. If confirmed in other obscured systems, this could provide a completely new stellar wind diagnostics. ii) A classical sgHMXB (Vela X-1) has been studied in depth to understand the origin of the off-states observed in this system. Among many models used to account for this observed behavior (clumpy wind, gating mechanism) we propose that self-organized criticality of the accretion st...

  20. Accretion in supergiant High Mass X-ray Binaries

    Manousakis Antonios

    2014-01-01

    Full Text Available Supergiant High Mass X-ray Binary systems (sgHMXBs consist of a massive, late type, star and a neutron star. The massive stars exhibits strong, radiatively driven, stellar winds. Wind accretion onto compact object triggers X-ray emission, which alters the stellar wind significantly. Hydrodynamic simulation has been used to study the neutron star - stellar wind interaction it two sgHMXBs: i A heavily obscured sgHMXB (IGR J17252–3616 discovered by INTEGRAL. To account for observable quantities (i.e., absorbing column density we have to assume a very slow wind terminal velocity of about 500 km/s and a rather massive neutron star. If confirmed in other obscured systems, this could provide a completely new stellar wind diagnostics. ii A classical sgHMXB (Vela X-1 has been studied in depth to understand the origin of the off-states observed in this system. Among many models used to account for this observed behavior (clumpy wind, gating mechanism we propose that self-organized criticality of the accretion stream is the likely reason for the observed behavior. In conclusion, the neutron star, in these two examples, acts very effciently as a probe to study stellar winds.

  1. On Low Mass X-ray Binaries and Millisecond Pulsar

    Burderi, Luciano

    2013-01-01

    The detection, in 1998, of the first Accreting Millisecond Pulsar, started an exciting season of continuing discoveries in the fashinating field of compact binary systems harbouring a neutron star. Indeed, in these last three lustres, thanks to the extraordinary performances of astronomical detectors, on ground as well as on board of satellites, mainly in the Radio, Optical, X-ray, and Gamma-ray bands, astrophysicists had the opportunity to thoroughly investigate the so-called Recycling Scenario: the evolutionary path leading to the formation of a Millisecond Radio Pulsar. The most intriguing phase is certainly the spin-up stage during which, because of the accretion of matter and angular momentum, the neutron star accumulates an extraordinary amount of mechanical rotational energy, up to one percent of its whole rest-mass energy. These millisecond spinning neutron stars are truly extreme physical objects: General and Special Relativity are fully in action, since their surfaces, attaining speeds close to one ...

  2. Swift uncovers that SAX J0840.7+2248 is not an X-ray Binary, but BeppoSAX X-ray Rich GRB 980429

    Romano, P; Guidorzi, C.; Sidoli, L.; E. Montanari; Capitanio, F; Amati, L.; Cucchiara, A.; Frontera, F.; Masetti, N.; Mereghetti, S.; Rossi, F.

    2008-01-01

    During our Swift/XRT program to obtain X-ray positions at arcsecond level for a sample of Galactic X-ray binaries, we discovered that SAX J0840.7+2248 is not a binary, but rather BeppoSAX/WFC+GRBM X-ray Rich GRB 980429. Here we report on this discovery and on the properties of this long, X-ray rich gamma-ray burst, from prompt to (very) late followup.

  3. Be/X-Ray Pulsar Binary Science with LOFT

    Wilson-Hodge, Colleen A.

    2011-01-01

    Accretion disks are ubiquitous in astronomical sources. Accretion powered pulsars are a good test bed for accretion disk physics, because unlike for other objects, the spin of the neutron star is directly observable allowing us to see the effects of angular momentum transfer onto the pulsar. The combination of a sensitive wide-field monitor and the large area detector on LOFT will enable new detailed studies of accretion powered pulsars which I will review. RXTE observations have shown an unusually high number of Be/X-ray pulsar binaries in the SMC. Unlike binaries in the Milky Way, these systems are all at the same distance, allowing detailed population studies using the sensitive LOFT WFM, potentially providing connections to star formation episodes. For Galactic accreting pulsar systems, LOFT will allow measurement of spectral variations within individual pulses, mapping the accretion column in detail for the first time. LOFT will also provide better constraints on magnetic fields in accreting pulsars, allowing measurements of cyclotron features, observations of transitions into the centrifugal inhibition regime, and monitoring of spin-up rate vs flux correlations. Coordinated multi-wavelength observations are crucial to extracting the best science from LOFT from these and numerous other objects.

  4. X-ray-binary spectra in the lamp post model

    Vincent, F. H.; Różańska, A.; Zdziarski, A. A.; Madej, J.

    2016-05-01

    Context. The high-energy radiation from black-hole binaries may be due to the reprocessing of a lamp located on the black hole rotation axis and emitting X-rays. The observed spectrum is made of three major components: the direct spectrum traveling from the lamp directly to the observer; the thermal bump at the equilibrium temperature of the accretion disk heated by the lamp; and the reflected spectrum essentially made of the Compton hump and the iron-line complex. Aims: We aim to accurately compute the complete reprocessed spectrum (thermal bump + reflected) of black-hole binaries over the entire X-ray band. We also determine the strength of the direct component. Our choice of parameters is adapted to a source showing an important thermal component. We are particularly interested in investigating the possibility to use the iron-line complex as a probe to constrain the black hole spin. Methods: We computed in full general relativity the illumination of a thin accretion disk by a fixed X-ray lamp along the rotation axis. We used the ATM21 radiative transfer code to compute the local, energy-dependent spectrum emitted along the disk as a function of radius, emission angle and black hole spin. We then ray traced this local spectrum to determine the final reprocessed spectrum as received by a distant observer. We consider two extreme values of the black hole spin (a = 0 and a = 0.98) and discuss the dependence of the local and ray-traced spectra on the emission angle and black hole spin. Results: We show the importance of the angle dependence of the total disk specific intensity spectrum emitted by the illuminated atmosphere when the thermal disk emission is fully taken into account. The disk flux, together with the X-ray flux from the lamp, determines the temperature and ionization structure of the atmosphere. High black hole spin implies high temperature in the inner disk regions, therefore, the emitted thermal disk spectrum fully covers the iron-line complex. As a

  5. GALACTIC ULTRACOMPACT X-RAY BINARIES: DISK STABILITY AND EVOLUTION

    Heinke, C. O.; Ivanova, N.; Engel, M. C.; Pavlovskii, K.; Sivakoff, G. R.; Gladstone, J. C. [Physics Department, University of Alberta, 4-183 CCIS, Edmonton, AB T6G 2E1 (Canada); Cartwright, T. F., E-mail: heinke@ualberta.ca [International Space University, 1 rue Jean-Dominique Cassini, 67400 Illkirch-Graffenstaden (France)

    2013-05-10

    We study the mass-transfer rates and disk stability conditions of ultracompact X-ray binaries (UCXBs) using empirical time-averaged X-ray luminosities from Paper I and compiled information from the literature. The majority of UCXBs are consistent with evolutionary tracks for white dwarf donors. Three UCXBs with orbital periods longer than 40 minutes have mass-transfer rates above 10{sup -10} M{sub Sun} yr{sup -1}, inconsistent with white dwarf donor tracks. We show that if helium star donors can retain their initial high entropy, they can explain the observed mass-transfer rates of these UCXBs. Several UCXBs show persistent luminosities apparently below the disk instability limit for irradiated He accretion disks. We point out that a predominantly C and/or O disk (as observed in the optical spectra of several) lowers the disk instability limit, explaining this disagreement. The orbital period and low time-averaged mass-transfer rate of 2S 0918-549 provide evidence that the donor star is a low-entropy C/O white dwarf, consistent with optical spectra. We combine existing information to constrain the masses of the donors in 4U 1916-053 (0.064 {+-} 0.010 M{sub Sun }) and 4U 1626-67 (<0.036 M{sub Sun} for a 1.4 M{sub Sun} neutron star). We show that 4U 1626-67 is indeed persistent, and not undergoing a transient outburst, leaving He star models as the best explanation for the donor.

  6. Supergiant fast X-ray transients as an under-luminous class of supergiant X-ray binaries

    Bozzo, E; Ducci, L; Bernardini, F; Falanga, M

    2014-01-01

    The usage of cumulative luminosity distributions, constructed thanks to the long-term observations available through wide field hard X-ray imagers, has been recently exploited to study the averaged high energy emission (>17 keV) from Supergiant Fast X-ray Transients (SFXTs) and classical Supergiant High Mass X-ray Binaries (SgXBs). Here, we take advantage of the long term monitorings now available with Swift/XRT to construct for the first time the cumulative luminosity distributions of a number of SFXTs and the classical SgXB IGR J18027-2016 in the soft X-ray domain with a high sensitivity focusing X-ray telescope (0.3-10 keV). By complementing previous results obtained in the hard X-rays, we found that classical SgXBs are characterized by cumulative distributions with a single knee around $\\sim$10$^{36}$-10$^{37}$ erg/s, while SFXTs are found to be systematically sub-luminous and their distributions are shifted at significantly lower luminosities (a factor of $\\sim$10-100). As the luminosity states in which ...

  7. Characterizing the quiescent X-ray variability of the black hole low mass x-ray binary V404 Cyg

    Bernardini, Federico

    2014-01-01

    We conducted the first long-term (75 days) X-ray monitoring of the black hole low mass X-ray binary V404 Cyg, with the goal of understanding and characterizing its variability during quiescence. The X-ray light curve of V404 shows several flares on timescales of hours with a count rate change of a factor of about 5-8. The root mean square variability is Fvar = 57.0(3.2) percent. The first order structure function is consistent with both a power spectrum of index -1 (flicker noise), or with a power spectrum of index 0 (white noise), implying that the light curve is variable on timescales from days to months. The X-ray spectrum is well fitted by a power law with spectral index {\\Gamma} = 2.10 - 2.35, and we found that the spectral shape remains roughly constant as the flux changes. A constant spectral shape with respect to a change in the X-ray flux may favour a scenario in which the X-ray emission is dominated by synchrotron radiation produced in a jet.

  8. Characterizing X-ray and Radio emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence

    Rana, Vikram; Corbel, Stephane; Tomsick, John A; Chakrabarty, Deepto; Walton, Dominic J; Barret, Didier; Boggs, Steven E; Christensen, Finn E; Craig, William; Fuerst, Felix; Gandhi, Poshak; Grefenstette, Brian W; Hailey, Charles; Harrison, Fiona A; Madsen, Kristin K; Rahoui, Farid; Stern, Daniel; Tendulkar, Shriharsh; Zhang, William W

    2015-01-01

    We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broad-band (0.3-30 keV) quiescent luminosity of the source is 8.9$\\times$10$^{32}$ erg s$^{-1}$ for a distance of 2.4 kpc. The source shows clear variability on short time scales in radio, soft X-ray and hard X-ray bands in the form of multiple flares. The broad-band X-ray spectra obtained from XMM-Newton and NuSTAR can be characterized with a power-law model having photon index {\\Gamma}=2.13$\\pm$0.07 (90% confidence errors); however, residuals at high energies indicate spectral curvature significant at a 3{\\sigma} confidence level with e-folding energy of the cutoff to be 19$^{+19}_{-7}$ keV. Such curvature can be explained using synchrotron emission from the base of a jet outflow. Radio observations using the JVLA reveal that the sp...

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

    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.

  10. Wind accretion in symbiotic X-ray binaries

    Postnov, K; González-Galán, A; Kuulkers, E; Kretschmar, P; Larsson, S; Finger, M H; Kochetkova, A; Lü, G; Yungelson, L

    2011-01-01

    The properties of wind accretion in symbiotic X-ray binaries (SyXBs) consisting of red-giant and magnetized neutron star (NS) are discussed. The spin-up/spin-down torques applied to NS are derived based on a hydrodynamic theory of quasi-spherical accretion onto magnetized NSs. In this model, a settling subsonic accretion proceeds through a hot shell formed around the NS magnetosphere. The accretion rate onto the NS is determined by the ability of the plasma to enter the magnetosphere.Due to large Reynolds numbers in the shell, the interaction of the rotating magnetosphere with plasma initiates a subsonic turbulence. The convective motions are capable of carrying the angular momentum through the shell. We carry out a population synthesis of SyXBs in the Galaxy with account for the spin evolution of magnetized NS. The Galactic number of SyXBs with bright (M_v<1) low-mass red-giant companion is found to be from \\sim 40 to 120, and their birthrate is \\sim 5\\times 10^{-5}-10^{-4} per year. According to our mode...

  11. On the origin of the hard X-ray tail in neutron-star X-ray binaries

    Reig, P

    2016-01-01

    Neutron star X-ray binaries emit a compact, optically thick, relativistic radio jet during low-luminosity, usually hard states, as Galactic black-hole X-ray binaries do. When radio emission is bright, a hard power-law tail without evidence for an exponential cutoff is observed in most systems. We have developed a jet model that explains many spectral and timing properties of black-hole binaries in the states where a jet is present. Our goal is to investigate whether our jet model can reproduce the hard tail, with the correct range of photon index and the absence of a high-energy cutoff, in neutron-star X-ray binaries. We have performed Monte Carlo simulations of the Compton upscattering of soft, accretion-disk or boundary layer photons, in the jet and computed the emergent energy spectra, as well as the time lag of hard photons with respect to softer ones as a function of Fourier frequency. We demonstrate that our jet model explains the observed power-law distribution with photon index in the range 1.8-3. Wit...

  12. X-ray reflection in oxygen-rich accretion discs of ultracompact X-ray binaries

    Madej, O. K.; Garcia, Jeronimo; Jonker, P. G.;

    2014-01-01

    donor star in these sources is a carbon-oxygen or oxygen-neon-magnesium white dwarf. Hence, the accretion disc is enriched with oxygen which makes the O viii Ly alpha line particularly strong. Modelling the X-ray reflection off a carbon- and oxygen-enriched, hydrogen- and helium-poor disc with models...... assuming solar composition likely biases several of the best-fitting parameters. In order to describe the X-ray reflection spectra self-consistently, we modify the currently available xillver reflection model. We present initial grids that can be used to model X-ray reflection spectra in UCXBs with carbon-oxygen......-rich (and hydrogen- and helium-poor) accretion disc. We find that the new reflection model provides a better overall description of the reflection spectra of 4U 0614+091 and 4U 1543-624 than the reflection models that assume solar abundances....

  13. X-ray irradiation of the winds in binaries with massive components

    Krticka, Jiri; Kubat, Jiri; Krtickova, Iva

    2015-01-01

    Binaries with hot massive components are strong X-ray sources. Besides the intrinsic X-ray emission of individual binary members originating in their winds, X-ray emission stems from the accretion on the compact companion or from wind collision. Since hot star winds are driven by the light absorption in the lines of heavier elements, wind acceleration is sensitive to the ionization state. Therefore, the over-ionization induced by external X-ray source strongly influences the winds of individu...

  14. Common Envelope Mechanisms: Constraints from the X-ray Luminosity Function of High Mass X-ray Binaries

    Zuo, Zhao-Yu

    2013-01-01

    We use the measured X-ray luminosity function (XLF) of high-mass X-ray binaries (HMXBs) to constrain the common envelope (CE) mechanisms, which usually serve as a key process governing the binary evolution. We show that the XLF can be reproduced quite closely under the canonical energy budget approach for CE evolution, while the angular momentum budget approach seems to predict HMXB population about 1 to 2 orders of magnitude greater than observed. In addition, the value of $\\alpha_{\\rm CE}$ can be constrained to be within about 0.5-1.0. We present the detailed components of the HMXB populations under the angular momentum budget approach and compare them with those in Zuo et al. and observations. We suggest the distinct observational properties, as well as period distributions of HMXBs may provide further clues to discriminate between these two types of CE mechanisms.

  15. On the relationship between circumstellar disc size and X-ray outbursts in Be/X-ray binaries

    Monageng, Itumeleng M; Coe, Malcolm J; Steele, Iain A; Reig, Pablo

    2016-01-01

    We present long term H$\\alpha$ monitoring results of five Be/X-ray binaries to study the Be disc size variations and their influence on Type II (giant) X-ray outbursts. The work is done in the context of the viscous decretion disc model which predicts that Be discs in binary systems are truncated by resonant torques induced by the neutron star in its orbit. Our observations show that type II outbursts are not correlated(nor anti-correlated) with the disc size, as they are seen to occur both at relatively small and large Be disc radii. We discuss these observations in context of alternate interpretation of Be disc behaviour, such as precession, elongation and density effects, and with cognisance of the limitations of our disc size estimates.

  16. Collective properties of neutron-star X-ray binary populations of galaxies. II. Pre-low-mass X-ray binary properties, formation rates, and constraints

    We continue our exploration of the collective properties of neutron-star X-ray binaries in the stellar fields (i.e., outside globular clusters) of normal galaxies. In Paper I of this series, we considered high-mass X-ray binaries (HMXBs). In this paper (Paper II), we consider low-mass X-ray binaries (LMXBs), whose evolutionary scenario is very different from that of HMXBs. We consider the evolution of primordial binaries up to the stage where the neutron star just formed in the supernova explosion of the primary is in a binary with its low-mass, unevolved companion, and this binary has circularized tidally, producing what we call a pre-low-mass X-ray binary (pre-LMXB). We study the constraints on the formation of such pre-LMXBs in detail (since these are low-probability events), and calculate their collective properties and formation rates. To this end, we first consider the changes in the binary parameters in the various steps involved, viz., the common-envelope phase, the supernova, and the tidal evolution. This naturally leads to a clarification of the constraints. We then describe our calculation of the evolution of the distributions of primordial binary parameters into those of pre-LMXB parameters, following the standard evolutionary scenario for individual binaries. We display the latter as both bivariate and monovariate distributions, discuss their essential properties, and indicate the influences of some essential factors on these. Finally, we calculate the formation rate of these pre-LMXBs. The results of this paper will be used in a subsequent one to compute the expected X-ray luminosity function of LMXBs.

  17. Collective properties of neutron-star X-ray binary populations of galaxies. II. Pre-low-mass X-ray binary properties, formation rates, and constraints

    Bhadkamkar, H. [Astronomy and Astrophysics, Raman Research Institute, Bengaluru 560080 (India); Ghosh, P. [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai 400005 (India)

    2014-04-01

    We continue our exploration of the collective properties of neutron-star X-ray binaries in the stellar fields (i.e., outside globular clusters) of normal galaxies. In Paper I of this series, we considered high-mass X-ray binaries (HMXBs). In this paper (Paper II), we consider low-mass X-ray binaries (LMXBs), whose evolutionary scenario is very different from that of HMXBs. We consider the evolution of primordial binaries up to the stage where the neutron star just formed in the supernova explosion of the primary is in a binary with its low-mass, unevolved companion, and this binary has circularized tidally, producing what we call a pre-low-mass X-ray binary (pre-LMXB). We study the constraints on the formation of such pre-LMXBs in detail (since these are low-probability events), and calculate their collective properties and formation rates. To this end, we first consider the changes in the binary parameters in the various steps involved, viz., the common-envelope phase, the supernova, and the tidal evolution. This naturally leads to a clarification of the constraints. We then describe our calculation of the evolution of the distributions of primordial binary parameters into those of pre-LMXB parameters, following the standard evolutionary scenario for individual binaries. We display the latter as both bivariate and monovariate distributions, discuss their essential properties, and indicate the influences of some essential factors on these. Finally, we calculate the formation rate of these pre-LMXBs. The results of this paper will be used in a subsequent one to compute the expected X-ray luminosity function of LMXBs.

  18. X-ray irradiation of the winds in binaries with massive components

    Krticka, Jiri; Krtickova, Iva

    2015-01-01

    Binaries with hot massive components are strong X-ray sources. Besides the intrinsic X-ray emission of individual binary members originating in their winds, X-ray emission stems from the accretion on the compact companion or from wind collision. Since hot star winds are driven by the light absorption in the lines of heavier elements, wind acceleration is sensitive to the ionization state. Therefore, the over-ionization induced by external X-ray source strongly influences the winds of individual components. We studied the effect of external X-ray irradiation on hot star winds. We used our kinetic equilibrium (NLTE) wind models to estimate the influence of external X-ray ionization for different X-ray luminosities and source distances. The models are calculated for parameters typical of O stars. The influence of X-rays is given by the X-ray luminosity, by the optical depth between a given point and the X-ray source, and by a distance to the X-ray source. Therefore, the results can be interpreted in the diagrams...

  19. X-ray Spectroscopy of the High Mass X-ray Binary Pulsar Centaurus X-3 over its Binary Orbit

    Naik, Sachindra; Ali, Zulfikar

    2011-01-01

    We present a comprehensive spectral analysis of the high mass X-ray binary (HMXB) pulsar Centaurus X-3 with the Suzaku observatory covering nearly one orbital period. The light curve shows the presence of extended dips which are rarely seen in HMXBs. These dips are seen up to as high as ~40 keV. The pulsar spectra during the eclipse, out-of-eclipse, and dips are found to be well described by a partial covering power-law model with high energy cut-off and three Gaussian functions for 6.4 keV, 6.7 keV, and 6.97 keV iron emission lines. The dips in the light curve can be explained by the presence of an additional absorption component with high column density and covering fraction, the values of which are not significant during the rest of the orbital phases. The iron line parameters during the dips and eclipse are significantly different compared to those during the rest of the observation. During the dips, the iron line intensities are found to be lesser by a factor of 2--3 with significant increase in the line...

  20. Broadband X-ray emission and the reality of the broad iron line from the Neutron Star - White Dwarf X-ray binary 4U 1820-30

    Mondal, Aditya S; Pahari, Mayukh; Misra, Ranjeev; Kembhavi, Ajit K; Raychaudhuri, Biplab

    2016-01-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disk. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here we investigate the reality of the broad iron line detected earlier from the neutron star low mass X-ray binary 4U~1820--30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broadband spectral study of the atoll source using \\suzaku{} and simultaneous \

  1. Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence

    Rana, Vikram; Loh, Alan; Corbel, Stephane; Tomsick, John A.; Chakrabarty, Deepto; Walton, Dominic J.; Barret, Didier; Boggs, Steven E.; Christensen, Finn E.; Craig, William; Fuerst, Felix; Gandhi, Poshak; Grefenstette, Brian W.; Hailey, Charles; Harrison, Fiona A.; Madsen, Kristin K.; Rahoui, Farid; Stern, Daniel; Tendulkar, Shriharsh; Zhang, William W.

    2016-04-01

    We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broadband (0.3-30 keV) quiescent luminosity of the source is 8.9 × 1032 erg s-1 for a distance of 2.4 kpc. The source shows clear variability on short timescales (an hour to a couple of hours) in the radio, soft X-ray, and hard X-ray bands in the form of multiple flares. The broadband X-ray spectra obtained from XMM-Newton and NuSTAR can be characterized with a power-law model having a photon index of Γ = 2.12 ± 0.07 (90% confidence errors); however, residuals at high energies indicate spectral curvature significant at a 3σ confidence level with the e-folding energy of the cutoff as {20}-7+20 keV. Such curvature can be explained using synchrotron emission from the base of a jet outflow. Radio observations using the VLA reveal that the spectral index evolves on very fast timescales (as short as 10 minutes), switching between optically thick and thin synchrotron emission, possibly due to instabilities in the compact jet or stochastic instabilities in the accretion rate. We explore different scenarios to explain this very fast variability.

  2. Tidal capture formation of Low Mass X-Ray Binaries from wide binaries in the field

    Michaely, Erez

    2015-01-01

    We present a potentially efficient dynamical formation scenario for Low Mass X-ray Binaries (LMXBs) in the field, focusing on black-hole (BH) LMXBs. In this formation channel LMXBs are formed from wide binaries $(>1000$ AU) with a BH component and a stellar companion. The wide binary is perturbed by fly-by's of field stars and its orbit random-walks and changes over time. This diffusion process can drive the binary into a sufficiently eccentric orbit such that the binary components tidally interact at peri-center and the binary evolves to become a short period binary, which eventually evolves into an LMXB. The formation rate of LMXBs through this channel mostly depends on the number of such BH wide binaries progenitors, which in turn depends on the velocity kicks imparted to BHs (or NSs) at birth. We consider several models for the formation and survival of such wide binaries, and calculate the LMXB formation rates for each model. We find that models where BHs form through direct collapse with no/little natal...

  3. The Soft X-ray Spectrum of the High Mass X-Ray Binary V0332+53 in Quiescence

    Elshamouty, Khaled G.; Heinke, Craig O.; Chouinard, Rhys

    2016-08-01

    The behaviour of neutron stars in high mass X-ray binaries (HMXBs) during periods of low mass transfer is of great interest. Indications of spectral softening in systems at low mass transfer rates suggest that some HMXBs are undergoing fundamental changes in their accretion regime, but the nature of the quiescent X-ray emission is not clear. We performed a 39 ks XMM-Newton observation of the transient HMXB V0332+53, finding it at a very low X-ray luminosity (Lx ˜ 4 × 1032 erg s-1). A power-law spectral fit requires an unusually soft spectral index (4.4^{+0.9}_{-0.6}), while a magnetized neutron star atmosphere model, with temperature LogTeff 6.7±0.2 K and inferred emitting radius of ˜0.2 - 0.3 km, gives a good fit. We suggest that the quiescent X-ray emission from V0332+53 is mainly from a hot spot on the surface of the neutron star. No conclusions on the presence of pulsations could be drawn due to the low count rate. Due to the high absorption column, thermal emission from the rest of the neutron star could be only weakly constrained, to LogTeff <6.14^{+0.05}_{-6.14} K, or <3 × 1033 erg s-1.

  4. Recognition of binary x-ray systems utilizing the doppler effect

    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.

  5. A Search For X-ray Emission From Colliding Magnetospheres In Young Eccentric Stellar Binaries

    Getman, Konstantin V; Kospal, Agnes; Salter, Demerese M; Garmire, Gordon P

    2016-01-01

    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 4 binaries the current X-ray data show an increasing average X-ray flux near periastron (at about 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 can not be...

  6. X-Ray Emission from M32: X-Ray Binaries or a micro-AGN?

    Eskridge, Paul B.; White III, Raymond E.; Davis, David S.

    1996-01-01

    We have analysed archival {\\it ROSAT} PSPC data for M32 in order to study the x-ray emission from this nearest elliptical galaxy. We fit spectra from three long exposures with Raymond-Smith, thermal bremsstrahlung, and power-law models. All models give excellent fits. The thermal fits have kT$\\approx$4 keV, the Raymond-Smith iron abundance is $0.4^{+0.7}_{-0.3}$ Solar, the power-law fit has $\\alpha$=1.6$\\pm$0.1, and all fits have $N_H$ consistent with the Galactic column. The source is center...

  7. Revisiting a fundamental test of the disc instability model for X-ray binaries

    Coriat, M.; Fender, R. P.; Dubus, G.

    2012-01-01

    We revisit a core prediction of the disc instability model (DIM) applied to X-ray binaries. The model predicts the existence of a critical mass transfer rate, which depends on disc size, separating transient and persistent systems. We therefore selected a sample of 52 persistent and transient neutron star and black hole X-ray binaries and verified if observed persistent (transient) systems do lie in the appropriate stable (unstable) region of parameter space predicted by the model. We find th...

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

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

    2003-01-01

    We present evidence, based on Chandra ACIS-S observations of the nearby spiral galaxy NGC 6946, that the extraodinary 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...

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

    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.

  10. Accretion disc atmospheres and winds in low-mass X-ray binaries

    Díaz Trigo, M.; Boirin, L.

    2016-05-01

    In the last decade, X-ray spectroscopy has enabled a wealth of discoveries of photoionised absorbers in X-ray binaries. Studies of such accretion disc atmospheres and winds are of fundamental importance to understand accretion processes and possible feedback mechanisms to the environment. In this work, we review the current observational state and theoretical understanding of accretion disc atmospheres and winds in low-mass X-ray binaries, focusing on the wind launching mechanisms and on the dependence on accretion state. We conclude with issues that deserve particular attention.

  11. Accretion disc atmospheres and winds in low-mass X-ray binaries

    Trigo, M Díaz

    2015-01-01

    In the last decade, X-ray spectroscopy has enabled a wealth of discoveries of photoionised absorbers in X-ray binaries. Studies of such accretion disc atmospheres and winds are of fundamental importance to understand accretion processes and possible feedback mechanisms to the environment. In this work, we review the current observational state and theoretical understanding of accretion disc atmospheres and winds in low-mass X-ray binaries, focusing on the wind launching mechanisms and on the dependence on accretion state. We conclude with issues that deserve particular attention.

  12. The Magellanic Bridge: evidence for a population of X-ray binaries

    McBride, V. A.; Bird, A. J.; Coe, M. J.; Townsend, L. J.; Corbet, R. H. D.; Haberl, F.

    2009-01-01

    INTEGRAL observations of the Small Magellanic Cloud region have resulted in the serendipitous detection of two transient hard X-ray sources in the Magellanic Bridge. In this paper we present the timing and spectral characteristics of these sources across the 2-100 keV energy range, which, in conjunction with their optical counterparts, demonstrate that they are high mass X-ray binaries in the Magellanic Bridge. Together with one previously known high mass X-ray binary system, and three candid...

  13. The nature of the X-ray pulsar in M31: an intermediate mass X-ray binary?

    Karino, Shigeyuki

    2016-01-01

    Recently the first finding of a spin period of an accreting neutron star in M31 is reported. The observed spin period is 1.2 s and it shows 1.27 d modulations due to orbital motion. From the orbital information, the mass donor could not be a giant massive star. On the other hand, the observed properties are quite odd for typical low mass X-ray binaries. In this study, we compare observed binary parameters with theoretical models given by a stellar evolution track and make a restriction on the possible mass range of the donor. According to the standard stellar evolution model, the donor star should be larger than 1.5 solar mass, and this suggests that this system is a new member of a rare category, intermediate mass X-ray binary. The magnetic field strength of the neutron star suggested by spin-up/down tendency in this system supports the possibility of intermediate mass donor.

  14. Dynamical effects on binary X-ray sources in dense stellar clusters

    We examine the model in which the globular-cluster X-ray sources are binaries. Collisions of field stars in cores of dense clusters may shrink the orbits of tightly bound (''hard'') binaries, with important consequences for the evolution of X-ray sources if one component is a collapsed star. Exchange capture of field stars enables the binary to recycle its mass supplier and to undergo a number of intermittent stages of X-ray activity. ''Hard'' binaries may be formed by three-body encounters or by two-body tidal capture in clusters with large core densities and low velocity dispersions. Alternatively, as suggested by Hills, such objects may form by neutron-star or black-hole capture in exchange collisions with primordial binaries

  15. The Magellanic Bridge: evidence for a population of X-ray binaries

    McBride, V A; Coe, M J; Townsend, L J; Corbet, R H D; Haberl, F

    2009-01-01

    INTEGRAL observations of the Small Magellanic Cloud region have resulted in the serendipitous detection of two transient hard X-ray sources in the Magellanic Bridge. In this paper we present the timing and spectral characteristics of these sources across the 2-100 keV energy range, which, in conjunction with their optical counterparts, demonstrate that they are high mass X-ray binaries in the Magellanic Bridge. Together with one previously known high mass X-ray binary system, and three candidates, these sources represent an emerging population of X-ray binaries in the Bridge, probably initiated by tidally induced star formation as a result of the gravitational interaction between the Large and Small Magellanic Clouds.

  16. The Be/X-ray binary system V 0332+53: A Short Review

    Caballero-Garcia, M D; Arabaci, M Ozbey; Hudec, R

    2015-01-01

    Be/X-ray binary systems provide an excellent opportunity to study the physics around neutron stars through the study of the behaviour of matter around them. Intermediate and low-luminosity type outbursts are interesting because they provide relatively clean environments around neutron stars. In these conditions the physics of the magnetosphere around the neutron star can be better studied without being very disturbed by other phenomena regarding the transfer of matter between the two components of the Be/X-ray binary system. A recent study presents the optical longterm evolution of the Be/X-ray binary V 0332+53 plus the X-ray emission mainly during the intermediate-luminosity outburst on 2008. In this paper we comment on the context of these observations and on the properties that can be derived through the analysis of them.

  17. X-ray reflection in oxygen-rich accretion discs of ultra-compact X-ray binaries

    Madej, O K; Jonker, P G; Parker, M L; Ross, R; Fabian, A C; Chenevez, J

    2014-01-01

    We present spectroscopic X-ray data of two candidate ultra-compact X-ray binaries: 4U~0614+091 and 4U~1543$-$624. We confirm the presence of a broad O VIII Ly$\\alpha$ reflection line (at $\\approx18\\ \\AA$) using {\\it XMM-Newton} and {\\it Chandra} observations obtained in 2012 and 2013. The donor star in these sources is carbon-oxygen or oxygen-neon-magnesium white dwarf. Hence, the accretion disc is enriched with oxygen which makes the O VIII Ly$\\alpha$ line particularly strong. We also confirm the presence of a strong absorption edge at $\\approx14$ \\AA\\ so far interpreted in the literature as due to absorption by neutral neon in the circumstellar and interstellar medium. However, the abundance required to obtain a good fit to this edge is $\\approx3-4$ times solar, posing a problem for this interpretation. Furthermore, modeling the X-ray reflection off a carbon and oxygen enriched, hydrogen and helium poor disc with models assuming solar composition likely biases several of the best-fit parameters. In order to...

  18. Suzaku view of Be/X-ray binary pulsar GX 304-1 during Type I X-ray outbursts

    Jaisawal, Gaurava K; Epili, Prahlad

    2016-01-01

    We report the timing and spectral properties of Be/X-ray binary pulsar GX 304-1 by using two Suzaku observations during its 2010 August and 2012 January X-ray outbursts. Pulsations at ~275 s were clearly detected in the light curves from both the observations. Pulse profiles were found to be strongly energy-dependent. During 2010 observation, prominent dips seen in soft X-ray ($\\leq$10 keV) pulse profiles were found to be absent at higher energies. However, during 2012 observation, the pulse profiles were complex due to the presence of several dips. Significant changes in the shape of the pulse profiles were detected at high energies ($>$35 keV). A phase shift of $\\sim$0.3 was detected while comparing the phase of main dip in pulse profiles below and above $\\sim$35 keV. Broad-band energy spectrum of pulsar was well described by a partially absorbed Negative and Positive power-law with Exponential cutoff (NPEX) model with 6.4 keV iron line and a cyclotron absorption feature. Energy of cyclotron absorption line...

  19. The Soft X-ray Spectrum of the High Mass X-Ray Binary V0332+53 in Quiescence

    Elshamouty, K; Chouinard, R

    2016-01-01

    The propeller effect should cut off accretion in fast-spinning neutron star high mass X-ray binaries (HMXBs) at low mass transfer rates. However, accretion continues in some HMXBs at $L_{x} < 10^{34}$ erg s$^{-1}$, as evidenced by continuing pulsations. Indications of spectral softening in systems in the propeller regime suggest that some HMXBs are undergoing fundamental changes in their accretion regime. A 39 ks \\textit{XMM-Newton} observation of the transient HMXB V0332+53 found it at a very low X-ray luminosity ($L_{x} \\sim 4\\times 10^{32}$ erg s${^{-1}}$). A power-law spectral fit requires an unusually soft spectral index ($4.4^{+0.9}_{-0.6}$), while a magnetized neutron star atmosphere model, with temperature \\lt\\ 6.7$\\pm 0.2$ K and inferred emitting radius of $\\sim0.2-0.3$ km, gives a good fit. We suggest that the quiescent X-ray emission from V0332+53 is mainly from a hot spot on the surface of the neutron star. We could not detect pulsations from V0332+53, due to the low count rate. Due to the high...

  20. Discovery of X-ray pulsations in the Be/X-ray binary IGR J21343+4738

    Reig, P

    2014-01-01

    We report on the discovery of X-ray pulsations in the Be/X-ray binary IGR J21343+4738 during an XMM-Newton observation. We obtained a barycentric corrected pulse period of 320.35+-0.06 seconds. The pulse profile displays a peak at low energy that flattens at high energy. The pulse fraction is 45+-3$% and independent of energy within the statistical uncertainties. The 0.2-12 keV spectrum is well fit by a two component model consisting of a blackbody with kT=0.11+-0.01 keV and a power law with photon index Gamma=1.02+-0.07. Both components are affected by photoelectric absorption with a equivalent hydrogen column density NH=(1.08+-0.15)x 10^{22} cm^{-2} The observed unabsorbed flux is 1.4x10^{-11} erg cm^{-2} s^{-1} in the 0.2-12 keV energy band. Despite the fact that the Be star's circumstellar disc has almost vanished, accretion continues to be the main source of high energy radiation. We argue that the observed X-ray luminosity (LX~10^{35} erg s^{-1}) may result from accretion via a low-velocity equatorial w...

  1. Identification of the Periodic Hard X-Ray Transient GRO J1849-03 with the X-Ray Pulsar GS 1843-02 = X1845-024 - a New Be/X-Ray Binary

    Soffitta, P.; Tomsick, J. A.; Harmon, B.A.; Costa, E.; Ford, E. C.; M. Tavani(IASF of Rome/INAF); Zhang, S.N.; Kaaret, P.

    1997-01-01

    We identify the periodic transient hard X-ray source GRO J1849-03 with the transient x-ray pulsar GS 1843-02 = X1845-024 based on the detection of x-ray outbursts from X1845-024 coincident with hard x-ray outbursts of GRO J1849--03. Based on its spin period of 94.8 s and its orbital period of 241 days, we classify the system as a Be/X-ray binary.

  2. Collective Properties of X-ray Binary Populations of Galaxies III. The Low-mass X-ray Binary Luminosity Function

    Bhadkamkar, Harshal; Ghosh, Pranab

    2013-01-01

    Continuing our exploration of the collective properties of low-mass X-ray binaries (LMXBs) in the stellar fields of normal galaxies, we compute in this paper the expected X-ray luminosity function (XLF) of LMXBs, starting from the results of the previous paper in the series (Paper II). We treat separately two classes of LMXB evolution, the first being close systems whose initial orbital periods are below the bifurcation period, wherein the companion is on the main sequence when Roche-lobe con...

  3. Discovery of an X-Ray-emitting Contact Binary System 2MASS J11201034‑2201340

    Hu, Chin-Ping; Yang, Ting-Chang; Chou, Yi; Liu, L.; Qian, S.-B.; Hui, C. Y.; Kong, Albert K. H.; Lin, L. C. C.; Tam, P. H. T.; Li, K. L.; Ngeow, Chow-Choong; Chen, W. P.; Ip, Wing-Huen

    2016-06-01

    We report the detection of orbital modulation, a model solution, and the X-ray properties of a newly discovered contact binary, Two Micron All Sky Survey (2MASS) J11201034‑2201340. We serendipitously found this X-ray point source outside the error ellipse when searching for possible X-ray counterparts of γ-ray millisecond pulsars among the unidentified objects detected by the Fermi Gamma-ray Space Telescope. The optical counterpart of the X-ray source (unrelated to the γ-ray source) was then identified using archival databases. The long-term Catalina Real-Time Transient Survey detected a precise signal with a period of P=0.28876208(56) days. A follow-up observation made by the Super Light Telescope of Lulin Observatory revealed the binary nature of the object. Utilizing archived photometric data of multi-band surveys, we construct the spectral energy distribution (SED), which is well fit by a K2V spectral template. The fitting result of the orbital profile using the Wilson–Devinney code suggests that 2MASS J11201034-2201340 is a short-period A-type contact binary and the more massive component has a cool spot. The X-ray emission was first noted in observations made by Swift, and then further confirmed and characterized by an XMM-Newton observation. The X-ray spectrum can be described by a power law or thermal Bremsstrahlung. Unfortunately, we could not observe significant X-ray orbital modulation. Finally, according to the SED, this system is estimated to be 690 pc from Earth with a calculated X-ray intensity of (0.7-1.5)× {10}30 erg s‑1, which is in the expected range of an X-ray emitting contact binary.

  4. Binary phase correlated X-ray intensity variations and flaring activity in the RS CVn binary HR 1099

    Agrawal, P. C.; Vaidya, J.

    1988-01-01

    The monitor proportional counter and the imaging proportional counter of the Einstein Observatory were used to observe the X-ray variability of the RS CVn binary HR 1099. The X-ray intensity is found to vary with the 2.837-day period of the binary. An intense X-ray flare was noted on February 17, 1980. The present results are explained using a star spot model, and it is suggested that the flare heated plasma cools either mainly by radiation or equally by conduction and radiation.

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

    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.

  6. Spectral and timing nature of the symbiotic X-ray binary 4U 1954+319: The slowest rotating neutron star in an X-ray binary system

    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 ∼5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (∼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-Kα line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (∼60%-80%), and the location in the Corbet diagram favor high B-field (≳ 1012 G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (1033-1035 erg s–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 ∼1013 G NS, this scheme can explain the ∼5.4 hr equilibrium rotation without employing the magnetar-like field (∼1016 G) required in the disk accretion case. The timescales of multiple irregular flares (∼50 s) can also be attributed to the free-fall time from the Alfvén shell for a ∼1013 G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

  7. Optical observations of binary X-ray sources

    Here I shall consider only those systems where the compact object is a neutron star (or in a few cases perhaps a black hole). Since van Paradijs (1982) has recently produced an excellent and comprehensive review of optical observations of compact galactic X-ray sources I shall summarise the basic properties of the optical counterparts and discuss a few representative systems in some detail. (orig./WL)

  8. Long-term optical variability of high-mass X-ray binaries. II. Spectroscopy

    Reig, P.; Nersesian, A.; Zezas, A.; Gkouvelis, L.; Coe, M. J.

    2016-05-01

    Context. High-mass X-ray binaries are bright X-ray sources. The high-energy emission is caused by the accretion of matter from the massive companion onto a neutron star. The accreting material comes from either the strong stellar wind in binaries with supergiant companions or the cirscumstellar disk in Be/X-ray binaries. In either case, the Hα line stands out as the main source of information about the state of the accreting material. Aims: We present the results of our monitoring program to study the long-term variability of the Hα line in high-mass X-ray binaries. Our aim is to characterise the optical variability timescales and study the interaction between the neutron star and the accreting material. Methods: We fitted the Hα line with Gaussian profiles and obtained the line parameters and equivalent width. The peak separation in split profiles was used to determine the disk velocity law and estimate the disk radius. The relative intensity of the two peaks (V/R ratio) allowed us to investigate the distribution of gas particles in the disk. The equivalent width was used to characterise the degree of variability of the systems. We also studied the variability of the Hα line in correlation with the X-ray activity. Results: Our results can be summarised as follows: i) we find that Be/X-ray binaries with narrow orbits are more variable than systems with long orbital periods; ii) we show that a Keplerian distribution of gas particles provides a good description of the disks in Be/X-ray binaries, as it does in classical Be stars; iii) a decrease in the Hα equivalent width is generally observed after major X-ray outbursts; iv) we confirm that the Hα equivalent width correlates with disk radius; v) while systems with supergiant companions display multi-structured profiles, most of the Be/X-ray binaries show, at some epoch, double-peak asymmetric profiles, which indicates that density inhomogeneities is a common property in the disk of Be/X-ray binaries; vi) the

  9. X-ray emission from interacting wind massive binaries: A review of 15 years of progress

    Rauw, Gregor; Nazé, Yaël

    2016-09-01

    Previous generations of X-ray observatories revealed a group of massive binaries that were relatively bright X-ray emitters. This was attributed to emission of shock-heated plasma in the wind-wind interaction zone located between the stars. With the advent of the current generation of X-ray observatories, the phenomenon could be studied in much more detail. In this review, we highlight the progress that has been achieved in our understanding of the phenomenon over the last 15 years, both on theoretical and observational grounds. All these studies have paved the way for future investigations using the next generation of X-ray satellites that will provide crucial information on the X-ray emission formed in the innermost part of the wind-wind interaction.

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

    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.

  11. On the Apparent Lack of Be X-ray Binaries with Black Holes

    Belczynski, Krzysztof

    2009-01-01

    In the Galaxy there are 64 Be X-ray binaries. Out of those, 42 host a neutron star, and for the reminder the nature of a companion is not known. None, so far, is known to host a black hole. There seems to be no apparent mechanism that would prevent formation or detection of Be stars with black holes. This disparity is referred to as a missing Be -- black hole X-ray binary problem. We point out that current evolutionary scenarios that lead to the formation of Be X-ray binaries predict that the ratio of these binaries with neutron stars to the ones with black holes is rather high F_NStoBH = 10--50, with the more likely formation models providing the values at the high end. The ratio is a natural outcome of (i) the stellar initial mass function that provides more neutron stars than black holes and (ii) common envelope evolution (i.e. a major mechanism involved in the formation of interacting binaries) that naturally selects progenitors of Be X-ray binaries with neutron stars (comparable mass binaries have more l...

  12. Jets in neutron star X-ray binaries: a comparison with black holes

    Migliari, S.; Fender, R. P.

    2005-01-01

    (Abridged) We present a comprehensive study of the relation between radio and X-ray emission in neutron star X-ray binaries, use this to infer the general properties of the disc-jet coupling in such systems, and compare the results quantitatively with those already established for black hole systems. There are clear qualitative similarities between the two classes of object: hard states below about 1% of the Eddington luminosity produce steady jets, while transient jets are associated with ou...

  13. Spectral states and state preference of galactic X-ray binaries

    2010-01-01

    Using observations in the past four years with the All Sky Monitor(ASM) onboard the Rossi X-ray Timing Explorer(RXTE) and the Burst Alert Telescope(BAT) onboard the Swift,we demonstrate that the hard state and the soft state are the primary spectral states in galactic black hole and neutron star X-ray binaries.In addition,we show quantitatively the preference of the two spectral states for each of the 22 bright persistent sources.

  14. The peculiar Galactic center neutron star X-ray binary XMM J174457-2850.3

    Degenaar, N; 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 Lx~5E32 erg/s and exhibits occasional accretion outbursts during which it brightens to Lx~1E35-1E36 erg/s for a few weeks (2-10 keV). However, the source often lingers in between outburst...

  15. X-Ray Variability of AGN and Relationship to Galactic Black Hole Binary Systems

    McHardy, I.M.

    2009-01-01

    Over the last 12 years, AGN monitoring by RXTE, has revolutionised our understanding of the X-ray variability of AGN, of the relationship between AGN and Galactic black hole X-ray binaries (BHBs) and hence of the accretion process itself, which fuels the emission in AGN and BHBs and is the major source of power in the universe. In this paper I review our current understanding of these topics. I begin by considering whether AGN and BHBs show the same X-ray spectral-timing `states' (e.g. low-fl...

  16. Low-Mass X-ray Binaries and Globular Clusters in Centaurus A

    Jordan, Andres; Sivakoff, Gregory R.; McLaughlin, Dean E.; Blakeslee, John P; Evans, Daniel A.; Kraft, Ralph P.; Hardcastle, Martin J.; Peng, Eric W.; Cote, Patrick; Croston, Judith H.; Juett, Adrienne M.; Minniti, Dante; Raychaudhury, Somak; Sarazin, Craig L.; Worrall, Diana M.

    2007-01-01

    We present results of Hubble Space Telescope and Chandra X-ray Observatory observations of globular clusters (GCs) and low-mass X-ray binaries (LMXBs) in the central regions of Centaurus A. Out of 440 GC candidates we find that 41 host X-ray point sources that are most likely LMXBs. We fit King models to our GC candidates in order to measure their structural parameters. We find that GCs that host LMXBs are denser and more compact, and have higher encounter rates and concentrations than the GC...

  17. The reverberation lag in the low mass X-ray binary H1743-322

    De Marco, B.; Ponti, G.

    2016-01-01

    The evolution of the inner accretion flow of a black hole X-ray binary (BHXRB) during the outburst is still a matter of active research. X-ray reverberation lags are powerful tools to constrain the disk-corona geometry. We present a study of X-ray lags in the black hole transient H1743-322. We compared results obtained from the analysis of all the publicly available XMM-Newton observations. These observations were carried out during two different outbursts, happened in 2008 and 2014. During a...

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

    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.

  19. Kinematical Studies of the Low Mass X-Ray Binary GR Mus (XB1254-690)

    Barnes, A D; Casares, J.; Cornelisse, R.; Charles, P. A.; Steeghs, D; Hynes, R.I.; O'Brien, K.

    2007-01-01

    We present simultaneous high-resolution optical spectroscopy and X-ray data of the X-ray binary system GR Mus (XB1254-690), obtained over a full range of orbital phases. The X-ray observations are used to re-establish the orbital ephemeris for this source. The optical data includes the first spectroscopic detection of the donor star in this system, through the use of the Doppler Tomography technique on the Bowen fluorescence blend (~4630-4650 A). In combination with an estimate for the orbita...

  20. FORMATION OF BLACK HOLE X-RAY BINARIES IN GLOBULAR CLUSTERS

    Inspired by the recent identification in extragalactic globular clusters of the first candidate black hole-white dwarf (BH-WD) X-ray binaries, where the compact accretors may be stellar-mass black holes (BHs), we explore how such binaries could be formed in a dynamical environment. We provide analyses of the formation rates via well-known formation channels like binary exchange and physical collisions and propose that the only possibility of forming BH-WD binaries is via coupling these usual formation channels with subsequent hardening and/or triple formation. In particular, we find that the most important mechanism for the creation of a BH-WD X-ray binary from an initially dynamically formed BH-WD binary is mass transfer induced in a triple system via the Kozai mechanism. Furthermore, we find that BH-WD binaries that evolve into X-ray sources can be formed by exchanges of a BH into a WD-WD binary or possibly by collisions of a BH and a giant star. If BHs undergo significant evaporation from the cluster or form a completely detached subcluster of BHs, then we cannot match the observationally inferred production rates even using the most optimistic estimates of formation rates. To explain the observations with stellar-mass BH-WD binaries, at least 1% of all formed BHs, or presumably 10% of the BHs present in the core now, must be involved in interactions with the rest of the core stellar population.

  1. Relations between X-ray timing features and spectral parameters of Galactic black hole X-ray binaries

    Stiele, H; Kalemci, E; Motta, S

    2012-01-01

    We present a study of correlations between spectral and timing parameters for a sample of black hole X-ray binary candidates. Data are taken from GX 339-4, H 1743-322, and XTE J1650-500, as the Rossi X-ray Timing Explorer (RXTE) observed complete outbursts of these sources. In our study we investigate outbursts that happened before the end of 2009 to make use of the high-energy coverage of the HEXTE detector and select observations that show a certain type of quasi-periodic oscillations (type-C QPOs). The spectral parameters are derived using the empirical convolution model simpl to model the Comptonized component of the emission together with a disc blackbody for the emission of the accretion disc. Additional spectral features, namely a reflection component, a high-energy cut-off, and excess emission at 6.4 keV, are taken into account. Our investigations confirm the known positive correlation between photon index and centroid frequency of the QPOs and reveal an anticorrelation between the fraction of up-scat...

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

    Madau, Piero

    2016-01-01

    We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior 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 z6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. 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 HeI photoionizations are the main source of IGM ...

  3. Long-term optical variability of high-mass X-ray binaries. II. Spectroscopy

    Reig, P; Zezas, A; Gkouvelis, L; Coe, M J

    2016-01-01

    We present the results of our monitoring program to study the long-term variability of the Halpha line in high-mass X-ray binaries. We have carried out the most complete optical spectroscopic study of the global properties of high-mass X-ray binaries so far with the analysis of more than 1100 spectra of 20 sources. Our aim is to characterise the optical variability timescales and study the interaction between the neutron star and the accreting material. Our results can be summarised as follows: i) we find that Be/X-ray binaries with narrow orbits are more variable than systems with long orbital periods, ii) we show that a Keplerian distribution of the gas particles provides a good description of the disks in Be/X-ray binaries, as it does in classical Be stars, iii) a decrease in the Halpha equivalent width is generally observed after major X-ray outbursts, iv) we confirm that the Halpha equivalent width correlates with disk radius, v) while systems with supergiant companions display, multi-structured profiles...

  4. Evolution of intermediate-mass X-ray binaries driven by magnetic braking of Ap/Bp stars: I. ultracompact X-ray binaries

    Chen, Wen-Cong

    2016-01-01

    It is generally believed that Ultracompact X-ray binaries (UCXBs) evolved from binaries consisting of a neutron star accreting from a low-mass white dwarf or helium star where mass transfer is driven by gravitational radiation. However, the standard white-dwarf evolutionary channel cannot produce the relatively long-period ($40 - 60$\\,min) UCXBs with high time-averaged mass-transfer rate. In this work, we explore an alternative evolutionary route toward UCXBs where the companions evolve from intermediate-mass Ap/Bp stars with an anomalously strong magnetic field ($100 - 10000$\\,G). Including the magnetic braking caused by the coupling between the magnetic field and an irradiation-driven wind induced by the X-ray flux from the accreting component, we show that intermediate-mass X-ray binaries (IMXBs) can evolve into UCXBs. Using the \\emph{MESA} code, we have calculated evolutionary sequences for a large number of IMXBs. The simulated results indicate that, for a small wind-driving efficiency $f=10^{-5}$, the a...

  5. THE YOUNG BINARY DQ Tau: A HUNT FOR X-RAY EMISSION FROM COLLIDING MAGNETOSPHERES

    The young high-eccentricity binary DQ Tau exhibits powerful recurring millimeter-band (mm) flaring attributed to collisions between the two stellar magnetospheres near periastron, when the stars are separated by only ∼8 R*. These magnetospheric interactions are expected to have scales and magnetic field strengths comparable to those of large X-ray flares from single pre-main-sequence stars observed in the Chandra Orion Ultradeep Project (COUP). To search for X-rays arising from processes associated with colliding magnetospheres, we performed simultaneous X-ray and mm observations of DQ Tau near periastron phase. We report here several results. (1) As anticipated, DQ Tau was caught in a flare state in both mm and X-rays. A single long X-ray flare spanned the entire 16.5 hr Chandra exposure. (2) The inferred morphology, duration, and plasma temperature of the X-ray flare are typical of those of large flares from COUP stars. (3) However, our study provides three lines of evidence that this X-ray flare likely arises from colliding magnetospheres: the chance of capturing a large COUP-like flare within the span of our observation is small, the relative timing of the X-ray and mm flares indicates the Neupert effect and is consistent with a common coronal structure, the size of the emitting coronal structure (4-5 R*) inferred from our analysis (which is admittedly model dependent and should be considered with caution) is comparable to half the binary separation. (4) The peak flare X-ray luminosity is in agreement with an estimate of the power dissipated by magnetic reconnection within the framework of a simple model of interacting magnetospheres.

  6. LFN, QPO and fractal dimension of X-ray light curves from black hole binaries

    Prosvetov, Art; Grebenev, Sergey

    The origin of the low frequency noise (LFN) and quasi-periodic oscillations (QPO) observed in X-ray flux of Galactic black hole binaries is still not recognized in spite of multiple studies and attempts to model this phenomenon. There are known correlations between the QPO frequency, X-ray power density, X-ray flux and spectral state of the system, but there is no model that can do these dependences understandable. For the low frequency (~1 Hz) QPO we still have no even an idea capable to explain their production and don't know even what part of an accretion disc is responsible for them. Here we attempted to measure the fractal dimension of X-ray light curves of several black hole X-ray binaries and to study its correlation with the frequency of quasi periodic oscillations observed in their X-ray light-curves. The fractal dimension is a measure of the space-filling capacity of the light curves' profile. To measure the fractal dimension we used R/S method, which is fast enough and has good reputation in financial analytic and materials sciences. We found that if no QPO were observed in X-ray flux from the particular source, the fractal dimension is equal to the unique value which is independent on the source, its luminosity or its spectral state. On the other hand if QPO were detected in the flux, the fractal dimension deviated from its usual value. Also, we found a clear correlation between the QPO frequency and the fractal dimension of the emission. The relationship between these two parameters is solid but nonlinear. We believe that the analysis of X-ray light curves of black hole binaries using the fractal dimension has a good scientific potential and may provide an addition information on the geometry of accretion flow and fundamental physical parameters of the system.

  7. INTEGRAL and New Classes of High-Mass X-ray Binaries

    Winkler, Christoph

    2007-01-01

    The gamma-ray observatory INTEGRAL, launched in October 2002, produces a wealth of discoveries and new results on compact high energy Galactic objects, nuclear gamma-ray line emission, diffuse line and continuum emission, cosmic background radiation, AGN and high energy transients. Two important serendipitous discoveries made by the INTEGRAL mission are new classes of X-ray binaries, namely the highly-obscured high-mass X-ray binaries, and the super-giant fast transients. In this paper I will...

  8. A Coordinated X-ray and Optical Campaign on the Nearest Massive Eclipsing Binary, Delta Ori Aa: I. Overview of the X-ray Spectrum

    Corcoran, M F; Pablo, H; Shenar, T; Pollock, A M T; Waldron, W L; Moffat, A F J; Richardson, N D; Russell, C M P; Hamaguchi, K; Huenemoerder, D P; Oskinova, L; Hamann, W -R; Naze, Y; Ignace, R; Evans, N R; Lomax, J R; Hoffman, J L; Gayley, K; Owocki, S P; Leutenegger, M; Gull, T R; Hole, K T; Lauer, J; Iping, R C

    2015-01-01

    We present an overview of four phase-constrained Chandra HETGS X-ray observations of Delta Ori A. Delta Ori A is actually a triple system which includes the nearest massive eclipsing spectroscopic binary, Delta Ori Aa, the only such object which can be observed with little phase-smearing with the Chandra gratings. Since the fainter star, Delta Ori Aa2, has a much lower X-ray luminosity than the brighter primary, Delta Ori A provides a unique system with which to test the spatial distribution of the X-ray emitting gas around Delta Ori Aa1 via occultation by the photosphere of and 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 ksec and covering nearly the entire binary orbit. Companion papers discuss the X-ray variability seen in the Chandra spectra, present new space-based photometry and ground-based radial velocities simultaneous with the X-ray data to better constrain the system parame...

  9. Evidence for Quasi-periodic X-Ray Dips from an Ultraluminous X-Ray Source: Implications for the Binary Motion

    Pasham, Dheeraj R

    2013-01-01

    We report results from long-term (approximately 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 contra...

  10. Black Hole Spin-Orbit Misalignment in Galactic X-ray Binaries

    Fragos, T; Rantsiou, E; Belczynski, K

    2010-01-01

    In black hole X-ray binaries, a misalignment between the spin axis of the black hole and the orbital angular momentum can occur during the supernova explosion that forms the compact object. In this letter we present population synthesis models of Galactic black hole X-ray binaries, and study the probability density function of the misalignment angle, and its dependence on our model parameters. In our modeling, we also take into account the evolution of misalignment angle due to accretion of material onto the black hole during the X-ray binary phase. The major factor that sets the misalignment angle for X-ray binaries is the natal kick that the black hole may receive at its formation. However, large kicks tend to disrupt binaries, while small kicks allow the formation of XRBs and naturally select systems with small misalignment angles. Our calculations predict that the majority (>67%) of Galactic field BH XRBs have rather small (>10 degrees) misalignment angles, while some systems may reach misalignment angles...

  11. Orbital Period Determinations for Four SMC Be/X-ray Binaries

    Schurch, M P E; McBride, V A; Townsend, L J; Udalski, A; Haberl, F; Corbet, R H D

    2010-01-01

    We present an optical and X-ray study of four Be/X-ray binaries located in the Small Magellanic Cloud (SMC). OGLE I-band data of up to 11 years of semi-continuous monitoring has been analysed for SMC X-2, SXP172 and SXP202B, providing both a measurement of the orbital period (Porb = 18.62, 68.90, and 229.9 days for the pulsars respectively) and a detailed optical orbital profile for each pulsar. For SXP172 this has allowed a direct comparison of the optical and X-ray emission seen through regular RXTE monitoring, revealing that the X-ray outbursts precede the optical by around 7 days. Recent X-ray studies by XMM-Newton have identified a new source in the vicinity of SXP15.3 raising doubt on the identification of the optical counterpart to this X-ray pulsar. Here we present a discussion of the observations that led to the proposal of the original counterpart and a detailed optical analysis of the counterpart to the new X-ray source, identifying a 21.7 d periodicity in the OGLE I-band data. The optical characte...

  12. Stacking Star Clusters in M51: Searching for Faint X-Ray Binaries

    Vulic, N; Gallagher, S C

    2012-01-01

    The population of low-luminosity (< 10^35 erg/s) X-Ray Binaries (XRBs) has been investigated in our Galaxy and M31 but not further. To address this problem, we have used data from the Chandra X-Ray Observatory and the Hubble Space Telescope to investigate the faint population of XRBs in the grand-design spiral galaxy M51. A matching analysis found 25 star clusters coincident with 20 X-ray point sources within 1.5" (60 pc). From X-ray and optical color-color plots we determine that this population is dominated by high-mass XRBs. A stacking analysis of the X-ray data at the positions of optically-identified star clusters was completed to probe low-luminosity X-ray sources. No cluster type had a significant detection in any X-ray energy band. An average globular cluster had the largest upper limit, 9.23 x 10^34 erg/s, in the full-band (0.3 - 8 keV) while on average the complete sample of clusters had the lowest upper limit, 6.46 x 10^33 erg/s in the hard-band (2 - 8 keV). We determined average luminosities of...

  13. The Young Binary DQ Tau: A Hunt For X-ray Emission From Colliding Magnetospheres

    Getman, Konstantin V; Salter, Demerese M; Garmire, Gordon P; Hogerheijde, Michiel R

    2011-01-01

    The young high-eccentricity binary DQ Tau exhibits powerful recurring millimeter-band (mm) flaring attributed to collisions between the two stellar magnetospheres near periastron, when the stars are separated by only ~8Rstar. These magnetospheric interactions are expected to have scales and magnetic field strengths comparable to those of large X-ray flares from single pre-main-sequence (PMS) stars observed in the Chandra Orion Ultradeep Project (COUP). To search for X-rays arising from processes associated with colliding magnetospheres, we performed simultaneous X-ray and mm observations of DQ Tau near periastron phase. We report here several results. 1) As anticipated, DQ Tau was caught in a flare state in both mm and X-rays. A single long X-ray flare spanned the entire 16.5 hour Chandra exposure. 2) The inferred morphology, duration, and plasma temperature of the X-ray flare are typical of those of large flares from COUP stars. 3) However, our study provides three lines of evidence that this X-ray flare lik...

  14. 3D Hydrodynamic & Radiative Transfer Models of X-ray Emission from Colliding Wind Binaries

    Russell, Christopher M P; Owocki, Stanley P; Corcoran, Michael F; Hamaguchi, Kenji; Sugawara, Yasuharu

    2014-01-01

    Colliding wind binaries (CWBs) are unique laboratories for X-ray astrophysics. The massive stars in these systems possess powerful stellar winds with speeds up to $\\sim$3000 km s$^{-1}$, and their collision leads to hot plasma (up to $\\sim10^8$K) that emit thermal X-rays (up to $\\sim$10 keV). Many X-ray telescopes have observed CWBs, including Suzaku, and our work aims to model these X-ray observations. We use 3D smoothed particle hydrodynamics (SPH) to model the wind-wind interaction, and then perform 3D radiative transfer to compute the emergent X-ray flux, which is folded through X-ray telescopes' response functions to compare directly with observations. In these proceedings, we present our models of Suzaku observations of the multi-year-period, highly eccentric systems $\\eta$ Carinae and WR 140. The models reproduce the observations well away from periastron passage, but only $\\eta$ Carinae's X-ray spectrum is reproduced at periastron; the WR 140 model produces too much flux during this more complicated p...

  15. Single order X-ray diffraction with binary sinusoidal transmission grating

    Cao, Leifeng

    2013-10-01

    All existing x-ray dispersive devices including crystals, multilayers and diffraction gratings generate spectra in multiple orders, whereas soft x-ray spectroscopy applications usually require only the first order spectrum. The other diffraction orders can overlap and contaminate the first order spectrum of interest. In this letter we describe how an axis-symmetrically-distributed sinusoidal-shaped aperture with binary transmittance values can be used to disperse x-rays and with a superior diffraction pattern where, along its symmetry axis, all higher-order diffractions can be effectively suppressed. Hence this sophisticated dispersive element generates pure soft x-ray spectra in the first diffraction order, free from interference from higher diffraction orders.

  16. Is the Lack of Pulsations in Low Mass X-Ray Binaries due to Comptonizing Coronae?

    Gogus, E; Gilfanov, M; Gogus, Ersin

    2006-01-01

    The spin periods of the neutron stars in most Low Mass X-ray Binary (LMXB) systems still remain undetected. One of the models to explain the absence of coherent pulsations has been the suppression of the beamed signal by Compton scattering of X-ray photons by electrons in a surrounding corona. We point out that simultaneously with wiping out the pulsation signal, such a corona will upscatter (pulsating or not) X-ray emission originating at and/or near the surface of the neutron star leading to appearance of a hard tail of Comptonized radiation in the source spectrum. We analyze the hard X-ray spectra of a selected set of LMXBs and demonstrate that the optical depth of the corona is not likely to be large enough to cause the pulsations to disappear.

  17. High Time Resolution Studies of Binary X-Ray Pulsars

    Cominsky, Lynn R.

    1996-05-01

    The work for this project was substantially more than anticipated, and involved recreating an analysis system for all the HEAO A-1 scanning data which had been converted to the ELE format. As a result of this work, a complete software analysis package was first created at Sonoma State University using Fortran, that can extract the data for any given X-ray source, and produce light curves from the scanning data. A second complete software analysis package was also created, this time in IDL, which can also display all the data in a timely manner, allowing data screening without the generation of hardcopy plots. The creation of the software systems was not the original goal of the project; rather this was a necessary result when the NRL computers became inoperable due to old age and could not be used to support the project, as originally planned. There were 6 sources originally proposed for analysis: SMC X-1, A0538-66, LMC X-1, LMC X-3, (these 3 sources are all located in the Large Magellanic Cloud region), 4UO115+63 and 4U1626-67. Results on these sources are summarized.

  18. Theoretical X-ray Line Profiles from Colliding Wind Binaries

    Henley, D B; Pittard, J M

    2003-01-01

    We present theoretical X-ray line profiles from a range of model colliding wind systems. In particular, we investigate the effects of varying the stellar mass-loss rates, the wind speeds, and the viewing orientation. We find that a wide range of theoretical line profile shapes is possible, varying with orbital inclination and phase. At or near conjunction, the lines have approximately Gaussian profiles, with small widths (HWHM ~ 0.1 v_infty) and definite blue- or redshifts (depending on whether the star with the weaker wind is in front or behind). When the system is viewed at quadrature, the lines are generally much broader (HWHM ~ v_infty), flat-topped and unshifted. Local absorption can have a major effect on the observed profiles - in systems with mass-loss rates of a few times 10^{-6} Msol/yr the lower energy lines (E <~ 1 kev) are particularly affected. This generally results in blueward-skewed profiles, especially when the system is viewed through the dense wind of the primary. The orbital variation ...

  19. Near-infrared observations of the Be/X-ray binary pulsar A0535+262

    Sachindra Naik; Blesson Mathew; D. P. K. Banerjee; N. M. Ashok; Rajeev R. Jaiswal

    2012-01-01

    We present the results obtained from extensive near-infrared (IR) spectro-scopic and photometric observations of the Be/X-ray binary A0535+262/HDE 245770 at different phases of its ~ 111 d orbital period.This observation campaign is part of the monitoring program of selective Be/X-ray binary systems aimed at understanding X-ray and near-IR properties at different orbital phases,especially during the periastron passage of the neutron star.The near-IR observations presented here were carried out using the 1.2 m telescope at the Mt.Abu IR Observatory.Though the source was relatively faint for spectroscopic observations with the 1.2 m telescope,we monitored the source closely during the 2011 February-March giant X-ray outburst to primarily investigate whether any drastic changes in the near-IR JHK spectra took place at the periastron passage.Changes of such a striking nature were expected to be detectable in our spectra.Photometric observations of the Be star show a gradual and systematic fading in the JHK light curves since the onset of the X-ray outburst,which could suggest a mild evacuation/truncation of the circumstellar disk of the Be companion.Near-IR spectroscopy of the object shows that the JHK spectra are dominated by the emission lines of hydrogen Brackett and Paschen series and HeI lines at 1.0830,1.7002 and 2.0585 μm.The presence of all the hydrogen emission lines in the JHK spectra,along with the absence of any significant change in the continuum of the Be companion during X-ray quiescent and X-ray outburst phases,suggests that the near- IR line emitting regions of the disk are not significantly affected during the X-ray outburst.

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

    Aharonian, F; 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-Ata, A; O'Connor-Drury, L; 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; Khelifi, B; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemiere, A; Lemoine-Goumard, M; Leroy, N; Lohse, T; Marcowith, A; Martin, J M; Martineau-Huynh, O; Masterson, C; McComb, T J L; De Naurois, Mathieu; 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 V; Sauge, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Spangler, D; Steenkamp, R; Stegmann, C; Tavernet, J P; Terrier, R; Theoret, C G; Tluczykont, M; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J

    2005-01-01

    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 >100 GeV from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

  1. On the disruption of pulsar and X-ray binaries in globular clusters

    Verbunt, Frank

    2013-01-01

    The stellar encounter rate Gamma has been shown to be strongly correlated with the number of X-ray binaries in clusters and also to the number of radio pulsars. However, the pulsar populations in different clusters show remarkably different characteristics: in some GCs the population is dominated by binary systems, in others by single pulsars and exotic systems that result from exchange encounters. In this paper, we describe a second dynamical parameter for globular clusters, the encounter rate for a single binary, gamma. We find that this parameter provides a good characterization of the differences between the pulsar populations of different globular clusters. The higher gamma is for any particular globular cluster the more isolated pulsars and products of exchange interactions are observed. Furthermore, we also find that slow and "young" pulsars are found almost exclusively in clusters with a high gamma; this suggests that these kinds of objects are formed by the disruption of X-ray binaries, thus halting ...

  2. Blazars and the emerging AGN/black hole X-ray binary paradigm

    P. Uttley(Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands)

    2005-01-01

    We briefly review the emerging paradigm which links the radio-quiet and radio-loud classes of AGN to the different accretion states observed in stellar mass black hole X-ray binary systems (BHXRBs), and discuss the relevance of the AGN/BHXRB connection to blazar variability.

  3. Extremely fast orbital decay of the black hole X-ray binary Nova Muscae 1991

    Hernández, J I González; Rebolo, R; Casares, J

    2016-01-01

    We present new medium-resolution spectroscopic observations of the black hole X-ray binary Nova Muscae 1991 taken with X-Shooter spectrograph installed at the 8.2m-VLT telecope. These observations allow us to measure the time of inferior conjunction of the secondary star with the black hole in this system that, together with previous measurements, yield an orbital period decay of $\\dot P=-20.7\\pm12.7$ ms yr$^{-1}$ ($-24.5\\pm15.1$ $\\mu $s per orbital cycle). This is significantly faster than those previously measured in the other black hole X-ray binaries A0620-00 and XTE J1118+480. No standard black hole X-ray binary evolutionary model is able to explain this extremely fast orbital decay. At this rate, the secondary star would reach the event horizon (as given by the Schwarzschild radius of about 32 km) in roughly 2.7 Myr. This result has dramatic implications on the evolution and lifetime of black hole X-ray binaries.

  4. X-ray illuminated stellar winds - Ionization effects in the radiative driving of stellar winds in massive X-ray binary systems

    This paper presents calculations of the effect of changing X-ray ionization conditions on the radiative force experienced by the stellar wind material in a massive X-ray binary system. The radiative line force from the radiation field of the primary is parameterized in terms of the Castor et al. (1975) force multiplier. The results show that the line force decreases sharply, but in a nonlinear way, with increasing X-ray ionization. The dynamic consequences of this effect are discussed. 27 refs

  5. High-mass X-ray binaries in the Small Magellanic Cloud

    Haberl, F.; Sturm, R.

    2016-02-01

    Aims: The last comprehensive catalogue of high-mass X-ray binaries in the Small Magellanic Cloud (SMC) was published about ten years ago. Since then new such systems were discovered, mainly by X-ray observations with Chandra and XMM-Newton. For the majority of the proposed HMXBs in the SMC no X-ray pulsations were discovered as yet, and unless other properties of the X-ray source and/or the optical counterpart confirm their HMXB nature, they remain only candidate HMXBs. Methods: From a literature search we collected a catalogue of 148 confirmed and candidate HMXBs in the SMC and investigated their properties to shed light on their real nature. Based on the sample of well-established HMXBs (the pulsars), we investigated which observed properties are most appropriate for a reliable classification. We defined different levels of confidence for a genuine HMXB based on spectral and temporal characteristics of the X-ray sources and colour-magnitude diagrams from the optical to the infrared of their likely counterparts. We also took the uncertainty in the X-ray position into account. Results: We identify 27 objects that probably are misidentified because they lack an infrared excess of the proposed counterpart. They were mainly X-ray sources with a large positional uncertainty. This is supported by additional information obtained from more recent observations. Our catalogue comprises 121 relatively high-confidence HMXBs (the vast majority with Be companion stars). About half of the objects show X-ray pulsations, while for the rest no pulsations are known as yet. A comparison of the two subsamples suggests that long pulse periods in excess of a few 100 s are expected for the "non-pulsars", which are most likely undetected because of aperiodic variability on similar timescales and insufficiently long X-ray observations. The highest X-ray variability together with the lowest observed minimum fluxes for short-period pulsars indicate that in addition to the eccentricity of the

  6. Coordinated X-ray, Ultraviolet, Optical, and Radio Observations of the PSR J1023+0038 System in a Low-mass X-ray Binary State

    Bogdanov, Slavko; Bassa, Cees; Deller, Adam; Halpern, Jules P; Heald, George; Hessels, Jason W T; Janssen, Gemma H; Lyne, Andrew G; Moldon, Javier; Paragi, Zsolt; Patruno, Alessandro; Perera, Benetge; Stappers, Ben W; Tendulkar, Shriharsh P; D'Angelo, Caroline R; Wijnands, Rudy

    2014-01-01

    The PSR J1023+0038 binary system hosts a neutron star and a low-mass, main-sequence-like star. It switches on year timescales between states as an eclipsing radio millisecond pulsar and a low-mass X-ray binary. We present a multi-wavelength observational campaign of PSR J1023+0038 in its most recent low-mass X-ray binary state. Two long XMM-Newton observations reveal that the system spends ~70% of the time in a ~$3\\times10^{33}$ erg/s X-ray luminosity mode, which, as shown in Archibald et al. (2014), exhibits coherent X-ray pulsations. This emission is interspersed with frequent lower flux mode intervals with ~$5\\times 10^{32}$ erg/s and sporadic flares reaching up to ~$10^{34}$ erg/s, with neither mode showing significant X-ray pulsations. The switches between the three flux modes occur on timescales of order 10 s. In the UV and optical, we observe occasional intense flares coincident with those observed in X-rays. Our radio timing observations reveal no pulsations at the pulsar period during any of the thre...

  7. Revealing a new symbiotic X-ray binary with Gemini NIFS

    Bahramian, Arash; Heinke, Craig O; Wijnands, Rudy; Kaur, Ramanpreet; Altamirano, Diego

    2014-01-01

    We use K-band spectroscopy of the counterpart to the rapidly variable X-ray transient XMMU J174445.5-295044 to identify it as a new symbiotic X-ray binary. XMMU J174445.5-295044 has shown a hard X-ray spectrum (we verify its association with an Integral/IBIS 18-40 keV detection in 2013 using a short Swift/XRT observation), high and varying N$_H$, and rapid flares on timescales down to minutes, suggesting wind accretion onto a compact star. We observed its near-infrared counterpart using the Near-infrared Integral Field Spectrograph (NIFS) at Gemini-North, and classify the companion as ~ M2 III. We infer a distance of $3.1^{+1.8}_{-1.1}$ kpc (conservative 1-sigma errors), and therefore calculate that the observed X-ray luminosity (2-10 keV) has reached to at least 4$\\times10^{34}$ erg/s. We therefore conclude that the source is a symbiotic X-ray binary containing a neutron star (or, less likely, black hole) accreting from the wind of a giant.

  8. MULTI-WAVELENGTH STUDY OF THE Be/X-RAY BINARY MXB 0656–072

    We present and analyze the optical photometric and spectroscopic data of the Be/X-ray binary MXB 0656–072 from 2006 to 2009. A 101.2 day orbital period is found, for the first time, from the present public X-ray data (Swift/BAT and RXTE/ASM). The anti-correlation between the Hα emission and the UBV brightness of MXB 0656–072 during our 2007 observations indicates that a mass ejection event took place in the system. After the mass ejection, a low-density region might develop around the Oe star. With the outward motion of the circumstellar disk, the outer part of the disk interacted with the neutron star around its periastron passage and a series of X-ray outbursts were triggered between MJD 54350 and MJD 54850. The Proportional Counter Array-HEXTE spectra during the 2007-2008 X-ray outbursts could be well fitted by a cutoff power law with low-energy absorption, together with an iron line around 6.4 keV, and a broad cyclotron resonance feature around 30 keV. The same variability of the soft and hard X-ray colors in 2.3-21 keV indicated that there were no overall changes in the spectral shape during the X-ray outbursts, which might only be connected with the changes of the mass accretion rate onto the neutron star.

  9. High-Mass X-ray binaries in the Small Magellanic Cloud

    Haberl, Frank

    2015-01-01

    The last comprehensive catalogue of high-mass X-ray binaries in the Small Magellanic Cloud (SMC) was published about 10 years ago. Since then new such systems were discovered, mainly by X-ray observations with Chandra and XMM-Newton. For the majority of the proposed HMXBs in the SMC no X-ray pulsations were discovered yet and unless other properties of the X-ray source and/or the optical counterpart confirm their HMXB nature, they remain only candidate HMXBs. From a literature search we collect a catalogue of 148 confirmed and candidate HMXBs in the SMC and investigate their properties to shed light on their real nature. Based on the sample of well established HMXBs (the pulsars), we investigate which observed properties are most appropriate for a reliable classification. Using spectral and temporal characteristics of the X-ray sources and colour-magnitude diagrams from the optical to the infrared of their likely counterparts and taking into account the uncertainty in the X-ray position we define different le...

  10. X-ray Measurements of Black Hole X-ray Binary Source GRS 1915+105 and the Evolution of Hard X-ray Spectrum

    R. K. Manchanda

    2000-06-01

    We report the spectral measurement of GRS 1915+105 in the hard X-ray energy band of 20-140keV. The observations were made on March 30th, 1997 during a quiescent phase of the source. We discuss the mechanism of emission of hard X-ray photons and the evolution of the spectrum by comparing the data with earlier measurements and an axiomatic model for the X-ray source.

  11. On the orbital parameters of Be/X-ray binaries in the Small Magellanic Cloud

    Townsend, L J; Corbet, R H D; Hill, A B

    2011-01-01

    The orbital motion of a neutron star about its optical companion presents a window through which to study the orbital parameters of that binary system. This has been used extensively in the Milky Way to calculate these parameters for several high-mass X-ray binaries. Using several years of RXTE PCA data, we derive the orbital parameters of four Be/X-ray binary systems in the SMC, increasing the number of systems with orbital solutions by a factor of three. We find one new orbital period, confirm a second and discuss the parameters with comparison to the Galactic systems. Despite the low metallicity in the SMC, these binary systems sit amongst the Galactic distribution of orbital periods and eccentricities, suggesting that metallicity may not play an important role in the evolution of high-mass X-ray binary systems. A plot of orbital period against eccentricity shows that the supergiant, Be and low eccentricity OB transient systems occupy separate regions of the parameter space; akin to the separated regions o...

  12. A Search for X-ray Emitting Binary Stars in the Globular Cluster Omega Centauri

    Deveny, Sarah; Gallien, Michael; Rickards Vaught, Ryan; Waters, Miranda; Cool, Adrienne; Bellini, Andrea; Anderson, Jay; Henleywillis, Simon; Haggard, Daryl; Heinke, Craig O.

    2016-06-01

    Omega Centauri is one of the most widely studied globular clusters, and is expected to harbor a significant population of binary stars. Binaries play a crucial role in determining the progression of stellar dynamics within globular clusters, and as such are relevant to questions concerning the possible formation of intermediate black holes at their centers. One effective way to identify certain classes of binary systems is to first locate X-ray sources in the cluster and then to search for their optical counterparts. Using Chandra X-ray Observatory's ACIS-I instrument we have identified 275 X-ray sources in and toward Omega Cen, more than 50 of which lie within the cluster's core radius. Here we present a search for the optical counterparts of these core sources using an extensive database of archival Hubble Space Telescope images. Using WFC3/UVIS data from 11 different filters, we construct color-magnitude diagrams that reveal a diverse array of objects, including (in addition to background and foreground objects) cataclysmic variables, coronally active binaries, and, interestingly, stars that lie on Omega Cen's anomalous giant branch. We discuss the significance of these results in the context of studies of the formation and evolution of binary stars in globular clusters.

  13. Supermassive binary black holes - possible observational effects in the x-ray emission

    Jovanović Predrag

    2014-01-01

    Full Text Available Here we discuss the possible observational effects in the X-ray emission from two relativistic accretion disks in a supermassive binary black hole system. For that purpose we developed a model and performed numerical simulations of the X-ray radiation from a relativistic accretion disk around a supermassive black hole, based on the ray-tracing method in the Kerr metric, and applied it to the case of the close binary supermassive black holes. Our results indicate that the broad Fe Kα line is a powerful tool for detecting such systems and studying their properties. The most favorable candidates for observational studies are the supermassive binary black holes in the galactic mergers during the phase when the orbital velocities of their components are very large and exceed several thousand kms -1. [Projekat Ministarstva nauke Republike Srbije, br. 176003: Gravitation and the Large Scale Structure of the Universe i br. 176001: Astrophysical Spectroscopy of Extragalactic Objects

  14. A discussion of the eccentric binary hypothesis for transient X-ray sources

    The eccentric binary hypothesis for transient x-ray sources in the framework of the gradual acceleration stellar wind model proposed by Barlow and Cohen is examined. It is found that a consideration of the ratio of maximum to minimum luminosities and of the ratio of the durations of the high and low states, for a typical transient x-ray source, yields a rather high eccentricity, despite the gradual acceleration of the wind. When typical physical parameters for the binary members are taken into account, we find that a consistent description is possible only for very eccentric orbits (e>=0.9), thus the model is inadequate as a general explanation of the x-ray transient phenomenon. The recurrent transient x-ray source 4U 1630-47, which was considered in ihe past to be a realization of the eccentric binary model is studied and it is demonstrated that it cannot be described consistently within the framework of the model, unless the optical primary is very peculiar. (author)

  15. A Global Look at Reflection in Black-Hole X-ray Binaries Using RXTE

    Steiner, James F.; Garcia, Javier; Reis, Ruben C.; McClintock, Jeffrey E.

    2014-08-01

    Spectral reflection is ubiquitous in black-hole X-ray binaries, and is produced by the coronal hard X-ray emission illuminating the cooler accretion disk. The observed interplay between coronal and reflection spectral components provides insight into the geometry of the corona - an attribute which is presently only weakly constrained We present first results from a new campaign analyzing all RXTE PCU-2 spectra of accreting stellar-mass black holes. A simple but self-consistent treatment of disk, coronal, and reflection emission highlights changes evident in the coronal geometry between soft and hard spectral states.

  16. Detection of a Quiescent Low Mass X-Ray Binary Companion in 47 Tucanae

    Edmonds, Peter D.; Heinke, Craig O.; Grindlay, Jonathan E.; Gilliland, Ronald L.

    2001-01-01

    We present the results of a search for optical counterparts to the two quiescent low mass X-ray binaries (X5 and X7) in the globular cluster 47 Tucanae, using high quality Chandra and HST images. A faint blue (V=21.7; U-V=0.9) star within 0.03" of the eclipsing system X5 shows variability on both short and long timescales, and is the counterpart of the X-ray source. The colors and variability of this object are consistent with the combination of light from an accretion disk and a red main seq...

  17. A search for radio emission from X-ray binaries and related objects

    5-GHz radio observations are reported of 117 X-ray binary stars and cataclysmic variable stars using the Jodrell Bank Lovell-Mk II broad-band interferometer. Sensitivity was sufficient to detect sources of 2-3 mJy. In addition to seven objects already known to be radio emitters, seven new radio sources were detected. VLA observations confirmed that two of the new radio sources are coincident with the X-ray positions, one of them probably an extragalactic radio source, and the other a pulsar. (author)

  18. The Ages of High Mass X-ray Binaries in NGC 2403 and NGC 300

    Williams, Benjamin F.; Binder, Breanna A.; Dalcanton, Julianne J.; Eracleous, Michael; Dolphin, Andrew

    2013-01-01

    We have examined resolved stellar photometry from HST imaging surrounding 18 high-mass X-ray binary (HMXB) candidates in NGC 300 and NGC 2403 as determined from combined Chandra/HST analysis. We have fit the color-magnitude distribution of the surrounding stars with stellar evolution models. All but one region in NGC 300 and two in NGC 2403 contain a population with an age between 20 and 70 Myr. One of the candidates is the ultraluminous X-ray source (ULX) in NGC 2403, which we associate with...

  19. The Correlation between Hard X-Ray Peak Flux and Soft X-Ray Peak Flux in the Outburst Rise of Low-Mass X-Ray Binaries

    W. Yu; M. van der Klis; R.P. Fender

    2004-01-01

    We have analyzed Rossi X-Ray Timing Explorer pointed observations of the outbursts of black hole and neutron star soft X-ray transients in which an initial low/hard state, or ``island'' state, followed by a transition to a softer state was observed. In three sources-the black hole transient XTE J155

  20. Multiwavelength observations of the Be/X-ray binary 4U1145-619

    Stevens, J B; Coe, M J; Buckely, D H; Fabregat, J; Steele, I A; Stevens, James B.; Reig, Pablo; Coe, Malcolm J.; Buckely, David H.; Fabregat, Juan; Steele, Iain A.

    1997-01-01

    We report optical and infrared observations of the massive X-ray binary system 4U1145-619 (V801 Cen) which show that the circumstellar disc of the Be star component is in decline. Infrared J,H,K,L magnitudes of V801Cen have been monitored from 1993 March to 1996 April. H alpha spectra have been obtained throughout the same period. We find that both the infrared excess and the Balmer emission have been in decline throughout the period of observations. A 13 year optical and X-ray history of the source has been collated, revealing a possible correlation between the optical and X-ray activity. In addition, we have used u,v,b,y,beta indices, corrected for both circumstellar and interstellar effects, to calculate the physical parameters of the underlying B star.

  1. DISCRETE MASS EJECTIONS FROM THE Be/X-RAY BINARY A0535+26/HD 245770

    We present long-term optical spectroscopic observations on the Be/X-ray binary A0535+26 from 1992 to 2010. Combined with the public V-band photometric data, we find that each giant X-ray outburst occurred in a fading phase of the optical brightness. The anti-correlation between the optical brightness and the Hα intensity during our 2009 observations indicates a mass ejection event had taken place before the 2009 giant X-ray outburst, which might cause the formation of a low-density region in the inner part of the disk. The similar anti-correlation observed around 1996 September indicates the occurrence of the mass ejection, which might trigger the subsequent disk loss event in A0535+26.

  2. High Mass X-ray Binaries: Progenitors of double neutron star systems

    Chaty, Sylvain

    2015-01-01

    In this review I briefly describe the nature of the three kinds of High-Mass X-ray Binaries (HMXBs), accreting through: (i) Be circumstellar disc, (ii) supergiant stellar wind, and (iii) Roche lobe filling supergiants. A previously unknown population of HMXBs hosting supergiant stars has been revealed in the last years, with multi-wavelength campaigns including high energy (INTEGRAL, Swift, XMM, Chandra) and optical/infrared (mainly ESO) observations. This population is divided between obscured supergiant HMXBs, and supergiant fast X-ray transients (SFXTs), characterized by short and intense X-ray flares. I discuss the characteristics of these types of supergiant HMXBs, propose a scenario describing the properties of these high-energy sources, and finally show how the observations can constrain the accretion models (e.g. clumpy winds, magneto-centrifugal barrier, transitory accretion disc, etc). Because they are the likely progenitors of Luminous Blue Variables (LBVs), and also of double neutron star systems,...

  3. Kinematical Studies of the Low Mass X-Ray Binary GR Mus (XB1254-690)

    Barnes, A D; Cornelisse, R; Charles, P A; Steeghs, D; Hynes, R I; O'Brien, K

    2007-01-01

    We present simultaneous high-resolution optical spectroscopy and X-ray data of the X-ray binary system GR Mus (XB1254-690), obtained over a full range of orbital phases. The X-ray observations are used to re-establish the orbital ephemeris for this source. The optical data includes the first spectroscopic detection of the donor star in this system, through the use of the Doppler Tomography technique on the Bowen fluorescence blend (~4630-4650 A). In combination with an estimate for the orbital parameters of the compact object using the wings of the He II 4686 emission line, dynamical mass constraints of 1.20 < M_X/M_{sun} < 2.64 for the neutron star and 0.45 < M_2/M_{sun} < 0.85 for the companion are derived.

  4. Formation of binary and ternary metal deposits on glass-ceramic carbon electrode surfaces: electron-probe X-ray microanalysis, total-reflection X-ray fluorescence analysis, X-ray photoelectron spectroscopy and scanning electron microscopy study

    The features of the formation of binary and ternary alloys during the electrochemical deposition and co-deposition of copper, cadmium and lead from aqueous solutions on disc glass-ceramic carbon electrode surfaces were studied by electron-probe X-ray microanalysis, total-reflection X-ray fluorescence analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The macroscopic properties of electrodeposits such as morphology, lateral distribution of the elements along the disc electrode surface and depth distribution of the elements in the electrodeposit bulk were established. The mechanisms of metal nucleation and growth of thin films of electrodeposits were discussed

  5. Simultaneous X-Ray and Radio Observations of the Unusual Binary LSI + 61 deg 303

    Harrison, Fiona A.; Leahy, Denis A.; Waltman, Elizabeth

    1996-01-01

    We present simultaneous 0.5 - 10 keV X-ray and two-frequency radio observations at 2.25 and 8.3 GHz of the unusual binary system LSI + 61 deg. 303. This system was observed twice in a single binary orbit by the ASCA satellite, and monitored daily at two radio frequencies during the same orbital cycle with the Greenbank Interferometer. During the first ASCA observation the source was detected with a 1 - 10 keV luminosity 3.6 x 10(exp 33) (d/2.0 kpc)(exp 2) erg 1/s and during the second at a similar level with evidence for a decrease in average flux of 30%. During the first pointing the radio source was at a quiescent 8 GHz flux level of 30 mJy while during the second the radio flux was rising dramatically with an average value of 100 mJy. No variability is seen in the X-ray flux during the first pointing, but during the second the flux is variable by approx. 50% on timescales of approx. 30 minutes. No pulsations are seen in either X-ray observation with an upper limit on pulsed flux of 20%. The low X-ray luminosity and lack of observed pulsations indicate that accretion onto a neutron star surface is not the origin for the high-energy emission. Rather, the X-rays must result either from accreted matter which is stopped at the magnetosphere because the magnetospheric boundry is rotating at super-Keplerian rates or due to a shock formed in the interaction of the dense wind of the Be star companion and a moderately young pulsar. We derive a required pulsar spin down luminosity of approx. 10(exp 37) erg 1/s, and argue that the shock model more easily explains the observed X-ray radio observations.

  6. Tracing the Reverberation Lag in the Hard State of Black Hole X-Ray Binaries

    De Marco, B.; Ponti, G.; Muñoz-Darias, T.; Nandra, K.

    2015-11-01

    We report results obtained from a systematic analysis of X-ray lags in a sample of black hole X-ray binaries, with the aim of assessing the presence of reverberation lags and studying their evolution during outburst. We used XMM-Newton and simultaneous Rossi X-ray Timing Explorer (RXTE) observations to obtain broadband energy coverage of both the disk and the hard X-ray Comptonization components. In most cases the detection of reverberation lags is hampered by low levels of variability-power signal-to-noise ratio (typically when the source is in a soft state) and/or short exposure times. The most detailed study was possible for GX 339-4 in the hard state, which allowed us to characterize the evolution of X-ray lags as a function of luminosity in a single source. Over all the sampled frequencies (˜0.05-9 Hz), we observe the hard lags intrinsic to the power-law component, already well known from previous RXTE studies. The XMM-Newton soft X-ray response allows us to detail the disk variability. At low frequencies (long timescales) the disk component always leads the power-law component. On the other hand, a soft reverberation lag (ascribable to thermal reprocessing) is always detected at high frequencies (short timescales). The intrinsic amplitude of the reverberation lag decreases as the source luminosity and the disk fraction increase. This suggests that the distance between the X-ray source and the region of the optically thick disk where reprocessing occurs gradually decreases as GX 339-4 rises in luminosity through the hard state, possibly as a consequence of reduced disk truncation.

  7. ENERGY FEEDBACK FROM X-RAY BINARIES IN THE EARLY UNIVERSE

    X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z ∼ 20) until today. We estimate that X-ray emission from XRBs dominates over AGN at z ∼> 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by ∼4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of ∼300 Myr and then decreases gradually at later times, showing little variation for mean stellar ages ∼> 3 Gyr. Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations

  8. Energy Feedback from X-ray Binaries in the Early Universe

    Fragos, T.; Lehmer, B..; Naoz, S.; Zezas, A.; Basu-Zych, A.

    2013-01-01

    X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z (redshift) approximately equal to 20) until today.We estimate that X-ray emission from XRBs dominates over AGN at z (redshift) greater than or approximately equal to 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by approximately 4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of approximately 300 Myr (million years) and then decreases gradually at later times, showing little variation for mean stellar ages 3 Gyr (Giga years, or billion years). Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

  9. Tracing the reverberation lag in the hard state of black hole X-ray binaries

    De Marco, B; Muñoz-Darias, T; Nandra, K

    2015-01-01

    We report results obtained from a systematic analysis of X-ray lags in a sample of black hole X-ray binaries, with the aim of assessing the presence of reverberation lags and studying their evolution during outburst. We used XMM-Newton and simultaneous RXTE observations to obtain broad-band energy coverage of both the disc and the hard X-ray Comptonization components. In most cases the detection of reverberation lags is hampered by low levels of variability signal-to-noise ratio (e.g. typically when the source is in a soft state) and/or short exposure times. The most detailed study was possible for GX 339-4 in the hard state, which allowed us to characterize the evolution of X-ray lags as a function of luminosity in a single source. Over all the sampled frequencies (~0.05-9 Hz) we observe the hard lags intrinsic to the power law component, already well-known from previous RXTE studies. The XMM-Newton soft X-ray response allows us to detail the disc variability. At low-frequencies (long time scales) the disc c...

  10. IGR J17451-3022: A dipping and eclipsing low mass X-ray binary

    Bozzo, E.; Pjanka, P.; Romano, P.; Papitto, A.; Ferrigno, C.; Motta, S.; Zdziarski, A. A.; Pintore, F.; Di Salvo, T.; Burderi, L.; Lazzati, D.; Ponti, G.; Pavan, L.

    2016-04-01

    In this paper we report on the available X-ray data collected by INTEGRAL, Swift, and XMM-Newton during the first outburst of the INTEGRAL transient IGR J17451-3022, discovered in 2014 August. The monitoring observations provided by the JEM-X instruments on board INTEGRAL and the Swift /XRT showed that the event lasted for about 9 months and that the emission of the source remained soft for the entire period. The source emission is dominated by a thermal component (kT ~ 1.2 keV), most likely produced by an accretion disk. The XMM-Newton observation carried out during the outburst revealed the presence of multiple absorption features in the soft X-ray emission that could be associated with the presence of an ionized absorber lying above the accretion disk, as observed in many high inclination, low mass X-ray binaries. The XMM-Newton data also revealed the presence of partial and rectangular X-ray eclipses (lasting about 820 s) together with dips. The rectangular eclipses can be associated with increases in the overall absorption column density in the direction of the source. The detection of two consecutive X-ray eclipses in the XMM-Newton data allowed us to estimate the source orbital period at Porb = 22620.5+2.0-1.8 s (1σ confidence level).

  11. The 2013 outburst of a transient very faint X-ray binary, 23" from Sgr A*

    Koch, E W; Heinke, C O; Mori, K; Rea, N; Degenaar, N; Haggard, D; Wijnands, R; Ponti, G; Miller, J M; Yusef-Zadeh, F; Dufour, F; Cotton, W D; Baganoff, F K; Reynolds, M T

    2014-01-01

    We report observations using the Swift/XRT, NuSTAR, and Chandra X-ray telescopes of the transient X-ray source CXOGC J174540.0-290005, during its 2013 outburst. Due to its location in the field of multiple observing campaigns targeting Sgr A*, this is one of the best-studied outbursts of a very faint X-ray binary (VFXB; peak $L_X<10^{36}$ erg/s) yet recorded, with detections in 173 ks of X-ray observations over 50 days. VFXBs are of particular interest, due to their unusually low outburst luminosities and time-averaged mass transfer rates, which are hard to explain within standard accretion physics and binary evolution. The 2013 outburst of CXOGC J174540.0-290005 peaked at $L_X$(2-10 keV)=$5.0\\times10^{35}$ erg/s, and all data above $10^{34}$ ergs/s were well-fit by an absorbed power-law of photon index $\\sim1.7$, extending from 2 keV out to $\\sim$70 keV. We discuss the implications of these observations for the accretion state of CXOGC J174540.0-290005.

  12. The role of metallicity in high mass X-ray binaries in galaxy formation models

    Artale, M C; Tissera, P B

    2014-01-01

    Context: Recent theoretical works claim that high-mass X-ray binaries (HMXBs) could have been important sources of energy feedback into the interstellar and intergalactic media, playing a major role in the reionization epoch. A metallicity dependence of the production rate or luminosity of the sources is a key ingredient generally assumed but not yet probed. Aims: Our goal is to explore the relation between the X-ray luminosity (Lx) and star formation rate of galaxies as a possible tracer of a metallicity dependence of the production rates and/or X-ray luminosities of HMXBs. Methods: We developed a model to estimate the Lx of star forming galaxies based on stellar evolution models which include metallicity dependences. We applied our X-ray binary models to galaxies selected from hydrodynamical cosmological simulations which include chemical evolution of the stellar populations in a self-consistent way. Results: Our models successfully reproduce the dispersion in the observed relations as an outcome of the com...

  13. Discovery of an X-ray Emitting Contact Binary System 2MASS J11201034$-$2201340

    Hu, Chin-Ping; Chou, Yi; Liu, L; Qian, S -B; Hui, C Y; Kong, Albert K H; Lin, L C C; Tam, P H T; Li, K L; Ngeow, Chow-Choong; Chen, W P; Ip, Wing-Huen

    2016-01-01

    We report the detection of orbital modulation, a model solution, and X-ray properties of a newly discovered contact binary, 2MASS J11201034$-$2201340. We serendipitously found this X-ray point source outside the error ellipse when searching for possible X-ray counterparts of $\\gamma$-ray millisecond pulsars among the unidentified objects detected by the {\\it Fermi Gamma-ray Space Telescope}. The optical counterpart of the X-ray source (unrelated to the $\\gamma$-ray source) was then identified using archival databases. The long-term CRTS survey detected a precise signal with a period of $P=0.28876208(56)$ days. A follow-up observation made by the SLT telescope of Lulin Observatory revealed the binary nature of the object. Utilizing archived photometric data of multi-band surveys, we construct the spectral energy distribution, which is well fitted by a K2V spectral template. The fitting result of the orbital profile using the Wilson--Devinney code suggests that 2MASS J11201034-2201340 is a short-period A-type c...

  14. A new gamma-ray loud, eclipsing low-mass X-ray binary

    Strader, Jay; Chomiuk, Laura; Heinke, Craig O; Udalski, Andrzej; Peacock, Mark; Shishkovsky, Laura; Tremou, Evangelia

    2016-01-01

    We report the discovery of an eclipsing low-mass X-ray binary at the center of the 3FGL error ellipse of the unassociated Fermi/Large Area Telescope gamma-ray source 3FGL J0427.9-6704. Photometry from OGLE and the SMARTS 1.3-m telescope and spectroscopy from the SOAR telescope have allowed us to classify the system as an eclipsing low-mass X-ray binary (P = 8.8 hr) with a main sequence donor and a neutron star accretor. Broad double-peaked H and He emission lines suggest the ongoing presence of an accretion disk. Remarkably, the system shows shows separate sets of absorption lines associated with the accretion disk and the secondary, and we use their radial velocities to find evidence for a massive (~ 1.8-1.9 M_sun) neutron star primary. In addition to a total X-ray eclipse of duration ~ 2200 s observed with NuSTAR, the X-ray light curve also shows properties similar to those observed among known transitional millisecond pulsars: short-term variability, a hard power-law spectrum (photon index ~ 1.7), and a co...

  15. The X-ray luminosity functions of field low-mass X-ray binaries in early-type galaxies: Evidence for a stellar age dependence

    Lehmer, B. D.; Tzanavaris, P.; Yukita, M. [The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Berkeley, M.; Basu-Zych, A.; Hornschemeier, A. E.; Ptak, A. [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Zezas, A. [Physics Department, University of Crete, Heraklion (Greece); Alexander, D. M. [Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Bauer, F. E. [Pontificia Universidad Catolica de Chile, Departamento de Astronomia y Astrofisica, Casilla 306, Santiago 22 (Chile); Brandt, W. N. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Fragos, T. [IESL, Foundation for Research and Technology, 71110 Heraklion, Crete (Greece); Kalogera, V. [Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Sivakoff, G. R. [Department of Physics, University of Alberta, CCIS 4-183 Edmonton, AB T6G 2E1 (Canada)

    2014-07-01

    We present direct constraints on how the formation of low-mass X-ray binary (LMXB) populations in galactic fields depends on stellar age. In this pilot study, we utilize Chandra and Hubble Space Telescope (HST) data to detect and characterize the X-ray point source populations of three nearby early-type galaxies: NGC 3115, 3379, and 3384. The luminosity-weighted stellar ages of our sample span ≈3-10 Gyr. X-ray binary population synthesis models predict that the field LMXBs associated with younger stellar populations should be more numerous and luminous per unit stellar mass than older populations due to the evolution of LMXB donor star masses. Crucially, the combination of deep Chandra and HST observations allows us to test directly this prediction by identifying and removing counterparts to X-ray point sources that are unrelated to the field LMXB populations, including LMXBs that are formed dynamically in globular clusters, Galactic stars, and background active galactic nuclei/galaxies. We find that the 'young' early-type galaxy NGC 3384 (≈2-5 Gyr) has an excess of luminous field LMXBs (L {sub X} ≳ (5-10) × 10{sup 37} erg s{sup –1}) per unit K-band luminosity (L{sub K} ; a proxy for stellar mass) than the 'old' early-type galaxies NGC 3115 and 3379 (≈8-10 Gyr), which results in a factor of ≈2-3 excess of L {sub X}/L{sub K} for NGC 3384. This result is consistent with the X-ray binary population synthesis model predictions; however, our small galaxy sample size does not allow us to draw definitive conclusions on the evolution field LMXBs in general. We discuss how future surveys of larger galaxy samples that combine deep Chandra and HST data could provide a powerful new benchmark for calibrating X-ray binary population synthesis models.

  16. The X-ray luminosity functions of field low-mass X-ray binaries in early-type galaxies: Evidence for a stellar age dependence

    We present direct constraints on how the formation of low-mass X-ray binary (LMXB) populations in galactic fields depends on stellar age. In this pilot study, we utilize Chandra and Hubble Space Telescope (HST) data to detect and characterize the X-ray point source populations of three nearby early-type galaxies: NGC 3115, 3379, and 3384. The luminosity-weighted stellar ages of our sample span ≈3-10 Gyr. X-ray binary population synthesis models predict that the field LMXBs associated with younger stellar populations should be more numerous and luminous per unit stellar mass than older populations due to the evolution of LMXB donor star masses. Crucially, the combination of deep Chandra and HST observations allows us to test directly this prediction by identifying and removing counterparts to X-ray point sources that are unrelated to the field LMXB populations, including LMXBs that are formed dynamically in globular clusters, Galactic stars, and background active galactic nuclei/galaxies. We find that the 'young' early-type galaxy NGC 3384 (≈2-5 Gyr) has an excess of luminous field LMXBs (L X ≳ (5-10) × 1037 erg s–1) per unit K-band luminosity (LK ; a proxy for stellar mass) than the 'old' early-type galaxies NGC 3115 and 3379 (≈8-10 Gyr), which results in a factor of ≈2-3 excess of L X/LK for NGC 3384. This result is consistent with the X-ray binary population synthesis model predictions; however, our small galaxy sample size does not allow us to draw definitive conclusions on the evolution field LMXBs in general. We discuss how future surveys of larger galaxy samples that combine deep Chandra and HST data could provide a powerful new benchmark for calibrating X-ray binary population synthesis models.

  17. A relativistically smeared spectrum in the neutron star X-ray binary 4U 1705-44: looking at the inner accretion disc with X-ray spectroscopy

    Di Salvo, C.; D'Aí, A.; Iaria, R.; Burderi, L.; Dovčiak, Michal; Karas, Vladimír; Matt, G.; Papitto, A.; Piraino, S.; Riggio, A.; Robba, N.R.; Santangelo, A.

    2009-01-01

    Roč. 398, č. 4 (2009), s. 2022-2027. ISSN 0035-8711 Institutional research plan: CEZ:AV0Z10030501 Keywords : line formation * individual stars4U 1705−44 * X-ray binaries Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.103, year: 2009

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

    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.; 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.

    2015-01-01

    We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution gratings spectral dataset of the Sigma Ori Aa binary system. The four observations, obtained with Chandra ACIS HETGS, have a total exposure time of approximately 479 kiloseconds and provide nearly complete binary phase coverage. Variability of the total X-ray flux in the range 5-25 angstroms is confirmed, with maximum amplitude of about plus or minus 15 percent within a single approximately 125 kiloseconds observation. Periods of 4.76 days and 2.04 days are found in the total X-ray flux, as well as an apparent overall increase in flux level throughout the 9-day observational campaign. Using 40 kiloseconds contiguous spectra derived from the original observations, we investigate 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 phi equals 0.0 when the secondary Aa2 is at inferior conjunction. We use the results of an SPH radiative transfer code model, customized for this project, to relate the presence of a low density cavity in the primary stellar wind embedded shock that is associated with the secondary star to the emission line width variability.

  19. A Coordinated X-ray and Optical Campaign of the Nearby Massive Binary $\\delta$ Orionis Aa: II. X-ray Variability

    Nichols, J S; 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

    2015-01-01

    We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution spectral dataset of the $\\delta$ Orionis 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 5-25 $\\AA$ is confirmed, with maximum amplitude of about +/-15% within a single ~125 ks observation. Periods of 4.76d and 2.04d are found in the total X-ray flux, as well as an apparent overall increase in flux level throughout the 9-day observational campaign. Using 40 ks contiguous spectra derived from the original observations, we investigate 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 phase=0.0 when the seconda...

  20. The low-mass X-ray binary-millisecond radio pulsar birthrate problem revisited

    2010-01-01

    We investigate the birthrate problem for low-mass X-ray binaries(LMXBs) and millisecond radio pulsars(MRPs) in this paper.We consider intermediate-mass and low-mass X-ray binaries(I/LMXBs) to be the progenitors of MRPs,and calculate their evolutionary response to the cosmic star formation rate(SFR) both semi-analytically and numerically.With a typical value(1 Gyr) of the LMXB lifetime,one may expect comparable birthrates of LMXBs and MRPs,but the calculated number of LMXBs is an order of magnitude higher than that observed in the Galaxy.Instead,we suggest that the birthrate problem could be solved if most MRPs have evolved from faint to rather than bright LMXBs.The former may have a population of-104 in the Galaxy.

  1. Revisiting a fundamental test of the disc instability model for X-ray binaries

    Coriat, M; Dubus, G

    2012-01-01

    We revisit a core prediction of the disc instability model (DIM) applied to X-ray binaries. The model predicts the existence of a critical mass transfer rate, which depends on disc size, separating transient and persistent systems. We therefore selected a sample of 52 persistent and transient neutron star and black hole X-ray binaries and verified if observed persistent (transient) systems do lie in the appropriate stable (unstable) region of parameter space predicted by the model. We find that, despite the significant uncertainties inherent to this kind of studies, the data are in very good agreement with the theoretical expectations. We then discuss some individual cases that do not clearly fit into this main conclusion. Finally, we introduce the transientness parameter as a measure of the activity of a source and showed a clear trend of the average outburst recurrence time to decrease with transientness in agreement with the DIM predictions. We therefore conclude that, despite difficulties in reproducing t...

  2. Optical properties of High-Mass X-ray Binaries (HMXB) in the Small Magellanic Cloud

    Coe, M J; McGowan, K E; McBride, V A; Schurch, M P E; Townsend, L J; Galache, J L; Negueruela, I; Buckley, D

    2008-01-01

    The SMC represents an exciting opportunity to observe the direct results of tidal interactions on star birth. One of the best indicators of recent star birth activity is the presence of signicant numbers of High-Mass X-ray Binaries (HMXBs) - and the SMC has them in abundance! We present results from nearly 10 years of monitoring these systems plus a wealth of other ground-based optical data. Together they permit us to build a picture of a galaxy with a mass of only a few percent of the Milky Way but with a more extensive HMXB population. However, as often happens, new discoveries lead to some challenging puzzles - where are the other X-ray binaries (eg black hole systems) in the SMC? And why do virtually all the SMC HMXBs have Be starcompanions? The evidence arising from these extensive optical observations for this apparently unusual stellar evolution are discussed.

  3. The low-mass X-ray binary-millisecond radio pulsar birthrate problem revisited

    Hailang, Dai

    2009-01-01

    We investigate the birthrate problem for low-mass X-ray binaries (LMXBs) and millisecond radio pulsars (MRPs) in this paper. We consider intermediate-mass and low-mss X-ray binaries (I/LMXBs) as the progenitors of MRPs, and calculate their evolutionary response to the cosmic star formation rate (SFR) both semi-analytically and numerically. With typical value (~1 Gyr) of the LMXB lifetime, one may expect comparable birthrates of LMXBs and MRPs, but the calculated number of LMXBs is an order of magnitude higher than observed in the Galaxy. Instead, we suggest that the birthrate problem could be solved if most MRPs have evolved from faint rather bright LMXBs. The former may have a population of ~ 104 in the Galaxy.

  4. PROBING THE X-RAY BINARY POPULATIONS OF THE RING GALAXY NGC 1291

    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 ≈40% of the bulge sources and ≈25% of the ring sources showing >3σ long-term variability in their X-ray count rate. The X-ray colors suggest that a significant fraction of the bulge (≈75%) and ring (≈65%) sources are likely low-mass X-ray binaries (LMXBs). The spectra of the nuclear source indicate that it is a low-luminosity active galactic nucleus (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 ≈1.5 × 1037 and ≈2.2 × 1037 erg s–1 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 an 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 overdensity 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.

  5. Hydrodynamical winds from two-temperature plasma in X-ray binaries

    Lin, David J.; Misra, R.; Taam, Ronald E.

    2000-01-01

    Hydrodynamical winds from a spherical two-temperature plasma surrounding a compact object are constructed. The mass-loss rate is computed as a function of electron temperature, optical depth and luminosity of the sphere, the values of which can be constrained by the fitting of the spectral energy distributions for known X-ray binary systems. The sensitive dependence of the mass loss rate with these parameters leads to the identification of two distinct regions in the parameter space separatin...

  6. Inhomogeneous accretion discs and the soft states of black hole X-ray binaries

    Dexter, Jason; Quataert, Eliot

    2012-01-01

    Observations of black hole binaries (BHBs) have established a rich phenomenology of X-ray states. The soft states range from the low variability, accretion disc dominated thermal state (TD) to the higher variability, non-thermal steep power law state (SPL). The disc component in all states is typically modeled with standard thin disc accretion theory. However, this theory is inconsistent with optical/UV spectral, variability, and gravitational microlensing observations of active galactic nucl...

  7. Hot accretion flow with radiative cooling: state transitions in black hole X-ray binaries

    Wu, Mao-Chun; Xie, Fu-Guo; Yuan, Ye-Fei; Gan, Zhao-Ming

    2016-01-01

    We investigate state transitions in black hole X-ray binaries through different parameters by using two-dimensional axisymmetric hydrodynamical simulation method. For radiative cooling in hot accretion flow, we take into account the bremsstrahlung, synchrotron and synchrotron-self Comptonization self-consistently in the dynamics. Our main result is that the state transitions occur when the accretion rate reaches a critical value $\\dot M \\sim 3\\alpha\\ \\dot M_{\\rm Edd}$, above which cold and de...

  8. Understanding Black Hole X-ray Binaries: The Case of Cygnus X-1

    Pottschmidt, Katja

    2008-01-01

    Black Hole X-ray Binaries are known to display distinct emission states that differ in their X-ray spectra, their X-ray timing properties (on times scales less than 1 s) and their radio emission. In recent years monitoring observations, specially with NASA's Rossi X-ray Timing Explorer (RXTE), have provided us with detailed empirical modeling of the phenomenology of the different states as well as a unification scheme of the long term evolution of black holes, transient and persistent, in terms of these states. Observations of the persistent High Mass X-ray Binary (HMXB) Cygnus X-l have been at the forefront of learning about black hole states since its optical identification through a state transition in 1973. In this talk I will present in depth studies of several different aspects of the accretion process in this system. The main data base for these studies is an ongoing RXTE and Ryle radio telescope bi-weekly monitoring campaign that started in 1997. I will discuss high-resolution timing results, especially power spectra, which first gave rise to the Lorentzian description now widely used for black hole and neutron star binaries, and time lags, which we found to be especially well suited to identify state transitions. The evolution of spectral, timing, and radio parameters over years will be shown, including the rms-flux relation and the observation of a clearly correlated radio/x-ray flare. We also observed Cygnus X-1 with INTEGRAL, which allowed us to extend timing and spectral studies to higher energies, with XMM, which provided strong constraints on the parameters of the 6.4 keV iron fluorescence line, and with Chandra, which provided the most in depth study to date of the stellar wind in this system. Models based on the physical conditions in the accretion region are still mainly concentrated on the one or other of the observational areas but they are expanding: as an example I will review results from a jet model for the quantitative description of the

  9. The formation of black-holes in low-mass X-ray binaries

    S. F. Portegies Zwart; Verbunt, F.; Ergma, E.

    1997-01-01

    We calculate the formation rates of low-mass X-ray binaries with a black hole. Both a semi-analytic and a more detailed model predict formation rates two orders of magnitude lower than derived from the observations. Solution of this conundrum requires either that stars with masses less than 20M$_\\odot$ can evolve into a black hole, or that stellar wind from a member of a binary is accompanied by a much larger loss of angular momentum than hitherto assumed.

  10. Long-term variability of low-mass X-ray binaries

    Filippova E.

    2014-01-01

    Full Text Available We consider modulations of mass captured by the compact object from the companion star’s stellar wind in Low Mass X-ray Binaries with late type giants. Based on 3D simulations with two different hydrodynamic codes used Lagrangian and Eulerian approaches – the SPH code GADGET and the Eulerian code PLUTO, we conclude that a hydrodynamical interaction of the wind matter within a binary system even without eccentricity results in variability of the mass accretion rate with characteristic time-scales close to the orbital period. Observational appearances of this wind might be similar to that of an accretion disc corona/wind.

  11. DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY

    Seward, F. D. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Charles, P. A. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Foster, D. L. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa); Dickel, J. R.; Romero, P. S. [Department of Physics and Astronomy, University of New Mexico, 1919 Lomas Boulevard NE, Albuquerque, NM 87131 (United States); Edwards, Z. I.; Perry, M.; Williams, R. M. [Department of Earth and Space Sciences, Columbus State University, Coca Cola Space Science Center, 701 Front Avenue, Columbus, GA 31901 (United States)

    2012-11-10

    A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M {sub Sun}.

  12. The Reverberation Lag in the Low-mass X-ray Binary H1743-322

    De Marco, Barbara; Ponti, Gabriele

    2016-07-01

    The evolution of the inner accretion flow of a black hole X-ray binary during an outburst is still a matter of active research. X-ray reverberation lags are powerful tools for constraining disk–corona geometry. We present a study of X-ray lags in the black hole transient H1743-322. We compared the results obtained from analysis of all the publicly available XMM-Newton observations. These observations were carried out during two different outbursts that occurred in 2008 and 2014. During all the observations the source was caught in the hard state and at similar luminosities ({L}3-10{keV}/{L}{Edd}∼ 0.004). We detected a soft X-ray lag of ∼60 ms, most likely due to thermal reverberation. We did not detect any significant change of the lag amplitude among the different observations, indicating a similar disk–corona geometry at the same luminosity in the hard state. On the other hand, we observe significant differences between the reverberation lag detected in H1743-322 and in GX 339-4 (at similar luminosities in the hard state), which might indicate variations of the geometry from source to source.

  13. Isotropic Detectable X-ray Counterparts to Gravitational Waves from Neutron Star Binary Mergers

    Kisaka, Shota; Nakamura, Takashi

    2015-01-01

    Neutron star binary mergers are strong sources of gravitational waves (GWs). Promising electromagnetic counterparts are short gamma-ray bursts (GRBs) but the emission is highly collimated. We propose that the scattering of the long-lasting plateau emission in short GRBs by the merger ejecta produces nearly isotropic emission for $\\sim 10^4$ s with flux $10^{-10}-10^{-13}$ erg cm$^{-2}$ s$^{-1}$ in X-ray. This is detectable by wide field X-ray detectors such as ISS-Lobster, eROSITA and WF-MAXI, which are desired by the infrared and optical follow-ups to localize and measure the distance to the host galaxy. The scattered X-rays obtain linear polarization, which correlates with the jet direction, X-ray luminosity and GW polarizations. The activity of plateau emission is also a natural energy source of a macronova (or kilonova) detected in short GRB 130603B without the $r$-process radioactivity.

  14. IGR J17451-3022: a dipping and eclipsing low mass X-ray binary

    Bozzo, E; Romano, P; Papitto, A; Ferrigno, C; Motta, S; Zdziarski, A A; Pintore, F; Di Salvo, T; Burderi, L; Lazzati, D; Ponti, G; Pavan, L

    2016-01-01

    In this paper, we report on the available X-ray data collected by INTEGRAL, Swift, and XMM-Newton during the first outburst of the INTEGRAL transient IGR J17451-3022, discovered in 2014 August. The monitoring observations provided by the JEM-X instruments on-board INTEGRAL and the Swift/XRT showed that the event lasted for about 9 months and that the emission of the source remained soft for the entire period. The source emission is dominated by a thermal component (kT~1.2 keV), most likely produced by an accretion disk. The XMM-Newton observation carried out during the outburst revealed the presence of multiple absorption features in the soft X-ray emission that could be associated to the presence of an ionized absorber lying above the accretion disk, as observed in many high-inclination low mass X-ray binaries. The XMM-Newton data also revealed the presence of partial and rectangular X-ray eclipses (lasting about 820 s), together with dips. The latter can be associated with increases in the overall absorptio...

  15. Suzaku Observation of Be/X-ray Binary Pulsar EXO 2030+375

    Naik, Sachindra

    2014-01-01

    In this paper we study the timing and spectral properties of Be/X-ray binary pulsar EXO 2030+375 using a $Suzaku$ observation on 2012 May 23, during a less intense Type I outburst. Pulsations were clearly detected in the X-ray light curves at a barycentric period of 41.2852 s which suggests that the pulsar is spinning-up. The pulse profiles were found to be peculiar e.g. unlike that obtained from the earlier Suzaku observation on 2007 May 14. A single-peaked narrow profile at soft X-rays (0.5-10 keV range) changed to a double-peaked broad profile in 12-55 keV energy range and again reverted back to a smooth single-peaked profile at hard X-rays (55-70 keV range). The 1.0-100.0 keV broad-band spectrum of the pulsar was found to be well described by three continuum models such as (i) a partial covering high energy cut-off power-law model, (ii) a partially absorbed power-law with high-energy exponential rolloff and (iii) a partial covering Negative and Positive power law with EXponential (NPEX) continuum model. U...

  16. Faint X-ray Binaries and Their Optical Counterparts in M31

    Vulic, N; Barmby, P

    2014-01-01

    X-ray binaries (XRBs) are probes of both star formation and stellar mass, but more importantly remain one of the only direct tracers of the compact object population. To investigate the XRB population in M31, we utilized all 121 publicly available observations of M31 totalling over 1 Ms from $\\it{Chandra's}$ ACIS instrument. We studied 83 star clusters in the bulge using the year 1 star cluster catalogue from the Panchromatic Hubble Andromeda Treasury Survey. We found 15 unique star clusters that matched to 17 X-ray point sources within 1'' (3.8 pc). This population is composed predominantly of globular cluster low-mass XRBs, with one previously unidentified star cluster X-ray source. Star clusters that were brighter and more compact preferentially hosted an X-ray source. Specifically, logistic regression showed that the F475W magnitude was the most important predictor followed by the effective radius, while color (F475W$-$F814W) was not statistically significant. We also completed a matching analysis of 1566...

  17. Formation, disruption and energy output of Population III X-ray binaries

    Ryu, Taeho; Perna, Rosalba

    2015-01-01

    The first astrophysical objects shaped the cosmic environment by reionizing and heating the intergalactic medium (IGM). In particular, X-rays are very efficient at heating the IGM before it became completely ionized, an effect that can be measured through the 21 cm line of neutral hydrogen. High-mass X-ray binaries (HMXBs), known to be prolific X-ray sources in star-forming galaxies at lower redshifts, are prime candidates for driving the thermal evolution of the IGM at redshifts $z > 20$. Despite their importance, the formation efficiency of HMXBs from the first stellar populations is not well understood---as such, their collective X-ray emission and the subsequent imprint on the 21 cm signature are usually evaluated using free parameters. Using $N$-body simulations, we estimate the rate of HMXB formation via mutual gravitational interactions of nascent, small groups of the first stars (Pop III stars). We run two sets of calculations: one in which stars form in small groups of five in nearly Keplerian initia...

  18. The reverberation lag in the low mass X-ray binary H1743-322

    De Marco, B

    2016-01-01

    The evolution of the inner accretion flow of a black hole X-ray binary (BHXRB) during the outburst is still a matter of active research. X-ray reverberation lags are powerful tools to constrain the disk-corona geometry. We present a study of X-ray lags in the black hole transient H1743-322. We compared results obtained from the analysis of all the publicly available XMM-Newton observations. These observations were carried out during two different outbursts, happened in 2008 and 2014. During all the observations the source is caught in the hard state and at similar luminosities ($\\mathrm{L_{3-10\\ keV}/L_{Edd}\\sim 0.004}$). We detected a soft X-ray lag of $\\sim$60 ms, most likely due to thermal reverberation. We did not detect any significant change of the lag amplitude among the different observations, indicating a similar disk-corona geometry at the same luminosity in the hard state. On the other hand, we observe significant differences between the reverberation lag detected in H1743-322 and in GX 339-4 (at s...

  19. WATCHDOG: A Comprehensive All-Sky Database of Galactic Black Hole X-ray Binaries

    Tetarenko, B E; Heinke, C O; Gladstone, J C

    2015-01-01

    With the advent of more sensitive all-sky instruments, the transient Universe is being probed in greater depth than ever before. Taking advantage of available resources, we have established a comprehensive database of black hole (and black hole candidate) X-ray binary (BHXB) activity between 1996 and 2015 as revealed by all-sky instruments, scanning surveys, and select narrow-field X-ray instruments aboard the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), Monitor of All-Sky X-ray Image (MAXI), Rossi X-ray Timing Explorer (RXTE), and Swift telescopes; the Whole-sky Alberta Time-resolved Comprehensive black-Hole Database Of the Galaxy or WATCHDOG. Over the past two decades, we have detected 132 transient outbursts, tracked and classified behavior occurring in 47 transient and 10 persistently accreting BHs, and performed a statistical study on a number of outburst properties across the Galactic population. We find that outbursts undergone by BHXBs that do not reach the thermally dominant accretion ...

  20. Classification of compact binaries: an X-ray analog to the HR diagram

    Dil Vrtilek, Saeqa; Raymond, John C.; Gopalan, Giri; Boroson, Bram Seth; Bornn, Luke

    2016-06-01

    X-ray binary systems (XRBs), when examined in an appropriate coordinate system derived from X-ray spectral and intensity information, appear to cluster based on their compact object type. We introduce such a coordinate system, in which two coordinates are hardness ratios and the third is a broadband X-ray intensity. In Gopalan, Vrtilek, & Bornn (2015) we developed a Bayesian statistical model that estimates the probability that an XRB contains a black hole, non-pulsing neutron star, or pulsing neutron star, depending on its location in our coordinate space. In particular, we utilized a latent variable model in which the latent variables follow a Gaussian process prior distribution. Here we expand our work to incorporate systems where the compact object is a white dwarf: cataclysmic variables (CVs). The fact that the CVs also fall into a location spatially distinct from the other XRB types supports the use of X-ray color-color-intensity diagrams as 3-dimensional analogs to the Hertzsprung-Russell diagram for normal stars.

  1. DETECTION OF THE SECOND ECLIPSING HIGH-MASS X-RAY BINARY IN M 33

    Chandra data of the X-ray source [PMH2004] 47 were obtained in the ACIS Survey of M 33 (ChASeM33) in 2006. During one of the observations, the source varied from a high state to a low state and back, in two other observations it varied from a low state to respectively intermediate states. These transitions are interpreted as eclipse ingresses and egresses of a compact object in a high-mass X-ray binary (HMXB) system. The phase of mideclipse is given by HJD 245 3997.476 ± 0.006, the eclipse half angle is 30.06 ± 1.02. Adding XMM-Newton observations of [PMH2004] 47 in 2001 we determine the binary period to be 1.732479 ± 0.000027 days. This period is also consistent with ROSAT HRI observations of the source in 1994. No short-term periodicity compatible with a rotation period of the compact object is detected. There are indications for a long-term variability similar to that detected for Her X-1. During the high state the spectrum of the source is hard (power-law spectrum with photon index ∼0.85) with an unabsorbed luminosity of 2 x1037 erg s-1 (0.2-4.5 keV). We identify as an optical counterpart a V ∼ 21.0 mag star with T eff>19000 K, log(g)>2.5. The Canada-France-Hawaii Telescope optical light curves for this star show an ellipsoidal variation with the same period as the X-ray light curve. The optical light curve together with the X-ray eclipse can be modeled by a compact object with a mass consistent with a neutron star or a black hole in an HMXB. However, the hard power-law X-ray spectrum favors a neutron star as the compact object in this second eclipsing X-ray binary in M 33. Assuming a neutron star with a canonical mass of 1.4 M sun and the best-fit companion temperature of 33,000 K, a system inclination i = 72 deg. and a companion mass of 10.9 M sun are implied.

  2. Unification of Low Luminosity AGN and Hard State X-ray Binaries

    Connolly, S.

    2015-09-01

    We present X-ray spectral variability of four low accretion rate and low luminosity AGN (LLAGN)- M81, NGC 1097, NGC 1052 and NGC 3998 - as observed by Swift and RXTE. All four objects were selected due to having spectra which hardened with increasing count rate, converse to the 'softer when brighter' behaviour normally observed in AGN with higher accretion rates. The spectra were summed in flux bins and fitted with a variety of models. A simple absorbed power law model was found to fit the spectra of M81, NGC 1097 and NGC 3998 well, whilst NGC 1052 required a partially covered power law model. In all four cases, the most likely cause of spectral variability is found to be hardening of the photon index of the power law component with increasing luminosity. Such a correlation has been seen previously within samples of low accretion rate AGN but in only one case has it been seen within observations of a single AGN. Here we show that such behaviour may be very common in LLAGN. A similar anticorrelation is found in X-ray binary systems in the 'hard state', at low accretion rates similar to those of the LLAGN discussed here. Our observations thus imply that LLAGN are the active galaxy equivalent of hard state X-ray binaries.

  3. On the Formation of Galactic Black Hole Low-Mass X-ray Binaries

    Wang, Chen; Li, Xiang-Dong

    2016-01-01

    Currently, there are 24 black hole (BH) X-ray binary systems that have been dynamically confirmed in the Galaxy. Most of them are low-mass X-ray binaries (LMXBs) comprised of a stellar-mass BH and a low-mass donor star. Although the formation of these systems has been extensively investigated, some crucial issues remain unresolved. The most noticeable one is that, the low-mass companion has difficulties in ejecting the tightly bound envelope of the massive primary during the spiral-in process. While initially intermediate-mass binaries are more likely to survive the common envelope (CE) evolution, the resultant BH LMXBs mismatch the observations. In this paper, we use both stellar evolution and binary population synthesis to study the evolutionary history of BH LMXBs. We test various assumptions and prescriptions for the supernova mechanisms that produce BHs, the binding energy parameter, the CE efficiency, and the initial mass distributions of the companion stars. We obtain the birthrate and the distribution...

  4. On the formation of galactic black hole low-mass X-ray binaries

    Wang, Chen; Jia, Kun; Li, Xiang-Dong

    2016-03-01

    Currently, there are 24 black hole (BH) X-ray binary systems that have been dynamically confirmed in the Galaxy. Most of them are low-mass X-ray binaries (LMXBs) comprised of a stellar-mass BH and a low-mass donor star. Although the formation of these systems has been extensively investigated, some crucial issues remain unresolved. The most noticeable one is that, the low-mass companion has difficulties in ejecting the tightly bound envelope of the massive primary during the spiral-in process. While initially intermediate-mass binaries are more likely to survive the common envelope (CE) evolution, the resultant BH LMXBs mismatch the observations. In this paper, we use both stellar evolution and binary population synthesis to study the evolutionary history of BH LMXBs. We test various assumptions and prescriptions for the supernova mechanisms that produce BHs, the binding energy parameter, the CE efficiency and the initial mass distributions of the companion stars. We obtain the birthrate and the distributions of the donor mass, effective temperature and orbital period for the BH LMXBs in each case. By comparing the calculated results with the observations, we put useful constraints on the aforementioned parameters. In particular, we show that it is possible to form BH LMXBs with the standard CE scenario if most BHs are born through failed supernovae.

  5. Were most Low Mass X ray Binaries born in Globular Clusters?

    D'Antona, F; Ventura, P; Antona, Francesca D'; Teodorescu, Anamaria; Ventura, Paolo

    2006-01-01

    We summarize the status of art of the secular evolution of low mass X-ray binaries (LMXBs) and take a close look at the orbital period distribution of LMXBs and of binary millisecond pulsars (MSP), in the hypothesis that this latter results from the LMXB evolution. The deficiency of systems below the period gap, which in cataclysmic binaries occurs between ~ 2 and 3 hr, points to a very different secular evolution of LMXBs with respect to their counterparts containing a white dwarf compact object. The presence of several ultrashort period LMXBs (some of which are also X-ray millisecond pulsars), the important fraction of binary MSPs at periods between 0.1 and 1 day, the periods (26 and 32hr) of two ``interacting'' MSPs in Globular Clusters are other pieces of the puzzle in the period distribution. We consider the possible explanations for these peculiarities, and point out that Grindlay's old proposal that all (most of) LMXBs in the field were originally born in globular clusters must be carefully reconsidere...

  6. Confirmation of IGR J01363 plus 6610 as a Be X-Ray Binary with Very Low Quiescent X-Ray Luminosity

    Tomsick, John A.; Heinke, Craig; Halpern, Jules; Kaaret, Philip; Chaty, Sylvain; Rodriguez, Jerome; Bodaghee, Arash

    2011-01-01

    The field containing the candidate High Mass X-ray Binary IGR J01 363+6610 was observed by XMM-Newton on 2009 July 31 for 28 ks. A Be star was previously suggested as the possible counterpart of the INTEGRAL source, and although Chandra, during a 2007 observation, did not detect an X-ray source at the position of the Be star, we find a variable source (XMMU 101 3549.5+661243) with an average X-ray flux of 2 x 10(exp -13)ergs/sq cm/s (0.2-12 keV, unabsorbed) at this position with XMM-Newton. The spectrum of this source is consistent with a hard power law with a photon index of r = 1.4+/-0.3 and a column density of N(sub H) = (15(+0.7/-0.5)) x 10(exp 22)/sq cm (90% confidence errors). These results, along with our optical investigation of other X-ray sources in the field, make the association with the Be star very likely, and the 2 kpc distance estimate for the Be star indicates an X-ray luminosity of 9.1 x 10(exp 31) ergs/s. This is lower than typical for a Be X-ray binary, and the upper limit on the luminosity was even lower ( < 1.4 x 10(exp 3)ergs/s assuming the same spectral model) during the Chandra observation. We discuss possible implications of the very low quiescent luminosity for the physical properties of IGR 101363+6610.

  7. X-ray accretion signatures in the close CTTS binary V4046 Sgr

    Günther, H; Schmitt, J H M M; Robrade, J; Ness, J U

    2006-01-01

    We present Chandra HETGS observations of the classical T Tauri star (CTTS) V4046 Sgr. The He-like triplets of O VII, Ne IX, and Si XIII are clearly detected. Similar to the CTTS TW Hya and BP Tau, the forbidden lines of O VII and Ne IX are weak compared to the intercombination line, indicating high plasma densities in the X-ray emitting regions. The Si XIII triplet, however, is within the low-density limit, in agreement with the predictions of the accretion funnel infall model with an additional stellar corona. V4046 Sgr is the first close binary exhibiting these features. Together with previous high-resolution X-ray data on TW Hya and BP Tau, and in contrast to T Tau, now three out of four CTTS show evidence of accretion funnels.

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

    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.

  9. Swift detection of an intermediately long X-ray burst from the very faint X-ray binary XMMU J174716.1-281048

    Degenaar, N; Kaur, R

    2011-01-01

    We report on the Swift detection of a thermonuclear X-ray burst from the very-faint quasi-persistent neutron star X-ray binary XMMU J174716.1-281048, which triggered the satellite's Burst Alert Telescope (BAT) on 2010 August 13. Analysis of the BAT spectrum yields an observed bolometric peak flux of ~4.5E-8 erg/cm2/s, from which we infer a source distance of <8.4 kpc. Follow-up observations with Swift's X-ray Telescope (XRT) suggest that the event had a duration of ~3 h, and classifies as an intermediately long X-ray burst. This is only the second X-ray burst ever reported from this source. Inspection of Swift/XRT observations performed between 2007-2010 suggests that the 2-10 keV accretion luminosity of the system is only ~5E34 erg/s for an assumed distance of 8.4 kpc. Despite being transient, XMMU J174716.1-281048 appears to have been continuously active since its discovery in 2003.

  10. The X-ray luminosity function of low mass X-ray binaries in early-type galaxies, their metal-rich, and metal-poor globular clusters

    Peacock, Mark B

    2015-01-01

    We present the X-ray luminosity function (XLF) of low mass X-ray binaries (LMXBs) in the globular clusters (GCs) and fields of seven early-types galaxies. These galaxies are selected to have both deep Chandra observations, which allow their LMXB populations to be observed to X-ray luminosities of $10^{37}-10^{38}$ erg/s, and HST optical mosaics which enable the X-ray sources to be separated into field LMXBs, GC LMXBs, and contaminating background and foreground sources. We find that at all luminosities the number of field LMXBs per stellar mass is similar in these galaxies. This suggests that the field LMXB populations in these galaxies are not effected by the GC specific frequency, and that properties such as binary fraction and the stellar initial mass function are either similar across the sample, or change in a way that does not effect the number of LMXBs. We compare the XLF of the field LMXBs to that of the GC LMXBs and find that they are significantly different with a p-value of $3\\times10^{-6}$ (equiva...

  11. Si K Edge Structure and Variability in Galactic X-Ray Binaries

    Schulz, Norbert S.; Corrales, Lia; Canizares, Claude R.

    2016-08-01

    We survey the Si K edge structure in various absorbed Galactic low-mass X-ray binaries (LMXBs) to study states of silicon in the inter- and circum-stellar medium. The bulk of these LMXBs lie toward the Galactic bulge region and all have column densities above 1022 cm‑2. The observations were performed using the Chandra High Energy Transmission Grating Spectrometer. The Si K edge in all sources appears at an energy value of 1844 ± 0.001 eV. The edge exhibits significant substructure that can be described by a near edge absorption feature at 1849 ± 0.002 eV and a far edge absorption feature at 1865 ± 0.002 eV. Both of these absorption features appear variable with equivalent widths up to several mÅ. We can describe the edge structure using several components: multiple edge functions, near edge absorption excesses from silicates in dust form, signatures from X-ray scattering optical depths, and a variable warm absorber from ionized atomic silicon. The measured optical depths of the edges indicate much higher values than expected from atomic silicon cross sections and interstellar medium abundances, and they appear consistent with predictions from silicate X-ray absorption and scattering. A comparison with models also indicates a preference for larger dust grain sizes. In many cases, we identify Si xiii resonance absorption and determine ionization parameters between log ξ = 1.8 and 2.8 and turbulent velocities between 300 and 1000 km s‑1. This places the warm absorber in close vicinity of the X-ray binaries. In some data, we observe a weak edge at 1.840 keV, potentially from a lesser contribution of neutral atomic silicon.

  12. WATCHDOG: A Comprehensive All-sky Database of Galactic Black Hole X-ray Binaries

    Tetarenko, B. E.; Sivakoff, G. R.; Heinke, C. O.; Gladstone, J. C.

    2016-02-01

    With the advent of more sensitive all-sky instruments, the transient universe is being probed in greater depth than ever before. Taking advantage of available resources, we have established a comprehensive database of black hole (and black hole candidate) X-ray binary (BHXB) activity between 1996 and 2015 as revealed by all-sky instruments, scanning surveys, and select narrow-field X-ray instruments on board the INTErnational Gamma-Ray Astrophysics Laboratory, Monitor of All-Sky X-ray Image, Rossi X-ray Timing Explorer, and Swift telescopes; the Whole-sky Alberta Time-resolved Comprehensive black-Hole Database Of the Galaxy or WATCHDOG. Over the past two decades, we have detected 132 transient outbursts, tracked and classified behavior occurring in 47 transient and 10 persistently accreting BHs, and performed a statistical study on a number of outburst properties across the Galactic population. We find that outbursts undergone by BHXBs that do not reach the thermally dominant accretion state make up a substantial fraction (∼40%) of the Galactic transient BHXB outburst sample over the past ∼20 years. Our findings suggest that this “hard-only” behavior, observed in transient and persistently accreting BHXBs, is neither a rare nor recent phenomenon and may be indicative of an underlying physical process, relatively common among binary BHs, involving the mass-transfer rate onto the BH remaining at a low level rather than increasing as the outburst evolves. We discuss how the larger number of these “hard-only” outbursts and detected outbursts in general have significant implications for both the luminosity function and mass-transfer history of the Galactic BHXB population.

  13. Star formation history and X-ray binary populations: the case of the Large Magellanic Cloud

    Antoniou, V.; Zezas, A.

    2016-06-01

    In this work we investigate the link between high-mass X-ray binaries (HMXBs) and star formation in the Large Magellanic Cloud (LMC), our nearest star-forming galaxy. Using optical photometric data, we identify the most likely counterpart of 44 X-ray sources. Among the 40 HMXBs classified in this work, we find 33 Be/X-ray binaries (Be-XRBs), and 4 supergiant XRBs. Using this census and the published spatially resolved star formation history map of the LMC, we find that the HMXBs (and as expected the X-ray pulsars) are present in regions with star formation bursts ∼6-25 Myr ago, in contrast to the Small Magellanic Cloud (SMC), for which this population peaks at later ages (∼25-60 Myr ago). We also estimate the HMXB production rate to be equal to one system per ∼43.5× 10-3 M⊙ yr-1 or one system per ∼143M⊙ of stars formed during the associated star formation episode. Therefore, the formation efficiency of HMXBs in the LMC is ∼17 times lower than that in the SMC. We attribute this difference primarily in the different ages and metallicity of the HMXB populations in the two galaxies. We also set limits on the kicks imparted on the neutron star during the supernova explosion. We find that the time elapsed since the supernova kick is ∼3 times shorter in the LMC than the SMC. This in combination with the average offsets of the HMXBs from their nearest star clusters results in ∼4 times faster transverse velocities for HMXBs in the LMC than in the SMC.

  14. Insights into the High-Mass X-ray Binary Population of the Magellanic Clouds

    Antoniou, V.; Zezas, A.; Hatzidimitriou, D.; Kalogera, V.

    2013-09-01

    In contrast to the Small Magellanic Cloud (SMC), the Large Magellanic Cloud (LMC), our nearest starforming galaxy with metallicity between the Galaxy and the SMC, has received little attention in X-rays so far. With the aim to compare the accreting X-ray binary (XRB) populations in two of our nearest star-forming galaxies, we recently compiled the most complete census of high-mass X-ray binaries (HMXBs) in the LMC. We found 43 members of which 13 are XRB pulsars, while we also identified their most likely optical counterpart (previously, half of these sources lacked an identification). Using this census, we investigated the link between the young accreting XRBs and their parent stellar populations. It was known that HMXBs can be used as star-formation (SF) rate indicators, but these first studies have been focused only on bright systems (Galaxy: >1038 erg s-1, Magellanic Clouds: >1036 erg s-1) and SF values for the whole galaxy. By including Magellanic Cloud sources with X-ray luminosities at least two order of magnitudes fainter than the above limits and by utilizing the detailed, spatially resolved, SF history maps of these galaxies, we were able to provide observational constraints on ill-understood parameters related to their formation and evolution (such as the kick velocities imparted into the neutron star during the supernova explosion) and to derive their formation efficiency. This work was mainly supported by the National Aeronautics and Space Administration under Grant No. NNX10AH47G issued through the Astrophysics Data Analysis Program.

  15. Displacement of X-ray binaries: constraints on the natal kicks

    Zuo, Zhao-Yu

    2015-01-01

    Context. This work uses the measured luminosity vs. displacement (LX vs. R) distribution of high-mass X-ray binaries (HMXBs) to constrain the dispersion of kick velocity σkick, which is an important parameter affecting the system velocity of a binary, and hence its spatial offset from the point of origin. Aims: The aim is to constrain the natal kicks and discriminate between models by comparing the observed LX vs. R distributions with the theoretical simulations. Methods: Using an up-to-date evolutionary population synthesis technique, the spatial offsets of HMXBs are modeled for a range of theoretical models describing the natal kicks, including different choices of the dispersion of kick velocity σkick, as well as different theoretical treatments for black hole (BH) natal kicks. Results: The study shows that the value of σkick for neutron stars (NSs) is constrained to be greater than ~100 km s-1, while σkick on the order of several tens of km s-1 may be excluded, though a low or absent natal kick for electron capture supernovae NSs is permitted. In particular, BH natal kicks are found not indispensable to account for the LX vs. R distributions. It is more interesting that full BH natal kicks (i.e., similar to those that NSs may receive) are likely to be ruled out in this study, which is in contrast with the recent finding to explain the observed distribution of low-mass X-ray binaries hosting BHs.

  16. The donor star winds in High-Mass X-ray Binaries

    Oskinova, Lida

    2014-10-01

    High-mass X-ray binaries (HMXBs) are essential astrophysical laboratories. These objects represent an advanced stage in the evolution of massive binary systems, after the initially more massive star has already collapsed in a supernova explosion, but its remnant, a neutron star or black hole, remains gravitationally bound. The stellar wind from the OB-type donor is partially accreted onto its compact companion powering its relatively high X-ray luminosity. Since HMXBs accrete from the stellar wind, parameters such as the donor's mass-loss rate, the velocity of the wind, and its clumpiness are of fundamental importance.This proposal takes advantage of the unique capabilities of HST/STIS for UV spectroscopy. We focus on the most populous in the Galaxy class of those HMXBs where the stellar wind of the OB donor is directly accreted onto a neutron star. Recently, a new sub-class of HMXBs - "supergiant fast X-ray transients" - was discovered. It has been proposed that these enigmatic objects can be explained by the specific properties of their donor-star winds. The only way to validate or disprove this hypothesis is by a studying the wind diagnostics lines in the UV spectra of donor stars. The observations proposed here will, for the first time, provide the UV spectra of this important new type of accreting binaries. Our state-of-the art non-LTE expanding stellar atmospheres and 3-D stellar wind simulations allow thorough exploitation of the STIS spectra. As a result we will obtain the wind parameters for a representative sample of six Galactic HMXBs, thus heightening our knowledge thereof considerably.

  17. Evolution of Low-Mass X-ray Binaries: the Effect of Donor Evaporation

    Jia, Kun

    2016-01-01

    Millisecond pulsars (MSPs) are thought to originate from low-mass X-ray binaries (LMXBs). The discovery of eclipsing radio MSPs including redbacks and black widows indicates that evaporation of the donor star by the MSP's irradiation takes place during the LMXB evolution. In this work, we investigate the effect of donor evaporation on the secular evolution of LMXBs, considering different evaporation efficiencies and related angular momentum loss. We find that for widening LMXBs, the donor star leaves a less massive white dwarf than without evaporation; for contracting systems, evaporation can speed up the evolution, resulting in dynamically unstable mass transfer and possibly the formation of isolated MSPs.

  18. Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

    Cantrell, Andrew Glenn

    We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

  19. Spectral Properties of the X-ray Binary Pulsar LMC X-4 during Different Intensity States

    S. Naik; B. Paul

    2002-03-01

    We present spectral variations of the binary X-ray pulsar LMC X-4 observed with the RXTE/PCA during different phases of its 30.5 day long third period. Only out-of-eclipse data were used for this study. The 3–25 keV spectrum, modeled with high energy cut-off power-law and iron line emission is found to show strong dependence on the intensity state. Correlations between the Fe line emission flux and different parameters of the continuum are presented here.

  20. The mysterious sdO X-ray binary BD+37 442

    Heber, U; Irrgang, A; Schneider, D; Barbu-Barna, I; Mereghetti, S; La Palombara, N

    2014-01-01

    Pulsed X-ray emission in the luminous, helium-rich sdO BD+37 442 has recently been discovered (La Palombara et al., 2012). It was suggested that the sdO star has a neutron star or white dwarf companion with a spin period of 19.2 s. After HD 49798, which has a massive white dwarf companion spinning at 13.2 s in an 1.55 day orbit, this is only the second O-type subdwarf from which X-ray emission has been detected. We report preliminary results of our ongoing campaign to obtain time-resolved high-resolution spectroscopy using the CAFE instrument at Calar Alto observatory and SARG at the Telescopio Nationale Galileo. Atmospheric parameters were derived via a quantitative NLTE spectral analysis. The line fits hint at an unusually large projected rotation velocity. Therefore it seemed likely that BD+37 442 is a binary similar to HD 49798 and that the orbital period is also similar. The level of X-ray emission from BD+37 442 could be explained by accretion from the sdO wind by a neutron star orbiting at a period of ...

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

    Bozzo, E; Feldmeier, A; Falanga, M

    2016-01-01

    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 non-stationary 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 time scale of several hours), the transition of the system through all different accretion regimes that are triggered by the intrinsic variations in the density and velocity of the non-stationary wind. Th...

  2. Discovery and modelling of disc precession in the M31 X-ray binary Bo 158?

    Barnard, R; Haswell, C A; Kolb, U; Murray, J R

    2005-01-01

    The low mass X-ray binary (LMXB) associated with the M31 globular cluster Bo 158 is known to exhibit intensity dips on a ~2.78 hr period. This is due to obscuration of the X-ray source on the orbital period by material on the outer edge of the accretion disc. However, the depth of dipping varied from <10% to \\~83% in three archival XMM-Newton observations of Bo 158. Previous work suggested that the dip depth was anticorrelated with the X-ray luminosity. However, we present results from three new XMM-Newton observations that suggest that the evolution of dipping is instead due to precession of the accretion disc. Such precession is expected in neutron star LMXBs with mass ratios <0.3 (i.e. with orbital periods <4 hr), such as the Galactic dipping LMXB 4U 1916-053. We simulated the accretion disc of Bo 158 using cutting-edge 3D smoothed particle hydrodynamics (SPH), and using the observed parameters. Our results show disc variability on two time-scales. The disc precesses in a prograde direction on a p...

  3. Intermittent dipping in a low-mass X-ray Binary

    Galloway, Duncan K; Upjohn, James; Stuart, Matthew

    2016-01-01

    Periodic dips observed in approx. 20% of low-mass X-ray binaries are thought to arise from obscuration of the neutron star by the outer edge of the accretion disk. We report the detection with the Rossi X-ray Timing Explorer of two dipping episodes in Aql X-1, not previously a known dipper. The X-ray spectrum during the dips exhibited an elevated neutral column density, by a factor between 1 and almost two orders of magnitude. Dips were not observed in every cycle of the 18.95-hr orbit, so that the estimated frequency for these events is 0.10 (+0.07,-0.05)/cycle. This is the first confirmed example of intermittent dipping in such a system. Assuming that the dips in Aql X-1 occur because the system inclination is intermediate between the non-dipping and dipping sources, implies a range of 72-79 deg. for the source. This result lends support for the presence of a massive (> 2 M_sun) neutron star in Aql X-1, and further implies that approx. 30 additional LMXBs may have inclinations within this range, raising the...

  4. Analysis of the Quiescent Low-Mass X-ray Binary Population in Galactic Globular Clusters

    Heinke, C O; Lugger, P M; Cohn, H N; Edmonds, P D; Lloyd, D A; Cool, A M

    2003-01-01

    Quiescent low-mass X-ray binaries (qLMXBs) containing neutron stars have been identified in several globular clusters using Chandra or XMM X-ray observations, using their soft thermal spectra. We report a complete census of the qLMXB population in these clusters, identifying three additional probable qLMXBs in NGC 6440. We conduct several analyses of the qLMXB population, and compare it with the harder, primarily CV, population of low-luminosity X-ray sources with 10^31

  5. Metallicity dependence of high-mass X-ray binary populations

    Douna, V. M.; Pellizza, L. J.; Mirabel, I. F.; Pedrosa, S. E.

    2015-07-01

    Context. High-mass X-ray binaries (HMXBs) might have contributed a non-negligible fraction of the energy feedback to the interstellar and intergalactic media at high redshift, becoming important sources for the heating and ionization history of the Universe. However, the importance of this contribution depends on the hypothesized increase in the number of HMXBs formed in low-metallicity galaxies and in their luminosities. Aims: In this work we test the aforementioned hypothesis, and quantify the metallicity dependence of HMXB population properties. Methods: We compile from the literature a large set of data on the sizes and X-ray luminosities of HMXB populations in nearby galaxies with known metallicities and star formation rates. We use Bayesian inference to fit simple Monte Carlo models that describe the metallicity dependence of the size and luminosity of the HMXB populations. Results: We find that HMXBs are typically ten times more numerous per unit star formation rate in low-metallicity galaxies (12 + log (O / H) < 8, namely <20% solar) than in solar-metallicity galaxies. The metallicity dependence of the luminosity of HMXBs is small compared to that of the population size. Conclusions: Our results support the hypothesis that HMXBs are more numerous in low-metallicity galaxies, implying the need to investigate the feedback in the form of X-rays and energetic mass outflows of these high-energy sources during cosmic dawn.

  6. High-Mass X-ray Binaries in the Milky Way: A closer look with INTEGRAL

    Walter, Roland; Bozzo, Enrico; Tsygankov, Sergey S

    2015-01-01

    High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broad- ened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient. The classical systems feature low eccentricity and variability factor of about 1000, mostly driven by hydrodynamic phenomena occurring on scales larger than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of ...

  7. Detection of the first infra-red quasi periodic oscillation in a black hole X-ray binary

    Kalamkar, M; Uttley, P; O'Brien, K; Russell, D; Maccarone, T; van der Klis, M; Vincentelli, F

    2015-01-01

    We present analysis of fast variability of Very Large Telescope/ISAAC (infra-red), \\textit{XMM-Newton}/OM (optical) and EPIC-pn (X-ray), and RXTE/PCA (X-ray) observations of the black hole X-ray binary GX 339-4 in a rising hard state of its outburst in 2010. We report the first detection of a Quasi Periodic Oscillation (QPO) in the infra-red band (IR) of a black hole X-ray binary. The QPO is detected at 0.08 Hz in the IR as well as two optical bands (U and V). Interestingly, these QPOs are at half the X-ray QPO frequency at 0.16 Hz, which is classified as the type-C QPO; a weak sub-harmonic close to the IR and optical QPO frequency is also detected in X-rays. The broad band sub-second time scale variability is strongly correlated in IR/X-ray bands, with X-rays leading the IR by over 100 ms. This short time delay, shape of the cross correlation function and spectral energy distribution strongly indicate that this broad band variable IR emission is the synchrotron emission from the jet. A jet origin for the IR ...

  8. The nature of the Island and Banana States in Atoll sources and a Unified Model for Low Mass X-ray Binaries

    Church, M J; Balucinska-Church, M

    2013-01-01

    We propose an explanation of the Island and Banana states and the relation between Atoll and Z-track sources, constituting a unified model for Low Mass X-ray Binaries (LMXB). We find a dramatic transition at a luminosity of 1 - 2.10^{37} erg/s above which the high energy cut-off E_CO of the Comptonized emission in all sources is low at a few keV. There is thermal equilibrium between the neutron star at ~2 keV and the Comptonizing accretion disk corona (ADC) causing the low E_CO in the Banana state of Atolls and all states of the Z-track sources. Below this luminosity, E_CO increases towards 100 keV causing the hardness of the island state. Thermal equilibrium is lost, the ADC becoming much hotter than the neutron star via an additional coronal heating mechanism. This suggests a unified model of LMXB: the Banana state is a basic state with the mass accretion rate Mdot increasing, corresponding to the Normal Branch of Z-track sources. The Island state has high ADC temperature, this state not existing in the Z-t...

  9. Escape probability methods versus ``exact" transfer for modelling the X-ray spectrum of Active Galactic Nuclei and X-ray binaries

    Dumont, A.-M.; Collin, S.; Paletou, F.; Coupé, S.; Godet, O.; Pelat, D.

    2003-08-01

    In the era of XMM-Newton and Chandra missions, it is crucial to use codes able to compute correctly the line spectrum of X-ray irradiated thick media (Thomson thickness of the order of unity), in order to build models for the structure and the emission of the central regions of Active Galactic Nuclei (AGN), or of X-ray binaries. In all photoionized codes except in our code Titan, the line intensities are computed with the so-called ``escape probability approximation". In its last version, Titan solves the transfer of a thousand lines and of the continuum with the ``Accelerated Lambda Iteration" method, which is one of the most efficient and at the same time the most secure for line transfer. We first review the escape probability formalism and mention various reasons why it should lead to wrong results concerning the line fluxes. Then we check several approximations commonly used instead of line transfer in photoionization codes, by comparing them to the full transfer computation. We find that for conditions typical of the AGN or X-ray binary emission medium, all approximations lead to an overestimation of the emitted X-ray line spectrum, which can reach more than one order of magnitude. We show that it is due mainly to the local treatment of line photons, implying a delicate balance between excitations of X-ray transitions by the very intense underlying diffuse X-ray continuum (which are not taken properly into account in escape probability approximations) and the net rate of excitations by the diffuse line flux. The most affected lines are those in the soft X-ray range. Such processes are much less important in cooler and thinner media (like the Broad Line Region of AGN), as the most intense lines lie in the optical and near ultraviolet range where the diffuse continuum is small. We conclude that it is very important to treat correctly the transfer of the continuum to get the best results for the line spectrum. On the other hand the approximations used for the

  10. Formation and Evolution of Galactic Intermediate/Low-Mass X-ray Binaries

    Shao, Yong

    2015-01-01

    We investigate the formation and evolutionary sequences of Galactic intermediate- and low-mass X-ray binaries (I/LMXBs) 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 find that the birthrate of the I/LMXB population is in the range of $ 9\\times10^{-6} - 3.4\\times10^{-5} \\, {\\rm yr^{-1}}$, compatible with that of BMSPs which are thought to descend from I/LMXBs. We show that during the evolution of I/LMXBs they are likely to be observed as relatively compact binaries with orbital periods $ \\lesssim $ 1 day and donor masses $\\lesssim 0.3 M_{\\odot}$. The resultant BMSPs have orbital periods ranging from less than 1 day to a few hundred days. These features...

  11. A thin diffuse component of the Galactic Ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries

    Molaro, Margherita; Sunyaev, Rashid

    2013-01-01

    We suggest a thin (scale height ~80 pc) diffuse component to the Galactic Ridge X-ray emission (GRXE) arising from the scattering of the radiation of bright X-ray binaries (XBs) by the interstellar medium. The morphology of the scattered component is expected to trace the clumpy molecular and HI clouds. We calculate this contribution to the GRXE from known Galactic XBs assuming that they are all persistent. The known XBs sample is however incomplete as it is flux-limited and spans the small lifetime of X-ray astronomy (~50 years), compared to the characteristic time of 1000-10000 years that would contribute to the diffuse emission observed today due to time delays. We therefore also use a simulated sample of sources, to estimate the diffuse emission we should expect in an optimistic case assuming that the X-ray luminosity of our Galaxy is on average similar to that of other galaxies. In the calculations we also take into account the enhancement of the total scattering cross section due to coherence effects in...

  12. What can we learn about black-hole formation from black-hole X-ray binaries?

    Nelemans, G.

    2004-01-01

    I discuss the effect of the formation of a black hole on a (close) binary and show some of the current constraints that the observed properties of black hole X-ray binaries put on the formation of black holes. In particular I discuss the evidence for and against asymmetric kicks imparted on the black hole at formation and find contradicting answers, as there seems to be evidence for kick for individual systems and from the Galactic $z$-distribution of black hole X-ray binaries, but not from t...

  13. Unsupervised spectral decomposition of X-ray binaries with application to GX 339-4

    Koljonen, K. I. I.

    2015-03-01

    In this paper, we explore unsupervised spectral decomposition methods for distinguishing the effect of different spectral components for a set of consecutive spectra from an X-ray binary. We use well-established linear methods for the decomposition, namely principal component analysis, independent component analysis and non-negative matrix factorization (NMF). Applying these methods to a simulated data set consisting of a variable multicolour disc blackbody and a cutoff power law, we find that NMF outperforms the other two methods in distinguishing the spectral components. In addition, due the non-negative nature of NMF, the resulting components may be fitted separately, revealing the evolution of individual parameters. To test the NMF method on a real source, we analyse data from the low-mass X-ray binary GX 339-4 and found the results to match those of previous studies. In addition, we found the inner radius of the accretion disc to be located at the innermost stable circular orbit in the intermediate state right after the outburst peak. This study shows that using unsupervised spectral decomposition methods results in detecting the separate component fluxes down to low flux levels. Also, these methods provide an alternative way of detecting the spectral components without performing actual spectral fitting, which may prove to be practical when dealing with large data sets.

  14. Unsupervised spectral decomposition of X-ray binaries with application to GX 339--4

    Koljonen, Karri I I

    2014-01-01

    In this paper we explore unsupervised spectral decomposition methods for distinguishing the effect of different spectral components for a set of consecutive spectra from an X-ray binary. We use well-established linear methods for the decomposition, namely principal component analysis (PCA), independent component analysis (ICA) and non-negative matrix factorisation (NMF). Applying these methods to a simulated dataset consisting of a variable multicolour disc black body and a cutoff power law, we find that NMF outperforms the other two methods in distinguishing the spectral components. In addition, due the non-negative nature of NMF, the resulting components may be fitted separately, revealing the evolution of individual parameters. To test the NMF method on a real source, we analyse data from the low-mass X-ray binary GX 339-4 and found the results to match those of previous studies. In addition, we found the inner radius of the accretion disc to be located at the innermost stable orbit in the intermediate sta...

  15. Potential Gamma-ray Emissions from Low-Mass X-ray Binary Jets

    Zhang, Jian-Fu; Liu, Tong; Xue, Li; Lu, Ju-Fu

    2015-01-01

    By proposing a pure leptonic radiation model, we study the potential gamma-ray emissions from jets of the low-mass X-ray binaries. In this model, the relativistic electrons that are accelerated in the jets are responsible for radiative outputs. Nevertheless, dynamics of jets are dominated by the magnetic and proton-matter kinetic energies. The model involves all kinds of related radiative processes and considers the evolution of relativistic electrons along the jet by numerically solving the kinetic equation. Numerical results show that the spectral energy distributions can extend up to TeV bands, in which synchrotron radiation and synchrotron self-Compton scattering are dominant components. As an example, we apply the model to the low-mass X-ray binary GX 339-4. The results can not only reproduce the currently available observations from GX 339-4, but also predict detectable radiation at GeV and TeV bands by Fermi and CTA telescopes. The future observations with Fermi and CTA can be used to test our model, w...

  16. Average spectral properties of galactic X-ray binaries with 3 years of MAXI data

    Islam, Nazma; Sugizaki, Mutsumi; Paul, Biswajit; Nath, Biman B

    2013-01-01

    The energy spectra of X-ray binaries (XRBs) have been investigated during the last few decades with many observatories in different energy bands and with different energy resolutions. However, these studies are carried out in selected states of XRBs like during outbursts, transitions, quiescent states, and are always done in limited time windows of pointed observations. It is now possible to investigate the long term averaged spectra of a large number of X-ray binaries with the all sky monitor MAXI, which also has a broad energy band. Here we present the average spectral behaviour of a few representative XRBs. The long term averaged spectrum of Cyg X-1 is described by a sum of two power-laws having $\\Gamma_{1}$ ~ 2.8 and $\\Gamma_{2}$ ~ 1.2, along with a multi color disk blackbody having an inner disk temperature of 0.5 keV, GX 301-2 is described by a power-law with a high energy cut-off at $E_{c}$ ~ 15 keV and a blackbody component at 0.2 keV and that of Aql X-1 is described by a multi color disk blackbody at...

  17. Hot accretion flow with radiative cooling: state transitions in black hole X-ray binaries

    Wu, Mao-Chun; Yuan, Ye-Fei; Gan, Zhao-Ming

    2016-01-01

    We investigate state transitions in black hole X-ray binaries through different parameters by using two-dimensional axisymmetric hydrodynamical simulation method. For radiative cooling in hot accretion flow, we take into account the bremsstrahlung, synchrotron and synchrotron-self Comptonization self-consistently in the dynamics. Our main result is that the state transitions occur when the accretion rate reaches a critical value $\\dot M \\sim 3\\alpha\\ \\dot M_{\\rm Edd}$, above which cold and dense clumpy/filamentary structures are formed, embedded within the hot gas. We argued this mode likely corresponds to the proposed two-phase accretion model, which may be responsible for the intermediate state of black hole X-ray binaries. When the accretion rate becomes sufficiently high, the clumpy/filamentary structures gradually merge and settle down onto the mid-plane. Eventually the accretion geometry transforms to a disc-corona configuration. In summary our results are consistent with the truncated accretion scenari...

  18. Attempt to explain black hole spin in X-ray binaries with new physics

    Bambi, Cosimo

    2014-01-01

    It is widely believed that the spin of black holes in X-ray binaries is mainly natal. A significant spin-up from accretion is not possible. If the secondary has a low mass, the black hole spin cannot change too much even if the black hole swallows the whole stellar companion. If the secondary has a high mass, its lifetime is too short to transfer the necessary amount of matter and spin the black hole up. However, while black holes formed from the collapse of a massive star with Solar metallicity are expected to have low birth spin, current spin measurements show that some black holes in X-ray binaries are rotating very rapidly. Here I show that, if these objects are not the Kerr black holes of general relativity, the accretion of a small amount of matter ($\\sim 2$~$M_\\odot$) can make them look like very fast-rotating Kerr black holes. Such a possibility is not in contradiction with any observation and it can explain current spin measurements in a very simple way.

  19. STAR FORMATION HISTORY AND X-RAY BINARY POPULATIONS: THE CASE OF THE SMALL MAGELLANIC CLOUD

    Using Chandra, XMM-Newton, and optical photometric catalogs we study the young X-ray binary (XRB) populations of the Small Magellanic Cloud. We find that the Be/X-ray binaries (Be-XRBs) are observed in regions with star formation rate bursts ∼25-60 Myr ago. The similarity of this age with the age of maximum occurrence of the Be phenomenon (∼40 Myr) indicates that the presence of a circumstellar decretion disk plays a significant role in the number of observed XRBs in the 10-100 Myr age range. We also find that regions with strong but more recent star formation (e.g., the Wing) are deficient in Be-XRBs. By correlating the number of observed Be-XRBs with the formation rate of their parent populations, we measure a Be-XRB production rate of ∼1 system per 3 x 10-3 Msun yr-1. Finally, we use the strong localization of the Be-XRB systems in order to set limits on the kicks imparted on the neutron star during the supernova explosion.

  20. Population synthesis of ultracompact X-ray binaries in the Galactic Bulge

    van Haaften, L M; Voss, R; Toonen, S; Zwart, S F Portegies; Yungelson, L R; van der Sluys, M V

    2013-01-01

    [abridged] Aims. We model the number and properties of ultracompact X-ray binaries (UCXBs) in the Galactic Bulge. The objective is to learn about the formation of UCXBs and their evolution, such as the onset of mass transfer and late-time behavior. Methods. The binary population synthesis code SeBa and stellar evolutionary tracks are used to model the UCXB population. The luminosity behavior of UCXBs is predicted using long-term X-ray observations of the known UCXBs and the thermal-viscous disk instability model. Results. In our model, the majority of UCXBs initially have a helium burning star donor. In the absence of a mechanism that destroys old UCXBs, we predict (0.2 - 1.9) x 10^5 UCXBs in the Galactic Bulge, mostly at orbital periods longer than 60 min (a large number of long-period systems also follows from the observed short-period UCXB population). About 5 - 50 UCXBs should be brighter than 10^35 erg/s, mostly persistent sources with orbital periods shorter than 30 min and with degenerate helium and ca...

  1. Hot accretion flow with radiative cooling: state transitions in black hole X-ray binaries

    Wu, Mao-Chun; Xie, Fu-Guo; Yuan, Ye-Fei; Gan, Zhaoming

    2016-06-01

    We investigate state transitions in black hole X-ray binaries through different parameters by using two-dimensional axisymmetric hydrodynamical simulation method. For radiative cooling in hot accretion flow, we take into account the bremsstrahlung, synchrotron and synchrotron self-Comptonization self-consistently in the dynamics. Our main result is that the state transitions occur when the accretion rate reaches a critical value dot{M} ˜ 3α dot{M}_Edd, above which cold and dense clumpy/filamentary structures are formed, embedded within the hot gas. We argued this mode likely corresponds to the proposed two-phase accretion model, which may be responsible for the intermediate state of black hole X-ray binaries. When the accretion rate becomes sufficiently high, the clumpy/filamentary structures gradually merge and settle down on to the mid-plane. Eventually the accretion geometry transforms to a disc-corona configuration. In summary, our results are consistent with the truncated accretion scenario for the state transition.

  2. M31 globular cluster structures and the presence of X-ray binaries

    Agar, J R R

    2013-01-01

    [Abridged] M31 has several times more globular clusters (GCs) than the Milky Way. It contains a correspondingly larger number of low mass X-ray binaries (LMXBs) associated with GCs, and can be used to investigate the GC properties which lead to X-ray binary formation. The best tracer of the spatial structure of M31 GCs is high-resolution imaging from the Hubble Space Telescope, and we have used HST data to derive structural parameters for 29 LMXB-hosting M31 GCs. These measurements are combined with structural parameters from the literature for a total of 41 (of 50 known) LMXB GCs and a comparison sample of 65 non-LMXB GCs. Structural parameters measured in blue bandpasses are found to show smaller core radii and higher concentrations than those measured in red bandpasses; this difference is enhanced in LMXB clusters and could be related to stellar population differences. Clusters with LMXBs show higher collision rates for their mass compared to those without LMXBs and collision rates estimated at the core ra...

  3. Stellar wind in state transitions of high-mass X-ray binaries

    Čechura, Jan

    2014-01-01

    Aims: We have developed a new code for the three-dimensional time-dependent raditation hydrodynamic simulation of the stellar wind in interacting binaries to improve models of accretion in high-mass X-ray binaries and to quantitatively clarify the observed variability of these objects. We used the code to test the influence of various parameters on the structure and properties of circumstellar matter. Methods: Our code takes into account acceleration of the wind due to the Roche effective potential, Coriolis force, gas pressure, and (CAK-) radiative pressure in the lines and continuum of the supergiant radiation field that is modulated by its gravity darkening and by the photo-ionization caused by X-ray radiation from the compact companion. The parameters of Cygnus X-1 were used to test the properties of our model. Results: Both two- and three-dimensional numerical simulations show that the Coriolis force substantially influences the mass loss and consequently the accretion rate onto the compact companion. Th...

  4. OPTICAL SPECTROSCOPY OF 20 Be/X-RAY BINARIES IN THE SMALL MAGELLANIC CLOUD

    We present a large sample (20 in total) of optical spectra of Small Magellanic Cloud (SMC) High-Mass X-ray Binaries obtained with the 2dF spectrograph at the Anglo-Australian Telescope. All of these sources are found to be Be/X-ray binaries (Be-XRBs), while for five sources we present original classifications. Several statistical tests on this expanded sample support previous findings for similar spectral-type distributions of Be-XRBs and Be field stars in the SMC, and of Be-XRBs in the Large Magellanic Cloud and the Milky Way, although this could be the result of small samples. On the other hand, we find that Be-XRBs follow a different distribution than Be stars in the Galaxy, also in agreement with previous studies. In addition, we find similar Be spectral-type distributions between the Magellanic Clouds samples. These results reinforce the relation between the orbital period and the equivalent width of the Hα line that holds for Be-XRBs. SMC Be stars have larger Hα equivalent widths when compared to Be-XRBs, supporting the notion of circumstellar disk truncation by the compact object.

  5. Attempt to explain black hole spin in X-ray binaries by new physics

    It is widely believed that the spin of black holes in X-ray binaries is mainly natal. A significant spin-up from accretion is not possible. If the secondary has a low mass, the black hole spin cannot change too much even if the black hole swallows the whole stellar companion. If the secondary has a high mass, its lifetime is too short to transfer the necessary amount of matter and spin the black hole up. However, while black holes formed from the collapse of a massive star with solarmetallicity are expected to have low birth spin, current spin measurements show that some black holes in X-ray binaries are rotating very rapidly. Here we show that, if these objects are not the Kerr black holes of general relativity, the accretion of a small amount of matter (∝2 Msun) can make them look like very fast-rotating Kerr black holes. Such a possibility is not in contradiction with any observation and it can explain current spin measurements in a very simple way. (orig.)

  6. Attempt to explain black hole spin in X-ray binaries by new physics

    Bambi, Cosimo

    2015-01-01

    It is widely believed that the spin of black holes in X-ray binaries is mainly natal. A significant spin-up from accretion is not possible. If the secondary has a low mass, the black hole spin cannot change too much even if the black hole swallows the whole stellar companion. If the secondary has a high mass, its lifetime is too short to transfer the necessary amount of matter and spin the black hole up. However, while black holes formed from the collapse of a massive star with solar metallicity are expected to have low birth spin, current spin measurements show that some black holes in X-ray binaries are rotating very rapidly. Here we show that, if these objects are not the Kerr black holes of general relativity, the accretion of a small amount of matter (2 ) can make them look like very fast-rotating Kerr black holes. Such a possibility is not in contradiction with any observation and it can explain current spin measurements in a very simple way.

  7. Three X-ray Flares Near Primary Eclipse of the RS CVn Binary XY UMa

    Gong, Hang; Maccarone, Thomas; Reale, Fabio; Liu, Jifeng; Heckert, Paul A

    2016-01-01

    We report on an archival X-ray observation of the eclipsing RS CVn binary XY UMa ($\\rm P_{orb}\\approx$ 0.48d). In two $\\emph{Chandra}$ ACIS observations spanning 200 ks and almost five orbital periods, three flares occurred. We find no evidence for eclipses in the X-ray flux. The flares took place around times of primary eclipse, with one flare occurring shortly ($<0.125\\rm P_{orb}$) after a primary eclipse, and the other two happening shortly ($<0.05\\rm P_{orb}$) before a primary eclipse. Two flares occurred within roughly one orbital period ($\\Delta \\phi\\approx1.024\\rm P_{orb}$) of each other. We analyze the light curve and spectra of the system, and investigate coronal length scales both during quiescence and during flares, as well as the timing of the flares. We explore the possibility that the flares are orbit-induced by introducing a small orbital eccentricity, which is quite challenging for this close binary.

  8. Hydrodynamical winds from two-temperature plasma in X-ray binaries

    Lin, D J; Taam, R E; Lin, David J.

    2000-01-01

    Hydrodynamical winds from a spherical two-temperature plasma surrounding a compact object are constructed. The mass-loss rate is computed as a function of electron temperature, optical depth and luminosity of the sphere, the values of which can be constrained by the fitting of the spectral energy distributions for known X-ray binary systems. The sensitive dependence of the mass loss rate with these parameters leads to the identification of two distinct regions in the parameter space separating wind-dominated from non wind dominated systems. A critical optical depth, tau_c, as a function of luminosity and electron temperature, is defined which differentiates these two regions. Systems with optical depths significantly smaller than tau_c are wind-dominated. The results are applied to black hole candidate X-ray binary systems in the hard spectral state (Cyg X-1, GX 339-4 and Nova Muscae), and it is found that the inferred optical depth (tau) is similar to tau_c suggesting that they are wind regulated systems. On...

  9. X Persei: The X-Ray Halo and Spectrum of a High-Latitude X-Ray Binary

    Mushotzky, Richard (Technical Monitor); Smith, Randall

    2004-01-01

    The observations were completed on February 25,2003. Although the source was in the FOV for 31.4 ksec, only 18.2 ksec of data were usable due to a strong flare in the first part of the observations. We have extracted the X-ray halo from the good portion of the data, and were then faced with the problem of calibrating the far-off-axis point spread function, which is needed only for X-ray halo analysis; the same problem affected Chandra halo observations. We used data from 3C273, MCG 6-30-15, LMC X-1, and Her X-1 to measure the PSF, and found that it is reasonably well fit with a power law of the form PSF(theta) = A theta^-G, where A = 0.0034 arcmin^-2, and G = 3.05 for energies between 1-4 keV. This suggests there are fewer large dust grains along the When fitting the spectrum of X Persei, we found NH = 3e21 cm^-2, as expected. However, the X-ray halo (using a Mathis, Rumpl, Nordsieck 1977 dust model) required at most a column density of 1.4+/-0.1 e21 cm^-2; other models required sightline to X Per than would have been expected. In addition, a smoothly distributed dust model fit the observations better than a single cloud model, also against our expectations. We are in the process of writing a paper to be submitted to ApJ with these results, and will also present them at the 2004 HEAD meeting in New Orleans.

  10. Tidal capture formation of low-mass X-ray binaries from wide binaries in the field

    Michaely, Erez; Perets, Hagai B.

    2016-06-01

    We present a dynamical formation scenario for low mass X-ray binaries (LMXBs) in the field, focusing on black hole (BH) LMXBs. In this formation channel, LMXBs are formed from wide binaries (>1000 au) with a BH component and a stellar companion. The wide binary is perturbed by fly-bys of field stars, its orbit random walks, until driven into a sufficiently eccentric orbit such that the binary components tidally interact and the binary evolves to become a short period binary, which eventually evolves into an LMXB. We consider several models for the formation and survival of such wide binaries, and calculate the LMXB formation rates for each model. We find that models where BHs form through direct collapse with no/little natal kicks can give rise to high formation rates comparable with those inferred from observations. This formation scenario had several observational signatures: (1) the number density of LMXBs generally follows the background stellar density, beside the densest regions, where the dependence is stronger, (2) the mass function of the BH stellar companion should be comparable to the mass function of the background stellar population, likely peaking at 0.4-0.6 M⊙, and (3) the LMXBs orbit should not correlate with the spin of the BH. These aspects generally differ from the expectations from previously suggested LMXB formation models following common envelope binary stellar evolution. We note that neutron star LMXBs can similarly form from wide binaries, but their formation rate through this channel is likely significantly smaller due to their much higher natal kicks.

  11. X-ray and optical study of the new SMC X-ray binary pulsar system SXP7.92 and its probable optical counterpart, AzV285

    Coe, M J; McBride, V A; Corbet, R H D; Townsend, L J; Udalski, A; Galache, J L

    2009-01-01

    Optical and X-ray observations are presented here of a newly reported X-ray transient system in the Small Magellanic Cloud - SXP7.92. A detailed analysis of the X-ray data reveal a coherent period of 7.9s. A search through earlier X-ray observations of the SMC reveal a previously unknown earlier detection of this system. Follow-up X-ray observations identified a new transient source within the error circle of the previous observations. An optical counterpart, AzV285, is proposed which reveals clear evidence for a 36.8d binary period.

  12. Deducing the Orientation of the Semimajor Axis of the Eta Carinae Binary System from X-ray Observations

    Soker, Amit Kashi Noam

    2009-01-01

    We study the usage of the X-ray light curve, column density toward the hard X-ray source, and emission measure (density square times volume), of the massive binary system Eta Carinae to determine the orientation of its semi-major axis. The source of the hard X-ray emission is the shocked secondary wind. We argue that, by itself, the observed X-ray flux cannot teach us much about the orientation of the semi-major axis. Minor adjustment of some unknown parameters of the binary system allows to fit theX-ray light curve with almost any inclination angle and orientation. The column density and X-ray emission measure, on the other hand, impose strong constrains on the orientation. We improve our previous calculations and show that the column density is more compatible with an orientation where for most of the time the secondary - the hotter, less massive star - is behind the primary star. The secondary comes closer to the observer only for a short time near periastron passage. The ten-week X-ray deep minimum, which...

  13. Discovery of SXP265, a Be/X-ray binary pulsar in the Wing of the Small Magellanic Cloud

    Sturm, R; Vasilopoulos, G; Bartlett, E S; Maggi, P; Rau, A; Greiner, J; Udalski, A

    2014-01-01

    We identify a new candidate for a Be/X-ray binary in the XMM-Newton slew survey and archival Swift observations that is located in the transition region of the Wing of the Small Magellanic Cloud and the Magellanic Bridge. We investigated and classified this source with follow-up XMM-Newton and optical observations. We model the X-ray spectra and search for periodicities and variability in the X-ray observations and the OGLE I-band light curve. The optical counterpart has been classified spectroscopically, with data obtained at the SAAO 1.9 m telescope, and photometrically, with data obtained using GROND at the MPG 2.2 m telescope. The X-ray spectrum is typical of a high-mass X-ray binary with an accreting neutron star. We detect X-ray pulsations, which reveal a neutron-star spin period of P = (264.516+-0.014) s. The source likely shows a persistent X-ray luminosity of a few 10^35 erg/s and in addition type-I outbursts that indicate an orbital period of ~146 d. A periodicity of 0.867 d, found in the optical li...

  14. Low-Mass X-Ray Binary MAXI J1421-613 Observed by MAXI GSC and Swift XRT

    Serino, Motoko; Ueda, Yoshihiro; Matsuoka, Masaru; Negoro, Hitoshi; Yamaoka, Kazutaka; Kennea, Jamie A; Fukushima, Kosuke; Nagayama, Takahiro

    2015-01-01

    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 and the Swift XRT 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 $\\approx$ 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...

  15. The Origin of Black Hole Spin in Galactic Low-Mass X-ray Binaries

    Fragos, Tassos

    2014-01-01

    Galactic field black hole (BH) low-mass X-ray binaries (LMXBs) are believed to form in situ via the evolution of isolated binaries. In the standard formation channel, these systems survived a common envelope phase, after which the remaining helium core of the primary star and the subsequently formed BH are not expected to be highly spinning. However, the measured spins of BHs in LMXBs cover the whole range of spin parameters from a*~0 to a*~1. We propose here that the BH spin in LMXBs is acquired through accretion onto the BH during their long and stable accretion phase. In order to test this hypothesis, we calculated extensive grids of binary evolutionary sequences in which a BH accretes matter from a close companion. For each evolutionary sequence, we examined whether, at any point in time, the calculated binary properties are in agreement with their observationally inferred counterparts of 16 observed Galactic LMXBs. Mass-transfer sequences that simultaneously satisfy all observational constraints represen...

  16. 2S1553-542: a Be/X-ray binary pulsar on the far side of the Galaxy

    Lutovinov, Alexander A; Townsend, Lee J; Tsygankov, Sergey S; Kennea, Jamie

    2016-01-01

    We report the results of a comprehensive analysis of X-ray (Chandra and Swift observatories), optical (Southern African Large Telescope, SALT) and near-infrared (the VVV survey) observations of the Be/X-ray binary pulsar 2S1553-542. Accurate coordinates for the X-ray source are determined and are used to identify the faint optical/infrared counterpart for the first time. Using VVV and SALTICAM photometry, we have constructed the spectral energy distribution (SED) for this star and found a moderate NIR excess that is typical for Be stars and arises due to the presence of circumstellar material (disk). A comparison of the SED with those of known Be/X-ray binaries has allowed us to estimate the spectral type of the companion star as B1-2V and the distance to the system as $>15$ kpc. This distance estimation is supported by the X-ray data and makes 2S1553-542 one of the most distant X-ray binaries within the Milky Way, residing on the far side in the Scutum-Centaurus arm or even further.

  17. Physical Identification of Binary System of Gliclazide-Hydrophilic Polymers Using X-Ray Diffraction

    Rachmawati, H.; Yatinasari, Faizatun, Syarie, S. A.

    2008-03-01

    The formation of binary system in pharmaceutical solid state is aimed to improve the physicochemical characteristics of active compound, such as its solubility. To identify the physical change of the binary system including crystallinity or particle morphology, there are many methods can be applied. In present report, we study the physical interaction of the binary system of gliclazide and hydrophilic polymers. In this binary system, gliclazide was either dispersed or mixed with polyvinyl pirrolidone (PVP K30) or polyethylene glycol (PEG 6000). The dispersion system of gliclazide in the polymeric carriers was prepared by solvation-evaporation method, using dichloromethane/methylene chloride as an organic solvent. The physical characterization of both dispersed and mixed of gliclazide was studied using X-ray diffraction at interval 6-50 °/2θ. As a comparison, the same procedure was performed for pure gliclazide. To confirm the diffractogram of this binary system, Fourier Transform Infrared (FT-IR) spectroscopy was carried out as well. Both diffarctogram and FT-IR spectra revealed that there was no new compound formed in the solid dispersion system of gliclazide:PEG 6000 and gliclazide:PVP K30. In contrast, the solubility as well as the dissolution rate of gliclazide in the presence of both hydrophilic polymers was increased as compared to pure gliclazide. We conclude therefore that solvatation followed by evaporation of gliclazide in the presence of either PEG 6000 or PVP K30 did not alter its crystalline characteristic. The improved of gliclazide solubility in the binary system might due to other mechanism such as increased in the wettability and the hydrophylicity effect of the polymers.

  18. Timing and spectral studies of the peculiar x-ray binary Circinus X-1

    Parkinson, Pablo Miguel Saz

    Cir X-1 is a unique Galactic X-ray binary which was initially classified as a black hole candidate but later reclassified as a neutron star due primarily to the observation of Type I X-ray Bursts by EXOSAT in 1985. In this work, I examine the timing and spectral properties of Cir X-1. FFT analyses are used to study the short (independent and model-independent color-color diagrams. Spectral fits were performed on USA data, from which physical parameters were derived. The spectral parameters indicate that a two-component model is valid for describing the Cir X-1 spectrum: a multicolor blackbody emission from an accretion disk and a Comptonized emission from a hot plasma (boundary layer or corona). The temperature of the disk remains constant, while there is an indication that the Comptonizing component increases in temperature with orbital phase. From the relative contribution of the disk I infer the neutron star is spinning very rapidly (>1 kHz). The long-term variability of Cir X-1 is studied using data from instruments going back over thirty years. I derive an X-ray ephemeris based showing that the period of Cir X-1 decreases rapidly (P/P˙ < 3000 yrs), possibly implying a very young age. I compute dynamic periodograms and find new, unexplained periodicities. A 250 day segment of data shows no detectable orbital period while displaying a new ˜40 day periodicity. A 335 day super-orbital period is found with hardness ratio perfectly anti-correlated, making it possible that this period is due to an obscuration effect from a precessing orbit.

  19. Formation, disruption and energy output of Population III X-ray binaries

    Ryu, Taeho; Tanaka, Takamitsu L.; Perna, Rosalba

    2016-02-01

    The first astrophysical objects shaped the cosmic environment by reionizing and heating the intergalactic medium (IGM). Particularly, X-rays are very efficient at heating the IGM before reionization is complete. High-mass X-ray binaries (HMXBs) in early stellar populations are prime candidates for driving the thermal evolution of the IGM at redshifts z ≳ 20; however, their formation efficiency is not well understood. Using N-body simulations, we estimate the HMXB formation rate via mutual gravitational interactions of nascent, small groups of the Population III stars. We run two sets of calculations: (i) stars formed in small groups of five in nearly Keplerian initial orbits and (ii) collision of two such groups (an expected outcome of mergers of host protogalaxies). We find that HMXBs form at a rate of one per ≳ 104 M⊙ in newly born stars, and that they emit with a power of ˜1041 erg s-1 in the 2-10 keV band per star formation rate. This value is a factor of ˜102 larger than what is observed in star-forming galaxies at lower redshifts; the X-ray production from early HMXBs would have been even more copious, if they also formed in situ or via migration in protostellar discs. Combining our results with earlier studies suggests that early HMXBs were highly effective at heating the IGM and leaving a strong 21-cm signature. We discuss broader implications of our results, such as the rate of long gamma-ray bursts from Population III stars and the direct collapse channel for massive black hole formation.

  20. A state change in the low-mass X-ray binary XSS J12270-4859

    Bassa, C G; Hessels, J W T; Keane, E F; Monard, B; Mahony, E K; Bogdanov, S; Corbel, S; Edwards, P G; Archibald, A M; Janssen, G H; Stappers, B W; Tendulkar, S

    2014-01-01

    Millisecond radio pulsars acquire their rapid rotation rates through mass and angular momentum transfer in a low-mass X-ray binary system. Recent studies of PSR J1824-2452I and PSR J1023+0038 have observationally demonstrated this link, and they have also shown that such systems can repeatedly transition back-and-forth between the radio millisecond pulsar and low-mass X-ray binary states. This also suggests that a fraction of such systems are not newly born radio millisecond pulsars but are rather suspended in a back-and-forth state switching phase, perhaps for giga-years. XSS J12270-4859 has been previously suggested to be a low-mass X-ray binary, and until recently the only such system to be seen at MeV-GeV energies. We present radio, optical and X-ray observations that offer compelling evidence that XSS J12270-4859 is a low-mass X-ray binary which transitioned to a radio millisecond pulsar state between 2012 November 14 and 2012 December 21. Though radio pulsations remain to be detected, we use optical and...

  1. Discovery of SXP 265, a Be/X-ray binary pulsar in the Wing of the Small Magellanic Cloud

    Sturm, R.; Haberl, F.; Vasilopoulos, G.; Bartlett, E. S.; Maggi, P.; Rau, A.; Greiner, J.; Udalski, A.

    2014-11-01

    We identify a new candidate for a Be/X-ray binary in the XMM-Newton slew survey and archival Swift observations that is located in the transition region of the Wing of the Small Magellanic Cloud and the Magellanic Bridge. We investigated and classified this source with follow-up XMM-Newton and optical observations. We model the X-ray spectra and search for periodicities and variability in the X-ray observations and the Optical Gravitational Lensing Experiment I-band light curve. The optical counterpart has been classified spectroscopically, with data obtained at the South African Astronomical Observatory 1.9 m telescope, and photometrically, with data obtained using the Gamma-ray Burst Optical Near-ir Detector at the MPG 2.2 m telescope. The X-ray spectrum is typical of a high-mass X-ray binary with an accreting neutron star. We detect X-ray pulsations, which reveal a neutron-star spin period of Ps = (264.516 ± 0.014) s. The source likely shows a persistent X-ray luminosity of a few 1035 erg s-1 and in addition type-I outbursts that indicate an orbital period of ˜146 d. A periodicity of 0.867 d, found in the optical light curve, can be explained by non-radial pulsations of the Be star. We identify the optical counterpart and classify it as a B1-2II-IVe star. This confirms SXP 265 as a new Be/X-ray binary pulsar originating in the tidal structure between the Magellanic Clouds.

  2. Exploring X-Ray Binary Populations in Compact Group Galaxies with Chandra

    Tzanavaris, P.; Hornschemeier, A. E.; Gallagher, S. C.; Lenkić, L.; Desjardins, T. D.; Walker, L. M.; Johnson, K. E.; Mulchaey, J. S.

    2016-02-01

    We obtain total galaxy X-ray luminosities, LX, originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of our galaxies, we find that the detected point sources most likely are local to their associated galaxy, and are thus extragalactic X-ray binaries (XRBs) or nuclear active galactic nuclei (AGNs). For spiral and irregular galaxies, we find that, after accounting for AGNs and nuclear sources, most CG galaxies are either within the ±1σ scatter of the Mineo et al. LX-star formation rate (SFR) correlation or have higher LX than predicted by this correlation for their SFR. We discuss how these “excesses” may be due to low metallicities and high interaction levels. For elliptical and S0 galaxies, after accounting for AGNs and nuclear sources, most CG galaxies are consistent with the Boroson et al. LX-stellar mass correlation for low-mass XRBs, with larger scatter, likely due to residual effects such as AGN activity or hot gas. Assuming non-nuclear sources are low- or high-mass XRBs, we use appropriate XRB luminosity functions to estimate the probability that stochastic effects can lead to such extreme LX values. We find that, although stochastic effects do not in general appear to be important, for some galaxies there is a significant probability that high LX values can be observed due to strong XRB variability.

  3. Low-Mass X-Ray Binaries, Millisecond Radio Pulsars, and the Cosmic Star Formation Rate

    White, N E; White, Nicholas E.; Ghosh, Pranab

    1998-01-01

    We report on the implications of the peak in the cosmic star-formation rate (SFR) at redshift z ~ 1.5 for the resulting population of low-mass X-ray binaries(LMXB) and for that of their descendants, the millisecond radio pulsars (MRP). Since the evolutionary timescales of LMXBs, their progenitors, and their descendants are thought be significant fractions of the time-interval between the SFR peak and the present epoch, there is a lag in the turn-on of the LMXB population, with the peak activity occurring at z ~ 0.5 - 1.0. The peak in the MRP population is delayed further, occurring at z < 0.5. We show that the discrepancy between the birthrate of LMXBs and MRPs, found under the assumption of a stead-state SFR, can be resolved for the population as a whole when the effects of a time-variable SFR are included. A discrepancy may persist for LMXBs with short orbital periods, although a detailed population synthesis will be required to confirm this. Further, since the integrated X-ray luminosity distribution of...

  4. Recent activity of the Be/X-ray binary system SAX J2103.5+4545

    Camero, A; Soto, J Gutierrez; Arabaci, M Ozbey; Nespoli, E; Kiaeerad, F; Beklen, E; Garcia-Rojas, J; Caballero-Garcia, M

    2014-01-01

    Aims. We present a multiwavelength study of the Be/X-ray binary system SAX J2103.5+4545 with the goal of better characterizing the transient behaviour of this source. Methods. SAX J2103.5+4545 was observed by Swift-XRT four times in 2007 from April 25 to May 5, and during quiescence in 2012 August 31. In addition, this source has been monitored from the ground-based astronomical observatories of El Teide (Tenerife, Spain), Roque de los Muchachos (La Palma, Spain) and Sierra Nevada (Granada, Spain) since 2011 August, and from the TUBITAK National Observatory (Antalya, Turkey) since 2009 June. We have performed spectral and photometric temporal analyses in order to investigate the different states exhibited by SAX J2103.5+4545. Results. In X-rays, an absorbed power law model provided the best fit for all the XRT spectra. An iron-line feature at ~6.42 keV was present in all the observations except for that taken during quiescence in 2012. The photon indexes are consistent with previous studies of SAX J2103.5+454...

  5. Absorption lines from magnetically-driven winds in X-ray binaries

    Chakravorty, S; Ferreira, J; Henri, G; Belmont, R; Clavel, M; Corbel, S; Rodriguez, J; Coriat, M; Drappeau, S; Malzac, J

    2016-01-01

    High resolution X-ray spectra of black hole X-ray binaries (BHBs) show blueshifted absorption lines from disk winds which seem to be equatorial. Winds occur in the Softer (disk-dominated) states of the outburst and are less prominent or absent in the Harder (power-law dominated) states. We use self-similar magneto-hydrodynamic (MHD) accretion-ejection models to explain the disk winds in BHBs. In our models, the density at the base of the outflow from the accretion disk is not a free parameter, but is determined by solving the full set of dynamical MHD equations. Thus the physical properties of the outflow are controlled by the global structure of the disk. We studied different MHD solutions characterized by different values of (a) the disk aspect ratio ($\\varepsilon$) and (b) the ejection efficiency ($p$). We use two kinds of MHD solutions depending on the absence (cold solution) or presence (warm solution) of heating at the disk surface. Such heating could be from e.g. dissipation of energy due to MHD turbul...

  6. The eclipsing bursting X-ray binary EXO 0748-676 revisited by XMM-Newton

    Bonnet-Bidaud, J M; Ferrando, P; Bennie, P J; Kendziorra, E

    2001-01-01

    The bright eclipsing and bursting low-mass X-ray binary EXO 0748-676 has been observed at several occasions by XMM-Newton during the initial calibration and performance verification (CAL/PV) phase. We present here the results obtained from observations with the EPIC cameras. Apart from several type-I X-ray bursts, the source shows a high degree of variability with the presence of soft flares. The wide energy coverage and high sensitivity of XMM-Newton allows for the first time a detailed description of the spectral variability. The source is found to be the superposition of a central (~2 10^8 cm) Comptonized emission, most probably a corona surrounding the inner edge of an accretion disk, associated with a more extended (~3 10^10 cm) thermal halo at a typical temperature of ~0.6 keV with an indication of non-solar abundances. Most of the variations of the source can be accounted for by a variable absorption affecting only the central comptonized component and reaching up to NH ~1.3 10^23 cm^{-2}. The characte...

  7. Clustering between high-mass X-ray binaries and OB associations in the Milky Way

    Bodaghee, Arash; Rodriguez, Jerome; James, J Berian

    2011-01-01

    We present the first direct measurement of the spatial cross-correlation function of high-mass X-ray binaries (HMXBs) and active OB star-forming complexes in the Milky Way. This result relied on a sample containing 79 hard X-ray selected HMXBs and 458 OB associations. Clustering between the two populations is detected with a significance above 7-sigmas for distances < 1 kpc. Thus, HMXBs closely trace the underlying distribution of the massive star-forming regions that are expected to produce the progenitor stars of HMXBs. The average offset of 0.4+-0.2 kpc between HMXBs and OB associations is consistent with being due to natal kicks at velocities of the order of 100+-50 km/s. The characteristic scale of the correlation function suggests an average kinematical age (since the supernova phase) of ~4 Myr for the HMXB population. Despite being derived from a global view of our Galaxy, these signatures of HMXB evolution are consistent with theoretical expectations as well as observations of individual objects.

  8. Discovery of the third transient X-ray binary in the galactic globular cluster Terzan 5

    We report and study the outburst of a new transient X-ray binary (XRB) in Terzan 5, the third detected in this globular cluster, Swift J174805.3-244637 or Terzan 5 X-3. We find clear spectral hardening in Swift/XRT data during the outburst rise to the hard state, thanks to our early coverage (starting at LX ∼ 4 × 1034 erg s–1) of the outburst. This hardening appears to be due to the decline in relative strength of a soft thermal component from the surface of the neutron star (NS) during the rise. We identify a Type I X-ray burst in Swift/XRT data with a long (16 s) decay time, indicative of hydrogen burning on the surface of the NS. We use Swift/BAT, MAXI/GSC, Chandra/ACIS, and Swift/XRT data to study the spectral changes during the outburst, identifying a clear hard-to-soft state transition. We use a Chandra/ACIS observation during outburst to identify the transient's position. Seven archival Chandra/ACIS observations show evidence for variations in Terzan 5 X-3's nonthermal component but not the thermal component during quiescence. The inferred long-term time-averaged mass accretion rate, from the quiescent thermal luminosity, suggests that if this outburst is typical and only slow cooling processes are active in the NS core, such outbursts should recur every ∼10 yr.

  9. Discovery of the Third Transient X-ray Binary in the Galactic Globular Cluster Terzan 5

    Bahramian, Arash; Sivakoff, Gregory R; Altamirano, Diego; Wijnands, Rudy; Homan, Jeroen; Linares, Manuel; Pooley, David; Degenaar, Nathalie; Gladstone, Jeanette C

    2013-01-01

    We report and study the outburst of a new transient X-ray binary (XRB) in Terzan 5, the third detected in this globular cluster, Swift J174805.3-244637 or Terzan 5 X-3. We find clear spectral hardening in Swift/XRT data during the outburst rise to the hard state, thanks to our early coverage (starting at L_X ~ 4x10^{34} ergs/s) of the outburst. This hardening appears to be due to the decline in relative strength of a soft thermal component from the surface of the neutron star (NS) during the rise. We identify a {Type I X-ray burst} in Swift/XRT data with a long (16 s) decay time, indicative of {hydrogen burning on the surface of the} NS. We use Swift/BAT, Maxi/GSC, Chandra/ACIS, and Swift/XRT data to study the spectral changes during the outburst, identifying a clear hard-to-soft state transition. We use a Chandra/ACIS observation during outburst to identify the transient's position. Seven archival Chandra/ACIS observations show evidence for variations in Terzan 5 X-3's non-thermal component, but not the ther...

  10. Determining the Nature of the SS 433 Binary Using an X-ray Spectrum During Eclipse

    Lopez, L A; Canizares, C R; Schulz, N S; Kane, J F; Lopez, Laura A.; Marshall, Herman L.; Canizares, Claude R.; Schulz, Norbert S.; Kane, Julie F.

    2006-01-01

    We test the physical model of the relativistic jets in the galactic X-ray binary SS 433 proposed in our previous paper using additional observations from the Chandra High Energy Transmission Grating Spectrometer. These observations sample two new orbital/precessional phase combinations. In the observation near orbital phase zero, the H- and He-like Fe lines from both receding and approaching jets are comparably strong and unocculted while the He-like Si line of the receding jet is significantly weaker than that of the approaching jet. This condition may imply the cooler parts of the receding jet are eclipsed by the companion. The X-ray spectrum from this observation has broader emission lines than obtained in Paper I that may arise from the divergence of a conical outflow or from Doppler shift variations during the observation. Using recent optical results, along with the length of the unobscured portion of the receding jet assuming adiabatic cooling, we calculate the radius of the companion to be 9.6+/-1.0 R...

  11. The nature of very faint X-ray binaries; hints from light curves

    Heinke, C O; Degenaar, N; Wijnands, R

    2014-01-01

    Very faint X-ray binaries (VFXBs), defined as having peak luminosities Lx of 10^34-10^36 erg/s, have been uncovered in significant numbers, but remain poorly understood. We analyse three published outburst light curves of two transient VFXBs using the exponential and linear decay formalism of King and Ritter (1998). The decay timescales and brink luminosities suggest orbital periods of order 1 hour. We review various estimates of VFXB properties, and compare these with suggested explanations of the nature of VFXBs. We suggest that: 1) VFXB outbursts showing linear decays might be explained as partial drainings of the disc of "normal" X-ray transients, and many VFXB outbursts may belong to this category; 2) VFXB outbursts showing exponential decays are best explained by old, short-period systems involving mass transfer from a low-mass white dwarf or brown dwarf; 3) persistent (or quasi-persistent) VFXBs, which maintain an Lx of 10^34-10^35 erg/s for years, may be explained by magnetospheric choking of the accr...

  12. THE AGES OF HIGH-MASS X-RAY BINARIES IN NGC 2403 AND NGC 300

    We have examined resolved stellar photometry from HST imaging surrounding 18 high-mass X-ray binary (HMXB) candidates in NGC 300 and NGC 2403 as determined from combined Chandra/HST analysis. We have fit the color-magnitude distribution of the surrounding stars with stellar evolution models. All but one region in NGC 300 and two in NGC 2403 contain a population with an age between 20 and 70 Myr. One of the candidates is the ultraluminous X-ray source in NGC 2403, which we associate with a 60 ± 5 Myr old population. These age distributions provide additional evidence that 16 of these 18 candidates are HMXBs. Furthermore, our results suggest that the most common HMXB age in these galaxies is 40-55 Myr. This preferred age is similar to observations of HMXBs in the Small Magellanic Cloud, providing new evidence of this formation timescale, but in higher metallicity populations. We suggest that this preferred HMXB age is the result of the fortuitous combination of two physical effects. First, this is the age of a population when the greatest rate of core-collapse events should be occurring, maximizing neutron star production. Second, this is the age when B stars are most likely to be actively losing mass. We also discuss our results in the context of HMXB feedback in galaxies, confirming HMXBs as a potentially important source of energy for the interstellar medium in low-mass galaxies.

  13. OBSERVATIONS OF THE HIGH-MASS X-RAY BINARY A 0535+26 IN QUIESCENCE

    Rothschild, Richard; Markowitz, Alex; Hemphill, Paul [University of California, San Diego, Center for Astrophysics and Space Sciences, 9500 Gilman Dr., La Jolla, CA 92093-0424 (United States); Caballero, Isabel [CEA Saclay, DSM/IRFU/SAp -UMR AIM (7158) CNRS/CEA/Universite P. Diderot, Orme des Merisiers, Bat. 709, F-91191 Gif-sur-Yvette (France); Pottschmidt, Katja [CRESST, UMBC, and NASA GSFC, Code 661, Greenbelt, MD 20771 (United States); Kuehnel, Matthias; Wilms, Joern [Dr. Karl-Remeis-Sternwarte and ECAP, Sternwartstr. 7, D-96049 Bamberg (Germany); Fuerst, Felix [Space Radiation Lab, MC 290-17 Cahill, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125 (United States); Doroshenko, Victor [Institut fuer Astronomie und Astrophysik, Universitaet Tuebingen, Sand 1, D-72076 Tuebingen (Germany); Camero-Arranz, Ascension, E-mail: rrothschild@ucsd.edu [Institut de Ciencies de l' Espai, (IEEC-CSIC), Campus UAB, Fac. de Ciencies, Torre C5, parell, 2a planta, E-08193 Barcelona (Spain)

    2013-06-10

    We have analyzed three observations of the high-mass X-ray binary A 0535+26 performed by the Rossi X-Ray Timing Explorer (RXTE) three, five, and six months after the last outburst in 2011 February. We detect pulsations only in the second observation. The 3-20 keV spectra can be fit equally well with either an absorbed power law or absorbed thermal bremsstrahlung model. Reanalysis of two earlier RXTE observations made 4 yr after the 1994 outburst, original BeppoSAX observations 2 yr later, reanalysis of four EXOSAT observations made 2 yr after the last 1984 outburst, and a recent XMM-Newton observation in 2012 reveal a stacked, quiescent flux level decreasing from {approx}2 to <1 Multiplication-Sign 10{sup -11} erg cm{sup -2} s{sup -1} over 6.5 yr after outburst. The detection of pulsations during half of the quiescent observations would imply that accretion onto the magnetic poles of the neutron star continues despite the fact that the circumstellar disk may no longer be present. The accretion could come from material built up at the corotation radius or from an isotropic stellar wind.

  14. Evidence for simultaneous jets and disk winds in luminous low-mass X-ray binaries

    Homan, Jeroen; Allen, Jessamyn L; Chakrabarty, Deepto; Fender, Rob; Fridriksson, Joel K; Remillard, Ronald A; Schulz, Norbert

    2016-01-01

    Recent work on jets and disk winds in low-mass X-ray binaries (LMXBs) suggests that they are to a large extent mutually exclusive, with jets observed in spectrally hard states and disk winds in spectrally soft states. In this paper we use existing literature on jets and disk winds in the luminous neutron star LMXB GX 13+1, in combination with archival RXTE data, to show that this source is likely able to produce jets and disk winds simultaneously. We find that jets and disk winds occur in the same location on the source's track in its X-ray color-color diagram. A further study of literature on other luminous LMXBs reveals that this behavior is more common, with indications for simultaneous jets and disk winds in the black hole LMXBs V404 Cyg and GRS 1915+105 and the neutron star LMXBs Sco X-1 and Cir X-1. For the three sources for which we have the necessary spectral information, we find that the simultaneous jets/winds all occur in their spectrally hardest states. Our findings indicate that in LMXBs with lum...

  15. The Ages of High Mass X-ray Binaries in NGC 2403 and NGC 300

    Williams, Benjamin F; Dalcanton, Julianne J; Eracleous, Michael; Dolphin, Andrew

    2013-01-01

    We have examined resolved stellar photometry from HST imaging surrounding 18 high-mass X-ray binary (HMXB) candidates in NGC 300 and NGC 2403 as determined from combined Chandra/HST analysis. We have fit the color-magnitude distribution of the surrounding stars with stellar evolution models. All but one region in NGC 300 and two in NGC 2403 contain a population with an age between 20 and 70 Myr. One of the candidates is the ultraluminous X-ray source (ULX) in NGC 2403, which we associate with a 60 Myr old population. These age distributions provide additional evidence that 16 of these 18 candidates are HMXBs. Furthermore, our results suggest that the most common HMXB age in these galaxies is 40-55 Myr. This preferred age is similar to observations of HMXBs in the Small Magellanic Cloud, providing new evidence of this formation timescale, but in higher metallicity populations. We suggest that this preferred HMXB age is the result of the fortuitous combination of two physical effects. First, this is the age of ...

  16. THE AGES OF HIGH-MASS X-RAY BINARIES IN NGC 2403 AND NGC 300

    Williams, Benjamin F.; Binder, Breanna A.; Dalcanton, Julianne J. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Eracleous, Michael [Department of Astronomy and Astrophysics and Center for Gravitational Wave Physics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16803 (United States); Dolphin, Andrew, E-mail: ben@astro.washington.edu, E-mail: bbinder@astro.washington.edu, E-mail: jd@astro.washington.edu, E-mail: mce@astro.psu.edu, E-mail: adolphin@raytheon.com [Raytheon Company, Tucson, AZ 85734 (United States)

    2013-07-20

    We have examined resolved stellar photometry from HST imaging surrounding 18 high-mass X-ray binary (HMXB) candidates in NGC 300 and NGC 2403 as determined from combined Chandra/HST analysis. We have fit the color-magnitude distribution of the surrounding stars with stellar evolution models. All but one region in NGC 300 and two in NGC 2403 contain a population with an age between 20 and 70 Myr. One of the candidates is the ultraluminous X-ray source in NGC 2403, which we associate with a 60 {+-} 5 Myr old population. These age distributions provide additional evidence that 16 of these 18 candidates are HMXBs. Furthermore, our results suggest that the most common HMXB age in these galaxies is 40-55 Myr. This preferred age is similar to observations of HMXBs in the Small Magellanic Cloud, providing new evidence of this formation timescale, but in higher metallicity populations. We suggest that this preferred HMXB age is the result of the fortuitous combination of two physical effects. First, this is the age of a population when the greatest rate of core-collapse events should be occurring, maximizing neutron star production. Second, this is the age when B stars are most likely to be actively losing mass. We also discuss our results in the context of HMXB feedback in galaxies, confirming HMXBs as a potentially important source of energy for the interstellar medium in low-mass galaxies.

  17. Inhomogeneous accretion discs and the soft states of black hole X-ray binaries

    Dexter, Jason; Quataert, Eliot

    2012-10-01

    Observations of black hole binaries (BHBs) have established a rich phenomenology of X-ray states. The soft states range from the low variability, accretion disc dominated thermal (TD) state to the higher variability, non-thermal steep power law (SPL) state. The disc component in all states is typically modelled with standard thin disc accretion theory. However, this theory is inconsistent with optical/UV spectral, variability and gravitational microlensing observations of active galactic nuclei (AGNs), the supermassive analogues of BHBs. An inhomogeneous disc (ID) model with large (≃0.4 dex) temperature fluctuations in each radial annulus can qualitatively explain all of these AGN observations. The inhomogeneity may be a consequence of instabilities in radiation-dominated discs, and therefore may be present in BHBs as well. We show that ID models can explain many features of the TD and SPL states of BHBs. The observed relationships between spectral hardness, disc fraction and rms variability amplitude in BHBs are reproduced with temperature fluctuations similar to those inferred in AGNs, suggesting a unified picture of luminous accretion discs across orders of magnitude in black hole mass. This picture can be tested with spectral fitting of ID models, X-ray polarization observations and radiation magnetohydrodynamic simulations. If BHB accretion discs are indeed inhomogeneous, only the most disc-dominated states (disc fraction ≳0.95) can be used to robustly infer black hole spin using current continuum fitting methods.

  18. Si K Edge Structure and Variability in Galactic X-Ray Binaries

    Schulz, Norbert S; Canizares, Claude R

    2016-01-01

    We survey the Si K edge structure in various absorbed Galactic low-mass X-ray binaries (LMXBs) to study states of silicon in the inter- and circum-stellar medium. The bulk of these LMXBs lie toward the Galactic bulge region and all have column densities above $10^{22}$ cm$^{-2}$. The observations were performed with the \\emph{Chandra} High Energy Transmission Grating Spectrometer. The Si K edge in all sources appears at an energy value of 1844$\\pm$0.001 eV. The edge exhibits significant substructure which can be described by a near edge absorption feature at 1849$\\pm$0.002 eV and a far edge absorption feature at 1865$\\pm$0.002 eV. Both of these absorption features appear variable with equivalent widths up to several m\\AA. We can describe the edge structure with several components: multiple edge functions, near edge absorption excesses from silicates in dust form, signatures from X-ray scattering optical depths, and a variable warm absorber from ionized atomic silicon. The measured optical depths of the edges ...

  19. Refined Neutron-Star Mass Determinations for Six Eclipsing X-Ray Pulsar Binaries

    Rawls, Meredith L; McClintock, Jeffrey E; Torres, Manuel A P; Bailyn, Charles D; Buxton, Michelle M

    2011-01-01

    We present an improved method for determining the mass of neutron stars in eclipsing X-ray pulsar binaries and apply the method to six systems, namely Vela X-1, 4U 1538-52, SMC X-1, LMC X-4, Cen X-3, and Her X-1. In previous studies to determine neutron star mass, the X-ray eclipse duration has been approximated analytically by assuming the companion star is spherical with an effective Roche lobe radius. We use a numerical code based on Roche geometry with various optimizers to analyze the published data for these systems, which we supplement with new spectroscopic and photometric data for 4U 1538-52. This allows us to model the eclipse duration more accurately and thus calculate an improved value for the neutron star mass. The derived neutron star mass also depends on the assumed Roche lobe filling factor beta of the companion star, where beta = 1 indicates a completely filled Roche lobe. In previous work a range of beta between 0.9 and 1.0 was usually adopted. We use optical ellipsoidal lightcurve data to c...

  20. Exploring X-ray Binary Populations in Compact Group Galaxies with $Chandra$

    Tzanavaris, P; Gallagher, S C; Lenkic, L; Desjardins, T D; Walker, L M; Johnson, K E; Mulchaey, J S

    2015-01-01

    We obtain total galaxy X-ray luminosities, $L_X$, originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of our galaxies, we find that the detected point sources most likely are local to their associated galaxy, and are thus extragalactic X-ray binaries (XRBs) or nuclear active galactic nuclei (AGNs). For spiral and irregular galaxies, we find that, after accounting for AGNs and nuclear sources, most CG galaxies are either within the $\\pm1\\sigma$ scatter of the Mineo et al. (2012) $L_X$ - star formation rate (SFR) correlation or have higher $L_X$ than predicted by this correlation for their SFR. We discuss how these "excesses" may be due to low metallicities and high interaction levels. For elliptical and S0 galaxies, after accounting for AGNs and nuclear sources, most CG galaxies are consistent with the Boroson et al. (2011) $L_X$ - stellar mass correlation for low-mass XRBs, with larger scatter, likely due to residual ef...

  1. X-ray Binaries and Star Clusters in the Antennae: Optical Cluster Counterparts

    Rangelov, Blagoy; Prestwich, Andrea; Whitmore, Bradley C

    2012-01-01

    We compare the locations of 82 X-ray binaries (XRBs) detected in the merging Antennae galaxies by Zezas et al., based on observations taken with the Chandra X-Ray Observatory, with a catalog of optically selected star clusters presented by Whitmore et al., based on observations taken with the Hubble Space Telescope. Within the 2 sigma positional uncertainty of 0.58", we find 22 XRBs are coincident with star clusters, where only 2-3 chance coincidences are expected. The ages of the clusters were estimated by comparing their UBVI, Halpha colors with predictions from stellar evolutionary models. We find that 14 of the 22 coincident XRBs (64%) are hosted by star clusters with ages of 6 Myr or less. Five of the XRBs are hosted by young clusters with ages 10-100 Myr, while three are hosted by intermediate age clusters with 100-300 Myr. Based on the results from recent N-body simulations, which suggest that black holes are far more likely to be retained within their parent clusters than neutron stars, we suggest tha...

  2. WISE Detection of the Galactic Low-Mass X-Ray Binaries

    Wang, Xuebing

    2014-01-01

    We report on the results from our search for the Wide-field Infrared Survey Explorer detection of the Galactic low-mass X-ray binaries. Among 187 binaries catalogued in Liu et al. (2007), we find 13 counterparts and two candidate counterparts. For the 13 counterparts, two (4U~0614+091 and GX~339$-$4) have already been confirmed by previous studies to have a jet and one (GRS~1915+105) to have a candidate circumbinary disk, from which the detected infrared emission arose. Having collected the broad-band optical and near-infrared data in literature and constructed flux density spectra for the other 10 binaries, we identify that three (A0620$-$00, XTE J1118+480, and GX 1+4) are candidate circumbinary disk systems, four (Cen X-4, 4U 1700+24, 3A 1954+319, and Cyg X-2) had thermal emission from their companion stars, and three (Sco X-1, Her X-1, and Swift J1753.5$-$0127) are peculiar systems with the origin of their infrared emission rather uncertain. We discuss the results and WISE counterparts' brightness distribu...

  3. A fast search strategy for gravitational waves from low-mass X-ray binaries

    Messenger, C

    2007-01-01

    We present a new type of search strategy designed specifically to find continuously emitting gravitational wave sources in known binary systems based on the incoherent sum of frequency modulated binary signal sidebands. The search pipeline can be divided into three stages: the first is a wide bandwidth, F-statistic search demodulated for sky position. This is followed by a fast second stage in which areas in frequency space are identified as signal candidates through the frequency domain convolution of the F-statistic with an approximate signal template. For this second stage only precise information on the orbit period and approximate information on the orbital semi-major axis are required apriori. For the final stage we propose a fully coherent Markov chain monte carlo based follow up search on the frequency subspace defined by the candidates identified by the second stage. This search is particularly suited to the low-mass X-ray binaries, for which orbital period and sky position are typically well known a...

  4. Main parameters of neutron stars from quasi-periodic oscillations in low mass X-ray binaries

    Boshkayev, Kuantay; Muccino, Marco

    2016-01-01

    We investigate the kilohertz quasi-periodic oscillations of low-mass X-ray binaries within the Hartle-Thorne spacetime. On the basis the relativistic precession model we extract the total mass $M$, angular momentum $J$, and quadrupole moment $Q$ of a compact object in a low-mass X-ray binary by analyzing the data of the Z -source GX 5-1. In view of the recent neutron star model we compute the radius, angular velocity and other parameters of this source by imposing the observational and theoretical constraints on the mass-radius relation.

  5. Herschel observations of dust around the high-mass X-ray binary GX 301-2

    Servillat, Mathieu; Coleiro, Alexis; Chaty, Sylvain; Rahoui, Farid; Heras, Juan Antonio Zurita

    2014-01-01

    We aim at characterising the structure of the gas and dust around the high mass X-ray binary GX 301-2, a highly obscured X-ray binary hosting a hypergiant star and a neutron star, in order to better constrain its evolution. We used Herschel PACS to observe GX 301-2 in the far infrared and completed the spectral energy distribution of the source using published data or catalogs, from the optical to the radio range (0.4 to 4x10^4 micrometer). GX 301-2 is detected for the first time at 70 and 10...

  6. RXTE observations of the neutron star low-mass X-ray binary GX 17+2 correlated X-ray spectral and timing behavior

    Homan, J; Jonker, P G; Wijnands, R; Kuulkers, E; Méndez, M; Lewin, W H G; Homan, Jeroen; Klis, Michiel van der; Jonker, Peter G.; Wijnands, Rudy; Kuulkers, Erik; Mendez, Mariano; Lewin, Walter H. G.

    2001-01-01

    We have analyzed ~600 ks of Rossi X-ray Timing Explorer data of the neutron star low-mass X-ray binary and Z source GX 17+2. A study was performed of the properties of the noise components and quasi-periodic oscillations (QPOs) as a function of the spectral properties, with the main goal to study the relation between the frequencies of the horizontal branch and upper kHz QPOs. It was found that when the upper kHz QPO frequency is below 1030 Hz these frequencies correlate, whereas above 1030 Hz they anti-correlate. GX 17+2 is the first source in which this is observed. We also found that the frequency difference of the high frequency QPOs was not constant and that the quality factors (Q values) of the HBO, its second harmonic, and the kHz QPOs are similar, and vary almost hand in hand by a factor of more than three. Observations of the normal branch oscillations during two type I X-ray bursts showed that their absolute amplitude decreased as the flux from the neutron star became stronger. We discuss these and ...

  7. X-Ray Spectra of The High-Mass X-RAY Binary 4U~1700-37 using BeppoSAX, Suzaku and RXTE Observations

    Seifina, Elena; Shaposhnikov, Nikolai

    2016-01-01

    We present an X-ray spectral analysis of the high-mass binary 4U~1700-37 during its hard-soft state evolution. We use the BeppoSAX, Suzaku and RXTE (Rossi X-ray Timing Explorer), Suzaku and BeppoSAX observations for this investigation. We argue that the X-ray broad-band spectra during all spectral states can be adequately reproduced by a model, consisting of a low-temperature Blackbody component, two Comptonized components both due to the presence of a Compton cloud (CC) that up-scatters seed photons of $T_{s1}$~< 1.4 keV, and $T_{s2}<$1 keV, and an iron-line component. We find using this model that the photon power-law index is almost constant, $\\Gamma_{1}\\sim 2$ for all spectral states. However, $\\Gamma_{2}$ shows a behavior depending on the spectral state. Namely, $\\Gamma_{2}$ is quasi-constant at the level of $\\Gamma_{2}\\sim 2$ while the CC plasma temperature $kT^{(2)}_e$ is less than 40 keV; on the other hand, $\\Gamma_{2}$ is in the range of $1.3<\\Gamma_{2}<2$, when $kT^{(2)}_e$ is greater th...

  8. X-ray outbursts of ESO 243-49 HLX-1: comparison with Galactic low-mass X-ray binary transients

    Yan, Zhen; Soria, Roberto; Altamirano, Diego; Yu, Wenfei

    2015-01-01

    We studied the outburst properties of the hyper-luminous X-ray source ESO 243-49 HLX-1, using the full set of Swift monitoring observations. We quantified the increase in the waiting time, recurrence time and e-folding rise timescale along the outburst sequence, and the corresponding decrease in outburst duration, total radiated energy, and e-folding decay timescale, which confirms previous findings. HLX-1 spends less and less time in outburst and more and more time in quiescence, but its peak luminosity remains approximately constant. We compared the HLX-1 outburst properties with those of bright Galactic low-mass X-ray binary transients (LMXBTs). Our spectral analysis strengthens the similarity between state transitions in HLX-1 and those in Galactic LMXBTs. We also found that HLX-1 follows the nearly linear correlations between the hard-to-soft state transition luminosity and the peak luminosity, and between the rate of change of X-ray luminosity during the rise phase and the peak luminosity, which indicat...

  9. THE ORIGIN OF BLACK HOLE SPIN IN GALACTIC LOW-MASS X-RAY BINARIES

    Fragos, T. [Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290 Sauverny (Switzerland); McClintock, J. E., E-mail: anastasios.fragkos@unige.ch [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-02-10

    Galactic field black hole (BH) low-mass X-ray binaries (LMXBs) are believed to form in situ via the evolution of isolated binaries. In the standard formation channel, these systems survived a common envelope phase, after which the remaining helium core of the primary star and the subsequently formed BH are not expected to be highly spinning. However, the measured spins of BHs in LMXBs cover the whole range of spin parameters. We propose here that the BH spin in LMXBs is acquired through accretion onto the BH after its formation. In order to test this hypothesis, we calculated extensive grids of detailed binary mass-transfer sequences. For each sequence, we examined whether, at any point in time, the calculated binary properties are in agreement with their observationally inferred counterparts of 16 Galactic LMXBs. The ''successful'' sequences give estimates of the mass that the BH has accreted since the onset of Roche-Lobe overflow. We find that in all Galactic LMXBs with measured BH spin, the origin of the spin can be accounted for by the accreted matter, and we make predictions about the maximum BH spin in LMXBs where no measurement is yet available. Furthermore, we derive limits on the maximum spin that any BH can have depending on current properties of the binary it resides in. Finally we discuss the implication that our findings have on the BH birth-mass distribution, which is shifted by ∼1.5 M {sub ☉} toward lower masses, compared to the currently observed one.

  10. Potential Optical Counterparts to High Mass X-Ray and γ-Ray Binaries

    Mitchell, Carl; McSwain, M. V.

    2011-01-01

    We seek to identify optical counterparts to several previously discovered high mass X-ray binaries and γ-ray sources from the Liu et al. and Fermi first year catalogues. Observations were taken with the CTIO 0.9-meter telescope, operated by the SMARTS Consortium. Photometric data were taken in the Strömgren b and y filters, as well as a narrow-band Hα filter. We present color-color diagrams of y-Hα vs. b-y for each field, and candidates for optical counterparts were selected based on their excesses of Hα emission. We also present spectral energy distributions for select candidates. This work is supported by the NSF REU site grant PHY-0849416, NASA DPR No. NNX09AT67G, and Lehigh University. We also thank the SMARTS Consortium, Rachael Roettenbacher, Tina Aragona, and Amber Marsh.

  11. Bifurcation timescales in power spectra of black hole binaries and ultraluminous X-ray sources

    2010-01-01

    For black hole binaries(BHBs) and active galactic nuclei(AGNs),bifurcation timescales(BTs) Δtb exist,below which time-domain power is significantly higher than the corresponding Fourier power.Quasi-periodic oscillations(QPOs) are removed from the Fourier spectra of BHBs.A relationship between BT,black hole mass and bolometric luminosity is derived.Strong anti-correlation between BT and luminosity of Cyg X-1 is found.After removing the QPOs,BTs are also obtained for two ultraluminous X-ray sources(ULXs),M82 X-1 and NGC5408 X-1.The results support that they harbor intermediate mass black holes(IMBHs).

  12. Jets in black-hole and neutron-star X-ray binaries

    Kylafis, Nikolaos

    2016-07-01

    Jets have been observed from both neutron-star and black-hole X-ray binaries. There are many similarities between the two and a few differences. I will offer a physical explanation of the formation and destruction of jets from compact objects and I will discuss the similarities and differences in the two types. The basic concept in the physical explanation is the Cosmic Battery, the mechanism that creates the required magnetic field for the jet ejection. The Cosmic Battery operates efficiently in accretion flows consisting of an inner hot flow and an outer thin accretion disk, independently of the nature of the compact object. It is therefore natural to always expect a jet in the right part of a spectral hardness - luminosity diagram and to never expect a jet in the left part. As a consequence, most of the phenomenology of an outburst can be explained with only one parameter, the mass accretion rate.

  13. Polarization modulation from Lense-Thirring precession in X-ray binaries

    Ingram, Adam; Poutanen, Juri; Krawczynski, Henric

    2015-01-01

    It has long been recognised that quasi-periodic oscillations (QPOs) in the X-ray light curves of accreting black hole and neutron star binaries have the potential to be powerful diagnostics of strong field gravity. However, this potential cannot be fulfilled without a working theoretical model, which has remained elusive. Perhaps the most promising model associates the QPO with Lense-Thirring precession of the inner accretion flow, with the changes in viewing angle and Doppler boosting modulating the flux over the course of a precession cycle. Here, we consider the polarization signature of a precessing inner accretion flow. We use simple assumptions about the Comptonization process generating the emitted spectrum and take all relativistic effects into account, parallel transporting polarization vectors towards the observer along null geodesics in the Kerr metric. We find that both the degree of linear polarization and the polarization angle should be modulated on the QPO frequency. We calculate the predicted...

  14. Inhomogeneous accretion discs and the soft states of black hole X-ray binaries

    Dexter, Jason

    2012-01-01

    Observations of black hole binaries (BHBs) have established a rich phenomenology of X-ray states. The soft states range from the low variability, accretion disc dominated thermal state (TD) to the higher variability, non-thermal steep power law state (SPL). The disc component in all states is typically modeled with standard thin disc accretion theory. However, this theory is inconsistent with optical/UV spectral, variability, and gravitational microlensing observations of active galactic nuclei (AGNs), the supermassive analogs of BHBs. An inhomogeneous disc (ID) model with large (~0.4 dex) temperature fluctuations in each radial annulus can qualitatively explain all of these AGN observations. The inhomogeneity may be a consequence of instabilities in radiation dominated discs, and therefore may be present in BHBs as well. We show that ID models can explain many features of the TD and SPL states of BHBs. The observed relationships between spectral hardness, disc fraction, and rms variability amplitude in BHBs ...

  15. Testing theories for longterm accretion variability in black hole X-ray binaries

    Cambier, Hal J.

    Many X-ray sources are now understood to be "black hole X-ray binaries'' in which a stellar remnant black hole either tidally "squeezes'' gas off a companion star, or pulls in some fraction the companion's wind. This gas can drain inward through a dense, thin disk characterized by thermalized radiation, or a sparse and radiatively-inefficient flow, or some combination of the two. Observations at other energies often provide crucial information, but our primary tools to study accretion, especially closest to the black hole, are X-ray spectra and their time evolution. This evolution includes numerous behaviors spanning orders of magnitude in timescale and luminosity, and also hints at spatial structure since draining is generally faster at smaller radii. This includes variability at time-scales of weeks to months which remains difficult to explain despite an abundance of possible variability mechanisms since direct simulations covering the full spatial and temporal range remain impractical. After reviewing general aspects of accretion, I present both more and less familiar forms of longterm variability. Based on these, I argue the problem involves finding a physical process (or combination) that can generate repeatable yet adjustable cycles in luminosity and evolution of low and high energy spectral components, while letting the ionization instability dominate conventional outbursts. Specific models examined include: disks embedded in, and interacting with, hot, sparse flows, and another instability that quenches viscous-draining of the disk at more fundamental level. Testing these theories, alone and in combination, motivates building a very general and simplified numerical model presented here. I find that two-phase flow models still predict excessive recondensation in LMC X-3 among other problems, while the viscosity-quenching instability may account for rapid drops and slow recoveries in disk accretion rate but also likely requires diffusivity orders of magnitude

  16. X-ray follow-ups of XSS J12270-4859: a low-mass X-ray binary with gamma-ray Fermi-LAT association

    de Martino, D.; Belloni, T.; Falanga, M.; Papitto, A.; Motta, S.; Pellizzoni, A.; Evangelista, Y.; Piano, G.; Masetti, N.; Bonnet-Bidaud, J.-M.; Mouchet, M.; Mukai, K.; Possenti, A.

    2013-02-01

    Context. XSS J1227.0-4859 is a peculiar, hard X-ray source recently positionally associated to the Fermi-LAT source 1FGL J1227.9-4852/2FGL J1227.7-4853. Multi-wavelength observations have added information on this source, indicating a low-luminosity low-mass X-ray binary (LMXB), but its nature is still unclear. Aims: To progress in our understanding, we present new X-ray data from a monitoring campaign performed in 2011 with the XMM-Newton, RXTE, and Swift satellites and combine them with new gamma-ray data from the Fermi and AGILE satellites. We complement the study with simultaneous near-UV photometry from XMM-Newton and with previous UV/optical and near-IR data. Methods: We analysed the temporal characteristics in the X-rays, near-UV, and gamma rays and studied the broad-band spectral energy distribution from radio to gamma rays. Results: The X-ray history of XSS J1227 over 7 yr shows a persistent and rather stable low-luminosity (6 × 1033 d1 kpc2 erg s-1) source, with flares and dips being peculiar and permanent characteristics. The associated Fermi-LAT source 2FGL J1227.7-4853 is also stable over an overlapping period of 4.7 yr. Searches for X-ray fast pulsations down to msec give upper limits to pulse fractional amplitudes of 15-25% that do not rule out a fast spinning pulsar. The combined UV/optical/near-IR spectrum reveals a hot component at ~13 kK and a cool one at ~4.6 kK. The latter would suggest a late-type K2-K5 companion star, a distance range of 1.4-3.6 kpc, and an orbital period of 7-9 h. A near-UV variability (≳6 h) also suggests a longer orbital period than previously estimated. Conclusions: The analysis shows that the X-ray and UV/optical/near-IR emissions are more compatible with an accretion-powered compact object than with a rotational powered pulsar. The X-ray to UV bolometric luminosity ratio could be consistent with a binary hosting a neutron star, but the uncertainties in the radio data may also allow an LMXB black hole with a compact

  17. Suzaku view of the Be/X-ray binary pulsar GX 304-1 during Type I X-ray outbursts

    Jaisawal, Gaurava K.; Naik, Sachindra; Epili, Prahlad

    2016-04-01

    We report the timing and spectral properties of the Be/X-ray binary pulsar GX 304-1 using two Suzaku observations during its 2010 August and 2012 January X-ray outbursts. Pulsations at ˜275 s were clearly detected in the light curves from both observations. Pulse profiles were found to be strongly energy-dependent. During the 2010 observation, the prominent dips seen in soft X-ray (≤10 keV) pulse profiles were found to be absent at higher energies. However, during the 2012 observation, the pulse profiles were complex as a result of the presence of several dips. Significant changes in the shape of the pulse profiles were detected at high energies (>35 keV). A phase shift of ˜0.3 was detected while comparing the phase of the main dip in the pulse profiles below and above ˜35 keV. The broad-band energy spectrum of the pulsar was well described by a partially absorbed negative and positive power law with exponential cut-off (NPEX) model with 6.4-keV iron line and a cyclotron absorption feature. The energy of the cyclotron absorption line was found to be ˜53 and 50 keV for the 2010 and 2012 observations, respectively, indicating a marginal positive dependence on source luminosity. Based on the results obtained from phase-resolved spectroscopy, the absorption dips in the pulse profiles can be interpreted as due to the presence of additional matter at same phases. Observed positive correlation between the cyclotron line energy and luminosity, and the significant pulse-phase variation of cyclotron parameters are discussed from the perspective of theoretical models on the cyclotron absorption line in X-ray pulsars.

  18. Contrasting Behaviour from Two Be/X-ray Binary Pulsars: Insights into Differing Neutron Star Accretion Modes

    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.

  19. Relation between the X-ray and Optical Luminosities in Binary Systems with Accreting Nonmagnetic White Dwarfs

    Revnivtsev, M G; Suleimanov, V F

    2014-01-01

    We investigate the relation between the optical (g-band) and X-ray (0.5-10 keV) luminosities of accreting nonmagnetic white dwarfs. According to the present-day counts of the populations of star systems in our Galaxy, these systems have the highest space density among the close binary systems with white dwarfs. We show that the dependence of the optical luminosity of accreting white dwarfs on their X-ray luminosity forms a fairly narrow one-parameter curve. The typical half-width of this curve does not exceed 0.2-0.3 dex in optical and X-ray luminosities, which is essentially consistent with the amplitude of the aperiodic flux variability for these objects. At X-ray luminosities Lx~1e32 erg/sec or lower, the optical g-band luminosity of the accretion flow is shown to be related to its X-ray luminosity by a factor ~2-3. At even lower X-ray luminosities (Lx~1e30 erg/sec), the contribution from the photosphere of the white dwarf begins to dominate in the optical spectrum of the binary system and its optical brig...

  20. Timing and Spectral Studies of the Peculiar X-ray Binary Circinus X-1

    Circinus X-1 (Cir X-1) is an X-ray binary displaying an array of phenomena which makes it unique in our Galaxy. Despite several decades of observation, controversy surrounds even the most basic facts about this system. It is generally classified as a Neutron Star (NS) Low Mass X-ray Binary (LMXB),though this classification is based primarily on the observation of Type I X-ray Bursts by EXOSAT in 1985. It is believed to be in a very eccentric ∼ 16.5 day orbit, displaying periodic outbursts in the radio and other frequency bands (including optical and IR) which reinforce the notion that this is in fact the orbital period. Cir X-1 lies in the plane of the Galaxy, where optical identification of the companion is made difficult due to dust obscuration. The companion is thought to be a low mass star, though a high mass companion has not currently been ruled out. In this work, the author analyzes recent observations of Cir X-1 made with the Unconventional Stellar Aspect (USA) experiment, as well as archival observations of Cir X-1 made by a variety of instruments, from as early as 1969. The fast (dot) mass of a neutron star, possibly partly explaining why this object appears so different to other neutron stars. The spectral evolution of Cir X-1 is studied by constructing both instrument-independent and model-independent color-color diagrams. Spectral fits are performed on all USA observations and physical parameters are derived. Cir X-1 periodically evolves from a high/soft state to a low/hard state within each orbital cycle. The spectral fits obtained indicate that a two-component model provides an appropriate description of the Cir X-1 spectrum with one component representing the emission from a multicolor blackbody accretion disk while the other component represents the higher energy Comptonized emission probably coming from a boundary layer on the surface of the neutron star. To study the long-term X-ray variability of Cir X-1 the author analyzes archival data from

  1. Detection of the first infra-red quasi-periodic oscillation in a black hole X-ray binary

    Kalamkar, M.; Casella, P.; Uttley, P.; O'Brien, K.; Russell, D.; Maccarone, T.; van der Klis, M.; Vincentelli, F.

    2016-08-01

    We present analysis of fast variability of Very Large Telescope/ISAAC (infra-red), \\textit{XMM-Newton}/OM (optical) and EPIC-pn (X-ray), and RXTE/PCA (X-ray) observations of the black hole X-ray binary GX 339-4 in a rising hard state of its outburst in 2010. We report the first detection of a Quasi Periodic Oscillation (QPO) in the infra-red band (IR) of a black hole X-ray binary. The QPO is detected at 0.08 Hz in the IR as well as two optical bands (U and V). Interestingly, these QPOs are at half the X-ray QPO frequency at 0.16 Hz, which is classified as the type-C QPO; a weak sub-harmonic close to the IR and optical QPO frequency is also detected in X-rays. The broad band sub-second time scale variability is strongly correlated in IR/X-ray bands, with X-rays leading the IR by over 100 ms. This short time delay, shape of the cross correlation function and spectral energy distribution strongly indicate that this broad band variable IR emission is the synchrotron emission from the jet. A jet origin for the IR QPO is strongly favoured, but cannot be definitively established with the current data. The spectral energy distribution indicates a thermal disc origin for the bulk of the optical emission, but the origin of the optical QPO is unclear. We discuss our findings in the context of the existing models proposed to explain the origin of variability.

  2. Heating the intergalactic medium by X-rays from population III binaries in high-redshift galaxies

    Due to their long mean free path, X-rays are expected to have an important impact on cosmic reionization by heating and ionizing the intergalactic medium (IGM) on large scales, especially after simulations have suggested that Population III (Pop III) stars may form in pairs at redshifts as high as 20-30. We use the Pop III distribution and evolution from a self-consistent cosmological radiation hydrodynamic simulation of the formation of the first galaxies and a simple Pop III X-ray binary model to estimate their X-ray output in a high-density region larger than 100 comoving (Mpc)3. We then combine three different methods—ray tracing, a one-zone model, and X-ray background modeling—to investigate the X-ray propagation, intensity distribution, and long-term effects on the IGM thermal and ionization state. The efficiency and morphology of photoheating and photoionization are dependent on the photon energies. The sub-kiloelectronvolt X-rays only impact the IGM near the sources, while the kiloelectronvolt photons contribute significantly to the X-ray background and heat and ionize the IGM smoothly. The X-rays just below 1 keV are most efficient in heating and ionizing the IGM. We find that the IGM might be heated to over 100 K by z = 10 and the high-density source region might reach 104 K, limited by atomic hydrogen cooling. This may be important for predicting the 21 cm neutral hydrogen signals. On the other hand, the free electrons from X-ray ionizations are not enough to contribute significantly to the optical depth of the cosmic microwave background to the Thomson scattering.

  3. On the kinematics of the neutron star low mass X-ray binary Cen X-4

    Hern'andez, J I G; Penarrubia, J; Casares, J; Israelian, G

    2005-01-01

    We present the first determination of the proper motion of the neutron star low mass X-ray binary {Cen X-4} measured from relative astrometry of the secondary star using optical images at different epochs. We determine the Galactic space velocity components of the system and find them to be significantly different from the mean values that characterize the kinematics of stars belonging to the halo, and the thin and the thick disc of the Galaxy. The high metallicity of the secondary star of the system rules out a halo origin and indicates that the system probably originated in the Galactic disc. A statistical analysis of the galactocentric motion revealed that this binary moves in a highly eccentric ($e\\simeq 0.85\\pm0.1$) orbit with an inclination of $\\simeq 110^\\circ$ to the Galactic plane. The large Galactic space velocity components strongly support that a high natal kick as a result of a supernova explosion could have propelled the system into such an orbit from a birth place in the Galactic disc. The high...

  4. Discovery of disc precession in the M31 dipping X-ray binary Bo 158

    Barnard, R; Haswell, C A; Kolb, U; Osborne, J P; Murray, J R

    2006-01-01

    We present results from three XMM-Newton observations of the M31 low mass X-ray binary XMMU J004314.4+410726.3 (Bo 158), spaced over 3 days in 2004, July. Bo 158 was the first dipping LMXB to be discovered in M31. Periodic intensity dips were previously seen to occur on a 2.78-hr period, due to absorption in material that is raised out of the plane of the accretion disc. The report of these observations stated that the dip depth was anti-correlated with source intensity. However, our new observations do not favour a strict intensity dependance, but rather suggest that the dip variation is due to precession of the accretion disc. This is to be expected in LMXBs with a mass ratio <~ 0.3 (period <~ 4 hr), as the disc reaches the 3:1 resonance with the binary companion, causing elongation and precession of the disc. A 3D smoothed particle hydrodynamics simulation of the disc in this system shows retrograde rotation of a disc warp on a period of ~11 P_orb, and prograde disc precession on a period of ~29 P_or...

  5. BLACK HOLE SPIN-ORBIT MISALIGNMENT IN GALACTIC X-RAY BINARIES

    In black hole (BH) X-ray binaries (XRBs), a misalignment between the spin axis of the BH and the orbital angular momentum can occur during the supernova explosion that forms the compact object. In this Letter, we present population synthesis (PS) models of Galactic BH XRBs and study the probability density function of the misalignment angle and its dependence on our model parameters. In our modeling, we also take into account the evolution of the misalignment angle due to accretion of material onto the BH during the XRB phase. The major factor that sets the misalignment angle for XRBs is the natal kick that the BH may receive at its formation. However, large kicks tend to disrupt binaries, while small kicks allow the formation of XRBs and naturally select systems with small misalignment angles. Our calculations predict that the majority (>67%) of Galactic field BH XRBs have rather small (∼0) misalignment angles, while some systems may reach misalignment angles as high as ∼900 and even higher. These results are robust among all PS models. The assumption of small misalignment angles is extensively used to observationally estimate BH spin magnitudes, and for the first time we are able to confirm this assumption using detailed PS calculations.

  6. A CHANDRA X-RAY STUDY OF THE INTERACTING BINARIES IN THE OLD OPEN CLUSTER NGC 6791

    Van den Berg, Maureen [Astronomical Institute ' ' Anton Pannekoek' ' , University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Verbunt, Frank [Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen (Netherlands); Tagliaferri, Gianpiero; Belloni, Tomaso [INAF/Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy); Bedin, Luigi R. [INAF/Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Platais, Imants, E-mail: M.C.vandenBerg@uva.nl [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2013-06-20

    We present the first X-ray study of NGC 6791, one of the oldest open clusters known (8 Gyr). Our Chandra observation is aimed at uncovering the population of close interacting binaries down to L{sub X} Almost-Equal-To 1 Multiplication-Sign 10{sup 30} erg s{sup -1} (0.3-7 keV). We detect 86 sources within 8' of the cluster center, including 59 inside the half-mass radius. We identify 20 sources with proper-motion cluster members, which are a mix of cataclysmic variables (CVs), active binaries (ABs), and binaries containing sub-subgiants. With follow-up optical spectroscopy, we confirm the nature of one CV. We discover one new, X-ray variable candidate CV with Balmer and He II emission lines in its optical spectrum; this is the first X-ray-selected CV in an open cluster. The number of CVs per unit mass is consistent with the field, suggesting that the 3-4 CVs observed in NGC 6791 are primordial. We compare the X-ray properties of NGC 6791 with those of a few old open (NGC 6819, M 67) and globular clusters (47 Tuc, NGC 6397). It is puzzling that the number of ABs brighter than 1 Multiplication-Sign 10{sup 30} erg s{sup -1} normalized by cluster mass is lower in NGC 6791 than in M 67 by a factor {approx}3-7. CVs, ABs, and sub-subgiants brighter than 1 Multiplication-Sign 10{sup 30} erg s{sup -1} are under-represented per unit mass in the globular clusters compared to the oldest open clusters, and this accounts for the lower total X-ray luminosity per unit mass of the former. This indicates that the net effect of dynamical encounters may be the destruction of even some of the hardest (i.e., X-ray-emitting) binaries.

  7. Discovery of the third transient X-ray binary in the galactic globular cluster Terzan 5

    Bahramian, Arash; Heinke, Craig O.; Sivakoff, Gregory R.; Gladstone, Jeanette C. [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB T6G 2E1 (Canada); Altamirano, Diego; Wijnands, Rudy [Astronomical Institute " Anton Pannekoek," University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Homan, Jeroen [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States); Linares, Manuel [Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain); Pooley, David [Department of Physics, Sam Houston State University, Huntsville, TX 77341 (United States); Degenaar, Nathalie, E-mail: bahramia@ualberta.ca [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)

    2014-01-10

    We report and study the outburst of a new transient X-ray binary (XRB) in Terzan 5, the third detected in this globular cluster, Swift J174805.3-244637 or Terzan 5 X-3. We find clear spectral hardening in Swift/XRT data during the outburst rise to the hard state, thanks to our early coverage (starting at L{sub X} ∼ 4 × 10{sup 34} erg s{sup –1}) of the outburst. This hardening appears to be due to the decline in relative strength of a soft thermal component from the surface of the neutron star (NS) during the rise. We identify a Type I X-ray burst in Swift/XRT data with a long (16 s) decay time, indicative of hydrogen burning on the surface of the NS. We use Swift/BAT, MAXI/GSC, Chandra/ACIS, and Swift/XRT data to study the spectral changes during the outburst, identifying a clear hard-to-soft state transition. We use a Chandra/ACIS observation during outburst to identify the transient's position. Seven archival Chandra/ACIS observations show evidence for variations in Terzan 5 X-3's nonthermal component but not the thermal component during quiescence. The inferred long-term time-averaged mass accretion rate, from the quiescent thermal luminosity, suggests that if this outburst is typical and only slow cooling processes are active in the NS core, such outbursts should recur every ∼10 yr.

  8. Contrasting behaviour from two Be/X-ray binary pulsars: insights into differing neutron star accretion modes

    Townsend, L J; 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 175.4s and 85.4s 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 ...

  9. Disc-Jet Coupling in the Terzan 5 Neutron Star X-ray Binary EXO 1745$-$248

    Tetarenko, A J; Sivakoff, G R; Tremou, E; Linares, M; Tudor, V; Miller-Jones, J C A; Heinke, C O; Chomiuk, L; Strader, J; Altamirano, D; Degenaar, N; Maccarone, T; Patruno, A; Sanna, A; Wijnands, R

    2016-01-01

    We present the results of VLA, ATCA, and Swift XRT observations of the 2015 outburst of the transient neutron star X-ray binary (NSXB), EXO 1745$-$248, located in the globular cluster Terzan 5. Combining (near-) simultaneous radio and X-ray measurements we measure a correlation between the radio and X-ray luminosities of $L_R\\propto L_X^\\beta$ with $\\beta=1.68^{+0.10}_{-0.09}$, linking the accretion flow (probed by X-ray luminosity) and the compact jet (probed by radio luminosity). While such a relationship has been studied in multiple black hole X-ray binaries (BHXBs), this work marks only the third NSXB with such a measurement. Constraints on this relationship in NSXBs are strongly needed, as comparing this correlation between different classes of XB systems is key in understanding the properties that affect the jet production process in accreting objects. Our best fit disc-jet coupling index for EXO 1745$-$248 is consistent with the measured correlation in NSXB 4U 1728$-$34 ($\\beta=1.5\\pm 0.2$) but inconsi...

  10. A `high-hard' outburst of the black hole X-ray binary GS 1354-64

    Koljonen, K. I. I.; Russell, D. M.; Corral-Santana, J. M.; Armas Padilla, M.; Muñoz-Darias, T.; Lewis, F.; Coriat, M.; Bauer, F. E.

    2016-07-01

    We study in detail the evolution of the 2015 outburst of GS 1354-64 (BW Cir) at optical, UV and X-ray wavelengths using Faulkes Telescope South/Las Cumbres Observatory Global Telescope Network, Small & Moderate Aperture Research Telescope System and Swift. The outburst was found to stay in the hard X-ray state, albeit being anomalously luminous with a peak luminosity of LX > 0.15 LEdd, which could be the most luminous hard state observed in a black hole X-ray binary. We found that the optical/UV emission is tightly correlated with the X-ray emission, consistent with accretion disc irradiation and/or a jet producing the optical emission. The X-ray spectra can be fitted well with a Comptonization model, and show softening towards the end of the outburst. In addition, we detect a QPO in the X-ray light curves with increasing centroid frequency during the peak and decay periods of the outburst. The long-term optical light curves during quiescence show a statistically significant, slow rise of the source brightness over the 7 years prior to the 2015 outburst. This behaviour as well as the outburst evolution at all wavelengths studied can be explained by the disc instability model with irradiation and disc evaporation/condensation.

  11. A "high-hard" outburst of the black hole X-ray binary GS 1354-64

    Koljonen, K I I; Corral-Santana, J M; Padilla, M Armas; Muñoz-Darias, T; Lewis, F; Coriat, M; Bauer, F E

    2016-01-01

    We study in detail the evolution of the 2015 outburst of GS 1354-64 (BW Cir) at optical, UV and X-ray wavelengths using Faulkes Telescope South, SMARTS and Swift. The outburst was found to stay in the hard X-ray state, albeit being anomalously luminous with a peak luminosity of L$_{X} >$ 0.15 L$_{Edd}$, which could be the most luminous hard state observed in a black hole X-ray binary. We found that the optical/UV emission is tightly correlated with the X-ray emission, consistent with accretion disc irradiation and/or a jet producing the optical emission. The X-ray spectra can be fitted well with a Comptonisation model, and show softening towards the end of the outburst. In addition, we detect a QPO in the X-ray lightcurves with increasing centroid frequency during the peak and decay periods of the outburst. The long-term optical lightcurves during quiescence show a statistically significant, slow rise of the source brightness over the 7 years prior to the 2015 outburst. This behaviour as well as the outburst ...

  12. A "high-hard" outburst of the black hole X-ray binary GS 1354-64

    Koljonen, K. I. I.; Russell, D. M.; Corral-Santana, J. M.; Armas Padilla, M.; Muñoz-Darias, T.; Lewis, F.; Coriat, M.; Bauer, F. E.

    2016-04-01

    We study in detail the evolution of the 2015 outburst of GS 1354-64 (BW Cir) at optical, UV and X-ray wavelengths using Faulkes Telescope South/LCOGT, SMARTS and Swift. The outburst was found to stay in the hard X-ray state, albeit being anomalously luminous with a peak luminosity of LX > 0.15 LEdd, which could be the most luminous hard state observed in a black hole X-ray binary. We found that the optical/UV emission is tightly correlated with the X-ray emission, consistent with accretion disc irradiation and/or a jet producing the optical emission. The X-ray spectra can be fitted well with a Comptonisation model, and show softening towards the end of the outburst. In addition, we detect a QPO in the X-ray lightcurves with increasing centroid frequency during the peak and decay periods of the outburst. The long-term optical lightcurves during quiescence show a statistically significant, slow rise of the source brightness over the 7 years prior to the 2015 outburst. This behaviour as well as the outburst evolution at all wavelengths studied can be explained by the disc instability model with irradiation and disc evaporation/condensation.

  13. Tests of General Relativity in the Strong-gravity Regime Based on X-Ray Spectropolarimetric Observations of Black Holes in X-Ray Binaries

    Krawczynski, Henric

    2012-08-01

    Although general relativity (GR) has been tested extensively in the weak-gravity regime, similar tests in the strong-gravity regime are still missing. In this paper, we explore the possibility to use X-ray spectropolarimetric observations of black holes in X-ray binaries to distinguish between the Kerr metric and the phenomenological metrics introduced by Johannsen & Psaltis (which are not vacuum solutions of Einstein's equation) and thus to test the no-hair theorem of GR. To this end, we have developed a numerical code that calculates the radial brightness profiles of accretion disks and parallel transports the wave vector and polarization vector of photons through the Kerr and non-GR spacetimes. We used the code to predict the observational appearance of GR and non-GR accreting black hole systems. We find that the predicted energy spectra and energy-dependent polarization degree and polarization direction do depend strongly on the underlying spacetime. However, for large regions of the parameter space, the GR and non-GR metrics lead to very similar observational signatures, making it difficult to observationally distinguish between the two types of models.

  14. Tests of General Relativity in the Strong Gravity Regime Based on X-Ray Spectropolarimetric Observations of Black Holes in X-Ray Binaries

    Krawczynski, Henric

    2012-01-01

    Although General Relativity (GR) has been tested extensively in the weak gravity regime, similar tests in the strong gravity regime are still missing. In this paper we explore the possibility to use X-ray spectropolarimetric observations of black holes in X-ray binaries to distinguish between the Kerr metric and the phenomenological metrics introduced by Johannsen and Psaltis (2011) (which are not vacuum solutions of Einstein's equation) and thus to test the no-hair theorem of GR. To this end, we have developed a numerical code that calculates the radial brightness profiles of accretion disks and parallel transports the wave vector and polarization vector of photons through the Kerr and non-GR spacetimes. We used the code to predict the observational appearance of GR and non-GR accreting black hole systems. We find that the predicted energy spectra and energy dependent polarization degree and polarization direction do depend strongly on the underlying spacetime. However, for large regions of the parameter spa...

  15. TESTS OF GENERAL RELATIVITY IN THE STRONG-GRAVITY REGIME BASED ON X-RAY SPECTROPOLARIMETRIC OBSERVATIONS OF BLACK HOLES IN X-RAY BINARIES

    Although general relativity (GR) has been tested extensively in the weak-gravity regime, similar tests in the strong-gravity regime are still missing. In this paper, we explore the possibility to use X-ray spectropolarimetric observations of black holes in X-ray binaries to distinguish between the Kerr metric and the phenomenological metrics introduced by Johannsen and Psaltis (which are not vacuum solutions of Einstein's equation) and thus to test the no-hair theorem of GR. To this end, we have developed a numerical code that calculates the radial brightness profiles of accretion disks and parallel transports the wave vector and polarization vector of photons through the Kerr and non-GR spacetimes. We used the code to predict the observational appearance of GR and non-GR accreting black hole systems. We find that the predicted energy spectra and energy-dependent polarization degree and polarization direction do depend strongly on the underlying spacetime. However, for large regions of the parameter space, the GR and non-GR metrics lead to very similar observational signatures, making it difficult to observationally distinguish between the two types of models.

  16. A Chandra X-ray study of the interacting binaries in the old open cluster NGC6791

    Berg, Maureen van den; Tagliaferri, Gianpiero; Belloni, Tomaso; Bedin, Luigi R; Platais, Imants

    2013-01-01

    We present the first X-ray study of NGC6791, one of the oldest open clusters known (8 Gyr). Our Chandra observation is aimed at uncovering the population of close interacting binaries down to Lx ~ 1e30 erg/s (0.3-7 keV). We detect 86 sources within 8 arcmin of the cluster center, including 59 inside the half-mass radius. We identify twenty sources with proper-motion cluster members, which are a mix of cataclysmic variables (CVs), active binaries (ABs), and binaries containing sub-subgiants. With follow-up optical spectroscopy we confirm the nature of one CV. We discover one new, X-ray variable candidate CV with Balmer and HeII emission lines in its optical spectrum; this is the first X-ray--selected CV confirmed in an open cluster. The number of CVs per unit mass is consistent with the field, suggesting that the 3-4 CVs observed in NGC6791 are primordial. We compare the X-ray properties of NGC6791 with those of a few old open (NGC6819, M67) and globular clusters (47Tuc, NGC6397). It is puzzling that the numbe...

  17. Correlated X-ray and Very High Energy emission in the gamma-ray binary LS I +61 303

    Anderhub, H; Antoranz, P; Backes, M; Baixeras, C; Balestra, S; Barrio, J A; Bastieri, D; González, J Becerra; Becker, J K; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Bigas, O Blanch; Bock, R K; Bonnoli, G; Bordas, P; Tridon, D Borla; Bosch-Ramon, V; Bose, D; Braun, I; Bretz, T; Britzger, D; Camara, M; Carmona, E; Carosi, A; Colin, P; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Dazzi, F; De Angelis, A; del Pozo, E de Cea; Reyes, R De los; De Lotto, B; De Maria, M; De Sabata, F; Mendez, C Delgado; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Elsaesser, D; Errando, M; Ferenc, D; Fernández, E; Firpo, R; Fonseca, M V; Font, L; Galante, N; López, R J García; Garczarczyk, M; Gaug, M; Godinovic, N; Göbel, F; Hadasch, D; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hrupec, D; Hsu, C C; Jogler, T; Klepser, S; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Miyamoto, H; Moldón, J; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Orito, R; Oya, I; Paoletti, R; Paredes, J M; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R G; Pérez-Torres, M A; Persic, M; Peruzzo, L; Prada, F; Prandini, E; Puchades, N; Puljak, I; Reichardt, I; Rhode, W; Ribó, M; Rico, J; Rissi, M; Robert, A; Rügamer, S; Saggion, A; Saito, T Y; Salvati, M; Sánchez-Conde, M; Satalecka, K; Scalzotto, V; Scapin, V; Schweizer, T; Shayduk, M; Shore, S N; Sidro, N; Sierpowska-Bartosik, A; Sillanpää, A; Sitarek, J; Sobczynska, D; Spanier, F; Spiro, S; Stamerra, A; Stark, L S; Suric, T; Takalo, L; Tavecchio, F; Temnikov, P; Tescaro, D; Teshima, M; Torres, D F; Turini, N; Vankov, H; Wagner, R M; Zabalza, V; Zandanel, F; Zanin, R; Zapatero, J; Falcone, A; Vetere, L; Gehrels, N; Trushkin, S; Dhawan, V; Reig, P

    2009-01-01

    The discovery of very high energy (VHE) gamma-ray emitting X-ray binaries has triggered an intense effort to better understand the particle acceleration, absorption, and emission mechanisms in compact binary systems, which provide variable conditions along eccentric orbits. Despite this, the nature of some of these systems, and of the accelerated particles producing the VHE emission, is unclear. To answer some of these open questions, we conducted a multiwavelength campaign of the VHE gamma-ray emitting X-ray binary LS I +61 303 including the MAGIC telescope, XMM-Newton, and Swift during 60% of an orbit in 2007 September. We detect a simultaneous outburst at X-ray and VHE bands, with the peak at phase 0.62 and a similar shape at both wavelengths. A linear fit to the simultaneous X-ray/VHE pairs obtained during the outburst yields a correlation coefficient of r=0.97, while a linear fit to all simultaneous pairs provides r=0.81. Since a variable absorption of the VHE emission towards the observer is not expecte...

  18. Spinning-up: the case of the symbiotic X-ray binary 3A 1954+319

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

    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-...

  19. The first low-mass black hole X-ray binary identified in quiescence outside of a globular cluster

    Tetarenko, B. E.; Bahramian, A.; Arnason, R. M.; Miller-Jones, J. C. A.; Repetto, S.; Heinke, C. O.; Maccarone, T. J.; Chomiuk, L.; Sivakoff, G. R.; Strader, J.; Kirsten, F.; Vlemmings, W

    2016-01-01

    The observed relation between the X-ray and radio properties of low-luminosity accreting black holes has enabled the identification of multiple candidate black hole X-ray binaries (BHXBs) in globular clusters. Here we report an identification of the radio source VLA J213002.08+120904 (aka M15 S2), recently reported in Kirsten et al. 2014, as a BHXB candidate. They showed that the parallax of this flat-spectrum variable radio source indicates a 2.2$^{+0.5}_{-0.3}$ kpc distance, which identifie...

  20. RXTE/ASM and Swift / BAT observations of spectral transitions in bright X-ray binaries in 2005-2010

    Jing Tang; Wen-Fei Yu; Zhen Yan

    2011-01-01

    We have studied X-ray spectral state transitions that can be seen in the longterm monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) onboard Swift during a period of five years from 2005 to 2010. We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X-ray binaries monitored by the ASM and the BAT. In total, we identified 128 hard-to-soft transitions, of which 59 occurred after 2008. We also determined the transition fluxes and the peak fluxes of the following soft states, updated the measurements of the luminosity corresponding to the H-S transition and the peak luminosity of the following soft state in about 30 bright persistent and transient black hole and neutron star binaries following Yu &Yan, and found the luminosity correlation and the luminosity range of spectral transitions in data between 2008-2010 are about the same as those derived from data before 2008. This further strengthens the idea that the luminosity at which the H-S spectral transition occurs in the Galactic X-ray binaries is determined by non-stationary accretion parameters such as the rate-of-change of the mass accretion rate rather than the mass accretion rate itself. The correlation is also found to hold in data of individual sources 4U 1608-52 and 4U 1636-53.

  1. Determining the spectroscopic mass ratio in interacting binaries Application to X-Ray Nova Sco 1994

    Shahbaz, T

    2003-01-01

    We present a model for determining the mass ratio in interacting binaries by directly fitting the observed spectrum with synthetic spectra. We make direct use of NextGen model atmospheres intensities which are the most comprehensive and detailed models available for cool stars. We fully take into account the varying temperature and gravity across the secondary star's photosphere, by incorporating the synthetic spectra into the secondary star's Roche geometry. As a result, we determine the exact rotationally broadened spectrum of the secondary star and so eliminate the need for a limb-darkening law, and the uncertainties associated with it. As an example we determine the mass ratio for the well studied soft X-ray transient Nova Sco 1994. In order to obtain a more accurate determination of the mass ratio, which does not depend on assumptions about the rotation profile and limb-darkening coefficients, we use our model to compute the exact rotationally broadened model spectrum, which we compare directly with the ...

  2. A Global Study of the Behaviour of Black Hole X-ray Binary Discs

    Dunn, Robert; Koerding, Elmar; Belloni, Tomaso; Merloni, Andrea

    2010-01-01

    We investigate the behaviour of the accretion discs in the outbursts of the low-mass black-hole X-ray binaries (BHXRB), an overview of which we have presented previously. Almost all of the systems in which there are sufficient observations in the most disc dominated states show a variation of the disc luminosity with temperature close to L ~\\propto T^4. This in turn implies that in these states, the disc radius, R_in, and the colour correction factor, f_col, are almost constant. Deviations away from the T^4 law are observed at the beginning and end of the most disc dominated states, during the intermediate states. Although these could be explained by an inward motion of the accretion disc, they are more likely to be the result of an increase in the value of f_col as the disc fraction decreases. By comparing the expected and observed disc luminosities, we place approximate limits on the allowed distances and masses of the BHXRB system. In a number of cases, the measured distances and masses of the BHXRB system...

  3. Long-term optical observations of Be/X-Ray binary system V0332+53

    Kiziloglu, U; Baykal, A; Yerli, S K; Ozbey, M

    2008-01-01

    We have been monitoring the binary system V0332+53 (optical counterpart is BQ Cam) since 2004 using 45 cm ROTSEIIId telescope and RTT150 (Russian-Turkish 1.5 m Telescope) located at Bakirlitepe, Antalya, Turkey. We report on the long-term variability of this system up to the present date. There exists a fading of 0.2 mag in the light of BQ Cam after MJD 53400. The fading in the light curve of BQ Cam could be due to a decrease in the density or in the size of the circumstellar disk. We present optical spectroscopic observations obtained before (at MJD 54730) and during (at MJD 54768) the new X-ray activity reported by Krimm et al. (2008). The observed Ha line profiles were single-peaked and almost symmetric. The present EW values are found to be similar to the ones observed during the fading of infrared magnitudes of Negueruela et al. (1999). Ha emission lines were found to be red-shifted by ~140 km/s which were larger than the findings of Corbet et al. (1986). We suggest that brightening of the disk after MJD...

  4. Reversibility of time series: revealing the hidden messages in X-ray binaries and cataclysmic variables

    Scaringi, S; Middleton, M

    2014-01-01

    We explore the non-linear, high-frequency, aperiodic variability properties in the three cataclysmic variables MV Lyr, KIC 8751494 and V1504 Cyg observed with Kepler, as well as the X-ray binary Cyg X-1 observed with RXTE. This is done through the use of a high-order Fourier statistic called the bispectrum and its related biphase and bicoherence, as well as the time-skewness statistic. We show how all objects display qualitatively similar biphase trends. In particular all biphase amplitudes are found to be smaller than $\\pi/2$, suggesting that the flux distributions for all sources are positively skewed on all observed timescales, consistent with the log-normal distributions expected from the fluctuating accretion disk model. We also find that for all objects the biphases are positive at frequencies where the corresponding power spectral densities display their high frequency break. This suggests that the noise-like flaring observed is rising more slowly than it is falling, and thus not time-reversible. This ...

  5. CAL 87 - an evolved wind-driven supersoft X-ray binary

    Oliveira, A S

    2007-01-01

    Compact binary supersoft X-ray sources (CBSS) are explained as being associated with hydrostatic nuclear burning on the surface of a white dwarf with high accretion rate. This high mass transfer rate has been suggested to be caused by dynamical instability, expected when the donor star is more massive than the accreting object. When the orbital period is smaller than ~6 hours, this mechanism does not work and the CBSS with such periods are believed to be fed by a distinct mechanism: the wind-driven accretion. Such a mechanism has been proposed to explain the properties of objects like SMC 13, T Pyx and V617 Sgr. One observational property that offers a critical test for discriminating between the above two possibilities is the orbital period change. As systems with wind-driven accretion evolve with increasing periods, some of them may reach quite long orbital periods. The above critical test may, therefore, also be applied to orbital periods longer than 6 hours. CAL 87 is an eclipsing system in the LMC with a...

  6. Low-mass X-ray binaries and globular clusters streamers and arcs in NGC 4278

    D' Abrusco, R.; Fabbiano, G. [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Brassington, N. J. [Center for Astrophysics Research, University of Hertfordshire, College Lane Campus, Hatfield, Hertordshire, AL10 9AB (United Kingdom)

    2014-03-01

    We report significant inhomogeneities in the projected two-dimensional spatial distributions of low-mass X-ray binaries (LMXBs) and globular clusters (GCs) of the intermediate mass elliptical galaxy NGC 4278. In the inner region of NGC 4278, a significant arc-like excess of LMXBs extending south of the center at ∼50'' in the western side of the galaxy can be associated with a similar overdensity of the spatial distribution of red GCs from Brassington et al. Using a recent catalog of GCs produced by Usher et al. and covering the whole field of the NGC 4278 galaxy, we have discovered two other significant density structures outside the D {sub 25} isophote to the W and E of the center of NGC 4278, associated with an overdensity and an underdensity, respectively. We discuss the nature of these structures in the context of the similar spatial inhomogeneities discovered in the LMXBs and GCs populations of NGC 4649 and NGC 4261, respectively. These features suggest streamers from disrupted and accreted dwarf companions.

  7. Low-Mass X-ray Binaries and Globular Clusters Streamers and Arcs in NGC4278

    D'Abrusco, R; Brassington, N J

    2014-01-01

    We report significant inhomogeneities in the projected two-dimensional (2D) spatial distributions of Low-Mass X-ray Binaries (LMXBs) and Globular Clusters (GCs) of the intermediate mass elliptical galaxy NGC4278. In the inner region of NGC4278, a significant arc-like excess of LMXBs extending south of the center at ~50" in the western side of the galaxy can be associated to a similar over-density of the spatial distribution of red GCs from~Brassington et al. (2009). Using a recent catalog of GCs produced by Usher et al.(2013) and covering the whole field of the NGC4278 galaxy, we have discovered two other significant density structures outside the D25 isophote to the W and E of the center of NGC4278, associated to an over-density and an under-density respectively. We discuss the nature of these structures in the context of the similar spatial inhomogeneities discovered in the LMXBs and GCs populations of NGC4649 and NGC4261, respectively. These features suggest streamers from disrupted and accreted dwarf comp...

  8. Spin-up of low luminosity low mass X-ray binaries

    Yi, I

    1998-01-01

    We examine the spin-up of low luminosity, low mass X-ray binaries (LMXBs) to millisecond pulsars (MSPs). In the conventional spin-up model of the Ghosh & Lamb type, where the stellar magnetic field interacts with the Keplerian accretion disk, MSPs could be produced from LMXBs if their magnetic field B < 10^{8}({\\dot M}/10^{16}g/s)^{1/2}G, where {\\dot M} is the mass accretion rate. However, for {\\dot M} < {\\dot M}_c ~ 10^{16}g/s accretion is likely to occur via a quasi-spherical flow with a sub-Keplerian rotation. The sub-Keplerian rotation rate is smaller than the Keplerian rate by a factor ~2-10. As a consequence, the spin-up of LMXBs produces pulsars with spin periods longer by a factor ~2-10 than those with a Keplerian accretion disk. The observed MSPs could be produced only for B < 10^7G even when {\\dot M}\\sim {\\dot M}_c ~ 10^{16}g/s. This suggests that the low luminosity LMXBs with {\\dot M} < {\\dot M}_c would not be able to spin-up to the observed MSPs. This rules out any undetected popul...

  9. On the Spin Period Distribution in Be/X-ray Binaries

    Cheng, Z -Q; Li, X -D

    2014-01-01

    There is a remarkable correlation between the spin periods of the accreting neutron stars in Be/X-ray binaries (BeXBs) and their orbital periods . Recently Knigge et al. (2011) showed that the distribution of the spin periods contains two distinct subpopulations peaked at $\\sim 10$ s and $\\sim 200$ s respectively, and suggested that they may be related to two types of supernovae for the formation of the neutron stars, i.e., core-collapse and electron-capture supernovae. Here we propose that the bimodal spin period distribution is likely to be ascribed to different accretion modes of the neutron stars in BeXBs. When the neutron star tends to capture material from the warped, outer part of the Be star disk and experiences giant outbursts, a radiatively-cooling dominated disk is formed around the neutron star, which spins up the neutron star, and is responsible for the short period subpopulation. In BeXBs that are dominated by normal outbursts or persistent, the accretion flow is advection-dominated or quasi-sph...

  10. On the spin period distribution in Be/X-ray binaries

    Cheng, Z.-Q.; Shao, Y.; Li, X.-D., E-mail: lixd@nju.edu.cn [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

    2014-05-10

    There is a remarkable correlation between the spin periods of the accreting neutron stars (NSs) in Be/X-ray binaries (BeXBs) and their orbital periods. Recently, Knigge et al. showed that the distribution of the spin periods contains two distinct subpopulations peaked at ∼10 s and ∼200 s, respectively, and suggested that they may be related to two types of supernovae for the formation of the NSs, i.e., core-collapse and electron-capture supernovae. Here we propose that the bimodal spin period distribution is likely to be ascribed to different accretion modes of the NSs in BeXBs. When the NS tends to capture material from the warped, outer part of the Be star disk and experiences giant outbursts, a radiatively cooling dominated disk is formed around the NS, which spins up the NS and is responsible for the short-period subpopulation. In BeXBs that are dominated by normal outbursts or are persistent, the accretion flow is advection-dominated or quasi-spherical. The spin-up process is accordingly inefficient, leading to longer periods of the neuron stars. The potential relation between the subpopulations and the supernova mechanism is also discussed.

  11. Exploration of Spin-down Rate of Neutron Star in High Mass X-ray Binaries

    Dai, Hai-Lang; Li, Xiang-Dong

    2016-01-01

    We use the evolutionary population synthesis method to investigate the statistical properties of the wind-fed neutron star (NS) compact ($P_{\\rm orb}<10$ days) high-mass X-ray binaries (HMXBs) in our Galaxy, based on different spin-down models. We find that the spin-down rate in the supersonic propeller phase given \\textbf{by assuming that the surrounding material is treated as forming a quasi-static atmosphere} or \\textbf{by assuming that the characteristic velocity of matter and the typical Alfv$\\acute{e}$n velocity of material in the magnetospheric boundary layer are comparable to the sound speed in the external medium} is too low to produce the observed number of compact HMXBs. We also find that the models suggested \\textbf{by assuming that the infalling material is ejected with the corotation velocity at the magnetospheric radius when the magnetospheric radius is larger than the corotation radius} and \\textbf{by simple integration of the magnetic torque over the magnetosphere} with a larger spin-down ...

  12. Optical/infrared observations unveiling the formation, nature and evolution of High-Mass X-ray Binaries

    Chaty, Sylvain

    2014-01-01

    In this review I first describe the nature of the three kinds of High-Mass X-ray Binaries (HMXBs), accreting through: (i) Be circumstellar disc, (ii) supergiant stellar wind, and (iii) Roche lobe filling supergiants. I then report on the discovery of two new populations of HMXBs hosting supergiant stars, recently revealed by a wealth of new observations, coming from the high energy side (INTEGRAL, Swift, XMM, Chandra satellites), and complemented by multi-wavelength optical/infrared observations (mainly ESO facilities). The first population is constituted of obscured supergiant HMXBs, the second one of supergiant fast X-ray transients (SFXTs), exhibiting short and intense X-ray flares. I finally discuss the formation and evolution of HMXBs, constrain the accretion models (e.g. clumpy winds, transitory accretion disc, magneto-centrifugal barrier), show evidences suggesting the existence of an evolutionary link, include comparisons with population synthesis models, and finally build a consistent scenario explai...

  13. The effect of vacuum birefringence on the polarization of X-ray binaries and pulsars

    Novick, R.; Weisskopf, M. C.; Angel, J. R. P.; Sutherland, P. G.

    1977-01-01

    In a strong magnetic field the vacuum becomes birefringent. This effect is especially important for pulsars at X-ray wavelengths. Any polarized X-ray emission from the surface of a magnetic neutron star becomes depolarized as it propagates through the magnetic field. The soft X-ray emission from AM Her, believed to be a magnetic white dwarf, may show about one radian of phase retardation. In this case, circular polarization of the X-ray flux would be a characteristic signature of vacuum birefringence.

  14. RXTE/ASM and Swift/BAT Observations of Spectral Transitions in Bright X-ray Binaries in 2005-2010

    Tang, Jing; Yu, Wenfei; Yan, Zhen

    2010-01-01

    We have studied X-ray spectral state transitions that can be seen in the long- term monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) on board the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) on board Swift during a period of five years from 2005 to 2010. We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X- ray binaries monitored by the ASM and the BAT. In total we identif...

  15. Absorption lines from magnetically driven winds in X-ray binaries

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

    2016-05-01

    Context. High resolution X-ray spectra of black hole X-ray binaries (BHBs) show blueshifted absorption lines suggesting the presence of outflowing winds. Furthermore, observations show that the disk winds are equatorial and they occur in the Softer (disk dominated) states of the outburst and are less prominent or absent in the Harder (power-law dominated) states. Aims: We want to test whether the self-similar magneto-hydrodynamic (MHD) accretion-ejection models can explain the observational results for accretion disk winds in BHBs. In our models, the density at the base of the outflow from the accretion disk is not a free parameter. This mass loading is determined by solving the full set of dynamical MHD equations without neglecting any physical term. Thus, the physical properties of the outflow depend on and are controlled by the global structure of the disk. Methods: We studied different MHD solutions characterized by different values of the disk aspect ratio (ɛ) and the ejection efficiency (p). We also generate two kinds of MHD solutions depending on the absence (cold solution) or presence (warm solution) of heating at the disk surface. Such heating could be either from dissipation of energy due to MHD turbulence in the disk or from illumination of the disk surface. Warm solutions can have large (>0.1) values of p, which would imply larger wind mass loading at the base of the outflow. We use each of these MHD solutions to predict the physical parameters (distance, density, velocity, magnetic field, etc.) of an outflow. Motivated by observational results, we have put limits on the ionization parameter (ξ), column density, and timescales. Further constraints were derived for the allowed values of ξ from thermodynamic instability considerations, particularly for the Hard SED. These physical constraints were imposed on each of these outflows to select regions within it, which are consistent with the observed winds. Results: The cold MHD solutions are found to be

  16. Rayleigh-Taylor Gravity Waves and Quasiperiodic Oscillation Phenomenon in X-ray Binaries

    Titarchuk, Lev

    2002-01-01

    Accretion onto compact objects in X-ray binaries (black hole, neutron star (NS), white dwarf) is characterized by non-uniform flow density profiles. Such an effect of heterogeneity in presence of gravitational forces and pressure gradients exhibits Rayleigh-Taylor gravity waves (RTGW). They should be seen as quasiperiodic wave oscillations (QPO) of the accretion flow in the transition (boundary) layer between the Keplerian disk and the central object. In this paper the author shows that the main QPO frequency, which is very close to the Keplerian frequency, is split into separate frequencies (hybrid and low branch) under the influence of the gravitational forces in the rotational frame of reference. The RTGWs must be present and the related QPOs should be detected in any system where the gravity, buoyancy and Coriolis force effects cannot be excluded (even in the Earth and solar environments). The observed low and high QPO frequencies are an intrinsic signature of the RTGW. The author elaborates the conditions for the density profile when the RTGW oscillations are stable. A comparison of the inferred QPO frequencies with QPO observations is presented. The author finds that hectohertz frequencies detected from NS binaries can be identified as the RTGW low branch frequencies. The author also predicts that an observer can see the double NS spin frequency during the NS long (super) burst events when the pressure gradients and buoyant forces are suppressed. The Coriolis force is the only force which acts in the rotational frame of reference and its presence causes perfect coherent pulsations with a frequency twice of the NS spin. The QPO observations of neutron binaries have established that the high QPO frequencies do not go beyond of the certain upper limit. The author explains this observational effect as a result of the density profile inversions. Also the author demonstrates that a particular problem of the gravity waves in the rotational frame of reference in the

  17. Around 200 new X-ray binary IDs from 13 YR of Chandra observations of the M31 center

    Barnard, R.; Garcia, M. R.; Primini, F. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Li, Z. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Baganoff, F. K. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Murray, S. S. [Johns Hopkins University, Baltimore, MD (United States)

    2014-01-01

    We have created 0.3-10 keV, 13 yr, unabsorbed luminosity lightcurves for 528 X-ray sources in the central 20' of M31. We have 174 Chandra observations spaced at ∼1 month intervals due to our transient monitoring program, deeper observations of the M31 nucleus, and some public data from other surveys. We created 0.5-4.5 keV structure functions (SFs) for each source for comparison with the ensemble SF of active galactic nuclei (AGN). We find 220 X-ray sources with luminosities ≳10{sup 35} erg s{sup –1} that have SFs with significantly more variability than the ensemble AGN SF, and which are likely X-ray binaries (XBs). A further 30 X-ray sources were identified as XBs using other methods. We therefore have 250 probable XBs in total, including ∼200 new identifications. This result represents great progress over the ∼50 XBs and ∼40 XB candidates previously identified out of the ∼2000 X-ray sources within the D {sub 25} region of M31; it also demonstrates the power of SF analysis for identifying XBs in external galaxies. We also identify a new transient black hole candidate, associated with the M31 globular cluster B128.

  18. Variable Doppler shifts of the thermal wind absorption lines in low-mass X-ray binaries

    Madej, O K; Trigo, M Diaz; Miskovicova, I

    2013-01-01

    In this paper we address the general applicability of the method pioneered by \\citet{Zhang2012} in which the motion of the compact object can be tracked using wind X-ray absorption lines. We present the velocity measurements of the thermal wind lines observed in the X-ray spectrum of a few low-mass X-ray binaries: GX 13+1, H 1743$-$322, GRO J1655$-$40 and GRS 1915+105. We find that the variability in the velocity of the wind lines in about all of the sources is larger than conceivable radial velocity variations of the compact object. GX 13+1 provides a potential exception, although it would require the red giant star to be massive with a mass of $\\approx 5-6\\ M_{\\odot}$. We conclude that the variability of the source luminosity occurring on a time scale of days/months can affect the outflow properties making it difficult to track the orbital motion of the compact object using current observations. Given the intrinsic variability of the outflows we suggest that low-mass X-ray binaries showing stable coronae in...

  19. X-ray emission from the double-binary OB-star system QZ Car (HD 93206)

    Parkin, E R; Townsley, L K; Pittard, J M; Moffat, A F J; Naze, Y; Rauw, G; Oskinova, L M

    2011-01-01

    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 orbit of systems A (O9.7 I+b2 v, PA = 21 d) and B (O8 III+o9 v, PB = 6 d) 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, characterised by cool, moderate, and hot plasma components at kT ~ 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of ~ 0.2 x 10^22 cm-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 ~ 7 x 10^-13 erg s-1 cm-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. ...

  20. Superorbital Periodic Modulation in Wind-Accretion High-Mass X-Ray Binaries from Swift Burst Alert Telescope Observations

    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.

  1. Common Patterns in the Evolution between the Luminous Neutron Star Low-Mass X-ray Binary Subclasses

    Fridriksson, Joel K; Remillard, Ronald A

    2015-01-01

    The X-ray transient XTE J1701-462 was the first source seen to evolve through all known subclasses of low-magnetic-field neutron star low-mass X-ray binaries (NS-LMXBs), as a result of large changes in its mass accretion rate. To investigate to what extent similar evolution is seen in other NS-LMXBs we have performed a detailed study of the color-color and hardness-intensity diagrams (CDs and HIDs) of Cyg X-2, Cir X-1, and GX 13+1 -- three luminous X-ray binaries, containing weakly magnetized neutron stars, known to exhibit strong secular changes in their CD/HID tracks. Using the full set of Rossi X-ray Timing Explorer Proportional Counter Array data collected for the sources over the 16-year duration of the mission, we show that Cyg X-2 and Cir X-1 display CD/HID evolution with close similarities to XTE J1701-462. Although GX 13+1 shows behavior that is in some ways unique, it also exhibits similarities to XTE J1701-462, and we conclude that its overall CD/HID properties strongly indicate that it should be c...

  2. The puzzling orbital period evolution of the low mass X-ray binary AX J1745.6-2901

    Ponti, G; Munoz-Darias, T; Stella, L; Nandra, K

    2015-01-01

    The orbital period evolution of X-ray binaries provides fundamental clues to understanding mechanisms of angular momentum loss from these systems. We present an X-ray eclipse timing analysis of the transient low mass X-ray binary AX J1745.6-2901. This system shows full eclipses and thus is one of the few objects for which accurate orbital evolution studies using this method can be carried out. We report on XMM-Newton and ASCA observations covering 30 complete X-ray eclipses spanning an interval of more than 20 years. We improve the determination of the orbital period to a relative precision of $2\\times10^{-8}$, two orders of magnitudes better than previous estimates. We determine, for the first time, a highly significant rate of decrease of the orbital period $\\dot{P}_{orb}=-4.03\\pm0.32\\times10^{-11}$~s/s. This is at least one order of magnitude larger than expected from conservative mass transfer and angular momentum losses due to gravitational waves and magnetic breaking, and might result from non-conservat...

  3. Star-formation history and X-ray binary populations: the case of the Large Magellanic Cloud

    Antoniou, Vallia

    2016-01-01

    In the present work we investigate the link between high-mass X-ray binaries (HMXBs) and star formation in the Large Magellanic Cloud (LMC), our nearest star-forming galaxy. Using optical photometric data, we identify the most likely counterpart of 44 X-ray sources. Among the 40 HMXBs classified in this work, we find 33 Be/X-ray binaries, and 4 supergiant XRBs. Using this census and the published spatially resolved star-formation history map of the LMC, we find that the HMXBs (and as expected the X-ray pulsars) are present in regions with star-formation bursts $\\sim$6-25 Myr ago, in contrast to the Small Magellanic Cloud (SMC), for which this population peaks at later ages ($\\sim$25-60 Myr ago). We also estimate the HMXB production rate to be equal to 1 system per $\\sim23.0_{-4.1}^{+4.4}\\times10^{-3}$ Mo/yr, or 1 system per $\\sim$143 Mo of stars formed during the associated star-formation episode. Therefore, the formation efficiency of HMXBs in the LMC is $\\sim$17 times lower than that in the SMC. We attribut...

  4. The first low-mass black hole X-ray binary identified in quiescence outside of a globular cluster

    Tetarenko, B E; Arnason, R M; Miller-Jones, J C A; Repetto, S; Heinke, C O; Maccarone, T J; Chomiuk, L; Sivakoff, G R; Strader, J; Kirsten, F; Vlemmings, W

    2016-01-01

    The observed relation between the X-ray and radio properties of low-luminosity accreting black holes has enabled the identification of multiple candidate black hole X-ray binaries (BHXBs) in globular clusters. Here we report an identification of the radio source VLA J213002.08+120904 (aka M15 S2), recently reported in Kirsten et al. 2014, as a BHXB candidate. They showed that the parallax of this flat-spectrum variable radio source indicates a 2.2$^{+0.5}_{-0.3}$ kpc distance, which identifies it as lying in the foreground of the globular cluster M15. We determine the radio characteristics of this source, and place a deep limit on the X-ray luminosity of $\\sim4\\times10^{29}$ erg s$^{-1}$. Furthermore, we astrometrically identify a faint red stellar counterpart in archival Hubble images, with colors consistent with a foreground star; at 2.2 kpc its inferred mass is 0.1-0.2 $M_{\\odot}$. We rule out that this object is a pulsar, neutron star X-ray binary, cataclysmic variable, or planetary nebula, concluding tha...

  5. Constraining the formation of black holes in short-period black hole low-mass X-ray binaries

    Repetto, Serena; Nelemans, Gijs

    2015-11-01

    The formation of stellar-mass black holes (BHs) is still very uncertain. Two main uncertainties are the amount of mass ejected in the supernova (SN) event (if any) and the magnitude of the natal kick (NK) the BH receives at birth (if any). Repetto et al., studying the position of Galactic X-ray binaries containing BHs, found evidence for BHs receiving high NKs at birth. In this paper, we extend that study, taking into account the previous binary evolution of the sources as well. The seven short-period BH X-ray binaries that we use are compact binaries consisting of a low-mass star orbiting a BH in a period less than 1 d. We trace their binary evolution backwards in time, from the current observed state of mass transfer, to the moment the BH was formed, and we add the extra information on the kinematics of the binaries. We find that several systems could be explained by no NK, just mass ejection, while for two systems (and possibly more) a high kick is required. So unless the latter have an alternative formation, such as within a globular cluster, we conclude that at least some BHs get high kicks. This challenges the standard picture that BH kicks would be scaled down from neutron star kicks. Furthermore, we find that five systems could have formed with a non-zero NK but zero mass ejected (i.e. no SN) at formation, as predicted by neutrino-driven NKs.

  6. X-ray diffraction and calorimetric phase study of a binary paraffin : C23H48-C24H50

    The phase diagram of the binary paraffin system C23H48-C24H50 was determined by calorimetric and X-ray diffraction methods. The present experimental results together with previous work on pure C23H48 and C24H50 paraffins allows to identify all the detected phases. The composition and temperature dependences of the crystalline lattice parameters were also investigated. (Author)

  7. Reversibility of time series: revealing the hidden messages in X-ray binaries and cataclysmic variables

    Scaringi, S.; Maccarone, T. J.; Middleton, M.

    2014-11-01

    We explore the non-linear, high-frequency, aperiodic variability properties in the three cataclysmic variables MV Lyr, KIC 8751494 and V1504 Cyg observed with Kepler, as well as the X-ray binary Cyg X-1 observed with RXTE. This is done through the use of a high-order Fourier statistic called the bispectrum and its related biphase and bicoherence, as well as the time-skewness statistic. We show how all objects display qualitatively similar biphase trends. In particular, all biphase amplitudes are found to be smaller than π/2, suggesting that the flux distributions for all sources are positively skewed on all observed time-scales, consistent with the lognormal distributions expected from the fluctuating accretion disc model. We also find that for all objects, the biphases are positive at frequencies where the corresponding power spectral densities display their high-frequency break. This suggests that the noise-like flaring observed is rising more slowly than it is falling, and thus not time-reversible. This observation is also consistent with the fluctuating accretion disc model. Furthermore, we observe the same qualitative biphase trends in all four objects, where the biphases display a distinct decrease at frequencies below the high-frequency break in their respective power spectral densities. This behaviour can also be observed in the time skewness of all four objects. As far as we are aware, there is no immediate explanation for the observed biphase decreases. The biphase decreases may thus suggest that the fluctuating accretion disc model begins to break down at frequencies below the high-frequency break.

  8. Formation of Black Hole Low-mass X-Ray Binaries in Hierarchical Triple Systems

    Naoz, Smadar; Fragos, Tassos; Geller, Aaron; Stephan, Alexander P.; Rasio, Frederic A.

    2016-05-01

    The formation of black hole (BH) low-mass X-ray binaries (LMXB) poses a theoretical challenge, as low-mass companions are not expected to survive the common-envelope scenario with the BH progenitor. Here we propose a formation mechanism that skips the common-envelope scenario and relies on triple-body dynamics. We study the evolution of hierarchical triples following the secular dynamical evolution up to the octupole-level of approximation, including general relativity, tidal effects, and post-main-sequence evolution such as mass loss, changes to stellar radii, and supernovae. During the dynamical evolution of the triple system the “eccentric Kozai-Lidov” mechanism can cause large eccentricity excitations in the LMXB progenitor, resulting in three main BH-LMXB formation channels. Here we define BH-LMXB candidates as systems where the inner BH-companion star crosses its Roche limit. In the “eccentric” channel (∼81% of the LMXBs in our simulations) the donor star crosses its Roche limit during an extreme eccentricity excitation while still on a wide orbit. Second, we find a “giant” LMXB channel (∼11%), where a system undergoes only moderate eccentricity excitations but the donor star fills its Roche-lobe after evolving toward the giant branch. Third, we identify a “classical” channel (∼8%), where tidal forces and magnetic braking shrink and circularize the orbit to short periods, triggering mass-transfer. Finally, for the giant channel we predict an eccentric (∼0.3–0.6) preferably inclined (∼40°, ∼140°) tertiary, typically on a wide enough orbit (∼104 au) to potentially become unbound later in the triple evolution. While this initial study considers only one representative system and neglects BH natal kicks, we expect our scenario to apply across a broad region of parameter space for triple-star systems.

  9. Radiative Feedback from high mass X-ray binaries on the formation of the first galaxies and early reionization

    Jeon, Myoungwon; Bromm, Volker; Milosavljevic, Milos

    2013-01-01

    Recent work suggests that the first generation of stars, the so-called Population III (Pop III), could have formed primarily in binaries or as members of small multiple systems. Here we investigate the impact of X-ray feedback from High-Mass X-ray Binaries (HMXBs) left behind in stellar binary systems after the primary forms a black hole (BH), accreting gas at a high rate from the companion, a process that is thought to be favored at the low metallicities characteristic of high-redshift gas. Thanks to their large mean free path, X-rays are capable of preionizing and preheating the gas in the intergalactic medium (IGM) and in haloes long before the reionization of the Universe is complete, and thus could have strongly affected the formation of subsequent generations of stars as well as reionization. We have carried out zoomed hydrodynamical cosmological simulations of minihaloes, accounting for the formation of Pop III stars and their collapse into BHs and HMXBs, and the associated radiation-hydrodynamic feedb...

  10. Estimates of black hole natal kick velocities from observations of low-mass X-ray binaries

    Mandel, Ilya

    2016-02-01

    The birth kicks of black holes, arising from asymmetric mass ejection or neutrino emission during core-collapse supernovae, are of great interest for both observationally constraining supernova models and population-synthesis studies of binary evolution. Recently, several efforts were undertaken to estimate black hole birth kicks from observations of black hole low-mass X-ray binaries. We follow up on this work, specifically focusing on the highest estimated black hole kick velocities. We find that existing observations do not require black hole birth kicks in excess of approximately 80 km s-1, although higher kicks are not ruled out.

  11. FEEDBACK FROM HIGH-MASS X-RAY BINARIES ON THE HIGH-REDSHIFT INTERGALACTIC MEDIUM: MODEL SPECTRA

    Power, Chris [International Centre for Radio Astronomy Research, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); James, Gillian; Wynn, Graham [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Combet, Celine, E-mail: chris.power@icrar.org [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1/CNRS/IN2P3/INPG, 53 avenue des Martyrs, F-38026 Grenoble (France)

    2013-02-10

    Massive stars at redshifts z {approx}> 6 are predicted to have played a pivotal role in cosmological reionization as luminous sources of ultraviolet (UV) photons. However, the remnants of these massive stars could be equally important as X-ray-luminous (L{sub X} {approx} 10{sup 38} erg s{sup -1}) high-mass X-ray binaries (HMXBs). Because the absorption cross section of neutral hydrogen decreases sharply with photon energy ({sigma}{proportional_to}E {sup -3}), X-rays can escape more freely than UV photons from the star-forming regions in which they are produced, allowing HMXBs to make a potentially significant contribution to the ionizing X-ray background during reionization. In this paper, we explore the ionizing power of HMXBs at redshifts z {approx}> 6 using a Monte Carlo model for a coeval stellar population of main-sequence stars and HMXBs. Using the archetypal Galactic HMXB Cygnus X-1 as our template, we propose a composite HMXB spectral energy distribution consisting of blackbody and power-law components, whose contributions depend on the accretion state of the system. We determine the time-dependent ionizing power of a combined population of UV-luminous stars and X-ray-luminous HMXBs and deduce fitting formulae for the boost in the population's ionizing power arising from HMXBs; these fits allow for simple implementation of HMXB feedback in numerical simulations. Based on this analysis, we estimate the contribution of high-redshift HMXBs to the present-day soft X-ray background, and we show that it is a factor of {approx}100-1000 smaller than the observed limit. Finally, we discuss the implications of our results for the role of HMXBs in reionization and in high-redshift galaxy formation.

  12. Using novel spectral-timing techniques to probe the rapid variability of X-Ray Binaries

    Wilkinson, Tony

    2011-01-01

    X-ray spectral variability is a powerful probe of the relationship between the accretion disc and corona in accreting compact objects. In this thesis, I present the use of variability techniques to disentangle the different variable components of X-ray spectra. By examining correlated variability over a range of timescales, I identify for the first time evidence of intrinsic disc variability on timescales of seconds. I go on to examine, utilising a range of spectral-timing techniques, the rol...

  13. Herschel OBSERVATIONS OF DUST AROUND THE HIGH-MASS X-RAY BINARY GX 301-2

    We aim at characterizing the structure of the gas and dust around the high-mass X-ray binary GX 301-2, a highly obscured X-ray binary hosting a hypergiant (HG) star and a neutron star, in order to better constrain its evolution. We used Herschel PACS to observe GX 301-2 in the far infrared and completed the spectral energy distribution of the source using published data or catalogs from the optical to the radio range (0.4 to 4 × 104 μm). GX 301-2 is detected for the first time at 70 and 100 μm. We fitted different models of circumstellar (CS) environments to the data. All tested models are statistically acceptable, and consistent with an HG star at ∼3 kpc. We found that the addition of a free-free emission component from the strong stellar wind is required and could dominate the far-infrared flux. Through comparisons with similar systems and discussion on the estimated model parameters, we favor a disk-like CS environment of ∼8 AU that would enshroud the binary system. The temperature goes down to ∼200 K at the edge of the disk, allowing for dust formation. This disk is probably a rimmed viscous disk with an inner rim at the temperature of the dust sublimation temperature (∼1500 K). The similarities between the HG GX 301-2, B[e] supergiants, and the highly obscured X-ray binaries (particularly IGR J16318-4848) are strengthened. GX 301-2 might represent a transition stage in the evolution of massive stars in binary systems, connecting supergiant B[e] systems to luminous blue variables

  14. Herschel OBSERVATIONS OF DUST AROUND THE HIGH-MASS X-RAY BINARY GX 301-2

    Servillat, M. [Laboratoire Univers et Théories (CNRS/INSU, Observatoire de Paris, Université Paris Diderot), 5 place Jules Janssen, F-92190 Meudon (France); Coleiro, A.; Chaty, S. [Laboratoire AIM (CEA/Irfu/SAp, CNRS/INSU, Universit Paris Diderot), CEA Saclay, Bat. 709, F-91191 Gif-sur-Yvette (France); Rahoui, F. [Harvard University, Department of Astronomy, 60 Garden Street, Cambridge, MA 02138 (United States); Zurita Heras, J. A., E-mail: mathieu.servillat@obspm.fr [AstroParticule et Cosmologie (Université Paris Diderot, CNRS/IN2P3, CEA/DSM, Observatoire de Paris, Sorbonne Paris Cité), 10 rue Alice Domon et Léonie Duquet, F-75205 Paris Cedex 13 (France)

    2014-12-20

    We aim at characterizing the structure of the gas and dust around the high-mass X-ray binary GX 301-2, a highly obscured X-ray binary hosting a hypergiant (HG) star and a neutron star, in order to better constrain its evolution. We used Herschel PACS to observe GX 301-2 in the far infrared and completed the spectral energy distribution of the source using published data or catalogs from the optical to the radio range (0.4 to 4 × 10{sup 4} μm). GX 301-2 is detected for the first time at 70 and 100 μm. We fitted different models of circumstellar (CS) environments to the data. All tested models are statistically acceptable, and consistent with an HG star at ∼3 kpc. We found that the addition of a free-free emission component from the strong stellar wind is required and could dominate the far-infrared flux. Through comparisons with similar systems and discussion on the estimated model parameters, we favor a disk-like CS environment of ∼8 AU that would enshroud the binary system. The temperature goes down to ∼200 K at the edge of the disk, allowing for dust formation. This disk is probably a rimmed viscous disk with an inner rim at the temperature of the dust sublimation temperature (∼1500 K). The similarities between the HG GX 301-2, B[e] supergiants, and the highly obscured X-ray binaries (particularly IGR J16318-4848) are strengthened. GX 301-2 might represent a transition stage in the evolution of massive stars in binary systems, connecting supergiant B[e] systems to luminous blue variables.

  15. A "high-hard" outburst of the black hole X-ray binary GS 1354-64

    Koljonen, Karri; Russell, David; Corral-Santana, Jesus; Armas Padilla, Montserrat; Munoz-Darias, Teo; Lewis, Fraser

    2016-06-01

    In the shadows of the V404 Cyg outburst in the summer of 2015, GS 1354-64 (BW Cir) went into outburst as well. We followed the evolution of the outburst at optical, UV and X-ray wavelengths using Faulkes Telescope South, SMARTS and Swift. The outburst was found to stay in the hard X-ray state, albeit being anomalously luminous with a peak X-ray luminosity exceeding 0.15 LEdd, which could be the most luminous hard state observed in a black hole X-ray binary. In this talk I will present our results showing that the the outburst evolution at all wavelengths can be explained by the disk instability model with irradiation and disk evaporation/condensation. In addition, I will present our long-term optical monitoring results that show a statistically significant, slow rise of the source brightness over the 7 years prior to the 2015 outburst. This could be the much-sought observational evidence of matter slowly accumulating in the accretion disk, and subsequently getting optically brighter, as predicted by the disk instability model.

  16. Energy dependence of normal branch quasi-periodic intensity oscillations in low-mass X-ray binaries

    Miller, Guy S.; Lamb, Frederick K.

    1992-04-01

    The properties of the approximately 6 Hz quasi-periodic X-ray intensity oscillations observed in the low-mass X-ray binary Cyg X-2 when it is on the normal spectral branch are shown to be consistent with a model in which photons from a central source with a fixed spectrum are Comptonized by an oscillating radial inflow. As the electron scattering optical depth of the flow varies, the spectrum of the escaping X-rays appears to rotate about a pivot energy that depends mainly on the electron temperature in the flow. The temperature derived from the observed energy dependence of the Cyg X-2 normal branch oscillations is approximately 1 keV, in good agreement with the estimated Compton temperature of its X-ray spectrum. The mean optical depth tau of the Comptonizing flow is inferred to be about 10, while the change in tau over an oscillation is estimated to be about 1; both values are in good agreement with radiation hydrodcode simulations of the radial flow.

  17. A relativistic iron emission line from the neutron star low-mass X-ray binary GX 3+1

    Piraino, S; Kaaret, P; Mück, B; DÁi', A; DI Salvo, T; Iaria, R; Robba, N; Burderi, L; Egron, E

    2012-01-01

    We present the results of a spectroscopic study of the Fe K{\\alpha} emission of the persistent neutron-star atoll low-mass X-ray binary and type I X-ray burster GX 3+1 with the EPIC-PN on board XMM-Newton. The source shows a flux modulation over several years and we observed it during its fainter phase, which corresponds to an X-ray luminosity of Lx~10^37 ergs/s. When fitted with a two-component model, the X-ray spectrum shows broad residuals at \\sim6-7 keV that can be ascribed to an iron K{\\alpha} fluorescence line. In addition, lower energy features are observed at \\sim3.3 keV, \\sim3.9 keV and might originate from Ar XVIII and Ca XIX. The broad iron line feature is well fitted with a relativistically smeared profile. This result is robust against possible systematics caused by instrumental pile-up effects. Assuming that the line is produced by reflection from the inner accretion disk, we infer an inner disk radius of \\sim25 Rg and a disk inclination of 35{\\deg} < i < 44{\\deg}.

  18. Be/X-ray binary SXP6.85 undergoes large Type II outburst in the Small Magellanic Cloud

    Townsend, L J; McBride, V A; Bird, A J; Schurch, M P E; Corbet, R H D; Haberl, F; Galache, J L; Udalski, A

    2009-01-01

    The Small Magellanic Cloud (SMC) Be/X-ray binary pulsar SXP6.85 = XTE J0103-728 underwent a large Type II outburst beginning on 2008 August 10. The source was consistently seen for the following 20 weeks (MJD = 54688 - 54830). We present X-ray timing and spectroscopic analysis of the source as part of our ongoing Rossi X-ray Timing Explorer (RXTE) monitoring campaign and INTEGRAL key programme monitoring the SMC and 47 Tuc. A comparison with the Optical Gravitational Lensing Experiment (OGLE) III light curve of the Be counterpart shows the X-ray outbursts from this source coincide with times of optical maximum. We attribute this to the circumstellar disk increasing in size, causing mass accretion onto the neutron star. Ground based IR photometry and H-alpha spectroscopy obtained during the outburst are used as a measure of the size of the circumstellar disk and lend support to this picture. In addition, folded RXTE light curves seem to indicate complex changes in the geometry of the accretion regions on the s...

  19. X-ray and optical observations of the unique binary system HD49798/RXJ0648.0-4418

    Mereghetti, S; Tiengo, A; Pizzolato, F; Esposito, P; Woudt, P A; Israel, G L; Stella, L

    2011-01-01

    We report the results of XMM-Newton observations of HD49798/RXJ0648.0-4418, the only known X-ray binary consisting of a hot sub-dwarf and a white dwarf. The white dwarf rotates very rapidly (P=13.2 s) and has a dynamically measured mass of 1.28+/-0.05 M_sun. Its X-ray emission consists of a strongly pulsed, soft component, well fit by a blackbody with kT~40 eV, accounting for most of the luminosity, and a fainter hard power-law component (photon index ~1.6). A luminosity of ~10^{32} erg/s is produced by accretion onto the white dwarf of the helium-rich matter from the wind of the companion, which is one of the few hot sub-dwarfs showing evidence of mass-loss. A search for optical pulsations at the South African Astronomical Observatory 1.9-m telescope gave negative results. X-rays were detected also during the white dwarf eclipse. This emission, with luminosity 2x10^{30} erg/s, can be attributed to HD 49798 and represents the first detection of a hot sub-dwarf star in the X-ray band. HD49798/RXJ0648.0-4418 is...

  20. A Radio-Selected Black Hole X-ray Binary Candidate in the Milky Way Globular Cluster M62

    Chomiuk, Laura; Maccarone, Thomas J; Miller-Jones, James C A; Heinke, Craig; Noyola, Eva; Seth, Anil C; Ransom, Scott

    2013-01-01

    We report the discovery of a candidate stellar-mass black hole in the Milky Way globular cluster M62. We detected the black hole candidate, which we term M62-VLA1, in the core of the cluster using deep radio continuum imaging from the Karl G. Jansky Very Large Array. M62-VLA1 is a faint source, with a flux density of 18.7 +/- 1.9 microJy at 6.2 GHz and a flat radio spectrum (alpha=-0.24 +/- 0.42, for S_nu = nu^alpha). M62 is the second Milky Way cluster with a candidate stellar-mass black hole; unlike the two candidate black holes previously found in the cluster M22, M62-VLA1 is associated with a Chandra X-ray source, supporting its identification as a black hole X-ray binary. Measurements of its radio and X-ray luminosity, while not simultaneous, place M62-VLA1 squarely on the well-established radio--X-ray correlation for stellar-mass black holes. In archival Hubble Space Telescope imaging, M62-VLA1 is coincident with a star near the lower red giant branch. This possible optical counterpart shows a blue exce...

  1. Revelations of X-ray spectral analysis of the enigmatic black hole binary GRS 1915+105

    Peris, Charith; Remillard, Ronald A.; Steiner, James; Dil Vrtilek, Saeqa; Varniere, Peggy; Rodriguez, Jerome; Pooley, Guy

    2016-01-01

    Of the black hole binaries discovered thus far, GRS 1915+105 stands out as an exceptional source primarily due to its wild X-ray variability, the diversity of which has not been replicated in any other stellar-mass black hole. Although extreme variability is commonplace in its light-curve, about half of the observations of GRS1915+105 show fairly steady X-ray intensity. We report on the X-ray spectral behavior within these steady observations. Our work is based on a vast RXTE/PCA data set obtained on GRS 1915+105 during the course of its entire mission and 10 years of radio data from the Ryle Telescope, which overlap the X-ray data. We find that the steady observations within the X-ray data set naturally separate into two regions in a color-color diagram, which we refer to as steady-soft and steady-hard. GRS 1915+105 displays significant curvature in the Comptonization component within the PCA band pass suggesting significantly heating from a hot disk present in all states. A new Comptonization model 'simplcut' was developed in order to model this curvature to best effect. A majority of the steady-soft observations display a roughly constant inner radius; remarkably reminiscent of canonical soft state black hole binaries. In contrast, the steady-hard observations display a growing disk truncation that is correlated to the mass accretion rate through the disk, which suggests a magnetically truncated disk. A comparison of X-ray model parameters to the canonical state definitions show that almost all steady-soft observations match the criteria of either thermal or steep power law state, while the thermal state observations dominate the constant radius branch. A large portion (80%) of the steady-hard observations matches the hard state criteria when the disk fraction constraint is neglected. These results suggest that within the complexity of this source is a simpler underlying basis of states, which map to those observed in canonical black hole binaries. When

  2. Studies of the Origin of High-frequency Quasi-periodic Oscillations of Mass-accreting Black Holes in X-Ray Binaries with Next-generation X-Ray Telescopes

    Beheshtipour, Banafsheh; Hoormann, Janie K.; Krawczynski, Henric

    2016-08-01

    Observations with RXTE (Rossi X-ray Timing Explorer) revealed the presence of high-frequency quasi-periodic oscillations (HFQPOs) of the X-ray flux from several accreting stellar-mass black holes. HFQPOs (and their counterparts at lower frequencies) may allow us to study general relativity in the regime of strong gravity. However, the observational evidence today does not yet allow us to distinguish between different HFQPO models. In this paper we use a general-relativistic ray-tracing code to investigate X-ray timing spectroscopy and polarization properties of HFQPOs in the orbiting Hotspot model. We study observational signatures for the particular case of the 166 Hz quasi-periodic oscillation (QPO) in the galactic binary GRS 1915+105. We conclude with a discussion of the observability of spectral signatures with a timing-spectroscopy experiment such as the LOFT (Large Observatory for X-ray Timing) and polarization signatures with space-borne X-ray polarimeters such as IXPE (Imaging X-ray Polarimetry Explorer), PolSTAR (Polarization Spectroscopic Telescope Array), PRAXyS(Polarimetry of Relativistic X-ray Sources), or XIPE (X-ray Imaging Polarimetry Explorer). A mission with high count rate such as LOFT would make it possible to get a QPO phase for each photon, enabling the study of the QPO-phase-resolved spectral shape and the correlation between this and the flux level. Owing to the short periods of the HFQPOs, first-generation X-ray polarimeters would not be able to assign a QPO phase to each photon. The study of QPO-phase-resolved polarization energy spectra would thus require simultaneous observations with a first-generation X-ray polarimeter and a LOFT-type mission.

  3. The Ionized and Variable Outflow in the Low-Mass X-Ray Binary GX 13+1

    Allen, Jessamyn; Schulz, Norbert S.; Homan, Jeroen; Chakrabarty, Deepto

    2016-04-01

    We present the analysis of 7 Chandra HETG and 16 simultaneous RXTE PCA observations of GX 13+1, a persistent neutron star low-mass X-ray binary. The observations cover activity between 2002 and 2011. The 0.5-10 keV continuum was consistent with a two component model, either a blackbody plus power law or multicolor disk and blackbody across luminosities of (5-7)x1037 erg sec-1, modified by a neutral absorption column requiring a silicon overabundance. We have identified significantly blue-shifted (voutflow > 500 km sec-1) Kα Fe, Ca, S, and Si hydrogen-like lines in all HETG observations, as well hydrogen-like Ar and Mg lines in the majority of observations. The significant outflow can be modeled as a photoionized plasma with an ionization parameter ≥ 3.5. For the first time we map the occurrence of these wind outflows onto the color-color diagram of GX 13+1 and compare their location with that of the jet outflows in this system. We will further present variable X-ray properties of the wind in GX 13+1 and discuss suggested launching mechanisms as well as how its properties relate to the wind-accretion state in low-mass X-ray binaries.

  4. Spin period change and the magnetic fields of neutron stars in Be X-ray binaries in the SMC

    Klus, H; Coe, M J; Corbet, R H D; Townsend, L J

    2013-01-01

    We report on the long term average spin period, rate of change of spin period and X-ray luminosity during outbursts for 42 Be X-ray binary systems in the Small Magellanic Cloud. We also collect and calculate parameters of each system and use this data to determine that all systems contain a neutron star which is accreting via a disc, rather than a wind, and that if these neutron stars are near spin equilibrium, then over half of them, including all with spin periods over about 100 seconds, have magnetic fields over the quantum critical level of 4.4x10^13 G. If these neutron stars are not close to spin equilibrium, then their magnetic fields are inferred to be much lower, on the order of 10^6-10^10 G, comparable to the fields of neutron stars in low mass X-ray binaries. Both results are unexpected and have implications for the rate of magnetic field decay and the isolated neutron star population.

  5. Spin period change and the magnetic fields of neutron stars in Be X-ray binaries in the SMC

    Klus, H.; Ho, W. C. G.; Coe, M. J.; Corbet, R. H. D.; Townsend, L. J.

    2014-01-01

    We report on the long term average spin period, rate of change of spin period and X-ray luminosity during outbursts for 42 Be X-ray binary systems in the Small Magellanic Cloud. We also collect and calculate parameters of each system and use this data to determine that all systems contain a neutron star which is accreting via a disc, rather than a wind, and that if these neutron stars are near spin equilibrium, then over half of them, including all with spin periods over about 100 seconds, have magnetic fields over the quantum critical level of 4.4×1013 G. If these neutron stars are not close to spin equilibrium, then their magnetic fields are inferred to be much lower, on the order of 106-1010 G, comparable to the fields of neutron stars in low mass X-ray binaries. Both results are unexpected and have implications for the rate of magnetic field decay and the isolated neutron star population.

  6. The 5 Hour Pulse Period and Broadband Spectrum of the Symbiotic X-Ray Binary 3A 1954+319

    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.

  7. Spin period change and the magnetic fields of neutron stars in Be X-ray binaries in the SMC

    Klus H.

    2014-01-01

    Full Text Available We report on the long term average spin period, rate of change of spin period and X-ray luminosity during outbursts for 42 Be X-ray binary systems in the Small Magellanic Cloud. We also collect and calculate parameters of each system and use this data to determine that all systems contain a neutron star which is accreting via a disc, rather than a wind, and that if these neutron stars are near spin equilibrium, then over half of them, including all with spin periods over about 100 seconds, have magnetic fields over the quantum critical level of 4.4×1013 G. If these neutron stars are not close to spin equilibrium, then their magnetic fields are inferred to be much lower, on the order of 106-1010 G, comparable to the fields of neutron stars in low mass X-ray binaries. Both results are unexpected and have implications for the rate of magnetic field decay and the isolated neutron star population.

  8. Galaxy Formation with Local Photoionization Feedback -II. Effect of X-Ray Emission from Binaries and Hot Gas

    Kannan, Rahul; Stinson, Greg S; Hennawi, Joe F; Marinacci, Federico; Springel, Volker; Maccio, Andrea V

    2015-01-01

    We study how X-rays from stellar binary systems and the hot intracluster medium (ICM) affect the radiative cooling rates of gas in galaxies. Our study uses a novel implementation of gas cooling in the moving-mesh hydrodynamics code \\textsc{arepo}. X-rays from stellar binaries do not affect cooling at all as their emission spectrum is too hard to effectively couple with galactic gas. In contrast, X-rays from the ICM couple well with gas in the temperature range $10^4 - 10^6$ K. Idealised simulations show that the hot halo radiation field has minimal impact on the dynamics of cooling flows in clusters because of the high virial temperature ($> 10^7$K), making the interaction between the gas and incident photons very ineffective. Satellite galaxies in cluster environments, on the other hand, experience a high radiation flux due to the emission from the host halo. Low mass satellites ($< 10^{12}\\rm{M_\\odot}$) in particular have virial temperatures that are exactly in the regime where the effect of the radiatio...

  9. Probing the hard and intermediate states of X-ray binaries using short time-scale variability

    Skipper, Chris J

    2016-01-01

    Below an accretion rate of approximately a few per cent of the Eddington accretion rate, X-ray binary systems are not usually found in the soft spectral state. However, at accretion rates a factor of a few lower still, in the hard state, there is another spectral transition which is well observed but not well understood. Below ~0.5-1 per cent of the Eddington accretion rate (m_crit), the spectral index hardens with increasing accretion rate, but above m_crit, although still in the hard state, the spectral index softens with increasing accretion rate. Here we use a combination of X-ray spectral fitting and a study of short time-scale spectral variability to examine the behaviour of three well-known X-ray binaries: Cygnus X-1, GX 339-4 and XTE J1118+480. In Cygnus X-1 we find separate hard and soft continuum components, and show using root-mean-square (rms) spectra that the soft component dominates the variability. The spectral transition at m_crit is clearly present in the hard-state hardness-intensity diagram...

  10. Dynamical formation of Black Hole Low-Mass X-Ray Binaries in the field - an alternative to common envelope

    Klencki, Jakub; Gładysz, Wojciech; Belczynski, Krzysztof

    2016-01-01

    Very wide binaries (> 500 AU) are subject to numerous encounters with flying-by stars in the Galactic field and can be perturbated into highly eccentric orbits (e ~ 0.99). For such systems tidal interactions at close pericenter passages can lead to orbit circularization and possibly mass transfer, consequently producing X-Ray binaries without the need for common envelope. We test this scenario for the case of Black Hole Low-Mass X-Ray Binaries (BH LMXBs) by performing a population synthesis from primordial binaries with numerical treatment of random stellar encounters. We test various models for the threshold pericenter distance under which tidal forces cause circularization. We find that fly-by interactions can produce a current population of ~ 60$-$220 BH LMXBs in the Galactic field and the results are sensitive to the assumption on tidal circularization efficiency. We show that the most likely donors are low-mass stars (< 1 Msun, at the onset of mass transfer) as observed in the population of known sour...

  11. Disc-jet coupling in an atoll-type neutron star X-ray binary: 4U 1728-34 (GX 354-0)

    Migliari, Simone; Fender, Rob; Rupen, Michael; Jonker, Peter; Klein-Wolt, Marc; Hjellming, Robert; van der Klis, Michiel

    2003-01-01

    We have analysed 12 simultaneous radio (VLA) and X-ray (RXTE) observations of the atoll-type X-ray binary 4U 1728-34, performed in two blocks in 2000 and 2001. We have found that the strongest and most variable emission seems to be associated with repeated transitions between hard (island) and softer (lower banana) X-ray states, while weaker, persistent radio emission is observed when the source is steadily in the hard X-ray state. There is a significant positive ranking correlation between t...

  12. X-Ray Observations of XSS J12270-4859 in a New Low State: A Transformation to a Disk-free Rotation-powered Pulsar Binary

    Bogdanov, S.; Patruno, A.; Archibald, A.M.; Bassa, C.; Hessels, J. W. T.; Janssen, G. H.; Stappers, B. W.

    2014-01-01

    We present XMM-Newton and Chandra observations of the low-mass X-ray binary XSS J12270--4859, which experienced a dramatic decline in optical/X-ray brightness at the end of 2012, indicative of the disappearance of its accretion disk. In this new state, the system exhibits previously absent orbital-phase-dependent, large-amplitude X-ray modulations with a decline in flux at superior conjunction. The X-ray emission remains predominantly non-thermal but with an order of magnitude lower mean lumi...

  13. Angular Momentum Transfer in the Binary X-ray Pulsar GX 1+4

    Greenhill, J; Murray, J R

    1999-01-01

    We describe three presentations relating to the X-ray pulsar GX 1+4 at a workshop on magnetic fields and accretion at the Astrophysical Theory Centre, Australian National University on 1998, November 12-13. Optical and X-ray spectroscopy indicate that GX 1+4 is seen through a cloud of gravitationaly bound matter. We discuss an unstable negative feedback mechanism (originally proposed by Kotani et al, 1999), based on X-ray heating of this matter which controls the accretion rate when the source is in a low X-ray luminosity state. A deep minimum lasting ~6 hours occurred during observations with the RXTE satellite over 1996, July 19-21. The shape of the X-ray pulses changed remarkably from before to after the minimum. These changes may be related to the transition from neutron star spin-down to spin-up which occurred at about the same time. Smoothed particle hydrodynamic simulations of the effect of adding matter with opposite angular momentum to an existing disc, show that it is possible for a number of concen...

  14. The First Low-mass Black Hole X-Ray Binary Identified in Quiescence Outside of a Globular Cluster

    Tetarenko, B. E.; Bahramian, A.; Arnason, R. M.; Miller-Jones, J. C. A.; Repetto, S.; Heinke, C. O.; Maccarone, T. J.; Chomiuk, L.; Sivakoff, G. R.; Strader, J.; Kirsten, F.; Vlemmings, W.

    2016-07-01

    The observed relation between the X-ray and radio properties of low-luminosity accreting black holes (BHs) has enabled the identification of multiple candidate black hole X-ray binaries (BHXBs) in globular clusters (GCs). Here, we report an identification of the radio source VLA J213002.08+120904 (aka M15 S2), recently reported in Kirsten et al., as a BHXB candidate. They showed that the parallax of this flat-spectrum variable radio source indicates a {2.2}-0.3+0.5 kpc distance, which identifies it as lying in the foreground of the GC M15. We determine the radio characteristics of this source and place a deep limit on the X-ray luminosity of ∼4 × 1029 erg s‑1. Furthermore, we astrometrically identify a faint red stellar counterpart in archival Hubble images with colors consistent with a foreground star; at 2.2 kpc, its inferred mass is 0.1–0.2 M ⊙. We rule out that this object is a pulsar, neutron star X-ray binary, cataclysmic variable, or planetary nebula, concluding that VLA J213002.08+120904 is the first accreting BHXB candidate discovered in quiescence outside of a GC. Given the relatively small area over which parallax studies of radio sources have been performed, this discovery suggests a much larger population of quiescent BHXBs in our Galaxy, 2.6 × 104–1.7 × 108 BHXBs at 3σ confidence, than has been previously estimated (∼102–104) through population synthesis.

  15. Long-term Periodicities in the Flux from Low Mass X-ray Binaries

    Dieters, Stefan; O'Neill, Paul; Farrell, Sean; Sood, Ravi

    2005-01-01

    Using data from the All Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE) we have searched for long term periodicities in the X-ray flux of GX 1+4, Sco X-2 (GX 349+2), and GX 339-4. For GX 1+4 we also used data from BATSE and Galactic Centre scans performed by RXTE. We find no evidence for X-ray modulations at the suggested ~304 d orbital period of GX 1+4. However, we find tentative evidence for a periodicity at 420 d to 460 d. An upper limit of 15% peak-to-peak is set on any sinuso...

  16. Bowen blend echo-tomography of low mass X-ray binaries

    Muñoz-Darias, T; Casares, J; Cornelisse, R; Dhillon, V S; Marsh, T R; Steeghs, D; O'Brien, K; Charles, P A; Still, M

    2007-01-01

    We present simultaneous high time resolution (1-10 Hz) X-ray and optical observations of the persistent LMXBs Sco X-1 and V801 Ara(=4U 1636-536). In the case of Sco X-1 we find that the Bowen/HeII emission lags the X-ray light-curves with a light travel time of ~11-16s which is consistent with reprocessing in the donor star. We also present the detection of three correlated X-ray/optical bursts in V801 ara. Although this latter project is still in progress our preliminary results obtained by subtracting the Continuum light-curve from the Bowen/HeII data provide evidence of orbital phase dependent echoes from the companion star.

  17. The XMM-Newton survey of the Small Magellanic Cloud: XMMUJ005011.2-730026 = SXP214, a Be/X-ray binary pulsar

    Coe, M J; Sturm, R; Pietsch, W; Townsend, L J; Bartlett, E S; Filipovic, M; Udalski, A; Corbet, R H D; Tiengo, A; Ehle, M; Payne, J L; Burton, D

    2011-01-01

    In the course of the XMM-Newton survey of the Small Magellanic Cloud (SMC), a region to the east of the emission nebula N19 was observed in November 2009. To search for new candidates for high mass X-ray binaries the EPIC PN and MOS data of the detected point sources were investigated and their spectral and temporal characteristics identified. A new transient (XMMUJ005011.2-730026= SXP214) with a pulse period of 214.05 s was discovered; the source had a hard X-ray spectrum with power-law index of ~0.65. The accurate X-ray source location permits the identification of the X-ray source with a ~15th magnitude Be star, thereby confirming this system as a new Be/X-ray binary.

  18. Evolution of low-mass X-ray binaries: dependence on the mass of the compact object

    Qian Xu; Tao Li; Xiang-Dong Li

    2012-01-01

    We perform numerical calculations to simulate the evolution of low-mass X-ray binary systems.For the accreting compact object we consider the initial mass of 1.4,10,20,100,200,500 and 1000 M☉,corresponding to neutron stars (NSs),stellarmass black holes (BHs) and intermediate-mass BHs.Mass transfer in these binaries is driven by nuclear evolution of the donors and/or orbital angular momentum loss due to magnetic braking and gravitational wave radiation.For the different systems,we determine their bifurcation periods Pbif that separate the formation of converging systems from the diverging ones,and show that Pbif changes from ~ 1 d to (≥)3 d for a 1 M☉ donor star,with increasing initial accretor mass from 1.4 to 1000 M☉.This means that the dominant mechanism of orbital angular momentum loss changes from magnetic braking to gravitational radiation.As an illustration we compare the evolution of binaries consisting of a secondary star of 1 M☉ at a fixed initial period of 2 d.In the case of the NS or stellar-mass BH accretor,the system evolves to a well-detached He white dwarf-neutron star/black hole pair,but it evolves to an ultracompact binary if the compact object is an intermediate-mass BH.Thus the binary evolution heavily depends upon the mass of the compact object.However,we show that the final orbital period-white dwarf mass relation found for NS low-mass X-ray binaries is fairly insensitive to the initial mass of the accreting star,even if it is an intermediate-mass BH.

  19. ON THE DYNAMICAL FORMATION OF VERY YOUNG, X-RAY EMITTING BLACK HOLE BINARIES IN DENSE STAR CLUSTERS

    We recently discovered a population of very young (τ ∼☉) star clusters, similar to the masses of BHB hosts in NGC 4449, through the first 10 Myr of their lives. Our goal is to determine whether dynamical interactions are responsible for the observed population of BHBs in NGC 4449. Our simulations span a wide range of initial size and density profiles, both with and without primordial mass segregation, testing both realistic initial conditions and extreme ones. We find that clusters without primordial mass segregation only dynamically produce BHBs within 10 Myr when they are extremely compact and centrally concentrated. Preliminary results that include primordial binaries support this conclusion. The introduction of strong primordial mass segregation, however, greatly increases the rapidity with which the binaries form, although these are still not tight enough that they will emit X-rays. We conclude that X-ray emitting BHBs are unlikely to form dynamically in clusters of this mass under realistic conditions. Instead, they probably originate from binaries that contain two massive stars with small orbital separations, which are present from the cluster's birth.

  20. Herschel observations of dust around the high-mass X-ray binary GX 301-2

    Servillat, Mathieu; Chaty, Sylvain; Rahoui, Farid; Heras, Juan Antonio Zurita

    2014-01-01

    We aim at characterising the structure of the gas and dust around the high mass X-ray binary GX 301-2, a highly obscured X-ray binary hosting a hypergiant star and a neutron star, in order to better constrain its evolution. We used Herschel PACS to observe GX 301-2 in the far infrared and completed the spectral energy distribution of the source using published data or catalogs, from the optical to the radio range (0.4 to 4x10^4 micrometer). GX 301-2 is detected for the first time at 70 and 100 micrometer. We fitted different models of circumstellar environments to the data. All tested models are statistically acceptable, and consistent with a hypergiant star at ~3 kpc. We found that the addition of a free-free emission component from the strong stellar wind is required and could dominate the far infrared flux. Through comparisons with similar systems and discussion on the estimated model parameters, we favour a disk-like circumstellar environment of ~8 AU that would enshroud the binary system. The temperature...

  1. Low-mass binary X-Ray sources: Monitoring with various satellites

    Šimon, Vojtěch

    2014-01-01

    Roč. 54, č. 3 (2014), s. 248-253. ISSN 1210-2709. [IBWS (INTEGRAL/BART) workshop. Karlovy Vary, 22.03.2013-25.3.2013] Grant ostatní: GA ČR(CZ) GA13-33324S Institutional support: RVO:67985815 Keywords : radiation mechanisms * accretion disks * X-rays Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  2. The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR21a

    Gosset, Eric; Nazé, Yaël

    2016-01-01

    Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR 21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase in strength of the emission is seen before periastron, following a 1 /D relative trend, where D is the separation between both components. This increase is rapidly followed by a decline due to strong absorption as the Wolf-Rayet (WR) comes i...

  3. Analytical model of strange star in the low-mass X-ray binary 4U 1820-30

    Kalam, Mehedi; Rahaman, Farook; Molla, Sajahan; Jafry, Md. Abdul Kayum(Department of Physics, Shibpur Dinobundhoo Institution (College), 711102, Howrah , West Bengal, India); Hossein, Sk. Monowar

    2014-01-01

    In this article, we propose a model for a realistic strange star under Tolman VII metric (Tolman, Phys Rev 55:364, 1939 ). Here the field equations are reduced to a system of three algebraic equations for anisotropic pressure. Mass, central density and surface density of strange star in the low-mass X-ray binary 4U 1820-30 are matched with the observational data according to our model. Strange materials clearly satisfy the stability condition (i.e. sound velocities < 1) and TOV equation. H...

  4. Spin-up/spin-down of neutron star in Be-X-ray binary system GX 304-1

    Postnov, K. A.; Mironov, A. I.; Lutovinov, A. A.; Shakura, N. I.; Kochetkova, A. Yu.; Tsygankov, S. S.

    2015-01-01

    We analyse spin-up/spin-down of the neutron star in Be-X-ray binary system GX 304-1 observed by Swift/X-ray telescope (XRT) and Fermi/gamma-ray burst monitor (GBM) instruments in the period of the source activity from 2010 April to 2013 January and discuss possible mechanisms of angular momentum transfer to/from the neutron star. We argue that the neutron star spin-down at quiescent states of the source with an X-ray luminosity of Lx ˜ 1034 erg s-1 between a series of Type I outbursts and spin-up during the outbursts can be explained by quasi-spherical settling accretion on to the neutron star. The outbursts occur near the neutron star periastron passages, where the density is enhanced due to the presence of an equatorial Be-disc tilted to the orbital plane. We also propose an explanation to the counterintuitive smaller spin-up rate observed at higher luminosity in a double-peak Type I outburst due to lower value of the specific angular momentum of matter captured from the quasi-spherical wind from the Be-star by the neutron star moving in an elliptical orbit with eccentricity e ≳ 0.5.

  5. The relation between radio and X-ray luminosity of black hole binaries: affected by inner cool disks?

    Meyer-Hofmeister, E

    2014-01-01

    Observations of the black hole X-ray binaries GX 339-4 and V404 Cygni have brought evidence of a strong correlation between radio and X-ray emission during the hard spectral state; however, now more and more sources, the so-called `outliers', are found with a radio emission noticeably below the established `standard' relation. Several explanations have already been considered, but the existence of dual tracks is not yet fully understood. We suggest that in the hard spectral state re-condensation of gas from the corona into a cool, weak inner disk can provide additional soft photons for Comptonization, leading to a higher X-ray luminosity in combination with rather unchanged radio emission, which presumably traces the mass accretion rate. As an example, we determined how much additional luminosity due to photons from an underlying disk would be needed to explain the data from the representative outlier source H1743-322. From the comparison with calculations of Compton spectra with and without the photons from ...

  6. Are spectral and timing correlations similar in different spectral states in black hole X-ray binaries?

    Kalamkar, M; van der Klis, M; Altamirano, D; Miller, J M

    2015-01-01

    We study the outbursts of the black hole X-ray binaries MAXI J1659-152, SWIFT J1753.5--0127 and GX 339-4 with the Swift X-ray Telescope. The bandpass of the X-ray Telescope has access to emission from both components of the accretion flow: the accretion disk and the corona/hot flow. This allows a correlated spectral and variability study, with variability from both components of the accretion flow. We present for the first time, a combined study of the evolution of spectral parameters (disk temperature and radius) and timing parameters (frequency and strength) of all power spectral components in different spectral states. Comparison of the correlations in different spectral states shows that the frequency and strength of the power spectral components exhibit dependencies on the disk temperature that are different in the (low-)hard and the hard-intermediate states; most of these correlations that are clearly observed in the hard-intermediate state (in MAXI J1659-152 and GX 339-4) are not seen in the (low-)hard...

  7. Discovery and identification of infrared counterpart candidates of four Galactic centre low mass X-ray binaries

    Curran, P A; Heras, J A Zurita

    2011-01-01

    The near infrared (nIR)/optical counterparts of low mass X-ray binaries (LMXBs) are often observationally dim and reside in high source density fields which make their identification problematic; however, without such a counterpart identification we are unable to investigate many of the properties of LMXB systems. Here, in the context of a larger identification campaign, we examine the fields of four LMXB systems near the Galactic centre, in a bid to identify nIR/optical counterparts to the previously detected X-ray point sources. We obtain nIR/optical images of the fields with the ESO - New Technology Telescope and apply standard photometric and astrometric calibrations; these data are supplemented by Spitzer-GLIMPSE catalog data. On the basis of positional coincidence with the arcsecond accurate X-ray positions, we identify unambiguous counterpart candidates for XTE J1637-498, IGR J17379-3747, IGR J17585-3057 and GX 9+1. We propose tentative nIR counterparts of four LMXBs which require further investigation...

  8. The Causal Connection Between Disc and Power-Law Variability in Hard State Black Hole X-Ray Binaries

    Uttley, P.; Wilkinson, T.; Cassatella, P.; Wilms, J.; Pottschimdt, K.; Hanke, M.; Boeck, M.

    2010-01-01

    We use the XMM-Newton EPIC-pn instrument in timing mode to extend spectral time-lag studies of hard state black hole X-ray binaries into the soft X-ray band. \\Ve show that variations of the disc blackbody emission substantially lead variations in the power-law emission, by tenths of a second on variability time-scales of seconds or longer. The large lags cannot be explained by Compton scattering but are consistent with time-delays due to viscous propagation of mass accretion fluctuations in the disc. However, on time-scales less than a second the disc lags the power-law variations by a few ms, consistent with the disc variations being dominated by X-ray heating by the power-law, with the short lag corresponding to the light-travel time between the power-law emitting region and the disc. Our results indicate that instabilities in the accretion disc are responsible for continuum variability on time-scales of seconds or longer and probably also on shorter time-scales.

  9. The accretion-ejection coupling in the black hole candidate X-ray binary MAXI J1836-194

    Russell, T D; Miller-Jones, J C A; Curran, P A; Markoff, S; Russell, D M; Sivakoff, G R

    2013-01-01

    We present the results of our quasi-simultaneous radio, sub-mm, infrared, optical and X-ray study of the Galactic black hole candidate X-ray binary MAXI J1836-194 during its 2011 outburst. We consider the full multi-wavelength spectral evolution of the outburst, investigating whether the evolution of the jet spectral break (the transition between optically-thick and optically-thin synchrotron emission) is caused by any specific properties of the accretion flow. Our observations show that the break does not scale with the X-ray luminosity or with the inner radius of the accretion disk, and is instead likely to be set by much more complex processes. We find that the radius of the acceleration zone at the base of the jet decreases from ~10$^6$ gravitational radii during the hard intermediate state to ~10$^3$ gravitational radii as the outburst fades (assuming a black hole mass of 8 M$_{\\odot}$), demonstrating that the electrons are accelerated on much larger scales than the radius of the inner accretion disk and...

  10. Swift reveals the eclipsing nature of the high mass X-ray binary IGR~J16195-4945

    Cusumano, G; Segreto, A; D'Aì, A

    2016-01-01

    IGR J16195-4945 is a hard X-ray source discovered by INTEGRAL during the Core Program observations performed in 2003. We analyzed the X-ray emission of this source exploiting the Swift-BAT survey data from December 2004 to March 2015, and all the available Swift-XRT pointed observations. The source is detected at a high significance level in the 123-month BAT survey data, with an average 15-150 keV flux of the source of ~1.6 mCrab. The timing analysis on the BAT data reveals with a significance higher than 6 standard deviations the presence of a modulated signal with a period of 3.945 d, that we interpret as the orbital period of the binary system. The folded light curve shows a flat profile with a narrow full eclipse lasting ~3.5% of the orbital period. We requested phase-constrained XRT observations to obtain a more detailed characterization of the eclipse in the soft X-ray range. Adopting resonable guess values for the mass and radius of the companion star, we derive a semi-major orbital axis of ~31 R_sun,...

  11. The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR21a

    Gosset, Eric

    2016-01-01

    Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase in strength of the emission is seen before periastron, following a 1/D relative trend, where D is the separation between both components. This increase is rapidly followed by a decline due to strong absorption as the Wolf-Rayet (WR) comes in front. The fitted local absorption value appears to be coherent with a mass-loss rate of about 1x10^{-5} M_sol/yr for the WR component. However, absorption is not the only parameter affecting the X-ray emission at periastron as even the hard X-ray emission decreases, suggesting a possible collapse of the colliding wind region near to or onto the photosphere of the companion just before or at periastron. An eclipse may appear as another potential scenario, but it would be in apparent contradiction with several lines of evi...

  12. Joint H-alpha and X-ray Observations of Massive X-ray Binaries. I. The B-Supergiant System LS I +65 010 = 2S 0114+650

    Grundstrom, E D; Gies, D R; Huang, W; McSwain, M V; Raghavan, D; Riddle, R L; Subasavage, J P; Wingert, D W; Levine, A M; Remillard, R A

    2006-01-01

    We report on a three year spectroscopic monitoring program of the H-alpha emission in the massive X-ray binary LS I +65 010 = 2S 0114+650, which consists of a B-supergiant and a slowly rotating X-ray pulsar. We present revised orbital elements that yield a period of P=11.5983 +/- 0.0006 d and confirm that the orbit has a non-zero eccentricity e=0.18 +/- 0.05. The H-alpha emission profile is formed in the base of the wind of the B-supergiant primary, and we show how this spectral feature varies on timescales that are probably related to the rotational period of the B-supergiant. We also examine the X-ray fluxes from the Rossi X-ray Timing Explorer All-Sky Monitor instrument, and we show that the X-ray orbital light curve has a maximum at periastron and a minimum at the inferior conjunction of the B-supergiant. We also show that the wind emission strength and the high energy X-ray flux appear to vary in tandem on timescales of approximately a year.

  13. Studies of the Origin of High-Frequency Quasi-Periodic Oscillations of Mass Accreting Black Holes in X-ray Binaries with Next-Generation X-ray Telescopes

    Beheshtipour, Banafsheh; Krawczynski, Henric

    2016-01-01

    Observations with RXTE (Rossi X-ray Timing Explorer) revealed the presence of High Frequency Quasi-Periodic Oscillations (HFQPOs) of the X-ray flux from several accreting stellar mass Black Holes. HFQPOs (and their counterparts at lower frequencies) may allow us to study general relativity in the strong gravity regime. However, the observational evidence today does not yet allow us to distinguish between different HFQPO models. In this paper we use a general relativistic ray-tracing code to investigate X-ray timing-spectroscopy and polarization properties of HFQPOs in the orbiting Hotspot model. We study observational signatures for the particular case of the 166 Hz quasi-periodic oscillation (QPO) in the galactic binary GRS 1915+105. We conclude with a discussion of the observability of spectral signatures with a timing-spectroscopy experiment like the LOFT (Large Observatory for X-ray Timing) and polarization signatures with space-borne X-ray polarimeters such as IXPE (Imaging X-ray Polarimetry Explorer), P...

  14. Multi-wavelength properties of IGR J05007-7047 (LXP 38.55) and identification as a Be X-ray binary pulsar in the LMC

    Vasilopoulos, G; Delvaux, C; Sturm, R; Udalski, A

    2016-01-01

    We report on the results of a $\\sim$40 d multi-wavelength monitoring of the Be X-ray binary system IGR J05007-7047 (LXP 38.55). During that period the system was monitored in the X-rays using the Swift telescope and in the optical with multiple instruments. When the X-ray luminosity exceeded $10^{36}$ erg/s we triggered an XMM-Newton ToO observation. Timing analysis of the photon events collected during the XMM-Newton observation reveals coherent X-ray pulsations with a period of 38.551(3) s (1 {\\sigma}), making it the 17$^{th}$ known high-mass X-ray binary pulsar in the LMC. During the outburst, the X-ray spectrum is fitted best with a model composed of an absorbed power law ($\\Gamma =0.63$) plus a high-temperature black-body (kT $\\sim$ 2 keV) component. By analysing $\\sim$12 yr of available OGLE optical data we derived a 30.776(5) d optical period, confirming the previously reported X-ray period of the system as its orbital period. During our X-ray monitoring the system showed limited optical variability wh...

  15. Optical and X-ray emission from stable millisecond magnetars formed from the merger of binary neutron stars

    Metzger, Brian D.; Piro, Anthony L.

    2014-04-01

    The coalescence of binary neutron stars (NSs) may in some cases produce a stable massive NS remnant rather than a black hole. Due to the substantial angular momentum from the binary, such a remnant is born rapidly rotating and likely acquires a strong magnetic field (a `millisecond magnetar'). Magnetic spin-down deposits a large fraction of the rotational energy from the magnetar behind the small quantity of mass ejected during the merger. If the magnetar outflow is indeed trapped behind the ejecta (instead of placing most of its energy into a collimated jet), this has the potential for creating a bright transient that could be useful for determining whether an NS or black hole was formed in the merger. We investigate the expected signature of such an event, including for the first time the important impact of e± pairs injected by the millisecond magnetar into the surrounding nebula. These pairs cool via synchrotron and inverse Compton emission, producing a pair cascade and hard X-ray spectrum. A fraction of these X-rays are absorbed by the ejecta walls and re-emitted as thermal radiation, leading to an optical/UV transient peaking at a luminosity of ˜1043-1044 erg s-1 on a time-scale of several hours to days. This is dimmer than predicted by simpler analytic models because the large optical depth of e± pairs across the nebula suppresses the efficiency with which the magnetar spin-down luminosity is thermalized. Nevertheless, the optical/UV emission is more than two orders of magnitude brighter than a radioactively powered `kilonova'. In some cases, nebular X-rays are sufficiently luminous to re-ionize the ejecta, in which case non-thermal X-rays escape the ejecta unattenuated with a similar peak luminosity and time-scale as the optical radiation. We discuss the implications of our results for the temporally extended X-ray emission that is observed to follow some short gamma-ray bursts (GRBs), including the kilonova candidates GRB 080503 and GRB 130603B.

  16. The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR 21a

    Gosset, Eric; Nazé, Yaël

    2016-05-01

    Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR 21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase in strength of the emission is seen before periastron, following a 1 /D relative trend, where D is the separation between both components. This increase is rapidly followed by a decline due to strong absorption as the Wolf-Rayet (WR) comes in front. The fitted local absorption value appears to be coherent with a mass-loss rate of about 1 × 10-5 M⊙ yr-1 for the WR component. However, absorption is not the only parameter affecting the X-ray emission at periastron as even the hard X-ray emission decreases, suggesting a possible collapse of the colliding wind region near to or onto the photosphere of the companion just before or at periastron. An eclipse may appear as another potential scenario, but it would be in apparent contradiction with several lines of evidence, notably the width of the dip in the X-ray light curve and the absence of variations in the UV light curve. Afterwards, the emission slowly recovers, with a strong hysteresis effect. The observed behaviour is compatible with predictions from general wind-wind collision models although the absorption increase is too shallow. Based on observations collected at ESO as well as with Swift, Chandra, and the ESA science mission XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).

  17. The Einstein objective grating spectrometer survey of galactic binary X-ray sources

    Vrtilek, S. D.; Mcclintock, J. E.; Seward, F. D.; Kahn, S. M.; Wargelin, B. J.

    1991-01-01

    The results of observations of 22 bright Galactic X-ray point sources are presented, and the most reliable measurements to date of X-ray column densities to these sources are derived. The results are consistent with the idea that some of the objects have a component of column density intrinsic to the source in addition to an interstellar component. The K-edge absorption due to oxygen is clearly detected in 10 of the sources and the Fe L and Ne K edges are detected in a few. The spectra probably reflect emission originating in a collisionally excited region combined with emission from a photoionized region excited directly by the central source.

  18. Probing black hole X-ray binaries with the Keck telescopes

    Harlaftis, E T; Harlaftis, Emilios T.; Filippenko, Alexei V.

    2000-01-01

    The advent of the large effective apertures of the Keck telescopes hasresulted in the determination with unprecedented accuracy of the mass functionsand mass ratios of faint (R ~ 21 mag) X-ray transients (GS 2000+25, GROJ0422+32, Nova Oph 1977, Nova Vel 1993), as well as constraining themain-sequence companion star parameters and producing images of the accretiondisks around the black holes.

  19. Modelling aperiodic X-ray variability in black hole binaries as propagating mass accretion rate fluctuations: a short review

    Ingram, Adam

    2015-01-01

    Black hole binary systems can emit very bright and rapidly varying X-ray signals when material from the companion accretes onto the black hole, liberating huge amounts of gravitational potential energy. Central to this process of accretion is turbulence. In the propagating mass accretion rate fluctuations model, turbulence is generated throughout the inner accretion flow, causing fluctuations in the accretion rate. Fluctuations from the outer regions propagate towards the black hole, modulating the fluctuations generated in the inner regions. Here, I present the theoretical motivation behind this picture before reviewing the array of statistical variability properties observed in the light curves of black hole binaries that are naturally explained by the model. I also discuss the remaining challenges for the model, both in terms of comparison to data and in terms of including more sophisticated theoretical considerations.

  20. Modelling aperiodic X-ray variability in black hole binaries as propagating mass accretion rate fluctuations: A short review

    Ingram, A. R.

    2016-05-01

    Black hole binary systems can emit very bright and rapidly varying X-ray signals when material from the companion accretes onto the black hole, liberating huge amounts of gravitational potential energy. Central to this process of accretion is turbulence. In the propagating mass accretion rate fluctuations model, turbulence is generated throughout the inner accretion flow, causing fluctuations in the accretion rate. Fluctuations from the outer regions propagate towards the black hole, modulating the fluctuations generated in the inner regions. Here, I present the theoretical motivation behind this picture before reviewing the array of statistical variability properties observed in the light curves of black hole binaries that are naturally explained by the model. I also discuss the remaining challenges for the model, both in terms of comparison to data and in terms of including more sophisticated theoretical considerations.

  1. Long-term Optical Observations of the Be/X-ray Binary X Per

    Li, Hui; Zhou, Jianeng; Liu, Qingzhong

    2014-01-01

    We present the optical spectroscopic observations of X Per from 1999 to 2013 with the 2.16m telescope at Xinglong Station and the 2.4m telescope at Lijiang station, National Astronomical Observatories of China. Combining with the public optical photometric data, we find certain epochs of anti-correlations between the optical brightness and the intensity of the H{\\alpha} and HeI 6678 lines, which may be attributed to the mass ejections from the Be star. Alternative explanations are however also possible. The variability of FeII 6317 line in the spectra of X Per might be also caused by the shocked waves formed after the mass ejections from the Be star. The X-ray activities of the system might also be connected with the mass ejection events from the Be star. When the ejected materials were transported from the surface of the Be star to the orbit of neutron star, an X-ray flare could be observed in its X-ray light curves. We use the neutron star as a probe to constrain the motion of the ejected material in the ci...

  2. The Spin of The Black Hole in the X-ray Binary Nova Muscae 1991

    Chen, Zihan; McClintock, Jeffrey E; Steiner, James F; Wu, Jianfeng; Xu, Weiwei; Orosz, Jerome; Xiang, Yanmei

    2016-01-01

    The bright soft X-ray transient Nova Muscae 1991 was intensively observed during its entire 8-month outburst using the Large Area Counter (LAC) onboard the Ginga satellite. Recently, we obtained accurate estimates of the mass of the black hole primary, the orbital inclination angle of the system, and the distance. Using these crucial input data and Ginga X-ray spectra, we have measured the spin of the black hole using the continuum-fitting method. For four X-ray spectra of extraordinary quality we have determined the dimensionless spin parameter of the black hole to be a/M = 0.63 (-0.19, +0.16) (1 sigma confidence level), a result that we confirm using eleven additional spectra of lower quality. Our spin estimate challenges two published results: It is somewhat higher than the value predicted by a proposed relationship between jet power and spin; and we find that the spin of the black hole is decidedly prograde, not retrograde as has been claimed.

  3. Galaxy formation with local photoionization feedback - II. Effect of X-ray emission from binaries and hot gas

    Kannan, R.; Vogelsberger, M.; Stinson, G. S.; Hennawi, J. F.; Marinacci, F.; Springel, V.; Macciò, A. V.

    2016-05-01

    We study how X-rays from stellar binary systems and the hot intracluster medium (ICM) affect the radiative cooling rates of gas in galaxies. Our study uses a novel implementation of gas cooling in the moving-mesh hydrodynamics code AREPO. X-rays from stellar binaries do not affect cooling at all as their emission spectrum is too hard to effectively couple with galactic gas. In contrast, X-rays from the ICM couple well with gas in the temperature range 104-106 K. Idealized simulations show that the hot halo radiation field has minimal impact on the dynamics of cooling flows in clusters because of the high virial temperature ( ≳ 107 K), making the interaction between the gas and incident photons very ineffective. Satellite galaxies in cluster environments, on the other hand, experience a high radiation flux due to the emission from the host halo. Low-mass satellites ( ≲ 1012 M⊙) in particular have virial temperatures that are exactly in the regime where the effect of the radiation field is maximal. Idealized simulations of satellite galaxies including only the effect of host halo radiation (no ram pressure stripping or tidal effects) fields show a drastic reduction in the amount of cool gas formed (˜40 per cent) on a short time-scale of about 0.5 Gyr. A galaxy merger simulation including all the other environmental quenching mechanisms, shows about 20 per cent reduction in the stellar mass of the satellite and about ˜30 per cent reduction in star formation rate after 1 Gyr due to the host hot halo radiation field. These results indicate that the hot halo radiation fields potentially play an important role in quenching galaxies in cluster environments.

  4. Probing the hard and intermediate states of X-ray binaries using short time-scale variability

    Skipper, Chris J.; McHardy, Ian M.

    2016-05-01

    Below an accretion rate of approximately a few per cent of the Eddington accretion rate, X-ray binary systems are not usually found in the soft spectral state. However, at accretion rates a factor of a few lower still, in the hard state, there is another spectral transition which is well observed but not well understood. Below {˜ }0.5-1 per cent of the Eddington accretion rate (dot{m}_crit), the spectral index hardens with increasing accretion rate, but above dot{m}_crit, although still in the hard state, the spectral index softens with increasing accretion rate. Here we use a combination of X-ray spectral fitting and a study of short time-scale spectral variability to examine the behaviour of three well-known X-ray binaries: Cygnus X-1, GX 339-4 and XTE J1118+480. In Cygnus X-1 we find separate hard and soft continuum components, and show using root mean square (rms) spectra that the soft component dominates the variability. The spectral transition at dot{m}_crit is clearly present in the hard-state hardness-intensity diagrams of Cygnus X-1. Above dot{m}_crit, GX 339-4 shows similar softer-when-brighter behaviour at both long and short time-scales. Similarly, XTE J1118+480, which remains well below dot{m}_crit, has harder-when-brighter behaviour on all time-scales. We interpret these results in terms of two continuum components: a hard power law which dominates the spectra when the accretion rate is low, probably arising from Comptonization of cyclo-synchrotron photons from the corona, and a soft power law which dominates at higher accretion rates, arising from Comptonization of seed photons from the accretion disc.

  5. Broadband x-ray properties of the gamma-ray binary 1FGL J1018.6-5856

    An, Hongjun; Bellm, Eric; Bhalerao, Varun;

    2015-01-01

    We report on NuSTAR, XMM-Newton, and Swift observations of the gamma-ray binary 1FGL J1018.6-5856. We measure the orbital period to be 16.544 ± 0.008 days using Swift data spanning 1900 days. The orbital period is different from the 2011 gamma-ray measurement which was used in the previous X-ray ...... broadband X-ray spectra measured with NuSTAR, XMM-Newton, and Swift are well fit with an unbroken power-law model. This spectrum suggests that the system may not be accretion-powered.......We report on NuSTAR, XMM-Newton, and Swift observations of the gamma-ray binary 1FGL J1018.6-5856. We measure the orbital period to be 16.544 ± 0.008 days using Swift data spanning 1900 days. The orbital period is different from the 2011 gamma-ray measurement which was used in the previous X...

  6. Optical and Infrared Light Curves of the Eclipsing X-ray Binary V395 Car = 2S 0921-630

    Ashcraft, Teresa A; Robinson, Edward L

    2012-01-01

    We present results of optical and infrared photometric monitoring of the eclipsing low-mass X-ray binary V395 Car (2S 0921-630). Our observations reveal a clear, repeating orbital modulation with an amplitude of about one magnitude in B, and V and a little less in J. Combining our data with archival observations spanning about 20 years, we derive an updated ephemeris with orbital period 9.0026+/-0.0001d. We attribute the modulation to a combination of the changing aspect of the irradiated face of the companion star and eclipses of the accretion disk around the neutron star. Both appear to be necessary as a secondary eclipse of the companion star is clearly seen. We model the B, V, and J lightcurves using a simple model of an accretion disk and companion star and find a good fit is possible for binary inclinations of 82.2+/-1.0 degrees. We estimate the irradiating luminosity to be about 8x10^35 erg/s, in good agreement with X-ray constraints.

  7. Big Game Hunting in the Andromeda Galaxy: identifiying and weighing black holes in low mass X-ray Binaries

    Barnard, R.

    2004-07-01

    We have devised a new technique for identifying stellar mass black holes in low mass X-ray binaries, and have applied it to XMM-Newton observations of two X-ray sources in M31. In particular we search for low accretion rate power density spectra; these are very similar for all LMXB, whether the primary is a black hole or a neutron star. Galactic neutron star LMXB exhibit these distinctive PDS at very low luminosities ( ˜ 1036 erg s-1) while black hole LMXB can exhibit them at luminosities > 1038 erg s-1! Following the work of van der Klis (1994), we assume a maximum accretion rate (as a fraction of the Eddington limit) for low accretion rate PDS that is constant for all LMXB, and obtain an empirical value of ˜ 10% Eddington. We have so far discovered two candidate black hole binaries in M31, exhibiting low accretion rate PDS at up to 3×1038 and 5×1037 erg s-1. If we assume that they are at 5×1037 erg s-1 is likely to have a black hole primary.

  8. Optical and X-ray emission from stable millisecond magnetars formed from the merger of binary neutron stars

    Metzger, Brian D

    2013-01-01

    The coalescence of binary neutron stars (NSs) may in some cases produce a stable massive NS remnant rather than a black hole. Due to the substantial angular momentum from the binary, such a remnant is born rapidly rotating and likely acquires a strong magnetic field (a `millisecond magnetar'). Magnetic spin-down deposits a large fraction of the rotational energy from the magnetar behind the small quantity of mass ejected during the merger. This has the potential for creating a bright transient that could be useful for determining whether a NS or black hole was formed in the merger. We investigate the expected signature of such an event, including for the first time the important impact of electron/positron pairs injected by the millisecond magnetar into the surrounding nebula. These pairs cool via synchrotron and inverse Compton emission, producing a pair cascade and hard X-ray spectrum. A fraction of these X-rays are absorbed by the ejecta walls and re-emitted as thermal radiation, leading to an optical/UV t...

  9. Review of low-mass X-ray binaries near the Galactic center

    Lutovinov, A.; Grebenev, S.; Molkov, S.; Sunyaev, R.

    2003-01-01

    Results of observations of several LMXBs in the Galactic center region carried out with the ART-P telescope on board \\Granat observatory are briefly reviewed. More than dozen sources were revealed in this region during five series of observations which were performed with the ART-P telescope in 1990-1992. The investigation of the spectral evolution of persistent emission of two X-ray bursters GX3+1 and KS1731-260, discussion of QPO and spectral variations detected from the very bright Z-sourc...

  10. X-ray accretion signatures in the close CTTS binary V4046 Sgr

    Günther, H. M.; Liefke, C.; Schmitt, J. H. M. M.; Robrade, J.; Ness, J. -U.

    2006-01-01

    We present Chandra HETGS observations of the classical T Tauri star (CTTS) V4046 Sgr. The He-like triplets of O VII, Ne IX, and Si XIII are clearly detected. Similar to the CTTS TW Hya and BP Tau, the forbidden lines of O VII and Ne IX are weak compared to the intercombination line, indicating high plasma densities in the X-ray emitting regions. The Si XIII triplet, however, is within the low-density limit, in agreement with the predictions of the accretion funnel infall model with an additio...

  11. Doppler tomography of the transient X-ray binary Centaurus X-4 in quiescence

    D'Avanzo, P.; Campana, S.; Casares, J.; Israel, G. L.; S. Covino(INAF National Institute for Astrophysics, I-00136 Rome, Italy); Charles, P. A.; Stella, L.

    2005-01-01

    We present ESO-NTT low resolution spectroscopy of the neutron star X-ray transient Cen X-4 in quiescence over a complete orbital cycle. Our data reveal the presence of a K3-7 V companion which contributes 63% to the 5600-6900A flux and orbits the neutron star with a velocity semi-amplitude of K_2=145.8 +/- 1.0 km s^{-1}. This, combined with a previous determination of the inclination angle and mass ratio, yields a neutron star and companion mass of M_1=1.5 +/- 1.0 M_Sun and M_2=0.31 +/- 0.27 ...

  12. 1RXS J180408.9-342058: An ultra compact X-ray binary candidate with a transient jet

    Baglio, M. C.; D'Avanzo, P.; Campana, S.; Goldoni, P.; Masetti, N.; Muñoz-Darias, T.; Patiño-Álvarez, V.; Chavushyan, V.

    2016-03-01

    Aims: We present a detailed near-infrared/optical/UV study of the transient low-mass X-ray binary 1RXS J180408.9-342058 performed during its 2015 outburst, which is aimed at determining the nature of its companion star. Methods: We obtained three optical spectra (R ~ 1000) at the 2.1 m San Pedro Mártir Observatory telescope (México). We performed optical and NIR photometric observations with both the REM telescope and the New Technology Telescope (NTT) in La Silla. We obtained optical and UV observations from the Swift archive. Finally, we performed optical polarimetry of the source using the EFOSC2 instrument mounted on the NTT. Results: The optical spectrum of the source is almost featureless since the hydrogen and He I emissions lines, typically observed in LMXBs, are not detected. Similarly, carbon and oxygen lines are not observed either. We marginally detect the He II 4686 Å emission line, suggesting the presence of helium in the accretion disc. No significant optical polarisation level was observed. Conclusions: The lack of hydrogen and He I emission lines in the spectrum implies that the companion is likely not a main-sequence star. Driven by the tentative detection of the He II 4686 Å emission line, we suggest that the system could harbour a helium white dwarf. If this is the case, 1RXS J180408.9-342058 would be an ultra-compact X-ray binary. By combining an estimate of the mass accretion rate together with evolutionary tracks for a He white dwarf, we obtain a tentative orbital period of ~40 min. We also built the NIR-optical-UV spectral energy distribution (SED) of the source at two different epochs. One SED was gathered when the source was in the soft X-ray state and this SED is consistent with the presence of a single thermal component. The second SED, obtained when the source was in the hard X-ray state, shows a thermal component along with a tail in the NIR, which likely indicates the presence of a (transient) jet. Based on observations made with

  13. On the Optical -- X-ray correlation from outburst to quiescence in Low Mass X-ray Binaries: the representative cases of V404 Cyg and Cen X-4

    Bernardini, F; Koljonen, K I I; Stella, L; Hynes, R I; Corbel, S

    2016-01-01

    Low mass X-ray binaries (LMXBs) show evidence of a global correlation of debated origin between X-ray and optical luminosity. We study for the first time this correlation in two transient LMXBs, the black hole V404 Cyg and the neutron star Cen X-4, over 6 orders of magnitude in X-ray luminosity, from outburst to quiescence. After subtracting the contribution from the companion star, the Cen X-4 data can be described by a single power law correlation of the form $L_{opt}\\propto\\,L_{X}^{0.44}$, consistent with disk reprocessing. We find a similar correlation slope for V404 Cyg in quiescence (0.46) and a steeper one (0.56) in the outburst hard state of 1989. However, V404 Cyg is about $160-280$ times optically brighter, at a given $3-9$ keV X-ray luminosity, compared to Cen X-4. This ratio is a factor of 10 smaller in quiescence, where the normalization of the V404 Cyg correlation also changes. We show that once the bolometric X-ray emission is considered and the known main differences between V404 Cyg and Cen X...

  14. The Mass of the Black Hole in the X-ray Binary Nova Muscae 1991

    Wu, Jianfeng; McClintock, Jeffrey E; Hasan, Imran; Bailyn, Charles D; Gou, Lijun; Chen, Zihan

    2016-01-01

    The optical counterpart of the black-hole soft X-ray transient Nova Muscae 1991 has brightened by $\\Delta{V}\\approx0.8$ mag since its return to quiescence 23 years ago. We present the first clear evidence that the brightening of soft X-ray transients in quiescence occurs at a nearly linear rate. This discovery, and our precise determination of the disk component of emission obtained using our $simultaneous$ photometric and spectroscopic data, have allowed us to identify and accurately model archival ellipsoidal light curves of the highest quality. The simultaneity, and the strong constraint it provides on the component of disk emission, is a key element of our work. Based on our analysis of the light curves, and our earlier measurements of the mass function and mass ratio, we have obtained for Nova Muscae 1991 the first accurate estimates of its systemic inclination $i=43.2^{+2.1}_{-2.7}$ deg, and black hole mass $M=11.0^{+2.1}_{-1.4}\\ M_\\odot$. Based on our determination of the radius of the secondary, we es...

  15. Doppler tomography of the transient X-ray binary Centaurus X-4 in quiescence

    D'Avanzo, P; Casares, J; Israel, G L; Covino, S; Charles, P A; Stella, L

    2005-01-01

    We present ESO-NTT low resolution spectroscopy of the neutron star X-ray transient Cen X-4 in quiescence over a complete orbital cycle. Our data reveal the presence of a K3-7 V companion which contributes 63% to the 5600-6900A flux and orbits the neutron star with a velocity semi-amplitude of K_2=145.8 +/- 1.0 km s^{-1}. This, combined with a previous determination of the inclination angle and mass ratio, yields a neutron star and companion mass of M_1=1.5 +/- 1.0 M_Sun and M_2=0.31 +/- 0.27 M_Sun, respectively. The mass donor is thus undermassive for the inferred spectral type indicating it is probably evolved, in agreement with previous studies. Doppler tomography of the H_alpha line shows prominent emission located on the companion and a slightly asymmetric accretion disc distribution similar to that seen in systems with precessing eccentric discs. Strong H_alpha emission from the companion can be explained by X-ray irradiation from the primary. No evidence is found for a hot spot in H_alpha, whereas one i...

  16. Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in Supergiant Fast X-ray Transient and classical Supergiant X-ray Binaries

    Gimenez-Garcia, A; Torrejon, J M; Oskinova, L; Martinez-Nunez, S; Hamann, W -R; Rodes-Roca, J J; Gonzalez-Galan, A; Alonso-Santiago, J; Gonzalez-Fernandez, C; Bernabeu, G; Sander, A

    2016-01-01

    Classical Supergiant X-ray Binaries (SGXBs) and Supergiant Fast X-ray Transients (SFXTs) are two types of High-mass X-ray Binaries (HMXBs) that present similar donors but, at the same time, show very different behavior in the X-rays. The reason for this dichotomy of wind-fed HMXBs is still a matter of debate. Among the several explanations that have been proposed, some of them invoke specific stellar wind properties of the donor stars. Only dedicated empiric analysis of the donors' stellar wind can provide the required information to accomplish an adequate test of these theories. However, such analyses are scarce. To close this gap, we perform a comparative analysis of the optical companion in two important systems: IGR J17544-2619 (SFXT) and Vela X-1 (SGXB). We analyse the spectra of each star in detail and derive their stellar and wind properties. We compare the wind parameters, giving us an excellent chance of recognizing key differences between donor winds in SFXTs and SGXBs. We find that the stellar para...

  17. An object that defies stereotypes. X-ray observations of SBS 1150+599A -- the binary nucleus of PN G135.9+55.9

    Tovmassian, G; Napiwotzki, R; Yungelson, L; Stasińska, G; Peña, M; Richer, M

    2007-01-01

    We present X-ray observations of the close binary nucleus of the planetary nebula PN G135.9+55.9 obtained with the XMM satellite. The nebula is the most oxygen-poor PN known to date and is located in the Galactic halo. It is known to harbor a close binary nucleus of which only one component can be observed in optical-UV range. New X-ray observations show that the invisible component is a very hot compact star. This finding allows us to reconstruct the immediate past of the object and predict its future. The parameters of the binary components we determine strongly suggest that the precursor was a symbiotic supersoft X-ray source that finished its life by Roche lobe overflow. PN G135.9+55.9 is an excelent candidate for a future type Ia supernova.

  18. The X-ray quiescence of Swift J195509.6+261406 (GRB 070610): an optical bursting X-ray binary?

    N. Rea; P.G. Jonker; G. Nelemans; J.A. Pons; M.M. Kasliwal; S.R. Kulkarni; R. Wijnands

    2011-01-01

    We report on an ~63 ks Chandra observation of the X-ray transient Swift J195509.6+261406 discovered as the afterglow of what was first believed to be a long-duration gamma-ray burst (GRB 070610). The outburst of this source was characterized by unique optical flares on timescales of second or less,

  19. The Nature of the X-Ray Binary IGR J19294+1816 from INTEGRAL, RXTE, and Swift Observations

    Rodriquez, J.; Tomsick, J. A.; Bodaghee, A.; ZuritaHeras, J.-A.; Chaty, S.; Paizis, A.; Corbel, S.

    2009-01-01

    We report the results of a high-energy multi-instrumental campaign with INTEGRAL, RXTE, and Swift of the recently discovered INTEGRAL source IGR J19294+ 1816. The Swift/XRT data allow us to refine the position of the source to R.A. (J2000) = 19h 29m 55.9s, Decl. (J2000) = +18 deg 18 feet 38 inches . 4 (+/- 3 inches .5), which in turn permits us to identify a candidate infrared counterpart. The Swift and RXTE spectra are well fitted with absorbed power laws with hard (Gamma approx 1) photon indices. During the longest Swift observation, we obtained evidence of absorption in true excess to the Galactic value, which may indicate some intrinsic absorption in this source. We detected a strong (P = 40%) pulsations at 12.43781 (+/- 0.00003) s that we interpret as the spin period of a pulsar. All these results, coupled with the possible 117 day orbital period, point to IGR J19294+ 1816 being an high-mass X-ray binary (HMXB) with a Be companion star. However, while the long-term INTEGRAL/IBIS/ISGRI 18-40 keV light curve shows that the source spends most of its time in an undetectable state, we detect occurrences of short (2000-3000 s) and intense flares that are more typical of supergiant fast X-ray transients. We therefore cannot make firm conclusions on the type of system, and we discuss the possible implication of IGR J19294+1816 being an Supergiant Fast X-ray Transient (SFXT).

  20. THE Be/X-RAY BINARY SWIFT J1626.6-5156 AS A VARIABLE CYCLOTRON LINE SOURCE

    DeCesar, Megan E.; Miller, M. Coleman [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Boyd, Patricia T. [NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States); Pottschmidt, Katja [Center for Research and Exploration in Space Science and Technology, NASA-GSFC, Greenbelt, MD 20771 (United States); Wilms, Joern [Dr. Karl Remeis-Sternwarte and ECAP, University of Erlangen-Nuremberg, Sternwartstr. 7, 96049 Bamberg (Germany); Suchy, Slawomir, E-mail: decesar@astro.umd.edu [Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424 (United States)

    2013-01-01

    Swift J1626.6-5156 is a Be/X-ray binary that was in outburst from 2005 December until 2008 November. We have examined Rossi X-ray Timing Explorer/Proportional Counter Array (PCA) and High Energy X-ray Timing Explorer spectra of three long observations of this source taken early in its outburst, when the PCA 2-20 keV count rate was >70 counts s{sup -1} PCU{sup -1}, as well as several combined observations from different stages of the outburst. The spectra are best fit with an absorbed cutoff power law with a {approx}6.4 keV iron emission line and a Gaussian optical depth absorption line at {approx}10 keV. We present strong evidence that this absorption-like feature is a cyclotron resonance scattering feature, making Swift J1626.6-5156 a new candidate cyclotron line source. The redshifted energy of {approx}10 keV implies a magnetic field strength of {approx}8.6(1 + z) Multiplication-Sign 10{sup 11} G in the region of the accretion column close to the magnetic poles where the cyclotron line is produced. Analysis of phase-averaged spectra spanning the duration of the outburst suggests a possible positive correlation between the fundamental cyclotron energy and source luminosity. Phase-resolved spectroscopy from a long observation reveals a variable cyclotron line energy, with phase dependence similar to a variety of other pulsars, as well as the first harmonic of the fundamental cyclotron line.

  1. A new look at spherical accretion in High Mass X-ray Binaries

    Ikhsanov, N R; Beskrovnaya, N G; 10.1063/1.3701365

    2012-01-01

    Currently used model of spherical accretion onto a magnetized rotating neutron star encounters major difficulties in explaining the entry rate of accreting material into the stellar field and spin evolution of long-period X-ray pulsars. These difficulties can be, however, avoided if the magnetic field of the material captured by the neutron star is incorporated into the model. The magnetic field of the flow itself under certain conditions controls the accretion process and significantly affects the parameters of the accreting material. The mode by which the accretion flow enters the stellar magnetosphere in that case can be associated with Bohm (or turbulent) diffusion and the torque applied to the neutron star appears to be substantially higher than that evaluated in the non-magnetized accretion scenario.

  2. Spin-up/spin-down of neutron star in Be-X-ray binary system GX 304-1

    Postnov, K A; Lutovinov, A A; Shakura, N I; Kochetkova, A Yu; Tsygankov, S S

    2014-01-01

    We analyze spin-up/spin-down of the neutron star in Be X-ray binary system GX\\,304-1 observed by \\textit{Swift}/XRT and \\textit{Fermi}/GBM instruments in the period of the source activity from April 2010 to January 2013 and discuss possible mechanisms of angular momentum transfer to/from the neutron star. We argue that the neutron star spin-down at quiescent states of the source with an X-ray luminosity of $L_x\\sim 10^{34}$~erg s$^{-1}$ between a series of Type I outbursts and spin-up during the outbursts can be explained by quasi-spherical settling accretion onto the neutron star. The outbursts occur near the neutron star periastron passages where the density is enhanced due to the presence of an equatorial Be-disc tilted to the orbital plane. We also propose an explanation to the counterintuitive smaller spin-up rate observed at higher luminosity in a double-peak Type I outburst due to lower value of the specific angular momentum of matter captured from the quasi-spherical wind from the Be-star by the neutr...

  3. Photometric observations of three high mass X-ray binaries and a search for variations induced by orbital motion

    We searched for long period variation in V-band, IC-band and RXTE X-ray light curves of the High Mass X-ray Binaries (HMXBs) LS 1698 / RX J1037.5-5647, HD 110432 / 1H 1249-637 and HD 161103 / RX J1744.7-2713 in an attempt to discover orbitally induced variation. Data were obtained primarily from the ASAS database and were supplemented by shorter term observations made with the 24- and 40-inch ANU telescopes and one of the robotic PROMPT telescopes. Fourier peri-odograms suggested the existence of long period variation in the V-band light curves of all three HMXBs, however folding the data at those periods did not reveal convincing periodic variation. At this point we cannot rule out the existence of long term V-band variation for these three sources and hints of longer term variation may be seen in the higher precision PROMPT data. Long term V-band observations, on the order of several years, taken at a frequency of at least once per week and with a precision of 0.01 mag, therefore still have a chance of revealing long term variation in these three HMXBs.

  4. Investigation of iron emission lines in the eclipsing high mass X-ray binary pulsar OAO 1657-415

    Jaisawal, Gaurava K

    2016-01-01

    We present the results obtained from timing and spectral studies of high mass X-ray binary pulsar OAO 1657-415 using a Suzaku observations in 2011 September. X-ray pulsations were detected in the light curves up to $\\sim$70 keV. The continuum spectra during the high- and low-flux regions in light curves were well described by high energy cutoff power-law model along with a blackbody component and iron fluorescent lines at 6.4 keV and 7.06 keV. Time resolved spectroscopy was carried out by dividing the entire observations into 18 narrow segments. Presence of additional dense matter at various orbital phases was confirmed as the cause of low-flux regions in the observations. Presence of additional matter at several orbital phases of the pulsar was interpreted as due to the inhomogeneously distributed clumps of matter around the neutron star. Using clumpy wind hypothesis, the physical parameters of the clumps causing the high- and low-flux episodes in the pulsar light curve were estimated. The equivalent width o...

  5. Superorbital Periodic Modulation in Wind-Accretion High-Mass X-ray Binaries from Swift BAT Observations

    Corbet, Robin H D

    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 (SFXTs) 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, RXTE PCA, and INTEGRAL light curves. 1E 1145.1-6141 may also be worthy of further attention due to the amount of low-frequency mo...

  6. Variability of the X-ray Broad Iron Spectral Features in Active Galactic Nuclei and Black-hole Binaries

    Mizumoto, Misaki; Tsujimoto, Masahiro; Inoue, Hajime

    2015-01-01

    The "broad iron spectral features" are often seen in X-ray spectra of Active Galactic Nuclei (AGN) and black-hole binaries (BHB). These features may be explained either by the "relativistic disc reflection" scenario or the "partial covering" scenario: It is hardly possible to determine which model is valid from time-averaged spectral analysis. Thus, X-ray spectral variability has been investigated to constrain spectral models. To that end, it is crucial to study iron structure of BHBs in detail at short time-scales, which is, for the first time, made possible with the Parallel-sum clocking (P-sum) mode of XIS detectors on board Suzaku. This observational mode has a time-resolution of 7.8~ms as well as a CCD energy-resolution. We have carried out systematic calibration of the P-sum mode, and investigated spectral variability of the BHB GRS 1915+105. Consequently, we found that the spectral variability of GRS 1915+105 does not show iron features at sub-seconds. This is totally different from variability of AGN ...

  7. Following the Colour of the Low Mass X-ray Binary 4U 1820-30 with INTEGRAL

    Tarana, A; Ubertini, P; Zdziarski, A A; Federici, M; Tarana, Antonella; Bazzano, Angela; Ubertini, Pietro

    2006-01-01

    The 4-200 keV spectral and temporal behaviour of the low mass X-ray binary 4U 1820-30 has been studied with INTEGRAL during 2003-2005. This source as been observed in both the soft (banana) and hard (island) spectral states. A high energy tail above 50 keV in the hard state has been revealed for the first time. This places the source in the category of X-ray bursters showing high-energy emission. The tail can be modeled as a soft power law component, with the photon index of ~ 2.4, on top of thermal Comptonization emission from a plasma with the electron temperature of kT_e ~ 6 keV and optical depth of $\\tau ~ 4. Alternatively, but at a lower goodness of the fit, the hard-state broad band spectrum can be accounted for by emission from a hybrid, thermal-nonthermal, plasma. During the observations, the source spent most of the time in the soft state, as previously reported and the $\\ge$4 keV spectra can be represented by thermal Comptonization with kT_e ~ 3 keV and $\\tau ~ 6-7.

  8. Hysteresis in the spectral states of the neutron star low-mass X-ray binary EXO 1745-248

    Mukherjee, Arunava

    2011-01-01

    We study the low-frequency timing properties and the spectral state evolution of the transient neutron star low-mass X-ray binary EXO 1745-248 using the entire Rossi X-ray Timing Explorer Proportional Counter Array data. We tentatively conclude that EXO 1745-248 is an atoll source, and report the discovery of a ~ 0.45 Hz low-frequency quasi-periodic oscillation and ~ 10 Hz peaked noises. If it is an atoll, this source is unusual because (1) instead of a `C'-like curve, it traced a clear overall clockwise hysteresis curve in each of the colour-colour diagram and the hardness-intensity diagram; and (2) the source took at least 2.5 months to trace the softer banana state, as opposed to a few hours to a day, which is typical for an atoll source. The shape of the hysteresis track was intermediate between the characteristic `q'-like curves of several black hole systems and `C'-like curves of atolls, implying that EXO 1745-248 is an important source for the unification of the black hole and neutron star accretion pr...

  9. RXTE observations of the dipping low-mass X-ray binary 4U 1624-49

    Lommen, D; Van der Klis, M; Anthonisse, B; Lommen, Dave; Straaten, Steve van; Klis, Michiel van der; Anthonisse, Brechtje

    2005-01-01

    We analyse ~ 360 ks of archival data from the Rossi X-Ray Timing Explorer (RXTE) of the 21 hr orbital period dipping low-mass X-ray binary 4U 1624-49. We find that outside the dips the tracks in the colour-colour and hardness-intensity diagrams (CDs and HIDs) are reminiscent of those of atoll sources in the middle and upper parts of the banana branch. The tracks show secular shifts up to ~ 10%. We study the power spectrum of 4U 1624-49 as a function of the position in the CD. This is the first time power spectra of this source are presented. No quasi-periodic oscillations (QPOs) are found. The power spectra are dominated by very low frequency noise (VLFN), characteristic for atoll sources in the banana state, and band limited noise (BLN) which is not reliably detected but may, uncharacteristically, strengthen and increase in frequency with spectral hardness. The VLFN fits to a power law, which becomes steeper when the source moves to the harder part of the CD. We conclude that 4U 1624-49 is an atoll source wh...

  10. Shock breakout driven by the remnant of a neutron star binary merger: An X-ray precursor of mergernova emission

    Li, Shao-Ze

    2015-01-01

    A supra-massive neutron star (NS) spinning extremely rapidly could survive from a merger of NS-NS binary. The spin-down of this remnant NS that is highly magnetized would power the isotropic merger ejecta to produce a bright mergernova emission in ultraviolet/optical bands. Before the mergernova, the early interaction between the NS wind and the ejecta can drive a forward shock to propagate outwards into the ejecta. As a result, a remarkable amount of heat can be accumulated to be deposited behind the shock front, the final escaping of which can produce a shock breakout emission. We describe the dynamics and thermal emission of this shock with a semi-analytical model. It is found that a sharp and luminous breakout emission, which is mainly in soft X-rays with a luminosity of $\\sim10^{45}~\\rm erg~s^{-1}$, appears at a few hours after the merger, by leading the mergernova emission as a precursor. Therefore, detections of such X-ray precursors would provide a smoking-gun evidence for identifying NS-powered merge...

  11. THE 5 hr PULSE PERIOD AND BROADBAND SPECTRUM OF THE SYMBIOTIC X-RAY BINARY 3A 1954+319

    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 (SyXBs), i.e., systems composed of a neutron star accreting from the inhomogeneous medium around an M-giant star. The extremely long pulse period of ∼5.3 hr is directly visible in the 2008 INTEGRAL-ISGRI outburst light curve. The pulse profile is double peaked and generally not significantly energy dependent although there is an indication of possible softening during the main pulse. During the outburst a strong spin-up of –1.8 × 10–4 hr hr–1 occurred. Between 2005 and 2008 a long-term spin-down trend of 2.1 × 10–5 hr hr–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 SyXBs.

  12. Suzaku Monitoring of Hard X-ray Emission from Eta Carinae over a Single Binary Orbital Cycle

    Hamaguchi, Kenji; Takahashi, Hiromitsu; Yuasa, Takayuki; Ishida, Manabu; Gull, Theodore R; Pittard, Julian M; Russell, Christopher M P; Madura, Thomas I

    2014-01-01

    The Suzaku X-ray observatory monitored the supermassive binary system Eta Carinae 10 times during the whole 5.5 year orbital cycle between 2005-2011. This series of observations presents the first long-term monitoring of this enigmatic system in the extremely hard X-ray band between 15-40 keV. During most of the orbit, the 15-25 keV emission varied similarly to the 2-10 keV emission, indicating an origin in the hard energy tail of the kT ~4 keV wind-wind collision (WWC) plasma. However, the 15-25 keV emission declined only by a factor of 3 around periastron when the 2-10 keV emission dropped by two orders of magnitude due probably to an eclipse of the WWC plasma. The observed minimum in the 15-25 keV emission occurred after the 2-10 keV flux had already recovered by a factor of ~3. This may mean that the WWC activity was strong, but hidden behind the thick primary stellar wind during the eclipse. The 25-40 keV flux was rather constant through the orbital cycle, at the level measured with INTEGRAL in 2004. Thi...

  13. Dust Scattering Halo from an Eclipsing X-ray Binary at 1.5 arcmin from Sgr A*

    Jin, Chichuan; Haberl, Frank; Ponti, Gabriele

    2016-07-01

    AX J1745.6-2901 is an eclipsing neutron star low mass X-ray binary. This source is bright in X-rays and it has a high column density of absorbing gas along the line of sight, showcasing a strong dust scattering halo. Moreover, the dust scattering halo shows time evolution during the eclipsing phase. The combination of these phenomena can provide important information about the location of the neutron star and the dust properties along the line of sight. In this talk, I will show that based on a large set of XMM-Newton and Chandra data, we can conduct, for the first time, a powerful combined analysis of the radial profile of the dust scattering halo and the time evolution of the halo during the eclipsing phase. Our study can put constraints on the location of the source, the distribution and composition of the dust, and the metal abundance towards the source. Due to the proximity of the source to Sgr A* (only 1.5 arcmin), these properties are highly relevant to the dust in the Galactic centre, and are likely to be similar as the dust properties on the line of sight towards Sgr A*.

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

    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.

  15. Multiwavelength study of the fast rotating supergiant high-mass X-ray binary IGR J16465-4507

    Chaty, Sylvain; Negueruela, Ignacio; Coleiro, Alexis; Castro, Norberto; Simon-Diaz, Sergio; Heras, Juan Antonio Zurita; Goldoni, Paolo; Goldwurm, Andrea

    2016-01-01

    Since its launch, the X-ray and gamma-ray observatory INTEGRAL satellite has revealed a new class of high-mass X-ray binaries (HMXB) displaying fast flares and hosting supergiant companion stars. Optical and infrared (OIR) observations in a multi-wavelength context are essential to understand the nature and evolution of these newly discovered celestial objects. The goal of this multiwavelength study (from ultraviolet to infrared) is to characterise the properties of IGR J16465-4507, to confirm its HMXB nature and that it hosts a supergiant star. We analysed all OIR, photometric and spectroscopic observations taken on this source, carried out at ESO facilities. Using spectroscopic data, we constrained the spectral type of the companion star between B0.5 and B1 Ib, settling the debate on the true nature of this source. We measured a high rotation velocity of v = 320 +/- 8 km/s from fitting absorption and emission lines in a stellar spectral model. We then built a spectral energy distribution from photometric ob...

  16. Inverse Compton Scattering Model for X-ray Emission of the Gamma-ray Binary LS 5039

    Yamaguchi, Masaki S

    2012-01-01

    We propose a model for the gamma-ray binary LS 5039 in which the X-ray emission is due to the inverse Compton (IC) process instead of the synchrotron radiation. Although the synchrotron model has been discussed in previous studies, it requires a strong magnetic field which leads to a severe suppression of the TeV gamma-ray flux in conflict with H.E.S.S. observations. In this paper, we calculate the IC emission by low energy electrons (\\gamma_e \\lesssim 10^3) in the Thomson regime. We find that IC emission of the low energy electrons can explain the X-ray flux and spectrum observed with Suzaku if the minimum Lorentz factor of injected electrons \\gamma_min is around 10^3. In addition, we show that the Suzaku light curve is well reproduced if \\gamma_min varies in proportion to the Fermi flux when the distribution function of injected electrons at higher energies is fixed. We conclude that the emission from LS 5039 is well explained by the model with the IC emission from electrons whose injection properties are d...

  17. Unraveling the Formation History of the Black Hole X-ray Binary LMC X-3 from ZAMS to Present

    Sørensen, Mads; Steiner, James F; Antoniou, Vallia; Meynet, Georges; Dosopoulou, Fani

    2016-01-01

    We have endeavoured to understand the formation and evolution of the black hole (BH) X-ray binary LMC X-3. We estimate the properties of the system at 4 evolutionary stages: 1) at the Zero Age Main Sequence (ZAMS), 2) just prior to the supernova (SN) explosion of the primary, 3) just after the SN, and 4) at the moment of RLO onset.} {We use a hybrid approach, combining detailed stellar structure and binary evolution calculations with approximate population synthesis models. This allows us to estimate potential natal kicks and the evolution of the BH spin. In the whole analysis we incorporate as model constraints the most up-to-date observational information, encompassing the binary's orbital properties, the companion star mass, effective temperature, surface gravity and radius, as well as the black hole's mass and spin.} {We find that LMC X-3 began as a ZAMS system with the mass of the primary star in the range $M_{\\rm{1,ZAMS}}$ = 22-31 $\\rm{M_{\\odot}}$ and a secondary star of $M_{\\rm{2,ZAMS}} = 5.0-8.3M_{\\od...

  18. Probing the neutron star spin evolution in the young Small Magellanic Cloud Be/X-ray binary SXP 1062

    Popov, S. B.; Turolla, R.

    2012-03-01

    The newly discovered Be/X-ray binary in the Small Magellanic Cloud, SXP 1062, provides the first example of a robust association with a supernova remnant (SNR). The short age estimated for the SNR qualifies SXP 1062 as the youngest known source in its class, ?. As such, it allows us to test current models of magnetorotational evolution of neutron stars in a still unexplored regime. Here we discuss possible evolutionary scenarios for SXP 1062 in an attempt to reconcile its long spin period, ?, and short age. Although several options can be considered, like an anomalously long initial period or the presence of a fossil disc, our results indicate that SXP 1062 may host a neutron star born with a large initial magnetic field, typically in excess of ˜ 1014 G, which then decayed to ˜ 1013 G.

  19. Evidence for Variable, Correlated X-ray and Optical/IR Extinction toward the Nearby, Pre-main Sequence Binary TWA 30

    Principe, David A; Kastner, Joel H; Stelzer, Beate; Alcala, Juan

    2016-01-01

    We present contemporaneous XMM-Newton X-ray and ground-based optical/near-IR spectroscopic observations of the nearby ($D \\approx 42$ pc), low-mass (mid-M) binary system TWA 30A and 30B. The components of this wide (separation $\\sim$3400 AU) binary are notable for their nearly edge-on disk viewing geometries, high levels of variability, and evidence for collimated stellar outflows. We obtained XMM-Newton X-ray observations of TWA 30A and 30B in 2011 June and July, accompanied (respectively) by IRTF SpeX (near-IR) and VLT XSHOOTER (visible/near-IR) spectroscopy obtained within $\\sim$20 hours of the X-ray observations. TWA 30A was detected in both XMM-Newton observations at relatively faint intrinsic X-ray luminosities ($L_{X}$$\\sim$$8\\times10^{27}$ $erg$ $s^{-1}$) compared to stars of similar mass and age . The intrinsic (0.15-2.0 keV) X-ray luminosities measured in 2011 had decreased by a factor 20-100 relative to a 1990 (ROSAT) X-ray detection. TWA 30B was not detected, and we infer an upper limit of ($L_{X}...

  20. Very-high-energy observations of the binaries V 404 Cyg and 4U 0115+634 during giant X-ray outbursts

    Archer, A; Bird, R; Bourbeau, E; Buchovecky, M; Buckley, J H; Bugaev, V; Byrum, K; Cerruti, M; Connolly, M P; Cui, W; Errando, M; Falcone, A; Feng, Q; Fernandez-Alonso, M; Finley, J P; Fleischhack, H; Flinders, A; Fortson, L; Furniss, A; Griffin, S; Grube, J; Hütten, M; Hanna, D; Hervet, O; Holder, J; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kelley-Hoskins, N; Kertzman, M; Kieda, D; Krause, M; Kumar, S; Lang, M J; Lin, T T Y; Maier, G; Moriarty, P; Mukherjee, R; Nieto, D; O'Brien, S; Ong, R A; Park, N; Pohl, M; Popkow, A; Pueschel, E; Quinn, J; Ragan, K; Reynolds, P T; Richards, G T; Roache, E; Rousselle, J; Rovero, A C; Sadeh, I; Schlenstedt, S; Sembroski, G H; Shahinyan, K; Staszak, D; Telezhinsky, I; Tyler, J; Wakely, S P; Wilcox, P; Wilhelm, A; Williams, D A

    2016-01-01

    Transient X-ray binaries produce major outbursts in which the X-ray flux can increase over the quiescent level by factors as large as $10^7$. The low-mass X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such major outbursts in June and October 2015, respectively. We present here observations at energies above hundreds of GeV with the VERITAS observatory taken during some of the brightest X-ray activity ever observed from these systems. No gamma-ray emission has been detected by VERITAS in 2.5 hours of observations of the microquasar V 404 Cyg from 2015, June 20-21. The upper flux limits derived from these observations on the gamma-ray flux above 200 GeV of F $< 4.4\\times 10^{-12}$ cm$^{-2}$ s$^{-1}$ correspond to a tiny fraction (about $10^{-6}$) of the Eddington luminosity of the system, in stark contrast to that seen in the X-ray band. No gamma rays have been detected during observations of 4U 0115+634 in the period of major X-ray activity in October 2015. The flux upper limit deriv...

  1. Study of luminosity and spin-up relation in X-ray binary pulsars with long-term monitoring by MAXI/GSC and Fermi/GBM

    Sugizaki, Mutsumi; Nakajima, Motoki; Yamaoka, Kazutaka

    2015-01-01

    We study the relation between luminosity and spin-period change in X-ray binary pulsars using long-term light curve obtained by the MAXI/GSC all-sky survey and pulse period data from the Fermi/GBM pulsar project. X-ray binaries, consisting of a highly magnetized neutron star and a stellar companion, originate X-ray emission according to the energy of the accretion matter onto the neutron star. The accretion matter also transfers the angular momentum at the Alfven radius, and then spin up the neutron star. Therefore, the X-ray luminosity and the spin-up rate are supposed to be well correlated. We analyzed the luminosity and period-change relation using the data taken by continuous monitoring of MAXI/GSC and Fermi/GBM for Be/X-ray binaries, GX 304$-$1, A 0535$+$26, GRO J1008$-$57, KS 1947$+$300, and 2S 1417$-$624, which occurred large outbursts in the last four years. We discuss the results comparing the obtained observed relation with that of the theoretical model by Ghosh \\& Lamb (1979).

  2. High mass X-ray binary SXP18.3 undergoes the longest Type II outburst ever seen in the Small Magellanic Cloud

    Schurch, M P E; Galache, J L; Corbet, R H D; McGowan, K E; McBride, V A; Townsend, L J; Udalski, A; Haberl, F

    2008-01-01

    On 30th August 2006 SXP18.3 a high mass X-ray binary (HMXB) in the Small Magellanic Cloud (SMC) with an 18.3s pulse period was observed by Rossi X-ray Timing Explorer (RXTE). The source was seen continuously for the following 36 weeks. This is the longest Type II outburst ever seen from a HMXB in the SMC. During the outburst SXP18.3 was located from serendipitous XMM-Newton observations. The identification of the optical counterpart has allowed SXP18.3 to be classified as a Be/X-ray binary. This paper will report on the analysis of the optical and weekly RXTE X-ray data that span the last 10 years. The extreme length of this outburst has for the first time enabled us to perform an extensive study of the pulse timing of an SMC Be/X-ray binary. We present a possible full orbital solution from the pulse timing data. An orbital period of 17.79d is proposed from the analysis of the OGLE III light curve placing SXP18.3 on the boundary of known sources in the Corbet diagram.

  3. Signs of Magnetic Accretion in the X-ray Pulsar Binary GX 301-2

    Ikhsanov, N R

    2012-01-01

    Observations of the cyclotron resonance scattering feature in the X-ray spectrum of GX 301-2 suggest that the surface field of the neutron star is B_CRSF ~ 4 x 10^{12}G. The same value has been derived in modelling the rapid spin-up episodes in terms of the Keplerian disk accretion scenario. However, the spin-down rate observed during the spin-down trends significantly exceeds the value expected in currently used spin-evolution scenarios. This indicates that either the surface field of the star exceeds 50 x B_CRSF, or a currently used accretion scenario is incomplete. We show that the above discrepancy can be avoided if the accreting material is magnetized. The magnetic pressure in the accretion flow increases more rapidly than its ram pressure and, under certain conditions, significantly affects the accretion picture. The spin-down torque applied to the neutron star in this case is larger than that evaluated within a non-magnetized accretion scenario. We find that the observed spin evolution of the pulsar ca...

  4. Broad-band spectroscopy of the transient X-ray binary pulsar KS 1947+300 during 2013 giant outburst: Detection of pulsating soft X-ray excess component

    Epili, Prahlad; Jaisawal, Gaurava K

    2016-01-01

    We present the results obtained from detailed timing and spectral studies of the Be/X-ray binary pulsar KS 1947+300 during its 2013 giant outburst. We used data from Suzaku observations of the pulsar at two epochs i.e. on 2013 October 22 (close to the peak of the outburst) and 2013 November 22. X-ray pulsations at $\\sim$18.81 s were clearly detected in the light curves obtained from both observations. Pulse periods estimated during the outburst showed that the pulsar was spinning up. The pulse profile was found to be single-peaked up to $\\sim$10 keV beyond which a sharp peak followed by a dip-like feature appeared at hard X-rays. The dip-like feature has been observed up to $\\sim$70 keV. The 1-110 keV broad-band spectroscopy of both observations revealed that the best-fit model comprised of a partially absorbed Negative and Positive power law with EXponential cutoff (NPEX) continuum model along with a blackbody component for the soft X-ray excess and two Gaussian functions at 6.4 and 6.7 keV for emission line...

  5. Broad-band monitoring tracing the evolution of the jet and disc in the black hole candidate X-ray binary MAXI J1659-152

    van der Horst, A. J.; Curran, P. A.; Miller-Jones, J. C. A.; Linford, J. D.; Gorosabel, J.; Russell, D. M.; de Ugarte Postigo, A.; Lundgren, A. A.; Taylor, G. B.; Maitra, D.; Guziy, S.; Belloni, T. M.; Kouveliotou, C.; Jonker, P. G.; Kamble, A.; Paragi, Z.; Homan, J.; Kuulkers, E.; Granot, J.; Altamirano, D.; Buxton, M. M.; Castro-Tirado, A.; Fender, R. P.; Garrett, M. A.; Gehrels, N.; Hartmann, D. H.; Kennea, J. A.; Krimm, H. A.; Mangano, V.; Ramirez-Ruiz, E.; Romano, P.; Wijers, R. A. M. J.; Wijnands, R.; Yang, Y. J.

    2013-12-01

    MAXI J1659-152 was discovered on 2010 September 25 as a new X-ray transient, initially identified as a gamma-ray burst, but was later shown to be a new X-ray binary with a black hole as the most likely compact object. Dips in the X-ray light curves have revealed that MAXI J1659-152 is the shortest period black hole candidate identified to date. Here we present the results of a large observing campaign at radio, submillimetre, near-infrared (nIR), optical and ultraviolet (UV) wavelengths. We have combined this very rich data set with the available X-ray observations to compile a broad-band picture of the evolution of this outburst. We have performed broad-band spectral modelling, demonstrating the presence of a spectral break at radio frequencies and a relationship between the radio spectrum and X-ray states. Also, we have determined physical parameters of the accretion disc and put them into context with respect to the other parameters of the binary system. Finally, we have investigated the radio-X-ray and nIR/optical/UV-X-ray correlations up to ˜3 yr after the outburst onset to examine the link between the jet and the accretion disc, and found that there is no significant jet contribution to the nIR emission when the source is in the soft or intermediate X-ray spectral state, consistent with our detection of the jet break at radio frequencies during these states.

  6. Binary Codes for Tagging X-Ray Images via Deep De-Noising Autoencoders

    Sze-To, Antonio; Tizhoosh, Hamid R; Wong, Andrew K. C.

    2016-01-01

    A Content-Based Image Retrieval (CBIR) system which identifies similar medical images based on a query image can assist clinicians for more accurate diagnosis. The recent CBIR research trend favors the construction and use of binary codes to represent images. Deep architectures could learn the non-linear relationship among image pixels adaptively, allowing the automatic learning of high-level features from raw pixels. However, most of them require class labels, which are expensive to obtain, ...

  7. Broad-band spectroscopy of the transient X-ray binary pulsar KS 1947+300 during 2013 giant outburst: Detection of pulsating soft X-ray excess component

    Epili, Prahlad; Naik, Sachindra; Jaisawal, Gaurava K.

    2016-05-01

    We present the results obtained from detailed timing and spectral studies of the Be/X-ray binary pulsar KS 1947+300 during its 2013 giant outburst. We used data from Suzaku observations of the pulsar at two epochs, i.e. on 2013 October 22 (close to the peak of the outburst) and 2013 November 22. X-ray pulsations at ∼18.81 s were clearly detected in the light curves obtained from both observations. Pulse periods estimated during the outburst showed that the pulsar was spinning up. The pulse profile was found to be single-peaked up to ∼10 keV beyond which a sharp peak followed by a dip-like feature appeared at hard X-rays. The dip-like feature has been observed up to ∼70 keV. The 1–110 keV broad-band spectroscopy of both observations revealed that the best-fit model was comprised of a partially absorbed Negative and Positive power law with EXponential cutoff (NPEX) continuum model along with a blackbody component for the soft X-ray excess and two Gaussian functions at 6.4 and 6.7 keV for emission lines. Both the lines were identified as emission from neutral and He-like iron atoms. To fit the spectra, we included the previously reported cyclotron absorption line at 12.2 keV. From the spin-up rate, the magnetic field of the pulsar was estimated to be ∼1.2×1012 G and found to be comparable to that obtained from the detection of the cyclotron absorption feature. Pulse-phase resolved spectroscopy revealed the pulsating nature of the soft X-ray excess component in phase with the continuum flux. This confirms that the accretion column and/or accretion stream are the most probable regions of the soft X-ray excess emission in KS1947+300. The presence of the pulsating soft X-ray excess in phase with continuum emission may be the possible reason for not observing the dip at soft X-rays.

  8. Superorbital variability of the X-ray flux in the Be-donor binaries SXP 138, GX-304, and γ Cas

    Chashkina, A. A.; Abolmasov, P. K.; Biryukov, A. V.; Shakura, N. I.

    2015-06-01

    RXTE observations of the X-ray binary systems SXP 138, GX-304, and γ Cas in 1997-2011 have shown for the first time that these objects (X-ray binaries with Be donors) display X-ray flux variations on timescales of ˜1000 days. This timescale is about 10 times longer than their orbital periods, and is comparable to the total time of the observations. The observed variations are apparently not strictly periodic and represent stochastic variability, as is characteristic of such systems in the optical. γ Cas is considered as an example. The series of optical observations of this system available in the AAVSO database covers 78 years, and is much longer than the timescale of the variability studied. Our analysis of this series has shown that γ Cas variability on a timescale of tens of years is predominantly stochastic with a power-law spectrum.

  9. The Global-Normal Disk Oscillations and the Persistent Low Frequency QPO in X-ray Binaries

    Titarchuk, L G; Titarchuk, Lev; Osherovich, Vladimir

    2000-01-01

    We suggest that persistent low-frequency quasi-periodic oscillations (QPOs) detected in X-ray, ultraviolet, optical energy ranges the black hole (BH) sources XTE J1118+480, GRO J1655-40 LMC X-1 at ~ 0.1 Hz, and QPOs in HZ Her/Her X-1 at ~ 0.05 Hz and in Neutron Star (NS) binaries 4U 1323-62, 4U 1746-31 and EXO 0748-76 at ~ 1 Hz are caused by the global disk oscillations in the direction normal to the disk (normal mode). We argue that these disk oscillations are a result of the gravitational interaction between the central compact object and the disk. A small displacement of the disk from the equatorial plane results in a linear gravitational restoring force opposite to this displacement. Our analysis shows that the frequency of this mode is a function of the mass of the central object and it also depends on the inner and outer radii of the disk which in turn are related to the rotation period of the binary system. We derive an analytical formula for the frequency of the normal disk mode and show that these fr...

  10. The chemical composition of donors in AM CVn stars and ultra-compact X-ray binaries: observational tests of their formation

    Nelemans, G.A.; Yungelson, L. R.; Van Der Sluys, M. V.; Tout, C. A.

    2009-01-01

    We study the formation of ultra-compact binaries (AM CVn stars and ultra-compact X-ray binaries) with emphasis on the surface chemical abundances of the donors in these systems. Hydrogen is not convincingly detected in the spectra of these systems. Three different proposed formation scenarios involve different donor stars, white dwarfs, helium stars or evolved main-sequence stars. Using detailed evolutionary calculations we show that the abundances of helium WD donors and evolved main-sequenc...

  11. XMM-Newton observations of the Small Magellanic Cloud: Be/X-ray binary pulsars active between October 2006 and June 2007

    Haberl, F.; Eger, P.; Pietsch, W.

    2008-10-01

    Aims: We analysed eight XMM-Newton observations toward the Small Magellanic Cloud (SMC), performed between October 2006 and June 2007, to investigate high mass X-ray binary systems. Methods: We produced images from the European Photon Imaging Cameras (EPIC) and extracted X-ray spectra and light curves in different energy bands from sources that yielded a sufficiently high number of counts for a detailed temporal and spectral analysis. To search for periodicity we applied Fourier transformations and folding techniques and determined pulse periods using a Bayesian approach. To identify optical counterparts we produced X-ray source lists for each observation using maximum likelihood source detection techniques and correlated them with optical catalogues. The correlations were also used for astrometric boresight corrections of the X-ray source positions. Results: We found new X-ray binary pulsars with periods of 202 s (XMMU J005929.0-723703), 342 s (XMMU J005403.8-722632), 645 s (XMMU J005535.2-722906) and 325 s (XMMU J005252.1-721715), in the latter case confirming the independent discovery in Chandra data. In addition we detected sixteen known Be/X-ray binary pulsars and six ROSAT-classified candidate high mass X-ray binaries. From one of the candidates, RX J0058.2-7231, we discovered X-ray pulsations with a period of 291 s which makes it the likely counterpart of XTE J0051-727. From the known pulsars, we revise the pulse period of CXOU J010206.6-714115 to 967 s, and we detected the 18.37 s pulsar XTE J0055-727 (=XMM J004911.4-724939) in outburst, which allowed us to localise the source. The pulse profiles of the X-ray pulsars show a wide variety of shapes from smooth to highly structured patterns and differing energy dependence. For all the candidate high mass X-ray binaries, optical counterparts can be identified with magnitudes and colours consistent with Be stars. Twenty of the Be/X-ray binaries were detected with X-ray luminosities in the range 1.5 × 1035-5.5

  12. New massive X-ray binary candidates from the ROSAT Galactic Plane Survey I - Results from a cross-correlation with OB star catalogues

    Motch, C.; Haberl, F.; Dennerl, K.; Pakull, M.; Janot-Pacheco, E.

    1996-01-01

    We report the discovery of several new OB/X-ray accreting binary candidates. These massive systems were found by cross-correlating in position SIMBAD OB star catalogues with the part of the ROSAT all-sky survey located at low galactic latitudes (|b| 10^31 erg/s. Fol...

  13. Optical spectra of the carbon-oxygen accretion discs in the ultra-compact X-ray binaries 4U 0614+09, 4U 1543-624 and 2S 0918-549

    Nelemans, G.; Jonker, P. G.; Marsh, T. R.; Klis, van der, M.

    2004-01-01

    We present optical spectra in the range 4600 -- 8600 A for three low-mass X-ray binaries which have been suggested to belong to the class of ultra-compact X-ray binaries based on their X-ray spectra. Our spectra show no evidence for hydrogen or helium emission lines, as are seen in classical X-ray binaries. The spectrum of 4U~0614+09 does show emission lines which we identify with carbon and oxygen lines of CII, CIII, OII and OIII. While the spectra of 4U 1543-624 and 2S 0918-549 have a lower...

  14. Puzzling thermonuclear burst behaviour from the transient low-mass X-ray binary IGR J17473-2721

    Chenevez, Jérôme; Altamirano, Diego; Galloway, Duncan;

    2010-01-01

    We investigate the thermonuclear bursting behaviour of IGR J17473−2721, an X-ray transient that in 2008 underwent a 6-month long outburst, starting (unusually) with an X-ray burst. We detected a total of 57 thermonuclear bursts throughout the outburst with AGILE, Swift, Rossi X-ray Timing Explore...

  15. Young pre-Low-Mass X-ray Binaries in propeller phase : Nature of the 6.7-hour periodic X-ray source 1E 161348-5055 in RCW 103

    Bhadkamkar, Harshal

    2009-01-01

    Discovery of the 6.7-hour periodicity in the X-ray source 1E 161348-5055 in RCW 103 has led to investigations of the nature of this periodicity. We explore a model for 1E 161348-5055, wherein a fast-spinning neutron star with a magnetic field $\\sim 10^{12}$ G in a young pre-Low-Mass X-ray Binary (pre-LMXB) with an eccentric orbit of period 6.7 hr operates in the "propeller" phase. The 6.7-hr light curve of 1E 161348-5055 can be quantitatively accounted by a model of orbitally-modulated mass transfer through a viscous accretion disk and subsequent propeller emission (both Illarionov-Sunyaev type and Romanova-Lovelace et al type), and spectral and other properties are also in agreement. Formation and evolution of model systems are shown to be in accordance both with standard theories.

  16. Upper Bounds on r-Mode Amplitudes from Observations of Low-Mass X-Ray Binary Neutron Stars

    Mahmoodifar, Simin; Strohmayer, Tod

    2013-01-01

    We present upper limits on the amplitude of r-mode oscillations and gravitational-radiation-induced spin-down rates in low-mass X-ray binary neutron stars, under the assumption that the quiescent neutron star luminosity is powered by dissipation from a steady-state r-mode. For masses <2M solar mass we find dimensionless r-mode amplitudes in the range from about 1×10(exp-8) to 1.5×10(exp-6). For the accreting millisecond X-ray pulsar sources with known quiescent spin-down rates, these limits suggest that approx. less than 1% of the observed rate can be due to an unstable r-mode. Interestingly, the source with the highest amplitude limit, NGC 6440, could have an r-mode spin-down rate comparable to the observed, quiescent rate for SAX J1808-3658. Thus, quiescent spin-down measurements for this source would be particularly interesting. For all sources considered here, our amplitude limits suggest that gravitational wave signals are likely too weak for detection with Advanced LIGO. Our highest mass model (2.21M solar mass) can support enhanced, direct Urca neutrino emission in the core and thus can have higher r-mode amplitudes. Indeed, the inferred r-mode spin-down rates at these higher amplitudes are inconsistent with the observed spin-down rates for some of the sources, such as IGR J00291+5934 and XTE J1751-305. In the absence of other significant sources of internal heat, these results could be used to place an upper limit on the masses of these sources if they were made of hadronic matter, or alternatively it could be used to probe the existence of exotic matter in them if their masses were known.

  17. Suzaku monitoring of hard X-ray emission from η Carinae over a single binary orbital cycle

    Hamaguchi, Kenji; Corcoran, Michael F. [CRESST and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States); Takahashi, Hiromitsu [Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Yuasa, Takayuki [Nishina Center, RIKEN, 2-1, Hirosawa, Wako, Saitama 351-0198 (Japan); Ishida, Manabu [Institute of Space and Astronautical Science/JAXA, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Gull, Theodore R.; Madura, Thomas I. [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Pittard, Julian M. [School of Physics and Astronomy, The University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Russell, Christopher M. P. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

    2014-11-10

    The Suzaku X-ray observatory monitored the supermassive binary system η Carinae 10 times during the whole 5.5 yr orbital cycle between 2005 and 2011. This series of observations presents the first long-term monitoring of this enigmatic system in the extremely hard X-ray band between 15 and 40 keV. During most of the orbit, the 15-25 keV emission varied similarly to the 2-10 keV emission, indicating an origin in the hard energy tail of the kT ∼ 4 keV wind-wind collision (WWC) plasma. However, the 15-25 keV emission declined only by a factor of three around periastron when the 2-10 keV emission dropped by two orders of magnitude due probably to an eclipse of the WWC plasma. The observed minimum in the 15-25 keV emission occurred after the 2-10 keV flux had already recovered by a factor of ∼3. This may mean that the WWC activity was strong, but hidden behind the thick primary stellar wind during the eclipse. The 25-40 keV flux was rather constant through the orbital cycle, at the level measured with INTEGRAL in 2004. This result may suggest a connection of this flux component to the γ-ray source detected in this field. The helium-like Fe Kα line complex at ∼6.7 keV became strongly distorted toward periastron as seen in the previous cycle. The 5-9 keV spectra can be reproduced well with a two-component spectral model, which includes plasma in collision equilibrium and a plasma in non-equilibrium ionization (NEI) with τ ∼ 10{sup 11} cm{sup –3} s{sup –1}. The NEI plasma increases in importance toward periastron.

  18. The formation efficiency of high-mass X-ray binaries in our two nearest star-forming galaxies

    Antoniou, Vallia; Zezas, Andreas

    2016-04-01

    We present the results of our investigation of the link between high-mass X-ray binaries (HMXBs) and star formation in the Magellanic Clouds, our nearest star-forming galaxies. Using the most complete census of HMXBs in the Large Magellanic Cloud (LMC) and the published spatially resolved star-formation history map of this galaxy, we find that the HMXBs (and as expected the X-ray pulsars) are present in regions with star-formation bursts ˜6-25 Myr ago. In contrast, this population peaks at later ages (˜25-60 Myr ago) in the Small Magellanic Cloud (SMC). Thus, this study (in combination with previous works) reinforces the idea that the HMXBs are associated with young stellar populations of ages ˜10-40 Myr. In addition, we estimate an HMXB production rate of 1 system per ˜(23.0-4.1+4.4)×10-3 M⊙/yr or 1 system per ˜143M⊙ of stars formed during the associated star-formation episode. Therefore, the formation efficiency of HMXBs in the LMC is ˜17 times lower than that in the SMC. We attribute this difference primarily in the different ages and metallicity of the HMXB populations in the two galaxies. We also set limits on the kicks imparted on the neutron star during the supernova explosion. We find that the time elapsed since the supernova kick is ˜3 times shorter in the LMC than the SMC. This in combination with the average offsets of the HMXBs from their nearest star clusters results in ˜4 times faster transverse velocities for HMXBs in the LMC than in the SMC.

  19. UPPER BOUNDS ON r-MODE AMPLITUDES FROM OBSERVATIONS OF LOW-MASS X-RAY BINARY NEUTRON STARS

    Mahmoodifar, Simin [Department of Physics, University of Maryland College Park, MD 20742 (United States); Strohmayer, Tod [Astrophysics Science Division, NASA' s Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-08-20

    We present upper limits on the amplitude of r-mode oscillations and gravitational-radiation-induced spin-down rates in low-mass X-ray binary neutron stars, under the assumption that the quiescent neutron star luminosity is powered by dissipation from a steady-state r-mode. For masses <2 M{sub Sun} we find dimensionless r-mode amplitudes in the range from about 1 Multiplication-Sign 10{sup -8} to 1.5 Multiplication-Sign 10{sup -6}. For the accreting millisecond X-ray pulsar sources with known quiescent spin-down rates, these limits suggest that {approx}< 1% of the observed rate can be due to an unstable r-mode. Interestingly, the source with the highest amplitude limit, NGC 6440, could have an r-mode spin-down rate comparable to the observed, quiescent rate for SAX J1808-3658. Thus, quiescent spin-down measurements for this source would be particularly interesting. For all sources considered here, our amplitude limits suggest that gravitational wave signals are likely too weak for detection with Advanced LIGO. Our highest mass model (2.21 M{sub Sun }) can support enhanced, direct Urca neutrino emission in the core and thus can have higher r-mode amplitudes. Indeed, the inferred r-mode spin-down rates at these higher amplitudes are inconsistent with the observed spin-down rates for some of the sources, such as IGR J00291+5934 and XTE J1751-305. In the absence of other significant sources of internal heat, these results could be used to place an upper limit on the masses of these sources if they were made of hadronic matter, or alternatively it could be used to probe the existence of exotic matter in them if their masses were known.

  20. Soft X-Ray Properties of the Binary Millisecond Pulsar J0437-4715

    Halpern, Jules P.; Martin, Christopher; Marshall, Herman, L.; Oliversen, Ronald (Technical Monitor)

    2001-01-01

    We obtained a light curve for the 5.75 ms pulsar J0437-4715 in the 65-120 A range with 0.5 ms time resolution using the Deep Survey instrument on the EUVE satellite. The single-peaked profile has a pulsed fraction of 0.27 +/- 0.05, similar to the ROSAT data in the overlapping energy band. A combined analysis of the EUVE and ROSAT data is consistent with a power-law spectrum of energy index alpha = 1.2 - 1.5, intervening column density N(sub H) = (5 - 8) x 10(exp 19)/sq cm, and luminosity 5.0 x 10(exp 30) ergs/s in the 0.1 - 2.4 keV band. We also use a bright EUVE/ROSAT source only 4.2 min. from the pulsar, the Seyfert galaxy RX J0437.4-4711 (= EUVE J0437-471 = IES 0435-472), to obtain an independent upper limit on the intervening absorption to the pulsar, N(sub H) less than 1.2 x 10(exp 20)/sq cm. Although a blackbody spectrum fails to fit the ROSAT data, two-component spectral fits to the combined EUVE/ROSAT data are used to limit the temperatures and surface areas of thermal emission that might make partial contributions to the flux. A hot polar cap of radius 50 - 600 m and temperature (1.0 - 3.3) x 10(exp 6) K could be present. Alternatively, a larger region with T = (4 - 12) x 10(exp 5) K and area less than 200 sq km, might contribute most of the EUVE and soft X-ray flux, but only if a hotter component were present as well. Any of these temperatures would require some mechanism(s) of surface reheating to be operating in this old pulsar, the most plausible being the impact of accelerated electrons and positrons onto the polar caps. The kinematically corrected spin-down power of PSR J0437-4715 is only 4 x 10(exp 33) ergs/s, which is an order of magnitude less than that of the lowest-luminosity gamma-ray pulsars Geminga and PSR B1055-52. The absence of high-energy gamma-rays from PSR J0437-4715 might signify an inefficient or dead outer gap accelerator, which in turn accounts for the lack of a more luminous reheated surface such as those intermediate-age gamma

  1. The Orbital Solution and Spectral Classification of the High-Mass X-Ray Binary IGR J01054-7253 in the Small Magellanic Cloud

    Townsend, L J; Corbet, R H D; McBride, V A; Hill, A B; Bird, A J; Schurch, M P E; Haberl, F; Sturm, R; Pathak, D; van Soelen, B; Bartlett, E S; Drave, S P; Udalski, A

    2010-01-01

    We present X-ray and optical data on the Be/X-ray binary (BeXRB) pulsar IGR J01054-7253 = SXP11.5 in the Small Magellanic Cloud (SMC). Rossi X-ray Timing Explorer (RXTE) observations of this source in a large X-ray outburst reveal an 11.483 +/- 0.002s pulse period and show both the accretion driven spin-up of the neutron star and the motion of the neutron star around the companion through Doppler shifting of the spin period. Model fits to these data suggest an orbital period of 36.3 +/- 0.4d and Pdot of (4.7 +/- 0.3) x 10^{-10} ss^{-1}. We present an orbital solution for this system, making it one of the best described BeXRB systems in the SMC. The observed pulse period, spin-up and X-ray luminosity of SXP11.5 in this outburst are found to agree with the predictions of neutron star accretion theory. Timing analysis of the long-term optical light curve reveals a periodicity of 36.70 +/- 0.03d, in agreement with the orbital period found from the model fit to the X-ray data. Using blue-end spectroscopic observat...

  2. Rapid optical spectroscopy of X-ray binaries with Keck II

    O'Brien, K

    2001-01-01

    The large collecting area of 4+ metre class telescopes allows atronomers to observe bright objects on faster timescales than previously possible. In order to exploit this capability, we designed a novel read-out mode for use on the 10-m Keck-II telescope on Mauna Kea, Hawaii. This took the form of a continuous read-out mode, enabling us to obtain a target spectrum between 3500 and 8500 \\AA, with a dispersion of ~2.5 \\AA/pix, every *70 milliseconds*. I present results from 5 nights of observations of Interacting Binaries, using this novel data acquisition system in July 1998. During the run we obtained more than 1.2 million optical spectra, many of which were simultaneous with pointed RXTE observations. This fast spectroscopic capability has allowed us to explore regimes previously only accessible with broadband instruments. I will concentrate on results from the coordinated Keck/RXTE observations, which have revealed interesting correlated variability on timescales from seconds to days. I will also show the r...

  3. RXTE/ASM and Swift/BAT Observations of Spectral Transitions in Bright X-ray Binaries in 2005-2010

    Tang, Jing; Yan, Zhen

    2010-01-01

    We have studied X-ray spectral state transitions that can be seen in the long- term monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) on board the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) on board Swift during a period of five years from 2005 to 2010. We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X- ray binaries monitored by the ASM and the BAT. In total we identified 128 hard-to-soft transitions, of which 59 occurred after 2008. We also determined the transition fluxes and the peak fluxes of the following soft states, updated the measurements of the luminosity corresponding to the H-S transition and the peak luminosity of the following soft state in about 30 bright persistent and transient black hole and neutron star binaries following Yu & Yan (2009), and found the luminosity correlation and the luminosity range of spectral transitions in data between 2008-2010 are about the ...

  4. SXP523 = Suzaku J0102-7204 = 2XMM J010247.4-720449, a Be/X-ray binary pulsar in the SMC

    Haberl, F.; Sturm, R.; Tsujimoto, M.; Wada, Q.; Ebisawa, K.; Miller, E.; Coe, M. J.; Klus, H.; Beardmore, A. P.

    2012-12-01

    After application of an attitude correction to the Suzaku observation of the supernova remnant 1E 0102.2-7219 described in ATel #4628, we derive an improved position for the X-ray pulsar Suzaku J0102-7204 of R.A. = 01:02:46.8, and Dec. = -72:04:56 (J2000, 1 sigma uncertainty of 20 arcsec). The new position is consistent with that of the Be/X-ray binary 2XMM J010247.4-720449 in the Small Magellanic Cloud seen by XMM-Newton, Swift and Chandra (ATel #3761) and most likely all detections are from the same source.

  5. Discovery of a broad O VIII Ly alpha line in the ultra-compact X-ray binary 4U 1543-624

    Madej, O.K.; Jonker, P. G

    2010-01-01

    We report the discovery of a broad emission feature at ~0.7 keV in the spectra of the ultra-compact X-ray binary 4U 1543-624, obtained with the high-resolution spectrographs of the XMM-Newton and Chandra satellites. We confirm the presence of the feature in the broad band MOS2 spectrum of the source. As suggested before in the literature, the donor star in this source is a CO or ONe white dwarf, which transfers oxygen-rich material to the accretor, conceivably a neutron star. The X-rays repro...

  6. RXTE/ASM and Swift/BAT observations of spectral transitions in bright X-ray binaries in 2005-2010

    We have studied X-ray spectral state transitions that can be seen in the long-term monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) onboard Swift during a period of five years from 2005 to 2010. We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X-ray binaries monitored by the ASM and the BAT. In total, we identified 128 hard-to-soft transitions, of which 59 occurred after 2008. We also determined the transition fluxes and the peak fluxes of the following soft states, updated the measurements of the luminosity corresponding to the H-S transition and the peak luminosity of the following soft state in about 30 bright persistent and transient black hole and neutron star binaries following Yu and Yan, and found the luminosity correlation and the luminosity range of spectral transitions in data between 2008-2010 are about the same as those derived from data before 2008. This further strengthens the idea that the luminosity at which the H-S spectral transition occurs in the Galactic X-ray binaries is determined by non-stationary accretion parameters such as the rate-of-change of the mass accretion rate rather than the mass accretion rate itself. The correlation is also found to hold in data of individual sources 4U 1608-52 and 4U 1636-53. (invited review)

  7. Disk reflection and a possible disk wind during a soft X-ray state in the neutron star low-mass X-ray binary 1RXS J180408.9-342058

    Degenaar, N; Parker, M; Miller-Jones, J C A; Miller, J M; Heinke, C O; Wijnands, R; Ludlam, R; Parikh, A; Hessels, J W T; Gusinskaia, N; Deller, A T; Fabian, A C

    2016-01-01

    1RXS J180408.9-342058 is a transient neutron star low-mass X-ray binary that exhibited a bright accretion outburst in 2015. We present Nustar, Swift, and Chandra observations obtained around the peak of this outburst. The source was in a soft X-ray spectral state and displayed an X-ray luminosity of Lx~(2-3)E37 (D/5.8 kpc)^2 erg cm-2 (0.5-10 keV). The Nustar data reveal a broad Fe-K emission line that we model as relativistically broadened reflection to constrain the accretion geometry. We found that the accretion disk is viewed at an inclination of i~27-35 degrees and extended close to the neutron star, down to Rin~5-7.5 gravitational radii (~11-17 km). This inner disk radius suggests that the neutron star magnetic field strength is B<2E8 G. We find a narrow absorption line in the Chandra/HEG data at an energy of ~7.64 keV with a significance of ~4.8 sigma. This feature could correspond to blue-shifted Fe xxvi and arise from an accretion disk wind, which would imply an outflow velocity of v~0.086c (~25800...

  8. An Ultra-fast X-Ray Disk Wind in the Neutron Star Binary GX 340+0

    Miller, J. M.; Raymond, J.; Cackett, E.; Grinberg, V.; Nowak, M.

    2016-05-01

    We present a spectral analysis of a brief Chandra/HETG observation of the neutron star low-mass X-ray binary GX 340+0. The high-resolution spectrum reveals evidence of ionized absorption in the Fe K band. The strongest feature, an absorption line at approximately 6.9 keV, is required at the 5σ level of confidence via an F-test. Photoionization modeling with XSTAR grids suggests that the line is the most prominent part of a disk wind with an apparent outflow speed of v = 0.04c. This interpretation is preferred at the 4σ level over a scenario in which the line is H-like Fe xxvi at a modest redshift. The wind may achieve this speed owing to its relatively low ionization, enabling driving by radiation pressure on lines; in this sense, the wind in GX 340+0 may be the stellar-mass equivalent of the flows in broad absorption line quasars. If the gas has a unity volume filling factor, the mass ouflow rate in the wind is over 10‑5 M ⊙ yr‑1, and the kinetic power is nearly 1039 erg s‑1 (or, 5–6 times the radiative Eddington limit for a neutron star). However, geometrical considerations—including a small volume filling factor and low covering factor—likely greatly reduce these values.

  9. The Be/X-ray Binary Swift J1626.6-5156 as a Variable Cyclotron Line Source

    DeCesar, Megan E; Pottschmidt, Katja; Wilms, Jörn; Suchy, Slawomir; Miller, M Coleman

    2012-01-01

    Swift J1626.6-5156 is a Be/X-ray binary that was in outburst from December 2005 until November 2008. We have examined RXTE/PCA and HEXTE spectra of three long observations of this source taken early in its outburst, when the PCA 2-20 keV count rate was >70 counts/s/PCU, as well as several combined observations from different stages of the outburst. The spectra are best fit with an absorbed cutoff power law with a ~6.4 keV iron emission line and a Gaussian optical depth absorption line at ~10 keV. We present strong evidence that this absorption-like feature is a cyclotron resonance scattering feature, making Swift J1626.6-5156 a new candidate cyclotron line source. The redshifted energy of ~10 keV implies a magnetic field strength of ~8.6(1+z) x 10^11 G in the region of the accretion column close to the magnetic poles where the cyclotron line is produced. Analysis of phase averaged spectra spanning the duration of the outburst suggests a possible positive correlation between the fundamental cyclotron energy an...

  10. The orbital phase resolved spectroscopy of X-ray binary 4U 1822‑371 with Suzaku

    Niu, Shu; Yan, Shu-Ping; Lei, Shi-Jun; Nowak, Michael A.; Schulz, Norbert S.; Ji, Li

    2016-04-01

    4U 1822‑371 is a typical edge-on eclipsing low mass X-ray binary and the prototype of accretion disk coronal sources. We report on the results of a spectral analysis over the energy range 0.5–45 keV observed by Suzaku in 2006. We extract spectra from five orbital phases. The spectra can be equally well described by various previously proposed models: an optically thick model described by a partially covered cutoff power law and an optically thin model described by a blackbody plus a cutoff power law. The optically thick model requires a covering fraction of about 55%, while the optically thin model requires a temperature of the central source of about 0.16 keV. The spectrum in the optically thick model also shows the previously detected cyclotron line feature at ∼30 keV with the same Suzaku observation. This feature confirms the presence of a strong magnetic field. The Fe Kα fluorescent line strengths as well as the detected Fe XXVI strengths are similar to previous Chandra and XMM-Newton detections in our phased spectral analysis; however, we also observe strong Fe XXVI during the eclipse, which indicates a slightly larger central corona.

  11. CONTINUED COOLING OF THE CRUST IN THE NEUTRON STAR LOW-MASS X-RAY BINARY KS 1731-260

    Some neutron star low-mass X-ray binaries have very long outbursts (lasting several years) which can generate a significant amount of heat in the neutron star crust. After the system has returned to quiescence, the crust then thermally relaxes. This provides a rare opportunity to study the thermal properties of neutron star crusts, putting constraints on the thermal conductivity and hence the structure and composition of the crust. KS 1731-260 is one of only four systems where this crustal cooling has been observed. Here, we present a new Chandra observation of this source approximately eight years after the end of the last outburst and four years since the last observation. We find that the source has continued to cool, with the cooling curve displaying a simple power-law decay. This suggests that the crust has not fully thermally relaxed yet and may continue to cool further. A simple power-law decay is in contrast to theoretical cooling models of the crust, which predict that the crust should now have cooled to the same temperature as the neutron star core.

  12. Optical Studies of 13 Hard X-Ray Selected Cataclysmic Binaries from the Swift-BAT Survey

    Halpern, Jules P.; Thorstensen, John R.

    2015-12-01

    From a set of 13 cataclysmic binaries that were discovered in the Swift Burst Alert Telescope (BAT) survey, we conducted time-resolved optical spectroscopy and/or time-series photometry of 11, with the goal of measuring their orbital periods and searching for spin periods. Seven of the objects in this study are new optical identifications. Orbital periods are found for seven targets, ranging from 81 minutes to 20.4 hr. PBC J0706.7+0327 is an AM Herculis star (polar) based on its emission-line variations and large amplitude photometric modulation on the same period. Swift J2341.0+7645 may be a polar, although the evidence here is less secure. Coherent pulsations are detected from two objects, Swift J0503.7-2819 (975 s) and Swift J0614.0+1709 (1412 s and 1530 s, spin and beat periods, respectively), indicating that they are probable intermediate polars (DQ Herculis stars). For two other stars, longer spin periods are tentatively suggested. We also present the discovery of a 2.00 hr X-ray modulation from RX J2015.6+3711, possibly a contributor to Swift J2015.9+3715, and likely a polar. Based on observations obtained at the MDM Observatory, operated by Dartmouth College, Columbia University, Ohio State University, Ohio University, and the University of Michigan.

  13. A BeppoSAX observation of the massive X-ray binary 4U1700-37

    Reynolds, A P; Kaper, L; Parmar, A N; Segreto, A

    1999-01-01

    A 0.5-200 keV BeppoSAX spectrum of the non-pulsating high-mass X-ray binary 4U1700-37 is presented. The spectrum is well characterized by the standard accreting pulsar model of an absorbed power-law with a photon index of 1.07 +0.02 -0.03, sharply modified by an exponential cutoff above 5.9 +/- 0.2 keV. The e-folding energy of the cutoff is 23.9 +/-0.5 keV. A soft bremsstrahlung component with a temperature of 0.2 +/- 0.1 keV is also required, together with a narrow iron line at 6.5 keV. Both continuum components are absorbed by a column of (5.1 +/- 0.2) x 10E22 atom/cm2. There is some evidence for the presence of a broad cyclotron absorption feature at ~37 keV, although we cannot exclude the possibility that this is due to an incorrect modeling of the continuum, or instrumental effects. The hypothesis that the compact object is a neutron star rather than a black hole seems most likely.

  14. 1RXS J180408.9-342058: an ultra compact X-ray binary candidate with a transient jet

    Baglio, M C; Campana, S; Goldoni, P; Masetti, N; Munoz-Darias, T; Patino-Alvarez, V; Chavushyan, V

    2016-01-01

    We present a detailed NIR/optical/UV study of the transient low mass X-ray binary 1RXS J180408.9-342058 performed during its 2015 outburst, aimed at determining the nature of its companion star. We obtained three optical spectra at the 2.1 m San Pedro Martir Observatory telescope (Mexico). We performed optical and NIR photometric observations with both the REM telescope and the New Technology Telescope (NTT) in La Silla. We obtained optical and UV observations from the Swift archive. Finally, we performed optical polarimetry of the source by using the EFOSC2 instrument mounted on the NTT. The optical spectrum of the source is almost featureless since the hydrogen and He I emissions lines, typically observed in LMXBs, are not detected. Similarly, carbon and oxygen lines are neither observed. We marginally detect the He II 4686 AA emission line, suggesting the presence of helium in the accretion disc. No significant optical polarisation level was observed. The lack of hydrogen and He I emission lines in the spe...

  15. The Magneto Hydro Dynamical Model of KHz Quasi Periodic Oscillations in Neutron Star Low Mass X-ray Binaries (II)

    Shi, Chang-Sheng; Li, Xiang-Dong

    2014-01-01

    We study the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low mass X-ray binaries (LMXBs) with a new magnetohydrodynamics (MHD) model, in which the compressed magnetosphere is considered. The previous MHD model (Shi \\& Li 2009) is re-examined and the relation between the frequencies of the kHz QPOs and the accretion rate in LMXBs is obtained. Our result agrees with the observations of six sources (4U 0614+09, 4U 1636--53, 4U 1608--52, 4U 1915--15, 4U 1728--34, XTE 1807--294) with measured spins. In this model the kHz QPOs originate from the MHD waves in the compressed magnetosphere. The single kHz QPOs and twin kHz QPOs are produced in two different parts of the accretion disk and the boundary is close to the corotation radius. The lower QPO frequency in a frequency-accretion rate diagram is cut off at low accretion rate and the twin kHz QPOs encounter a top ceiling at high accretion rate due to the restriction of innermost stable circular orbit.

  16. An Ultra-Fast X-ray Disk Wind in the Neutron Star Binary GX 340+0

    Miller, J M; Cackett, E; Grinberg, V; Nowak, M

    2016-01-01

    We present a spectral analysis of a brief Chandra/HETG observation of the neutron star low-mass X-ray binary GX~340+0. The high-resolution spectrum reveals evidence of ionized absorption in the Fe K band. The strongest feature, an absorption line at approximately 6.9 keV, is required at the 5 sigma level of confidence via an F-test. Photoionization modeling with XSTAR grids suggests that the line is the most prominent part of a disk wind with an apparent outflow speed of v = 0.04c. This interpretation is preferred at the 4 sigma level over a scenario in which the line is H-like Fe XXVI at a modest red-shift. The wind may achieve this speed owing to its relatively low ionization, enabling driving by radiation pressure on lines; in this sense, the wind in GX 340+0 may be the stellar-mass equivalent of the flows in broad absorption line quasars (BALQSOs). If the gas has a unity volume filling factor, the mass ouflow rate in the wind is over 10^-5 Msun/year, and the kinetic power is nearly 10^39 erg/s (or, 5-6 ti...

  17. Low-temperature X-ray diffraction study of martensite lattice parameters in binary Ti-Ni alloys

    Concentration and temperature dependency of the B19'-martensite lattice parameters (MLP) in binary Ti-Ni alloys as well as the effect of the structural state of a parent austenite on these parameters were studied using low-temperature X-ray diffraction analysis. The existence of a concentration dependence of the MLP found for the hyper-equiatomic nickel concentration range is proved for cryogenic temperature range and extended, at least, up to 51.2 at.% of nickel. Temperature dependency of MLP is observed in the studied nickel concentration range, and they are approximately the same for different alloys in the temperature range of stable martensite. During heating in the temperature range of the martensite existence, all parameters of the B19'-martensite monoclinic cell change towards the values of corresponding parameters of the austenite tetragonal cell with which they have 'genetic' relations. The maximum transformation lattice strain calculated at the martensite-start temperature of each alloy, and, hence, the resource of the recoverable strain, are higher for pre-equiatomic and equiatomic alloys than that for alloys in hyper-equiatomic nickel concentration range. For Ti-50.7 at.% Ni alloy, the lattice parameters of martensite formed from the austenite containing a well-developed dislocation substructure deviate from the corresponding lattice parameters of the quenched martensite formed from a low-dislocated recrystallized austenite. This distinction is a general feature for the alloys undergoing B2 → B19' and B2 → R → B19' martensitic transformations

  18. A possible imprint of quasi-periodic oscillations in the X-ray spectra of black hole binaries

    Varniere, P; Rodriguez, J

    2016-01-01

    While nobody would deny the presence of Quasi-Periodic Oscillations in the power density spectrum of Black hole binaries nor their importance in the understanding of the mechanisms powering the X-ray emissions, the possible impact on the time-averaged disk energy spectrum from the phenomenon responsible for the Quasi-Periodic Oscillations is largely ignored in models of sources emission. Here we investigate the potential impact of such structure on the resultant energy spectrum. Using data from the well documented outbursts of XTE J$1550$-$564$ we looked at possible hints that the presence of Quasi-Periodic Oscillations actually impacts the energy spectrum emitted by the source. In particular we look at the evolution of the relation between the inner disc radius and the inner disc temperature obtained from fits to the spectral data. We then test this further by developing a simple model in order to simulate spectra of a disk with a structure mimicking an increasing in strength Quasi-Periodic Oscillation and c...

  19. Testing the transition layer model of quasi-periodic oscillations in neutron star X-ray binarie

    Wu, X B

    2001-01-01

    We compare the theoretical predictions of the transition layer model with some observational features of quasi-periodic oscillations (QPOs) in neutron star X-ray binaries. We found that the correlation between horizontal branch oscillation (HBO) frequencies and kilohertz (kHz) QPO frequencies, the difference between the low-frequency QPOs in atoll sources and HBOs in Z sources, and the correlation between the frequencies of low-frequency QPOs and break frequencies can be well explained by the transition layer model, provided the neutron star mass is around 1.4 solar mass and the angle between magnetosphere equator and accretion disk plane is around 6 degree. The observed decrease of peak separation between two kHz QPO frequencies with the increase of kHz QPO frequencies and the increase of QPO frequencies with the increase of inferred mass accretion rate are also consistent with the theoretical predictions of transition layer model. In addition, we derive a simple equation that can be adopted to estimate the ...

  20. A Suzaku observation of the low-mass X-ray binary GS 1826-238 in the hard state

    Ono, Ko; Sakurai, Soki; Zhang, Zhongli; Nakazawa, Kazuhiro; Makishima, Kazuo

    2016-06-01

    The neutron star low-mass X-ray binary GS 1826-238 was observed with Suzaku on 2009 October 21, for a total exposure of 1030 ks. Except for the type I bursts, the source intensity was constant within ˜10%. Combining the Suzaku XIS, HXD-PIN, and HXD-GSO data, burst-removed persistent emission was detected over the 0.8-100 keV range, at an unabsorbed flux of 2.6 × 10-9 erg s-1 cm-2. Although the implied 0.8-100 keV luminosity, 1.5 × 1037 erg s-1 (assuming a distance of 7 kpc), is relatively high, the observed hard spectrum confirms that the source was in the hard state. The spectrum was successfully explained by an emission from a soft standard accretion disk partially Comptonized by a hot electron cloud, and a blackbody emission Comptonized by another hotter electron cloud. These results are compared with those from previous studies, including those on the same source by Thompson et al. (2005, ApJ, 634, 1261) and Cocchi, Farinelli, and Paizis (2011, A&A, 529, A155), as well as that of Aql X-1 in the hard state obtained with Suzaku (Sakurai et al. 2014, PASJ, 66, 10).

  1. Optical Studies of Thirteen Hard X-ray Selected Cataclysmic Binaries from the Swift-BAT Survey

    Halpern, J P

    2015-01-01

    From a set of thirteen cataclysmic binaries that were discovered in the Swift Burst Alert Telescope (BAT) survey, we conducted time-resolved optical spectroscopy and/or time-series photometry of eleven, with the goal of measuring their orbital periods and searching for spin periods. Seven of the objects in this study are new optical identifications. Orbital periods are found for seven targets, ranging from 81 minutes to 20.4 hours. PBC J0706.7+0327 is an AM Herculis star (polar) based on its emission-line variations and large amplitude photometric modulation on the same period. Swift J2341.0+7645 may be a polar, although the evidence here is less secure. Coherent pulsations are detected from two objects, Swift J0503.7-2819 (975 s) and Swift J0614.0+1709 (1412 s and 1530 s, spin and beat periods, respectively), indicating that they are probable intermediate polars (DQ Herculis stars). For two other stars, longer spin periods are tentatively suggested. We also present the discovery of a 2.00 hour X-ray modulati...

  2. Detection of cyclotron resonance scattering feature in high-mass X-ray binary pulsar SMC X-2

    Jaisawal, Gaurava K.; Naik, Sachindra

    2016-09-01

    We report broad-band spectral properties of the high-mass X-ray binary pulsar SMC X-2 by using three simultaneous Nuclear Spectroscopy Telescope Array and Swift/XRT observations during its 2015 outburst. The pulsar was significantly bright, reaching a luminosity up to as high as ˜5.5 × 1038 erg s-1 in 1-70 keV range. Spin period of the pulsar was estimated to be 2.37 s. Pulse profiles were found to be strongly luminosity dependent. The 1-70 keV energy spectrum of the pulsar was well described with three different continuum models such as (i) negative and positive power law with exponential cutoff, (ii) Fermi-Dirac cutoff power law and (iii) cutoff power-law models. Apart from the presence of an iron line at ˜6.4 keV, a model independent absorption like feature at ˜27 keV was detected in the pulsar spectrum. This feature was identified as a cyclotron absorption line and detected for the first time in this pulsar. Corresponding magnetic field of the neutron star was estimated to be ˜2.3 × 1012 G. The cyclotron line energy showed a marginal negative dependence on the luminosity. The cyclotron line parameters were found to be variable with pulse phase and interpreted as due to the effect of emission geometry or complicated structure of the pulsar magnetic field.

  3. Neutron star crustal plate tectonics. I. Magnetic dipole evolution in millisecond pulsars and low-mass X-ray binaries

    Crust lattices in spinning-up or spinning-down neutron stars have growing shear stresses caused by neutron superfluid vortex lines pinned to lattice nuclei. For the most rapidly spinning stars, this stress will break and move the crust before vortex unpinning occurs. In spinning-down neutron stars, crustal plates will move an equatorial subduction zone in which the plates are forced into the stellar core below the crust. The opposite plate motion occurs in spinning-up stars. Magnetic fields which pass through the crust or have sources in it move with the crust. Spun-up neutron stars in accreting low-mass X-ray binaries LMXBs should then have almost axially symmetric magnetic fields. Spun-down ones with very weak magnetic fields should have external magnetic fields which enter and leave the neutron star surface only near its equator. The lowest field millisecond radiopulsars seem to be orthogonal rotators implying that they have not previously been spun-up in LMXBs but are neutron stars initially formed with periods near 0.001 s that subsequently spin down to their present periods. Accretion-induced white dwarf collapse is then the most plausible genesis for them. 29 refs

  4. Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in supergiant fast X-ray transient and classical supergiant X-ray binaries

    Giménez-García, A.; Shenar, T.; Torrejón, J. M.; Oskinova, L.; Martínez-Núñez, S.; Hamann, W.-R.; Rodes-Roca, J. J.; González-Galán, A.; Alonso-Santiago, J.; González-Fernández, C.; Bernabeu, G.; Sander, A.

    2016-06-01

    Context. Classical supergiant X-ray binaries (SGXBs) and supergiant fast X-ray transients (SFXTs) are two types of high-mass X-ray binaries (HMXBs) that present similar donors but, at the same time, show very different behavior in the X-rays. The reason for this dichotomy of wind-fed HMXBs is still a matter of debate. Among the several explanations that have been proposed, some of them invoke specific stellar wind properties of the donor stars. Only dedicated empiric analysis of the donors' stellar wind can provide the required information to accomplish an adequate test of these theories. However, such analyses are scarce. Aims: To close this gap, we perform a comparative analysis of the optical companion in two important systems: IGR J17544-2619 (SFXT) and Vela X-1 (SGXB). We analyze the spectra of each star in detail and derive their stellar and wind properties. As a next step, we compare the wind parameters, giving us an excellent chance of recognizing key differences between donor winds in SFXTs and SGXBs. Methods: We use archival infrared, optical and ultraviolet observations, and analyze them with the non-local thermodynamic equilibrium (NLTE) Potsdam Wolf-Rayet model atmosphere code. We derive the physical properties of the stars and their stellar winds, accounting for the influence of X-rays on the stellar winds. Results: We find that the stellar parameters derived from the analysis generally agree well with the spectral types of the two donors: O9I (IGR J17544-2619) and B0.5Iae (Vela X-1). The distance to the sources have been revised and also agree well with the estimations already available in the literature. In IGR J17544-2619 we are able to narrow the uncertainty to d = 3.0 ± 0.2 kpc. From the stellar radius of the donor and its X-ray behavior, the eccentricity of IGR J17544-2619 is constrained to e< 0.25. The derived chemical abundances point to certain mixing during the lifetime of the donors. An important difference between the stellar winds of the

  5. From Uhuru at CfA to SAS-3 at MIT: Looking for X-Ray Binaries in all the Right Places

    Cominsky, Lynn R.

    2013-01-01

    My career in X-ray astronomy started almost accidentally, when in 1975 I was hired fresh out of college as a “data aide” for the Uhuru satellite, in Riccardo Giacconi’s group at the Harvard-Smithsonian Center for Astrophysics. Working first for Mel Ulmer, and later for Bill Forman and Christine Jones, I learned the fundamentals of data analysis, and helped produce the Fourth Uhuru catalog of X-ray sources (Forman et al. 1978), as well as studying transient X-ray sources (Cominsky et al. 1978). Christine was the first woman scientist I had ever met, and with her encouragement, I applied to graduate school to continue on in X-ray astronomy. Lured down the street to MIT by the chance to work on SAS-3, I eagerly learned how to operate the satellite from a control room in the Center for Space Research. The SAS-3 group was led by Prof. George Clark, and it was my good luck that he was around during the holiday break in January 1978 when everyone else in the group was at an AAS meeting in Hawaii. A source I recognized from my Uhuru work, 4U0115+63, had reappeared, and I knew that it was likely to be a pulsar. With the help of George and Project Scientist Bill Mayer, I managed to send the commands to stop SAS-3 and point at the source. The 3.6 second pulsations were so strong that they could be seen in the raw data! This discovery made the New York Times, as 4U0115+63 was the first transient x-ray source shown to be in a binary system (Cominsky et al. 1978, Rappaport et al. 1978). Another personal SAS-3 highlight included working on Prof. Walter Lewin’s “World-wide Burst Watch” - coordinated multi-wavelength observations of x-ray burst sources which led to the discoveries of slightly delayed but coincident optical bursts (Grindlay et al. 1978, McClintock et al. 1979). Although live operations of SAS-3 ended when it re-entered on April 9, 1979, many years of additional data analysis remained. And later, as a continuation of work I began in my Ph.D. Thesis on X-ray

  6. Broad-band X-ray emission and the reality of the broad iron line from the neutron star-white dwarf X-ray binary 4U 1820-30

    Mondal, Aditya S.; Dewangan, G. C.; Pahari, M.; Misra, R.; Kembhavi, A. K.; Raychaudhuri, B.

    2016-09-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disc. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here, we investigate the reality of the broad iron line detected earlier from the neutron-star low-mass X-ray binary 4U 1820-30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broad-band spectral study of the atoll source using Suzaku and simultaneous NuSTAR and Swift observations. We have used different continuum models involving accretion disc emission, thermal blackbody and thermal Comptonization of either disc or blackbody photons. The Suzaku data show positive and negative residuals in the region of Fe K band. These features are well described by two absorption edges at 7.67 ± 0.14 keV and 6.93 ± 0.07 keV or partial covering photoionized absorption or by blurred reflection. Though, the simultaneous Swift and NuSTAR data do not clearly reveal the emission or absorption features, the data are consistent with the presence of either absorption or emission features. Thus, the absorption based models provide an alternative to the broad iron line or reflection model. The absorption features may arise in winds from the inner accretion disc. The broad-band spectra appear to disfavour continuum models in which the blackbody emission from the neutron-star surface provides the seed photons for thermal Comptonization. Our results suggest emission from a thin accretion disc (kTdisc ˜ 1 keV), Comptonization of disc photons in a boundary layer most likely covering a large fraction of the neutron-star surface and innermost parts of the accretion disc, and blackbody emission (kTbb ˜ 2 keV) from the polar regions.

  7. Chaotic and stochastic processes in the accretion flows of the black hole X-ray binaries revealed by recurrence analysis

    Suková, Petra; Grzedzielski, Mikolaj; Janiuk, Agnieszka

    2016-02-01

    Aims: Both the well known microquasar GRS 1915+105, as well as its recently discovered analogue, IGR J17091-3624, exhibit variability that is characteristic of a deterministic chaotic system. Their specific kind of quasi-periodic flares that are observed in some states is intrinsically connected with the global structure of the accretion flow, which are governed by the nonlinear hydrodynamics. One plausible mechanism that is proposed to explain this kind of variability is the thermal-viscous instability that operates in the accretion disk. The purely stochastic variability that occurs because of turbulent conditions in the plasma, is quantified by the power density spectra and appears in practically all types of sources and their spectral states. Methods: We pose a question as to whether these two microquasars are one of a kind, or if the traces of deterministic chaos, and hence the accretion disk instability, may also be hidden in the observed variability of other sources. We focus on the black hole X-ray binaries that accrete at a high rate and are, therefore, theoretically prone to the development of radiation pressure-induced instability. To study the nonlinear behaviour of the X-ray sources and distinguish between the chaotic and stochastic nature of their emission, we propose a novel method, which is based on recurrence analysis. Widely known in other fields of physics, this powerful method is used here for the first time in an astrophysical context. We estimate the indications of deterministic chaos quantitatively, such as the Rényi's entropy for the observed time series, and we compare them with surrogate data. Results: Using the observational data collected by the RXTE satellite, we reveal the oscillations pattern and the observable properties of six black hole systems. For five of them, we confirm the signatures of deterministic chaos being the driver of their observed variability. Conclusions: We test the method and confirm the deterministic nature of

  8. Discovery of the neutron star spin and orbital period from the Be/X-ray binary IGR J05414-6858 in the LMC

    Sturm, R; Rau, A; Bartlett, E S; Zhang, X -L; Schady, P; Pietsch, W; Greiner, J; Coe, M J; Udalski, A

    2012-01-01

    The number of known Be/X-ray binaries in the Large Magellanic Cloud is small compared to the observed population of the Galaxy or the Small Magellanic Cloud. The discovery of a system in outburst provides the rare opportunity to measure its X-ray properties in detail. IGR J05414-6858 was serendipitously found in outburst with the Swift satellite in August 2011. In order to characterise the system, we analysed the data from a follow-up XMM-Newton target of opportunity observation and investigate the stellar counterpart with photometry and spectroscopy. We modelled the X-ray spectra from the EPIC instruments on XMM-Newton and compared them with Swift archival data. In the X-ray and optical light curves, we searched for periodicities and variability. The optical counterpart was classified using spectroscopy obtained with ESO's Faint Object Spectrograph at NTT. The X-ray spectra as seen in 2011 are relatively hard with a photon index of ~0.3 - 0.4 and show only low absorption. They deviate significantly from earl...

  9. XTE J1701-462 and its Implications for the Nature of Subclasses in Low-Magnetic-Field Neutron Star Low-Mass X-Ray Binaries

    Homan, Jeroen; Fridriksson, Joel K; Remillard, Ronald A; Wijnands, Rudy; Mendez, Mariano; Lin, Dacheng; Altamirano, Diego; Casella, Piergiorgio; Belloni, Tomaso; Lewin, Walter H G

    2010-01-01

    We report on an analysis of RXTE data of the transient neutron star low-mass X-ray binary (NS-LMXB) XTE J1701-462, obtained during its 2006-2007 outburst. The X-ray properties of the source changed between those of various types of NS-LMXB subclasses. At high luminosities the source switched between two types of Z source behavior and at low luminosities we observed a transition from Z source to atoll source behavior. These transitions between subclasses primarily manifest themselves as changes in the shapes of the tracks in X-ray color-color and hardness-intensity diagrams, but they are accompanied by changes in the kHz quasi-periodic oscillations, broad-band variability, burst behavior, and/or X-ray spectra. We find that the low-energy X-ray flux is a good parameter to track the gradual evolution of the tracks in color-color and hardness-intensity diagrams, allowing us to resolve the evolution of the source in greater detail than before and relate the observed properties to other NS-LMXBs. We further find th...

  10. Long-term TeV and X-ray Observations of the Gamma-ray Binary HESS J0632+057

    Aliu, E; Aune, T; Behera, B; Beilicke, M; Benbow, W; Berger, K; Bird, R; Bouvier, A; Buckley, J H; Bugaev, V; Byrum, K; Cerruti, M; Chen, X; Ciupik, L; Connolly, M P; Cui, W; Duke, C; Dumm, J; Errando, M; Falcone, A; Federici, S; Feng, Q; Finley, J P; Fortin, P; Fortson, L; Furniss, A; Galante, N; Gillanders, G H; Griffin, S; Griffiths, S T; Grube, J; Gyuk, G; Hanna, D; Holder, J; Hughes, G; Humensky, T B; Kaaret, P; Kertzman, M; Khassen, Y; Kieda, D; Krawczynski, H; Krennrich, F; Lang, M J; Madhavan, A S; Maier, G; Majumdar, P; McCann, A; Moriarty, P; Mukherjee, R; Nieto, D; de Bhróithe, A O'Faoláin; Ong, R A; Otte, A N; Park, N; Perkins, J S; Pohl, M; Popkow, A; Prokoph, H; Quinn, J; Ragan, K; Rajotte, J; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Rousselle, J; Sembroski, G H; Sheidaei, F; Skole, C; Smith, A W; Staszak, D; Stroh, M; Telezhinsky, I; Theiling, M; Tucci, J V; Tyler, J; Varlotta, A; Vincent, S; Wakely, S P; Weinstein, A; Welsing, R; Williams, D A; Zajczyk, A; Zitzer, B; :,; Abramowski, A; Aharonian, F; Benkhali, F Ait; Akhperjanian, A G; Angüner, E; Anton, G; Balenderan, S; Balzer, A; Barnacka, A; Becherini, Y; Tjus, J Becker; Bernlöhr, K; Birsin, E; Bissaldi, E; Biteau, J; Böttcher, M; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Carrigan, S; Casanova, S; Chadwick, P M; Chalme-Calvet, R; Chaves, R C G; Cheesebrough, A; Chrétien, M; Colafrancesco, S; Cologna, G; Conrad, J; Couturier, C; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; deWilt, P; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Edwards, T; Egberts, K; Eger, P; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fernandez, D; Fiasson, A; Fontaine, G; Forster, A; Füßling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Giavitto, G; Giebels, B; Glicenstein, J F; Grondin, M -H; Grudzińska, M; Häffner, S; Hahn, J; Harris, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Janiak, M; Jankowsky, F; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Kieffer, M; Klepser, S; Klochkov, D; Kluźniak, W; Kneiske, T; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Krayzel, F; Krüger, P P; Laffon, H; Lamanna, G; Lefaucheur, J; Lemiére, A; Lemoine-Goumard, M; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Marx, R; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Méhault, J; Menzler, U; Meyer, M; Moderski, R; Mohamed, M; Moulin, E; Murach, T; Naumann, C L; de Naurois, M; Niemiec, J; Nolan, S J; Oakes, L; Ohm, S; Wilhelmi, E de Onña; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Poon, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Rob, L; Romoli, C; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sol, H; Spengler, G; Spies, F; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Tavernier, T; Taylor, A M; Terrier, R; Tluczykont, M; Trichard, C; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorster, M; Wagner, S J; Wagner, P; Ward, M; Weidinger, M; Weitzel, Q; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Zacharias, M; Zdziarski, A A; Zech, A; Zechlin, H -S

    2013-01-01

    HESS J0632+057 is the only gamma-ray binary known so far whose position in the sky allows observations with ground-based observatories both in the northern and southern hemispheres. Here we report on long-term observations of HESS J0632+057 conducted with the VERITAS and H.E.S.S. Cherenkov Telescopes and the X-ray Satellite Swift, spanning a time range from 2004 to 2012 and covering most of the system's orbit. The VHE emission is found to be variable, and is correlated with that at X-ray energies. An orbital period of $315 ^{+6}_{-4}$ days is derived from the X-ray data set, which is compatible with previous results, $P = (321 \\pm 5$) days. The VHE light curve shows a distinct maximum at orbital phases close to 0.3, or about 100 days after periastron passage, which coincides with the periodic enhancement of the X-ray emission. Furthermore, the analysis of the TeV data shows for the first time a statistically significant ($> 6.5 \\sigma$) detection at orbital phases 0.6--0.9. The obtained gamma-ray and X-ray li...

  11. Swift X-ray Telescope study of the Black Hole Binary MAXI J1659-152: Variability from a two component accretion flow

    Kalamkar, M; Heil, L; Homan, J

    2015-01-01

    We present an energy dependent X-ray variability study of the 2010 outburst of the black hole X-ray binary MAXI J1659-152 with the Swift X-ray Telescope (XRT). The broad-band noise components and the quasi periodic oscillations (QPO) observed in the power spectra show a strong and varied energy dependence. Combining Swift XRT data with data from the Rossi X-ray Timing Explorer, we report, for the first time, an rms spectrum (fractional rms amplitude as a function of energy) of these components in the 0.5-30 keV energy range. We find that the strength of the low-frequency component ( 0.1 Hz) whose strengths increase with energy. In the context of the propagating fluctuations model for X-ray variability, we suggest that the low-frequency component originates in the accretion disk (which dominates emission below ~ 2 keV) and the higher frequency components are formed in the hot flow (which dominates emission above ~ 2 keV). As the properties of the QPO suggest that it may have a different driving mechanism, we i...

  12. Gamma-ray observations of the Be/pulsar binary 1A 0535+262 during a giant X-ray outburst

    Acciari, V A; Araya, M; Arlen, T; Aune, T; Beilicke, M; Benbow, W; Bradbury, S M; Buckley, J H; Bugaev, V; Byrum, K; Cannon, A; Cesarini, A; Ciupik, L; Collins-Hughes, E; Cui, W; Dickherber, R; Duke, C; Falcone, A; Finley, J P; Fortson, L; Furniss, A; Galante, N; Gall, D; Godambe, S; Griffin, S; Guenette, R; Gyuk, G; Hanna, D; Holder, J; Hughes, G; Hui, C M; Humensky, T B; Imran, A; Kaaret, P; Kertzman, M; Krawczynski, H; Krennrich, F; Madhavan, A S; Maier, G; Majumdar, P; McArthur, S; Moriarty, P; Ong, R A; Otte, A N; Pandel, D; Park, N; Perkins, J S; Pohl, M; Prokoph, H; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Rose, H J; Saxon, D B; Sembroski, G H; Senturk, G Demet; Smith, A W; Tešić, G; Theiling, M; Thibadeau, S; Varlotta, A; Vincent, S; Vivier, M; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; Weisgarber, T; Weng, S; Williams, D A; Wood, M; Zitzer, B

    2011-01-01

    Giant X-ray outbursts, with luminosities of about $ 10^{37}$ erg s$^{-1}$, are observed roughly every 5 years from the nearby Be/pulsar binary 1A 0535+262. In this article, we present observations of the source with VERITAS at very-high energies (VHE; E$>$100 GeV) triggered by the X-ray outburst in December 2009. The observations started shortly after the onset of the outburst, and they provided comprehensive coverage of the episode, as well as the 111-day binary orbit. No VHE emission is evident at any time. We also examined data from the contemporaneous observations of 1A 0535+262 with the Fermi/LAT at high energy photons (HE; E$>$0.1 GeV) and failed to detect the source at GeV energies. The X-ray continua measured with the Swift/XRT and the RXTE/PCA can be well described by the combination of blackbody and Comptonized emission from thermal electrons. Therefore, the gamma-ray and X-ray observations suggest the absence of a significant population of non-thermal particles in the system. This distinguishes 1A~...

  13. Discovery of kilohertz quasi-periodic oscillations and state transitions in the low-mass X-ray binary 1E~1724-3045 (Terzan 2)

    Altamirano, D; Méndez, M; Wijnands, R; Markwardt, C; Swank, J

    2008-01-01

    We have studied the rapid X-ray time variability in 99 pointed observations with the Rossi X-ray Timing Explorer (RXTE)'s Proportional Counter Array of the low-mass X-ray binary 1E~1724--3045 which includes, for the first time, observations of this source in its island and banana states, confirming the atoll nature of this source. We report the discovery of kilohertz quasi-periodic oscillations (kHz QPOs). Although we have 5 detections of the lower kHz QPO and one detection of the upper kHz QPO, in none of the observations we detect both QPOs simultaneously. By comparing the dependence of the rms amplitude with energy of kHz QPOs in different atoll sources, we conclude that this information cannot be use to unambiguously identify the kilohertz QPOs as was previously thought. We find that Terzan~2 in its different states shows timing behavior similar to that seen in other neutron-star low mass X-ray binaries (LMXBs). We studied the flux transitions observed between February 2004 and October 2005 and conclude t...

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

    Montes, Gabriela; De Colle, Fabio; Strickler, Rachel

    2013-01-01

    The problem of explaining the X-ray emission properties of the massive, close binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR 20a is composed of two nearly identical Wolf- Rayet stars of 82 and 83 solar masses orbiting with a period of only 3.7 days. Although Chandra observations were taken during the secondary optical eclipse, the X-ray light curve shows no signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous and softer during the optical eclipse, opposite to what has been observed in other binary systems. To aid in our interpretation of the data, we compare with the results of hydrodynamical simulations using the adaptive mesh refinement code Mezcal that includes radiative cooling and a radiative acceleration force term. It is shown that the X-ray emission can be successfully explained in models where the wind-wind collision interface in this system occurs while the outflowing material is still being accelerated. Consequently, WR 20a serves as a criti...

  15. Activity from the Be/X-ray binary system V0332+53 during its low-luminosity outburst in 2008

    Caballero-Garcia, M D; Arabaci, M Ozbey; Zurita, C; Suso, J; Gutierrez-Soto, J; Beklen, E; Kiaeerad, F; Garrido, R; Hudec, R

    2015-01-01

    Aims: We present a multiwavelength study of the Be/X-ray binary system V0332+53 with the main goal of better characterizing its behavior during a low luminosity X-ray event. We also aim to shed light on the mechanism/s which trigger the X-ray activity for this source. Methods: V0332+53 was observed by RXTE and Swift during the decay of the normal X-ray outburst of 2008, as well as with Suzaku before the rising of the third normal outburst of the 2010 series. In addition, this source has been monitored from the ground-based astronomical observatories of El Teide (Tenerife, Spain) during August 2014 to February 2015, Roque de los Muchachos (La Palma, Spain) during July and September 2012 and Sierra Nevada (Granada, Spain) since October 2012, and from the TUBITAK National Observatory (Antalya, Turkey) since September 2006. We have performed spectral and photometric temporal analyses in order to investigate the transient behavior of this binary system during Type I outbursts. Results: Our optical study revealed t...

  16. Puzzling thermonuclear burst behaviour from the transient low-mass X-ray binary IGR J17473-2721

    Chenevez, Jérôme

    2010-01-01

    We investigate the thermonuclear bursting behaviour of IGR J17473-2721, an X-ray transient that in 2008 underwent a six month long outburst, starting (unusually) with an X-ray burst. We detected a total of 57 thermonuclear bursts throughout the outburst with AGILE, Swift, RXTE, and INTEGRAL. The ...

  17. Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in supergiant fast X-ray transient and classical supergiant X-ray binaries

    Giménez-García, A.; Shenar, T.; Torrejón, J. M.; Oskinova, L.; Martínez-Núñez, S.; Hamann, W.-R.; Rodes-Roca, J. J.; González-Galán, A.; Alonso-Santiago, J.; González-Fernández, C.; Bernabeu, G.; Sander, A.

    2016-06-01

    Context. Classical supergiant X-ray binaries (SGXBs) and supergiant fast X-ray transients (SFXTs) are two types of high-mass X-ray binaries (HMXBs) that present similar donors but, at the same time, show very different behavior in the X-rays. The reason for this dichotomy of wind-fed HMXBs is still a matter of debate. Among the several explanations that have been proposed, some of them invoke specific stellar wind properties of the donor stars. Only dedicated empiric analysis of the donors' stellar wind can provide the required information to accomplish an adequate test of these theories. However, such analyses are scarce. Aims: To close this gap, we perform a comparative analysis of the optical companion in two important systems: IGR J17544-2619 (SFXT) and Vela X-1 (SGXB). We analyze the spectra of each star in detail and derive their stellar and wind properties. As a next step, we compare the wind parameters, giving us an excellent chance of recognizing key differences between donor winds in SFXTs and SGXBs. Methods: We use archival infrared, optical and ultraviolet observations, and analyze them with the non-local thermodynamic equilibrium (NLTE) Potsdam Wolf-Rayet model atmosphere code. We derive the physical properties of the stars and their stellar winds, accounting for the influence of X-rays on the stellar winds. Results: We find that the stellar parameters derived from the analysis generally agree well with the spectral types of the two donors: O9I (IGR J17544-2619) and B0.5Iae (Vela X-1). The distance to the sources have been revised and also agree well with the estimations already available in the literature. In IGR J17544-2619 we are able to narrow the uncertainty to d = 3.0 ± 0.2 kpc. From the stellar radius of the donor and its X-ray behavior, the eccentricity of IGR J17544-2619 is constrained to ephysically characterize them and their spectra. In addition, the orbital parameters of the systems are similar too, with a nearly circular orbit and short

  18. Constraining the formation of black-holes in short-period Black-Hole Low-Mass X-ray Binaries

    Repetto, Serena

    2015-01-01

    The formation of stellar mass black holes is still very uncertain. Two main uncertainties are the amount of mass ejected in the supernova event (if any) and the magnitude of the natal kick the black hole receives at birth (if any). Repetto et al. (2012), studying the position of Galactic X-ray binaries containing black holes, found evidence for black holes receiving high natal kicks at birth. In this Paper we extend that study, taking into account the previous binary evolution of the sources as well. The seven short-period black-hole X-ray binaries that we use, are compact binaries consisting of a low-mass star orbiting a black hole in a period less than $1$ day. We trace their binary evolution backwards in time, from the current observed state of mass-transfer, to the moment the black hole was formed, and we add the extra information on the kinematics of the binaries. We find that several systems could be explained by no natal kick, just mass ejection, while for two systems (and possibly more) a high kick is...

  19. A model of the steep power law spectra and high-frequency quasi-periodic oscillations in luminous black hole X-ray binaries

    Dexter, Jason; Blaes, Omer

    2013-01-01

    We propose a new model of the steep power law state of luminous black hole X-ray binaries. The model uses the fact that at high luminosities, the inner radii of radiation pressure dominated accretion discs are expected to i) become effectively optically thin and ii) produce significant luminosities. The gas temperature therefore rises sharply inwards, producing local saturated Compton spectra with rapidly increasing peak energy. These spectra sum together to form a steep power law tail to the...

  20. Wetting transition and pretransitional thin films in binary liquids: alcohol/perfluoromethylcyclohexane mixtures studied by x-ray reflectivity

    In this study the wetting transition at the liquid-vapour interface of binary organic liquid mixtures has been investigated by x-ray reflectivity. Mixtures of various isomeric alcohols with perfluoromethylcyclohexane (PFMC) served as model systems, with alcohol carbon numbers ranging from 1 to 4. Remarkably different pretransitional behaviour of the thin films below the wetting temperature was observed, which could be classified according to the carbon number. At two-phase coexistence, no pretransitional thin films could be detected for methanol and ethanol, whereas thin-to-thick-film transitions were found for propanol and butanol and their isomers. For 1-propanol and 2-propanol, the surface of the upper, alcohol-rich phase of the gravity-separated mixture displays a wetting transition at Tw = 31.5 deg. C and 38.3 deg. C, respectively, where the thickness of a PFMC-rich film jumps from less than 25 A to values exceeding the experimental resolution of about 1200 A. For 1-butanol, 2-butanol and i-butanol, we found pretransitional film thicknesses increasing up to 100 A, with wetting transitions at Tw = 45.0 deg. C, 34.2 deg. C and 40.1 deg. C, respectively. In the single-phase region, the study of adsorption isotherms above Tw revealed novel behaviour of the adsorbed PFMC-rich film. We observed both a growing film thickness and a significantly changing composition as the coexistence line was approached. Nevertheless, the variation of the excess adsorption with distance from coexistence could still be described by a power law. (author)