- ID:
- ivo://CDS.VizieR/J/ApJ/706/L7
- Title:
- The Fermi LAT sky as seen by INTEGRAL/IBIS
- Short Name:
- J/ApJ/706/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this Letter we present the result of the cross correlation between the fourth INTEGRAL/IBIS soft gamma-ray catalog, in the range 20-100keV, and the Fermi LAT bright source list of objects emitting in the 100MeV-100GeV range. The main result is that only a minuscule part of the more than 720 sources detected by INTEGRAL and the population of 205 Fermi LAT sources are detected in both spectral regimes. This is in spite of the mCrab INTEGRAL sensitivity for both galactic and extragalactic sources and the breakthrough, in terms of sensitivity, achieved by Fermi at MeV-GeV energies. The majority of the 14 Fermi LAT sources clearly detected in the fourth INTEGRAL/IBIS catalog are optically identified active galactic nuclei (10) complemented by two isolated pulsars (Crab and Vela) and two high-mass X-ray binaries (LS I +61 303 and LS 5039). Two more possible associations have been found: one is 0FGL J1045.6-5937, possibly the counterpart at high energy of the massive colliding wind binary system Eta Carinae, discovered to be a soft gamma ray emitter by recent INTEGRAL observations and 0FGL J1746.0-2900 coincident with IGR J17459-2902, but still not identified with any known object at lower energy. For the remaining 189 Fermi LAT sources no INTEGRAL counterpart was found and we report the 2{sigma} upper limit in the energy band 20-40keV.
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- ID:
- ivo://CDS.VizieR/J/ApJS/194/18
- Title:
- The Galactic Bulge Survey: X-ray observations
- Short Name:
- J/ApJS/194/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce the Galactic Bulge Survey (GBS) and we provide the Chandra source list for the region that has been observed to date. Among the goals of the GBS are constraining the neutron star (NS) equation of state and the black hole (BH) mass distribution via the identification of eclipsing NS and BH low-mass X-ray binaries (LMXBs). The GBS targets two strips of 6{deg}x1{deg} (12deg^2^ in total), one above (1{deg}<b<2{deg}) and one below (-2{deg}<b<-1{deg}) the Galactic plane in the direction of the Galactic center at both X-ray and optical wavelengths. By avoiding the Galactic plane (-1{deg}<b<1{deg}) we limit the influence of extinction on the X-ray and optical emission but still sample relatively large number densities of sources. The survey is designed such that a large fraction of the X-ray sources can be identified from their optical spectra. The X-ray survey, by design, covers a large area on the sky while the depth is shallow using 2ks per Chandra pointing. In this way we maximize the predicted number ratio of (quiescent) LMXBs to cataclysmic variables. The survey is approximately homogeneous in depth to a 0.5-10keV flux of 7.7x10^-14^erg/cm^2^/s. So far, we have covered about two-thirds (8.3deg^2^) of the projected survey area with Chandra providing over 1200 unique X-ray sources. We discuss the characteristics and the variability of the brightest of these sources.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/32
- Title:
- The Multi-INstrument Burst ARchive (MINBAR)
- Short Name:
- J/ApJS/249/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest sample of type I (thermonuclear) X-ray bursts yet assembled, comprising 7083 bursts from 85 bursting sources. The sample is drawn from observations with Xenon-filled proportional counters on the long-duration satellites RXTE, BeppoSAX, and International Gamma-Ray Astrophysics Laboratory between 1996 February 8 and 2012 May 3. The burst sources were drawn from a comprehensive catalog of 115 burst sources, assembled from earlier catalogs and the literature. We carried out a consistent analysis for each burst light curve (normalized to the relative instrumental effective area) and provide measurements of rise time, peak intensity, burst timescale, and fluence. For bursts observed with the RXTE/PCA and BeppoSAX/Wide Field Camera we also provide time-resolved spectroscopy, including estimates of bolometric peak flux and fluence, and spectral parameters at the peak of the burst. For 950 bursts observed with the PCA from sources with previously detected burst oscillations, we include an analysis of the high time resolution data, providing information on the detectability and amplitude of the oscillations, as well as where in the burst they are found. We also present analysis of 118,848 observations of the burst sources within the sample time frame. We extracted 3-25keV X-ray spectra from most observations, and (for observations meeting our signal-to-noise criterion) we provide measurements of the flux, spectral colors, and, for selected sources, the position on the color-color diagram, for the best-fit spectral model. We present a description of the sample, a summary of the science investigations completed to date, and suggestions for further studies.
- ID:
- ivo://CDS.VizieR/J/ApJS/245/19
- Title:
- Thermonuclear burst oscillations (TBOs) with RXTE
- Short Name:
- J/ApJS/245/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a blind uniform search for thermonuclear burst oscillations (TBOs) in the majority of Type I bursts observed by the Rossi X-ray Timing Explorer (RXTE) (2118 bursts from 57 neutron stars). We examined 2-2002Hz power spectra from the Fourier transform in sliding 0.5-2s windows, using fine-binned light curves in the 2-60keV energy range. The significance of the oscillation candidates was assessed by simulations which took into account light-curve variations, dead time, and the sliding time windows. Some of our sources exhibited multi-frequency variability at <~15Hz that cannot be readily removed with light-curve modeling and may have an astrophysical (non-TBO) nature. Overall, we found that the number and strength of potential candidates depends strongly on the parameters of the search. We found candidates from all previously known RXTE TBO sources, with pulsations that had been detected at similar frequencies in multiple independent time windows, and discovered TBOs from SAXJ1810.8-2658. We could not confirm most previously reported tentative TBO detections or identify any obvious candidates just below the detection threshold at similar frequencies in multiple bursts. We computed fractional amplitudes of all TBO candidates and placed upper limits on non-detections. Finally, for a few sources we noted a small excess of candidates with powers comparable to fainter TBOs, but appearing in single independent time windows at random frequencies. At least some of these candidates may be noise spikes that appear interesting due to selection effects. The potential presence of such candidates calls for extra caution if claiming single-window TBO detections.
- ID:
- ivo://CDS.VizieR/J/ApJ/747/77
- Title:
- Thermonuclear X-ray bursts. II. Eddington limit
- Short Name:
- J/ApJ/747/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Time-resolved X-ray spectroscopy of thermonuclear bursts observed from low-mass X-ray binaries offer a unique tool to measure neutron-star masses and radii. In this paper, we continue our systematic analysis of all the X-ray bursts observed with Rossi X-ray Timing Explorer from X-ray binaries. We determine the events that show clear evidence for photospheric radius expansion and measure the Eddington limits for these accreting neutron stars using the bolometric fluxes attained at the touchdown moments of each X-ray burst. We employ a Bayesian technique to investigate the degree to which the Eddington limit for each source remains constant between bursts. We find that for sources with a large number of radius expansion bursts, systematic uncertainties are at a 5%-10% level. Moreover, in six sources with only pairs of Eddington-limited bursts, the distribution of fluxes is consistent with a ~10% fractional dispersion. This indicates that the spectroscopic measurements of neutron-star masses and radii using thermonuclear X-ray bursts can reach the level of accuracy required to distinguish between different neutron-star equations of state, provided that uncertainties related to the overall flux calibration of X-ray detectors are of comparable magnitude.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/14
- Title:
- The Swift/BAT hard X-ray transient monitor
- Short Name:
- J/ApJS/209/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Swift/Burst Alert Telescope (BAT) hard X-ray transient monitor provides near real-time coverage of the X-ray sky in the energy range 15-50 keV. The BAT observes 88% of the sky each day with a detection sensitivity of 5.3 mCrab for a full-day observation and a time resolution as fine as 64s. The three main purposes of the monitor are (1) the discovery of new transient X-ray sources, (2) the detection of outbursts or other changes in the flux of known X-ray sources, and (3) the generation of light curves of more than 900 sources spanning over eight years. The primary interface for the BAT transient monitor is a public Web site. Between 2005 February 12 and 2013 April 30, 245 sources have been detected in the monitor, 146 of them persistent and 99 detected only in outburst. Among these sources, 17 were previously unknown and were discovered in the transient monitor. In this paper, we discuss the methodology and the data processing and filtering for the BAT transient monitor and review its sensitivity and exposure. We provide a summary of the source detections and classify them according to the variability of their light curves. Finally, we review all new BAT monitor discoveries. For the new sources that are previously unpublished, we present basic data analysis and interpretations.
- ID:
- ivo://CDS.VizieR/J/ApJS/161/271
- Title:
- The X-ray binary population in M33. I
- Short Name:
- J/ApJS/161/271
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present the source list for three Chandra observations of the Local Group galaxy M33. The observations are centered on the nucleus and on the star-forming region NGC 604. We detect a total of 261 sources in an area of 0.2{deg}^2^ down to a flux limit of 3x10^-16^ergs/s/cm^2^, which corresponds to a luminosity of 2x10^34^ergs/s at a distance of 840kpc.
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/1468
- Title:
- Transient black hole X-ray binaries XMM obs.
- Short Name:
- J/MNRAS/471/1468
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- All observations of Galactic X-ray binaries are affected by absorption from gas and dust in the interstellar medium (ISM) which imprints narrow (line) and broad (photoelectric edges) features on the continuum emission spectrum of the binary. Any spectral model used to fit data from a Galactic X-ray binary must therefore take account of these features; when the absorption is strong (as for most Galactic sources) it becomes important to accurately model the ISM absorption in order to obtain unbiased estimates of the parameters of the (emission) spectrum of the binary system. In this paper, we present analysis of some of the best spectroscopic data from the XMM-Newton RGS instrument using the most up-to-date photoabsorption model of the gaseous ISM ISMabs. We calculate column densities for H, O, Ne and Fe for seven transient black hole X-ray binary systems. We find that the hydrogen column densities in particular can vary greatly from those presented elsewhere in the literature. We assess the impact of using inaccurate column densities and older X-ray absorption models on spectral analysis using simulated data. We find that poor treatment of absorption can lead to large biases in inferred disc properties and that an independent analysis of absorption parameters can be used to alleviate such issues.
- ID:
- ivo://CDS.VizieR/J/ApJS/157/59
- Title:
- Ultraluminous X-ray sources in nearby galaxies
- Short Name:
- J/ApJS/157/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- X-ray observations have revealed in other galaxies a class of extranuclear X-ray point sources with X-ray luminosities of 10^39^-10^41^ergs/s, exceeding the Eddington luminosity for stellar mass X-ray binaries. These ultraluminous X-ray sources (ULXs) may be powered by intermediate-mass black holes of a few thousand M_Sun_ or stellar mass black holes with special radiation processes. In this paper, we present a survey of ULXs in 313 nearby galaxies with D_25_>1 within 40Mpc with 467 ROSAT High Resolution Imager (HRI) archival observations. The HRI observations are reduced with uniform procedures, refined by simulations that help define the point source detection algorithm employed in this survey. A sample of 562 extragalactic X-ray point sources with L_X_=10^38^-10^43^ergs/s is extracted from 173 survey galaxies, including 106 ULX candidates within the D_25_ isophotes of 63 galaxies and 110 ULX candidates between 1D_25_ and 2D_25_ of 64 galaxies, from which a clean sample of 109 ULXs is constructed to minimize the contamination from foreground or background objects.
- ID:
- ivo://CDS.VizieR/J/AJ/146/107
- Title:
- Velocity curves of 10 cataclysmic binaries
- Short Name:
- J/AJ/146/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on ground-based optical observations of 10 cataclysmic binaries that were discovered through their X-ray emission. Time-resolved radial velocity spectroscopy yields unambiguous orbital periods for eight objects and ambiguous results for the remaining two. The orbital periods range from 87 minutes to 9.38 hr. We also obtained time-series optical photometry for six targets, four of which have coherent pulsations. These periods are 1218s for 1RXSJ045707.4+452751, 628s for AXJ1740.2-2903, 477s for AXJ1853.3-0128, and 935s for IGRJ19267+1325. A total of seven of the sources have coherent oscillations in X-rays or optical, indicating that they are intermediate polars (DQ Herculis stars). Time-resolved spectroscopy of one object, SwiftJ2218.4+1925, shows that it is an AM Herculis star, or polar, and IGRJ19552+0044 may also be in that class. For another object, SwiftJ0746.2-1611, we find an orbital period of 9.384 hr and detect the spectrum of the secondary star. The secondary's spectral contribution implies a distance of 900 (+190, -150)pc, where the error bars are estimated using a Monte Carlo technique to account for correlated uncertainties.
