- ID:
- ivo://CDS.VizieR/J/ApJS/222/15
- Title:
- WATCHDOG: an all-sky database of Galactic BHXBs
- Short Name:
- J/ApJS/222/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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 (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 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.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/641/410
- Title:
- XMM and Chandra X-ray sources near 4U 1755-33
- Short Name:
- J/ApJ/641/410
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on new X-ray observations of the large-scale jets recently discovered in X-rays from the black hole candidate 4U 1755-33. Our observations in 2004 show that the jets found in 2001 are still present in X-rays. However, sensitive radio observations in 2004 failed to detect the jets.
- ID:
- ivo://CDS.VizieR/J/A+A/659/A188
- Title:
- 4XMM-DR9-HECATE-based ULX catalogue
- Short Name:
- J/A+A/659/A188
- Date:
- 25 Mar 2022 09:09:32
- Publisher:
- CDS
- Description:
- Ultraluminous X-ray sources (LX>1x10^39^erg/s, ULXs) are excellent probes for extreme accretion physics, star formation history in galaxies, and intermediate-mass black holes searches. As the sample size of X-ray data from modern observatories such as XMM-Newton and Chandra increases, producing extensive catalogues of ULXs and studying their collective properties has become both a possibility and a priority. Our aim is to build a clean updated ULX catalogue based on one of the most recent XMM-Newton X-ray serendipitous survey data releases, 4XMM-DR9, and the most recent and exhaustive catalogue of nearby galaxies, HECATE. We performed a preliminary population study to test if the properties of the expanded XMM-Newton ULX population are consistent with previous findings. We performed positional cross-matches between XMM-Newton sources and HECATE objects to identify host galaxies, and we used distance and luminosity arguments to identify ULX candidates. We flagged interlopers by finding known counterparts in external catalogues and databases such as Gaia DR2 SSDS, Pan-STARRS1, the NASA/IPAC Extragalactic Database, and SIMBAD. Source, galaxy and variability parameters from 4XMM-DR9, HECATE, and 4XMM-DR9s were used to study the spectral, abundances and variability properties of the ULX sample. We identify 779 ULX candidates, 94 of which hold LX>5x10^40^erg/s. Spiral galaxies are more likely to host ULXs. For early spiral galaxies the number of ULX candidates per star-forming rate is consistent with previous studies, while a significant ULX population in elliptical and lenticular galaxies also exists. Candidates hosted by late-type galaxies tend to present harder spectra and to undergo more extreme inter-observation variability than those hosted by early-type galaxies. Approximately 30 candidates with LX>1x10^41^erg/s are also identified, constituting the most interesting candidates for intermediate-mass black hole searches. We have built the largest ULX catalogue to date. Our results on the spectral and abundance properties of ULXs confirm the findings made by previous studies based on XMM-Newton and Chandra data, while our population-scale study on variability properties is unprecedented. Our study, however, provides limited insight into the properties of the brightest ULX candidates due to the small sample size. The expected growth of X-ray catalogues and potential future follow-ups will aid in drawing a clearer picture.
- ID:
- ivo://CDS.VizieR/J/ApJ/636/200
- Title:
- XMM-Newton LMXB in NGC4649
- Short Name:
- J/ApJ/636/200
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an XMM-Newton X-ray observation of the X-ray bright E2 elliptical galaxy NGC 4649. In addition to bright diffuse emission, we resolve 158 discrete sources, ~50 of which are likely to be LMXBs associated with NGC 4649.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/129
- Title:
- XMM-Newton X-ray sources in NGC 6553
- Short Name:
- J/ApJ/738/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports the search for quiescent low-mass X-ray binaries (qLMXBs) in the globular cluster (GC) NGC 6553 using an XMM-Newton observation designed specifically for that purpose. We spectrally identify one candidate qLMXB in the core of the cluster, based on the consistency of the spectrum with a neutron star H-atmosphere model at the distance of NGC 6553. Specifically, the best-fit radius found using the three XMM European Photon Imaging Camera spectra is R_NS_=6.3^+2.3^_-0.8_ km (for M_NS_=1.4 M_{sun}_) and the best-fit temperature is kT_eff_=136^+21^_-34_ eV. Both physical parameters are in accordance with typical values of previously identified qLMXBs in GC and in the field, i.e., R_NS_~5-20 km and kT_eff_=50-150 eV. A power-law (PL) component with a photon index {Gamma}=2.1^+0.5^_-0.8_ is also required for the spectral fit and contributes ~33% of the total flux of the X-ray source. A detailed analysis supports the hypothesis that the PL component originates from nearby sources in the core, unresolved with XMM. The analysis of an archived Chandra observation provides marginal additional support to the stated hypothesis. Finally, a catalog of all the sources detected within the XMM field of view is presented here.
- ID:
- ivo://CDS.VizieR/J/BaltA/24/395
- Title:
- X-ray and radio sources in binaries
- Short Name:
- J/BaltA/24/395
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The goal of the present study was to compile complete list of binaries discovered at non-optical bands: X-ray binaries (XRB) and radio pulsars in binaries. Due to the lack of a unified identification system for XRB we had to select them from five principal catalogues of X-ray sources. After cross-identification and positional cross-matching, a general catalogue of 373 XRB was constructed for the first time. It contains coordinates, indication of photometric and spectroscopic binarity and extensive cross-identification. In the preparation of the catalogue, a number of XRB classification collisions were resolved, some catalogued identifiers and coordinates were corrected, and duplicated entries in the original catalogues were found.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/150
- Title:
- X-ray binaries in M101 with HST optical data
- Short Name:
- J/ApJ/890/150
- Date:
- 17 Jan 2022 00:32:05
- Publisher:
- CDS
- Description:
- The high-energy emission from nearby, star-forming galaxies is dominated by X-ray binaries, where a neutron star or black hole is accreting mass from either a low-mass (<~M_{sun}_) or high-mass (>~8M_{sun}_) star. Donor stars with intermediate masses ~3-7M_{sun}_ are also possible, but rarer in our Galaxy. Since it is not possible to separate low-, intermediate-, and high-mass X-ray binaries (LMXBs, IMXBs, and HMXBs) from their X-ray properties alone, we use optical images of M101 taken with the Hubble Space Telescope to directly constrain the masses of donor stars in X-ray binaries down to ~3M_{sun}_. For X-ray binaries that still live within their parent star cluster, the age of the cluster provides strong constraints on the mass of the donor and hence type of binary. We present the classification, on a source-by-source basis, of 140 X-ray point sources in the nearby spiral galaxy M101 (D=6.4+/-0.2Mpc). We find that, overall, HMXBs appear to follow the spiral arms, while LMXBs dominate the bulge region as expected, but also appear to form an inter-arm disk population. The X-ray luminosity functions for HMXBs and LMXBs are well fit by a power-law distribution, dN/dL_X_{propto}L^{alpha}^, with {alpha}=-1.71+/-0.06 (HMXBs) and {alpha}=-1.96+/-0.08 (LMXBs), and the brightest sources are consistent with the expectations from sampling statistics without requiring a physical cutoff. Overall, our results for HMXB and LMXB populations agree well with the specific star formation rate map presented for M101 recently by Lehmer and collaborators.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/130
- Title:
- X-ray binaries in NGC 1291 with Chandra
- Short Name:
- J/ApJ/749/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Chandra studies of the X-ray binary (XRB) populations in the bulge and ring regions of the ring galaxy NGC 1291. We detect 169 X-ray point sources in the galaxy, 75 in the bulge and 71 in the ring, utilizing the four available Chandra observations totaling an effective exposure of 179 ks. We report photometric properties of these sources in a point-source catalog. There are {approx}40% of the bulge sources and {approx}25% of the ring sources showing >3{sigma} long-term variability in their X-ray count rate. The X-ray colors suggest that a significant fraction of the bulge ({approx}75%) and ring ({approx}65%) sources are likely low-mass X-ray binaries (LMXBs). The spectra of the nuclear source indicate that it is a low-luminosity 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 {approx}1.5x10^37^ and {approx}2.2x10^37^ erg/s for the bulge and ring populations, respectively. Both XLFs can be fit with a broken power-law model, and the shapes are consistent with those expected for populations dominated by LMXBs. We perform detailed population synthesis modeling of the XRB populations in NGC 1291, which suggests that the observed combined XLF is dominated by 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/780/83
- Title:
- X-ray binaries observed in M31 with Chandra
- Short Name:
- J/ApJ/780/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have created 0.3-10keV, 13yr, unabsorbed luminosity light curves 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 0.5-4.5keV 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 >~10^35^erg/s 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_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.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/95
- Title:
- X-ray observations of HCG galaxies
- Short Name:
- J/ApJ/817/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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 +/-1{sigma} scatter of the Mineo et al. 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. L_X_-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 L_X_ 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 L_X_ values can be observed due to strong XRB variability.
