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Spectroscopic identification of INTEGRAL high-energy sources with VLT/ISAAC
Abstract
Context . The INTEGRAL satellite has been observing the γ -ray sky for 15 years and has detected over 900 X-ray sources of various nature. However, more than 200 of these sources still lack precise identification.
Aims . Our goal is to reveal the nature of the high-energy sources detected by INTEGRAL. In particular, we want to improve the census of X-ray binaries.
Methods . Photometry and spectroscopy were performed in July 2012 on 14 INTEGRAL sources in near-infrared at the Very Large Telescope on the European Southern Observatory-UT3 telescope equipped with the ISAAC spectrograph. We used K s images reaching to a depth of magnitude 18.5 to look for unique counterparts to high-energy detections to check for both extended sources and photometric variability. The analysis of near-infrared spectral features allows us to constrain the nature of these X-ray sources by comparing them to stellar spectra atlases.
Results . We present photometric and/or spectroscopic data for 14 sources (IGR J00465–4005, IGR J10447–6027, IGR J12489–6243, IGR J13020–6359, IGR J13186–6257, IGR J15293–5609, IGR J17200–3116, IGR J17404–3655, IGR J17586–2129, IGR J17597–2201, IGR J18457+0244, IGR J18532+0416, IGR J19308+0530, and IGR J19378–0617). We conclude that 5 of these are active galactic nuclei, 5 are cataclysmic variables, 2 are low- or intermediate-mass X-ray binaries, and 2 are Be high-mass X-ray binaries.
... Two of our CV triples were classified as X-ray binaries (XRBs) in the VSX catalog. These are IGR J19308+0530, which was classified as an Intermediate-Mass X-ray Binary (IMXB; Fortin et al. 2018) and SWIFT J2124.6+0500, which was classified as a Low-Mass X-ray Binary (LMXB; Halpern 2013). Both of these XRB candidates have long orbital periods (15 and 20 hours), and their nature as XRBs has been debated. ...
... Initially, Ratti et al. (2013) suggest that the system is consistent with being a CV, though they note that a neutron star accretor cannot be ruled out. Later on, Fortin et al. (2018) propose that the system is more consistent with having a neutron star accretor, making it an IMXB. Given that the system has a relatively close tertiary companion (720 au), we investigate it in more detail. ...
... For a typical F4 star with M donor = 1.4 M ⊙ , this implies an accretor mass of M 1 = 0.82 M ⊙ , consistent with a WD and with the results of Ratti et al. (2013). Fortin et al. (2018) and Avakyan et al. (2023) argue that IGR J19408+0530 is likely an IMXB (i.e., that it has a neutron star accretor) based primarily on its soft X-ray spectrum. Given the companion's low inferred mass and the source's low X-ray luminosity, we consider a WD companion much more likely and therefore include it in our sample. ...
The formation of cataclysmic variables (CVs) has long been modeled as a product of common envelope evolution (CEE) in isolated binaries. However, a significant fraction of intermediate-mass stars -- the progenitors of the white dwarfs (WDs) in CVs -- are in triples. We therefore investigate the importance of triple star dynamics in CV formation. Using Gaia astrometry and existing CV catalogs, we construct a sample of CVs in hierarchical triples within 1 kpc of the Sun, containing main-sequence (MS) and WD tertiaries at separations of 100 - 30,000 au. We infer that at least 10% of CVs host wide tertiaries. To interpret this discovery, we evolve a population of 2000 triples using detailed three-body simulations, 47 of which become CVs. We predict that 20% of CVs in triples form without ever experiencing CEE, where the WD and donor are brought together by the eccentric Kozai-Lidov (EKL) mechanism after the formation of the WD. These systems favor larger donor stars and longer birth orbital periods (8-20 hrs) than typical CVs. Among systems that do undergo CEE, about half would not have interacted without the presence of the tertiary. Triple formation channels both with and without CEE require initially wide inner orbits ( au), which in turn require larger tertiary separations to be stable. Consistent with this prediction, we find that the observed Gaia CV triples have wider separations on average than normal wide binaries selected in the same way. Our work underscores the importance of triples in shaping interacting binary populations including CVs, ultracompact binaries, and low-mass X-ray binaries.
... In addition to HMXBs, other large groups of IGR sources are Cataclysmic Variables (CVs) and Low-Mass X-ray Binaries (LMXBs, see e.g. Fortin et al., 2018;Lutovinov et al., 2020), Active Galactic Nuclei (AGN, see e.g. Tomsick et al., 2015), and pulsars or Pulsar Wind Nebulae (PWNe). ...
... Indeed, Stephen et al. (2006) showed a low (<2%) chance coincidence probability between the positions of INTEGRAL detections and those of softer X-ray sources within the hard X-ray error circle; similar figures are found using radio surveys (e.g., Maiorano et al., 2011). This approach largely helps pinpointing the actual optical, as well as NIR, counterpart of the object responsible for the hard X-ray emission detected with INTE-GRAL, which can then be studied through optical/NIR spectroscopy (see Fig. 9 for a sketch; for details, see Chaty et al., 2008;Zurita Heras and Chaty, 2008;Butler et al., 2009;Coleiro et al., 2013;Fortin et al., 2018;Masetti et al., 2013;Bikmaev et al., 2006Bikmaev et al., , 2008Burenin et al., 2008Burenin et al., , 2009Lutovinov et al., 2012bLutovinov et al., , 2013aÖzbey Arabacı et al., 2012;Karasev et al., 2018Karasev et al., , 2020, and references therein), and also through mid-IR observations . ...
... Fifteen years of optical and NIR spectroscopic follow-up studies of unidentified INTEGRAL sources performed by several groups worldwide led to a host of identifications: to the best of our knowledge, 265 such objects had their nature identified or better described through optical/NIR spectroscopy, with the following percentage breakdown: 58% AGNs, 28% Galactic X-ray binaries (3/4 of them identified as HMXBs), 13% CVs and about 1% active stars. We notice that, if one takes into account the NIR spectroscopic identifications only, the overwhelming majority of sources is made of HMXBs (∼90%), with just about 10% of AGNs (Coleiro et al., 2013;Fortin et al., 2018) and references therein. A large fraction of the INTE-GRAL AGN have been characterized in terms of optical and X-ray properties by Malizia et al. (2016), as demonstrated in the all-sky map in Fig. 10. ...
The INTEGRAL hard X-ray surveys have proven to be of fundamental importance. INTEGRAL has mapped the Galactic plane with its large field of view and excellent sensitivity. Such hard X-ray snapshots of the whole Milky Way on a time scale of a year are beyond the capabilities of past and current narrow-FOV grazing incidence X-ray telescopes. By expanding the INTEGRAL X-ray survey into shorter timescales, a productive search for transient X-ray emitters was made possible. In more than fifteen years of operation, the INTEGRAL observatory has given us a sharper view of the hard X-ray sky, and provided the triggers for many follow-up campaigns from radio frequencies to gamma-rays. In addition to conducting a census of hard X-ray sources across the entire sky, INTEGRAL has carried out, through Earth occultation maneuvers, unique observations of the large-scale cosmic X-ray background, which will without question be included in the annals of X-ray astronomy as one of the mission's most salient contribution to our understanding of the hard X-ray sky.
... More recently, deeper infrared spectroscopy did detect the He I line, as well as Brγ and a weak C IV emission line (VLT/ ISAAC, Fortin et al. 2018). Fortin et al. argue that the nondetection of Pfund emission rules out a hot B-type star and, based on the NIR study of CVs by Harrison et al. (2004), conclude that IGR J17402-3656 could be a CV with a K3-5 V companion if at a distance d=530-700 pc. ...
... mas (Gaia DR2, 12 Gaia Collaboration et al. 2018). This translates into a distance = -+ d 2.6 0.8 1.9 kpc (Bailer-Jones et al. 2018), significantly greater than the one anticipated by Fortin et al. (2018). At 2.6 kpc, IGR J17402-3656 would have an X-ray luminosity L 3-79 keV ∼1.6×10 ...
... 34 erg s −1 , which is too high for a Polar (e.g., Sazonov et al. 2006) and fully compatible with the average luminosity derived from IPs with known distances (e.g., Schwope 2018; Suleimanov et al. 2019). In this scenario, the infrared (IR) luminosity of the IP system is likely to be dominated by the emission of the accretion disk, explaining why it could be about one order of magnitude higher than what has been anticipated for the companion star by Fortin et al. (2018). Landi et al. (2010) identified the soft X-ray (later named 1SXPS J205642.6+494009 in Swift catalogs, e.g., Evans et al. 2014), NIR (2MASS J20564271+4940068), and radio (NVSS 205642+494005) counterparts of IGR J20569+4940. ...
The NuSTAR Legacy program titled Unidentified INTEGRAL Sources targeted faint hard X-ray sources revealed by INTEGRAL in the Galactic plane in order to provide conclusive identification of their nature and insights on the population of faint hard X-ray sources. The NuSTAR and Swift X-Ray Telescope observations obtained in 2015–2017 contributed to the successful identification of five persistent sources. Here, we report on the spectral and variability analyses that helped to consolidate the classifications of IGR J10447–6027, IGR J16181–5407, and IGR J20569+4940 as active galactic nuclei and IGR J17402–3656 as an intermediate polar. An optical spectrum of the blazar IGR J20569+4940 is also presented. Combining these results with successful identifications of other such faint and persistent INTEGRAL sources reported in the literature, we investigate possible implications for the population of persistent high-mass X-ray binaries (HMXBs) below the identification completion limit of the INTEGRAL survey. The current trend hints at a deficit of persistent HMXBs below F 17–60 keV = 10 ⁻¹¹ erg cm ⁻² s ⁻¹ , but additional efforts dedicated to classifying faint hard X-ray sources are needed before we can draw solid conclusions.
... More recently, NIR spectroscopy from VLT/ISAAC provided a redshift measurement of this source (z = 0.047±0.001, Fortin et al. 2018) demonstrating the extragalactic nature of IGR J10447-6027, possibly a Seyfert 2 AGN. ...
... More recently, deeper infrared spectroscopy did detect the He i line, as well as Brγ and a weak C iv emission line (VLT/ISAAC, Fortin et al. 2018). They argue that the non-detection of Pfund emission rules out a hot B-type star and, based on the NIR study of CVs by Harrison et al. (2004), conclude that IGR J17402-3656 could be a CV with a K3-5 V companion if at a distance d = 530-700 pc. ...
... The Chandra counterpart of IGR J17402-3656 also corresponds to a single Gaia source having a parallax Table 3. measurement of 0.38 ± 0.14 mas (Gaia DR2 7 , Gaia Collaboration et al. 2018). This translates into a distance d = 2.6 +1.9 −0.8 kpc (Bailer-Jones et al. 2018), significantly greater than the one anticipated by Fortin et al. (2018). 7 The other four targets of this Legacy program (Table 2) do not have reliable parallax measurements due to either an absence of optical counterparts or the presence of a significant astrometric excess noise. ...
The NuSTAR Legacy program 'Unidentified INTEGRAL sources' targeted faint hard X-ray sources revealed by INTEGRAL in the Galactic plane in order to provide conclusive identification of their nature and insights on the population of faint hard X-ray sources. The NuSTAR and Swift/XRT observations obtained in 2015-2017 contributed to the successful identification of five persistent sources. Here, we report on the spectral and variability analyses which helped to consolidate the classifications of IGR J10447-6027, IGR J16181-5407 and IGR J20569+4940 as active galactic nuclei, and IGR J17402-3656 as an intermediate polar. An optical spectrum of the blazar IGR J20569+4940 is also presented. Combining these results with successful identifications of other such faint and persistent INTEGRAL sources reported in the literature, we investigate possible implications for the population of persistent high mass X-ray binaries (HMXBs) below the identification completion limit of the INTEGRAL survey. The current trend hints at a deficit of persistent HMXBs below erg cm s, but additional efforts dedicated to classifying faint hard X-ray sources are needed before we can draw solid conclusions.
... This particular AGN resides in a region of very high Galactic extinction ( =9.5), and the redshift is based on an He 10830 line measurement from the literature (Fortin et al. 2018). ...
... Of the remaining six BZB sources we could not detect strong host galaxy features for a redshift, there are five sources with an existing redshift from NED or SIMBAD, which we use as the redshift measurement. There is one very high-extinction AGN ( =9.5) 2MASS J10445192-6025115, which was found to have a redshift of =0.047 (Fortin et al. 2018) based on He 10830 line. The beamed and lensed AGN PKS 1830-21, was measured using H in the NIR at =2.507 (Lidman et al. 1999) due to it's high extinction ( ) from being in the Galactic plane. ...
We present the AGN catalog and optical spectroscopy for the second data release of the Swift BAT AGN Spectroscopic Survey (BASS DR2). With this DR2 release we provide 1425 optical spectra, of which 1181 are released for the first time, for the 858 hard X-ray selected AGN in the Swift BAT 70-month sample. The majority of the spectra (813/1425, 57%) are newly obtained from VLT/Xshooter or Palomar/Doublespec. Many of the spectra have both higher resolution (R>2500, N~450) and/or very wide wavelength coverage (3200-10000 A, N~600) that are important for a variety of AGN and host galaxy studies. We include newly revised AGN counterparts for the full sample and review important issues for population studies, with 44 AGN redshifts determined for the first time and 780 black hole mass and accretion rate estimates. This release is spectroscopically complete for all AGN (100%, 858/858) with 99.8% having redshift measurements (857/858) and 96% completion in black hole mass estimates of unbeamed AGN (outside the Galactic plane). This AGN sample represents a unique census of the brightest hard X-ray selected AGN in the sky, spanning many orders of magnitude in Eddington ratio (Ledd=10^-5-100), black hole mass (MBH=10^5-10^10 Msun), and AGN bolometric luminosity (Lbol=10^40-10^47 ergs/s).
... Schlegel et al. (1998) and the extinction law derived by Cardelli et al. (1989). a This particular AGN resides in a region of very high Galactic extinction (A V = 9.5), and the redshift is based on an He II λ10830 line measurement from the literature (Fortin et al. 2018). ( Here we provide a list of multiple soft X-ray AGNs that are detected within the BAT beam but are weakly associated (∼70-700 kpc; Table 5). ...
... Of the remaining six BZB sources for which we could not detect strong host galaxy features for a redshift, there are five sources with an existing redshift from NED or SIMBAD, which we use as the redshift measurement. There is one very high extinction AGN (A V = 9.5), 2MASS J10445192-6025115, which was found to have a redshift of z = 0.047 (Fortin et al. 2018) based on the He II λ10830 line. The beamed and lensed AGN PKS 1830-21 was measured using Hα in the NIR at z = 2.507 (Lidman et al. 1999) owing to its high extinction (A V ) from being in the Galactic plane. ...
We present the active galactic nucleus (AGN) catalog and optical spectroscopy for the second data release of the Swift BAT AGN Spectroscopic Survey (BASS DR2). With this DR2 release we provide 1449 optical spectra, of which 1182 are released for the first time, for the 858 hard-X-ray-selected AGNs in the Swift BAT 70-month sample. The majority of the spectra (801/1449, 55%) are newly obtained from Very Large Telescope (VLT)/X-shooter or Palomar/Doublespec. Many of the spectra have both higher resolution ( R > 2500, N ∼ 450) and/or very wide wavelength coverage (3200–10000 Å, N ∼ 600) that are important for a variety of AGN and host galaxy studies. We include newly revised AGN counterparts for the full sample and review important issues for population studies, with 47 AGN redshifts determined for the first time and 790 black hole mass and accretion rate estimates. This release is spectroscopically complete for all AGNs (100%, 858/858), with 99.8% having redshift measurements (857/858) and 96% completion in black hole mass estimates of unbeamed AGNs (722/752). This AGN sample represents a unique census of the brightest hard-X-ray-selected AGNs in the sky, spanning many orders of magnitude in Eddington ratio ( L / L Edd = 10 ⁻⁵ –100), black hole mass ( M BH = 10 ⁵ –10 ¹⁰ M ⊙ ), and AGN bolometric luminosity ( L bol = 10 ⁴⁰ –10 ⁴⁷ erg s ⁻¹ ).
... The authors finally chose the source with the hardest X-ray emission as the true counterpart and concluded it was either a CV or an HMXB. A study by Fortin et al. ( 2018 ) was also done in infrared and the source was found to be a CV with K or M companion star, despite the lack of molecular absorption in the spectrum. The y e xplained this peculiarity by saying that the white dwarf accreted a portion of the atmosphere of the low-mass star. ...
Since its launch, the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has discovered hundreds of X-ray sources, many of which lack proper classification. This mission also led to the discovery of new categories of high mass X-ray binaries (HMXB). We use the spectra of the X-Shooter instrument at the Very Large Telescope (VLT) of the European Southern Observatory (ESO) to better understand the nature of 3 accreting binaries (IGR J10101-5654, IGR J11435-6109 and IGR J12489-6243) discovered by INTEGRAL. We mainly focused on the lines and continuum from the X-Shooter spectra. We used atlases to constrain the nature of the sources and also complemented the spectra with measurements taken by Spitzer and the Wide-field Infrared Survey Explorer (WISE) in infrared, and parallaxes from Gaia for the distances. We determined the nature of each binary system: a BeHMXB system with a companion star of spectral type B0.5Ve with peculiar carbon emission for IGR J10101-5654 and IGR J11435-6109, and a CV system with an evolved K star (K0IV-K2IV) for IGR J12489-6243. We also estimated some geometrical parameters of the decretion disk and neutron star’s orbit in the case of IGR J11435-6109.
... Subsequently, optical and/or near-infrared (NIR) spectroscopy is performed on their putative lower-energy counterpart(s) with the aim to uncover their nature (see e.g. Rahoui et al. 2008;Masetti et al. 2013;Parisi et al. 2014;Rojas et al. 2017;Fortin et al. 2018;Karasev et al. 2018;Marchesini et al. 2019, and references therein, to name a few). As a result, the nature of more than 300 INTEGRAL-discovered sources (IGRs) have been identified on a total of 560 listed in Bird et al. (2016) -mainly active galactic nuclei, cataclysmic variables (CV), but also high-mass X-ray binaries (HMXB) and low-mass Xray binaries (LMXB) and a similar number is available for the new BAT transients, though the latter are dominated by extra-galactic sources. ...
In recent years, thanks to the continuous surveys performed by INTEGRAL and Swift satellites, our knowledge of the hard X-ray/soft gamma-ray sky has greatly improved. As a result it is now populated with about 2000 sources, both Galactic and extra-galactic, mainly discovered by IBIS and BAT instruments. Many different follow-up campaigns have been successfully performed by using a multiwavelength approach, shedding light on the nature of a number of these new hard X-ray sources. However, a fraction are still of an unidentified nature. This is mainly due to the lack of lower energy observations, which usually deliver a better constrained position for the sources, and the unavailability of the key observational properties, needed to obtain a proper physical characterization. Here, we report on the classification of two poorly studied Galactic X-ray transients IGR J20155+3827 and Swift J1713.4−4219, for which the combination of new and/or archival X-ray and optical/NIR (near-infrared) observations have allowed us to pinpoint their nature. In particular, thanks to XMM–Newton archival data together with new optical spectroscopic and archival optical/NIR photometric observations, we have been able to classify IGR J20155+3827 as a distant HMXB (high-mass X-ray binaries). The new INTEGRAL and Swift data collected during the 2019 X-ray outburst of Swift J1713.4−4219, in combination with the archival optical/NIR observations, suggest an LMXB (low-mass X-ray binaries) classification for this source.
... Subsequently, optical and/or near-infrared (NIR) spectroscopy is performed on their putative lower-energy counterpart(s) with the aim to uncover their nature (see e.g. Rahoui et al. 2008;Masetti et al. 2013;Parisi et al. 2014;Rojas et al. 2017;Fortin et al. 2018;Karasev et al. 2018;Marchesini et al. 2019, and references therein, to name a few). As a result, the nature of more than 300 INTEGRAL-discovered sources (IGRs) have been identified on a total of 560 listed in Bird et al. (2016) -mainly active galactic nuclei, cataclysmic variables (CV), but also high-mass X-ray binaries (HMXB) and low-mass Xray binaries (LMXB) and a similar number is available for the new BAT transients, though the latter are dominated by extra-galactic sources. ...
In recent years, thanks to the continuous surveys performed by INTEGRAL and Swift satellites, our knowledge of the hard X-ray/soft gamma-ray sky has greatly improved. As a result it is now populated with about 2000 sources, both Galactic and extra-galactic, mainly discovered by IBIS and BAT instruments. Many different follow-up campaigns have been successfully performed by using a multi-wavelength approach, shedding light on the nature of a number of these new hard X-ray sources. However, a fraction are still of a unidentified nature. This is mainly due to the lack of lower energy observations, which usually deliver a better constrained position for the sources, and the unavailability of the key observational properties, needed to obtain a proper physical characterization. Here we report on the classification of two poorly studied Galactic X-ray transients IGR J20155+3827 and Swift J1713.4-4219, for which the combination of new and/or archival X-ray and Optical/NIR observations have allowed us to pinpoint their nature. In particular, thanks to XMM\Newton archival data together with new optical spectroscopic and archival Optical/NIR photometric observations, we have been able to classify IGR J20155+3827 as a distant HMXB. The new INTEGRAL and Swift data collected during the 2019 X-ray outburst of Swift J1713.4-4219, in combination with the archival optical/NIR observations, suggest a LMXB classification for this source.
... The bulk (∼90%) of these identifications stemmed from the program of Masetti and collaborators which encompassed the use of at least a dozen telescopes across the globe (see Masetti et al. (2013) and references therein). Further AGN identifications from other groups have also been reported in the literature like in Bikmaev et al. (2006Bikmaev et al. ( , 2008Zurita Heras et al. (2009);Karasev et al. (2018); Fortin et al. (2018). It is worth noting that an overlap of detected sources is present across the INTE-GRAL and Swift/BAT (e.g. ...
AGN are among the most energetic phenomena in the Universe and in the last two decades INTEGRAL's contribution in their study has had a significant impact. Thanks to the INTEGRAL extragalactic sky surveys, all classes of soft X-ray detected (in the 2-10 keV band) AGN have been observed at higher energies as well. Up to now, around 450 AGN have been catalogued and a conspicuous part of them are either objects observed at high-energies for the first time or newly discovered AGN. The high-energy domain (20-200 keV) represents an important window for spectral studies of AGN and it is also the most appropriate for AGN population studies, since it is almost unbiased against obscuration and therefore free of the limitations which affect surveys at other frequencies. Over the years, INTEGRAL data have allowed to characterise AGN spectra at high energies, to investigate their absorption properties, to test the AGN unification scheme and to perform population studies. In this review the main results are reported and INTEGRAL's contribution to AGN science is highlighted for each class of AGN. Finally, new perspectives are provided, connecting INTEGRAL's science with that at other wavelengths and in particular to the GeV/TeV regime which is still poorly explored.
... Optical [98]. In turn, spectral identification of the optical counterpart as an evolved red giant star (spectral classes KIII -MIII) is a sufficient base to suggest that the given INTEGRAL source is a symbiotic star (see, e.g., [72,68]). ...
Accreting white dwarfs (WDs) constitute a significant fraction of the hard X-ray sources detected by the INTEGRAL observatory. Most of them are magnetic Cataclysmic Variables (CVs) of the intermediate polar (IP) and polar types, but the contribution of the Nova-likes systems and the systems with optically thin boundary layers, Dwarf Novae (DNs) and Symbiotic Binaries (or Symbiotic Stars, SySs) in quiescence is also not negligible. Here we present a short review of the results obtained from the observations of cataclysmic variables and symbiotic binaries by INTEGRAL. The highlight results include the significant increase of the known IP population, determination of the WD mass for a significant fraction of IPs, the establishment of the luminosity function of magnetic CVs, and uncovering origin of the Galactic ridge X-ray emission which appears to largely be associated with hard emission from magnetic CVs.
Context . Low-mass X-ray binaries (LMXBs) are high-energy sources that require multi-wavelength follow-up campaigns to be fully characterised. New transients associated with LMXBs are regularly discovered, and previously known systems are often revisited by astronomers to constrain their intrinsic parameters. All of this information compiled into a catalogue may build a useful tool for subsequent studies on LMXBs and their population.
Aims . We aim to provide an update on past LMXB catalogues dating back 16 yr and propose to the community a database on Galactic LMXBs with the most complete, manually curated set of parameters and their original references. On top of a fixed version accessible through Vizier, we propose hosting the catalogue independently on our GitHub collaboration, side-by-side with our previous catalogue on high-mass X-ray binaries. The database will be regularly updated based on new publications and community inputs.
Methods . We built a working base by cross-matching previous LMXB catalogues and supplementing them with lists of hard X-ray sources detected over the past 20 yr. We compiled information from Simbad on LMXBs as a starting point for a thorough, manual search in the literature to retrieve important parameters that characterize LMXBs. We retrieved newly detected LMXBs and candidates directly from literature searches. Counterparts to these LMXBs are compiled from hard X-ray to infrared and radio domains. Every piece of information presented on the LMXBs is curated and backed by accurate references.
Results . We present a catalogue of 339 Galactic LMXBs listing their coordinates, companion star spectral type, systemic radial velocity, component masses and compact object nature, the presence of type I X-ray bursts, as well as orbital data. Coordinates and identifiers of counterparts at various wavelengths are given, including 140 LMXBs detected in Gaia DR3.
We present a new catalogue of low-mass X-ray binaries (LMXBs) in the Galaxy. The catalogue contains source names, coordinates, source types, fluxes, distances, system parameters, and other characteristic properties of 349 LMXBs, including systems that have been newly discovered or reclassified since the most recently reported LMXB catalogues. The aim of this catalogue is to provide a list of all currently known Galactic objects identified as LMXBs with some basic information on each system (including X-ray and optical/IR properties where possible). Literature published before May 2023 has been taken into account where possible when compiling this information. References for all reported properties as well as object-finding charts in several energy bands are provided as part of the catalogue. We plan to update the catalogue regularly, in particular to reflect new objects discovered in the ongoing large-scale surveys such as Gaia and eROSITA.
Context. High-mass X-ray binaries (HMXBs) are a particular class of high-energy sources that require multi-wavelength observational efforts to be properly characterised. New identifications and the refinement of previous measurements are regularly published in the literature by independent teams of researchers and might, when they are collected in a catalogue, offer a tool for facilitating further studies of HMXBs.
Aims. We update previous instances of HMXB catalogues in the Galaxy and provide the community easy access to the most complete set of observables on Galactic HMXBs. In addition to the fixed version that is available in Vizier, we also aim to host and maintain a dynamic version that can be updated upon request from users. Any modification will be logged in this version.
Methods. Using previous HMXB catalogues supplemented by listings of hard X-ray sources detected in the past 20 yr, we produced a base set of HMXBs and candidates by means of identifier and sky coordinate cross matches. We queried in Simbad for unreferenced HMXBs. We searched for as many hard X-ray, soft X-ray, optical, and infrared counterparts to the HMXBs as we could in well-known catalogues and compiled their coordinates. Each HMXB was subjected to a meticulous search in the literature to find relevant measurements and the original reference.
Results. We provide a catalogue of 152 HMXBs in the Galaxy with their best known coordinates, the spectral type of the companion star, systemic radial velocities, component masses, orbital period, eccentricity, and spin period when available. We also provide the coordinates and identifiers for each counterpart we found from hard X-rays to the near-infrared, including 111 counterparts from the recent Gaia DR3 catalogue.
We present an incremental version (4FGL-DR3, for Data Release 3) of the fourth Fermi Large Area Telescope (LAT) catalog of γ -ray sources. Based on the first 12 years of science data in the energy range from 50 MeV to 1 TeV, it contains 6658 sources. The analysis improves on that used for the 4FGL catalog over eight years of data: more sources are fit with curved spectra, we introduce a more robust spectral parameterization for pulsars, and we extend the spectral points to 1 TeV. The spectral parameters, spectral energy distributions, and associations are updated for all sources. Light curves are rebuilt for all sources with 1 yr intervals (not 2 month intervals). Among the 5064 original 4FGL sources, 16 were deleted, 112 are formally below the detection threshold over 12 yr (but are kept in the list), while 74 are newly associated, 10 have an improved association, and seven associations were withdrawn. Pulsars are split explicitly between young and millisecond pulsars. Pulsars and binaries newly detected in LAT sources, as well as more than 100 newly classified blazars, are reported. We add three extended sources and 1607 new point sources, mostly just above the detection threshold, among which eight are considered identified, and 699 have a plausible counterpart at other wavelengths. We discuss the degree-scale residuals to the global sky model and clusters of soft unassociated point sources close to the Galactic plane, which are possibly related to limitations of the interstellar emission model and missing extended sources.
Context. All neutron star progenitors in neutron-star high-mass X-ray binaries (NS HMXBs) undergo a supernova event that may lead to a significant natal kick impacting the motion of the whole binary system. The space observatory Gaia performs a deep optical survey with exquisite astrometric accuracy, for both position and proper motions, that can be used to study natal kicks in NS HMXBs.
Aims. Our aim is to survey the observed Galactic NS HMXB population and to quantify the magnitude of the kick imparted onto their NSs, and to highlight any possible differences arising between the various HMXB types.
Methods. We performed a census of Galactic NS HMXBs and cross-matched existing detections in X-rays, optical, and infrared with the Gaia Early Data Release 3 database. We retrieved their parallaxes, proper motions, and radial velocities (when available), and performed a selection based on the quality of the parallax measurement. We then computed their peculiar velocities with respect to the rotating reference frame of the Milky Way, and including their respective masses and periods, we estimated their kick velocities through Markov chain Monte Carlo simulations of the orbit undergoing a supernova event.
Results. We infer the posterior kick distributions of 35 NS HMXBs. After an inconclusive attempt at characterising the kick distributions with Maxwellian statistics, we find that the observed NS kicks are best reproduced by a gamma distribution of mean 116 −15 +18 km s ⁻¹ . We note that supergiant systems tend to have higher kick velocities than Be HMXBs. The peculiar velocity versus non-degenerate companion mass plane hints at a similar trend, supergiant systems having a higher peculiar velocity independently of their companion mass.
A large fraction of X-ray sources in our Galaxy are low-mass X-ray binaries, containing a black hole or a neutron star accreting from a gravitationally bound low-mass (1 M) companion star. These systems are among the older population of stars and accreting systems in the Galaxy, and typically have long accretion histories. Low-mass X-ray binaries are categorized into various sub-classes based on their observed properties such as X-ray variability and brightness, nature of the companion star and/or the compact object, and binary configuration. In this Chapter, we review the phenomenology of sub-classes of these systems and summarize observational finding regarding their characteristics, populations, and their distribution in the Galaxy.
The International Gamma-Ray Astrophysics Laboratory (INTEGRAL), launched in 2002, continues its successful work in observing the sky at energies E > 20 keV. The legacy of the mission already includes a large number of discovered or previously poorly studied hard X-ray sources. The growing INTEGRAL archive allows one to conduct an all-sky survey including a number of deep extragalactic fields and the deepest ever hard X-ray survey of the Galaxy. Taking advantage of the data gathered over 17 years with the IBIS coded-mask telescope of INTEGRAL, we conducted survey of hard X-ray sources, providing flux information from 17 to 290 keV. The catalog includes 929 objects, 890 of which exceed a detection threshold of 4.5σ and the rest are detected at 4.0 − 4.5σ and belong to known cataloged hard X-ray sources. Among the identified sources of known or suspected nature, 376 are associated with the Galaxy and Magellanic clouds, including 145 low-mass and 115 high-mass X-ray binaries, 79 cataclysmic variables, and 37 of other types; and 440 are extragalactic, including 429 active galactic nuclei (AGNs), 2 ultra-luminous sources, one supernova (AT2018cow) and 8 galaxy clusters. 113 sources remain unclassified. 46 objects are detected in the hard X-ray band for the first time. The LogN-LogS distribution of 356 non-blazar AGNs is measured down to a flux of 2 × 10−12 erg s−1 cm−2 and can be described by a power law with a slope of 1.44 ± 0.09 and normalization 8 × 10−3 deg−2 at 10−11 erg s−1 cm−2. The LogN-LogS distribution of unclassified sources indicates that the majority of them are of extragalactic origin.
The orbital International Gamma-Ray Astrophysics Laboratory (INTEGRAL), launched in 2002, continues its successful work in observing the sky at energies above 20 keV. The growing INTEGRAL data archive allows one to conduct a hard X-ray all-sky survey including a number of deep extragalactic fields and the deepest ever hard X-ray survey of the Galaxy. Taking advantage of the data gathered over 17 years with the IBIS coded-mask telescope on board INTEGRAL, we conducted a survey of hard X-ray sources in the 17-60 keV band, providing flux information in different energy bands up to 290 keV. The catalog of sources includes 929 objects, 890 of which exceed a detection threshold of 4.5 sigma and the rest are detected at 4.0-4.5 sigma and belong to known cataloged INTEGRAL sources and sources from the on-going all-sky survey by the BAT telescope of the Neil Gehrels Swift Observatory. Among the identified sources with known or suspected nature, 376 are associated with Galaxy and Magellanic clouds, including 145 low-mass X-ray binaries, 115 high-mass X-ray binaries, 79 cataclysmic variables, and 37 of other types; and 440 are extragalactic, including 429 active galactic nuclei (AGNs), 2 ultra-luminous sources (ULXs), supernova remnant AT2018cow and 8 galaxy clusters. 113 sources from the catalog remain unclassified. 46 objects are detected in the hard X-ray band for the first time. The cumulative LogN-LogS distribution of non-blazar AGNs, based on 356 sources detected at S/N>4.5 sigma, is measured down to flux 2E-12 erg/s/cm^2 and can be described by a power law with a slope of 1.44 +/- 0.09 and a normalization of 8E-3 sources per deg^2 at fluxes >1E-11 erg/s/cm^2. The LogN-LogS distribution of unclassified sources indicates that the majority of them are of extragalactic origin.
The INTEGRAL hard X-ray surveys have proven to be of fundamental importance. INTEGRAL has mapped the Galactic plane with its large field of view and excellent sensitivity. Such hard X-ray snapshots of the whole Milky Way on a time scale of a year are beyond the capabilities of past and current narrow-FOV grazing incidence X-ray telescopes. By expanding the INTEGRAL X-ray survey into shorter timescales, a productive search for transient X-ray emitters was made possible. In more than fifteen years of operation, the INTEGRAL observatory has given us a sharper view of the hard X-ray sky, and provided the triggers for many follow-up campaigns from radio frequencies to gamma-rays. In addition to conducting a census of hard X-ray sources across the entire sky, INTEGRAL has carried out, through Earth occultation maneuvers, unique observations of the large-scale cosmic X-ray background, which will without question be included in the annals of X-ray astronomy as one of the mission’s most salient contribution to our understanding of the hard X-ray sky.
Accreting white dwarfs (WDs) constitute a significant fraction of the hard X-ray sources detected by the INTEGRAL observatory. Most of them are magnetic Cataclysmic Variables (CVs) of the intermediate polar (IP) and polar types, but the contribution of the Nova-likes systems and the systems with optically thin boundary layers, Dwarf Novae (DNs) and Symbiotic Binaries (or Symbiotic Stars, SySs) in quiescence is also not negligible. Here we present a short review of the results obtained from the observations of cataclysmic variables and symbiotic binaries by INTEGRAL. The highlight results include the significant increase of the known IP population, determination of the WD mass for a significant fraction of IPs, the establishment of the luminosity function of magnetic CVs, and uncovering origin of the Galactic ridge X-ray emission which appears to largely be associated with hard emission from magnetic CVs.
High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in nearby Galaxies. Thanks to their highly variable emissions and complex phenomenology, they have attracted the interest of the high energy astrophysical community since the dawn of X-ray Astronomy. In more recent years, they have challenged our comprehension of physical processes in many more energy bands, ranging from the infrared to very high energies.
In this review, we provide a broad but concise summary of the physical processes dominating the emission from high mass X-ray binaries across virtually the whole electromagnetic spectrum. These comprise the interaction of stellar winds with the high gravitational and magnetic fields of compact objects, the behaviour of matter under extreme magnetic and gravity conditions, and the perturbation of the massive star evolutionary processes by presence in a binary system.
We highlight the role of the INTEGRAL mission in the discovery of many of the most interesting objects in the high mass X-ray binary class and its contribution in reviving the interest for these sources over the past two decades. We show how the INTEGRAL discoveries have not only contributed to significantly increase the number of high mass X-ray binaries known, thus advancing our understanding of the population as a whole, but also have opened new windows of investigation that stimulated the multi-wavelength approach nowadays common in most astrophysical research fields.
We conclude the review by providing an overview of future facilities being planned from the X-ray to the very high energy domain that will hopefully help us in finding an answer to the many questions left open after more than 18 years of INTEGRAL scientific observations.
High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in nearby Galaxies. Thanks to their highly variable emissions and complex phenomenology, they have attracted the interest of the high energy astrophysical community since the dawn of X-ray Astronomy. In more recent years, they have challenged our comprehension of physical processes in many more energy bands, ranging from the infrared to very high energies. In this review, we provide a broad but concise summary of the physical processes dominating the emission from high mass X-ray binaries across virtually the whole electromagnetic spectrum. These comprise the interaction of stellar winds with the high gravitational and magnetic fields of compact objects, the behaviour of matter under extreme magnetic and gravity conditions, and the perturbation of the massive star evolutionary processes by presence in a binary system. We highlight the role of the INTEGRAL mission in the discovery of many of the most interesting objects in the high mass X-ray binary class and its contribution in reviving the interest for these sources over the past two decades. We show how the INTEGRAL discoveries have not only contributed to significantly increase the number of high mass X-ray binaries known, thus advancing our understanding of the population as a whole, but also have opened new windows of investigation that stimulated the multi-wavelength approach nowadays common in most astrophysical research fields. We conclude the review by providing an overview of future facilities being planned from the X-ray to the very high energy domain that will hopefully help us in finding an answer to the many questions left open after more than 18 years of INTEGRAL scientific observations.
The International Gamma-Ray Astrophysics Laboratory ( INTEGRAL ) satellite has detected in excess of 1000 sources in the ∼20–100 keV band during its surveys of the sky over the past 17 years. We obtained 5 ks observations of 15 unclassified INTEGRAL Gamma-Ray (IGR) sources with the Chandra X-ray Observatory in order to localize them, to identify optical/IR counterparts, to measure their soft X-ray spectra, and to classify them. For 10 of the IGR sources, we detect Chandra sources that are likely (or in some cases certain) to be the counterparts. IGR J18007–4146 and IGR J15038–6021 both have Gaia parallax distances, placing them at and kpc, respectively. We tentatively classify both of them as intermediate polar-type cataclysmic variables. Also, IGR J17508–3219 is likely to be a Galactic source, but it is unclear if it is a Dwarf Nova or another type of transient. For IGR J17118–3155, we provide a Chandra localization, but it is unclear if the source is Galactic or extragalactic. Based on either near-IR/IR colors or the presence of extended near-IR emission, we classify four sources as active galactic nuclei (AGNs; IGR J16181–5407, IGR J16246–4556, IGR J17096–2527, and IGR J19294+1327), and IGR J20310+3835 and IGR J15541–5613 are AGN candidates. In addition, we identified an AGN in the INTEGRAL error circle of IGR J16120–3543 that is a possible counterpart.
. High Mass X-ray Binaries (HMXB) have been revealed by a wealth of multi-wavelength observations, from X-ray to optical and infrared domain. After describing the 3 different kinds of HMXB, we focus on 3 HMXB hosting supergiant stars: IGR J16320-4751, IGR J16465-4507 and IGR J16318-4848, respectively called “The Good”, “The Bad” and “The Ugly”. We review in these proceedings what the observations of these sources have brought to light concerning our knowledge of HMXB, and what part still remains in the dark side. Many questions are still pending, related to accretion processes, stellar wind properties in these massive and active stars, and the overall evolution due to transfer of mass and angular momentum between the companion star and the compact object. Future observations should be able to answer these questions, which constitute the dark side of HMXB.
We present intermediate-resolution (R ~ 8000-12,000) high signal-to-noise (S/N) H- and K-band spectroscopy of a sample of 37 optically visible stars, ranging in spectral type from O3 to B3 and representing most luminosity classes. Spectra of this quality can be used to constrain the temperature, luminosity, and general wind properties of OB stars, when used in conjunction with sophisticated atmospheric model codes. Most important is the need for moderately high resolutions (R ≥ 5000) and very high signal-to-noise (S/N ≥ 150) spectra for a meaningful profile analysis. When using near-infrared spectra for a classification system, moderately high signal-to-noise (S/N ~ 100) is still required, though the resolution can be relaxed to just a thousand or two. In the Appendix we provide a set of very high-quality near-infrared spectra of Brackett lines in six early-A dwarfs. These can be used to aid in the modeling and removal of such lines when early-A dwarfs are used for telluric spectroscopic standards.
Thanks to the large collecting area (3 x ~1500 cm at 1.5 keV) and wide
field of view (30' across in full field mode) of the X-ray cameras on board the
European Space Agency X-ray observatory XMM-Newton, each individual pointing
can result in the detection of hundreds of X-ray sources, most of which are
newly discovered. Recently, many improvements in the XMM-Newton data reduction
algorithms have been made. These include enhanced source characterisation and
reduced spurious source detections, refined astrometric precision of sources,
greater net sensitivity for source detection and the extraction of spectra and
time series for fainter sources, with better signal-to-noise. Further, almost
50% more observations are in the public domain compared to 2XMMi-DR3, allowing
the XMM-Newton Survey Science Centre (XMM-SSC) to produce a much larger and
better quality X-ray source catalogue. The XMM-SSC has developed a pipeline to
reduce the XMM-Newton data automatically and using improved calibration a new
catalogue version has been made from XMM-Newton data made public by 2013 Dec.
31 (13 years of data). Manual screening ensures the highest data quality. This
catalogue is known as 3XMM. In the latest release, 3XMM-DR5, there are 565962
X-ray detections comprising 396910 unique X-ray sources. For the 133000
brightest sources, spectra and lightcurves are provided. For all detections,
the positions on the sky, a measure of the detection quality, and an evaluation
of variability is provided, along with the fluxes and count rates in 7 X-ray
energy bands, the total 0.2-12 keV band counts, and four hardness ratios. To
identify the detections, a cross correlation with 228 catalogues is also
provided for each X-ray detection. 3XMM-DR5 is the largest X-ray source
catalogue ever produced. Thanks to the large array of data products, it is an
excellent resource in which to find new and extreme objects.
Context: Absorption by molecules in the Earth's atmosphere strongly affects
ground-based astronomical observations. The resulting absorption line strength
and shape depend on the highly variable physical state of the atmosphere, i.e.
pressure, temperature, and mixing ratio of the different molecules involved.
Usually, supplementary observations of so-called telluric standard stars (TSS)
are needed to correct for this effect, which is expensive in terms of telescope
time. We have developed the software package molecfit to provide synthetic
transmission spectra based on parameters obtained by fitting narrow ranges of
the observed spectra of scientific objects. These spectra are calculated by
means of the radiative transfer code LBLRTM and an atmospheric model. In this
way, the telluric absorption correction for suitable objects can be performed
without any additional calibration observations of TSS. Aims: We evaluate the
quality of the telluric absorption correction using molecfit with a set of
archival ESO-VLT X-Shooter visible and near-infrared spectra. Methods: Thanks
to the wavelength coverage from the U to the K band, X-Shooter is well suited
to investigate the quality of the telluric absorption correction with respect
to the observing conditions, the instrumental set-up, input parameters of the
code, the signal-to-noise of the input spectrum, and the atmospheric profiles.
These investigations are based on two figures of merit, I_off and I_res, that
describe the systematic offsets and the remaining small-scale residuals of the
corrections. We also compare the quality of the telluric absorption correction
achieved with moelcfit to the classical method based on a telluric standard
star. (Abridged)
Context: The interaction of the light from astronomical objects with the
constituents of the Earth's atmosphere leads to the formation of telluric
absorption lines in ground-based collected spectra. Correcting for these lines,
mostly affecting the red and infrared region of the spectrum, usually relies on
observations of specific stars obtained close in time and airmass to the
science targets, therefore using precious observing time. Aims: We present
molecfit, a tool for correcting for telluric absorption lines based on
synthetic modelling of the Earth's atmospheric transmission. Molecfit is
versatile and can be used with data obtained with various ground-based
telescopes and instruments. Methods: Molecfit combines a publicly available
radiative transfer code, a molecular line database, atmospheric profiles, and
various kernels to model the instrument line spread function. The atmospheric
profiles are created by merging a standard atmospheric profile representative
of a given observatory's climate, of local meteorological data, and of
dynamically retrieved altitude profiles for temperature, pressure, and
humidity. We discuss the various ingredients of the method, its applicability,
and its limitations. We also show examples of telluric line correction on
spectra obtained with a suite of ESO Very Large Telescope (VLT) instruments.
Results: Compared to previous similar tools, molecfit takes the best results
for temperature, pressure, and humidity in the atmosphere above the observatory
into account. As a result, the standard deviation of the residuals after
correction of unsaturated telluric lines is frequently better than 2% of the
continuum. Conclusion: Molecfit is able to accurately model and correct for
telluric lines over a broad range of wavelengths and spectral resolutions.
(Abridged)
The source IGR J17200−3116 was discovered in the hard X-ray band by INTEGRAL. A periodic X-ray modulation at ∼326 s was detected in its Swift light curves by our group (and subsequently confirmed by a Swift campaign). In this paper, we report on the analysis of all the Swift observations, which were collected between 2005 and 2011, and of an ∼20 ks XMM–Newton pointing that was carried out in 2013 September. During the years covered by the Swift and XMM–Newton observations, the 1–10 keV fluxes range from ∼1.5 to 4 × 10−11 erg cm−2 s−1. IGR J17200−3116 displays spectral variability as a function of the pulse phase and its light curves show at least one short
(a few hundreds of seconds) dip, during which the flux dropped at 20–30 per cent of the average level. Overall, the timing
and spectral characteristics of IGR J17200−3116 point to an accreting neutron star in a high-mass system but, while the pulse-phase
spectral variability can be accounted for by assuming a variable local absorbing column density, the origin of the dip is
unclear. We discuss different possible explanations for this feature, favouring a transition to an ineffective accretion regime,
instead of an enhanced absorption along the line of sight.
Since it started observing the sky, the INTEGRAL satellite has discovered new
categories of high mass X-ray binaries (HMXB) in our Galaxy. These observations
raise important questions on the formation and evolution of these rare and
short-lived objects. We present here new infrared observations from which to
reveal or constrain the nature of 15 INTEGRAL sources, which allow us to update
and discuss the Galactic HMXB population statistics. After previous photometric
and spectroscopic observing campaigns in the optical and near-infrared, new
photometry and spectroscopy was performed in the near-infrared with the SofI
instrument on the ESO/NTT telescope in 2008 and 2010 on a sample of INTEGRAL
sources. These observations, and specifically the detection of certain features
in the spectra, allow the identification of these high-energy objects by
comparison with published nIR spectral atlases of O and B stars. We present
photometric data of nine sources (IGR J10101-5654, IGR J11187-5438, IGR
J11435-6109, IGR J14331-6112, IGR J16328-4726, IGR J17200-3116, IGR
J17354-3255, IGR J17404-3655, and IGR J17586-2129) and spectroscopic
observations of 13 sources (IGR J10101-5654, IGR J11435-6109, IGR J13020-6359,
IGR J14331-6112, IGR J14488-5942, IGR J16195-4945, IGR J16318-4848, IGR
J16320-4751, IGR J16328-4726, IGR J16418-4532, IGR J17354-3255, IGR
J17404-3655, and IGR J17586-2129). Our spectroscopic measurements indicate
that: five of these objects are Oe/Be high-mass X-ray binaries (BeHMXB), six
are supergiant high-mass X-ray binaries (sgHMXB), and two are sgB[e]. From a
statistical point of view, we estimate the proportion of confirmed sgHMXB to be
42% and that of the confirmed BeHMXB to be 49%. The remaining 9% are peculiar
HMXB.
We present an atlas of spectra of O- and B-type stars, obtained with the Short Wavelength Spectrometer (SWS) during the Post-Helium program of the Infrared Space Observatory (ISO). This program is aimed at extending the Morgan & Keenan classification scheme into the near-infrared. Later type stars will be discussed in a separate publication. The observations consist of 57 SWS Post-Helium spectra from 2.4 to 4.1 mu m, supplemented with 10 spectra acquired during the nominal mission with a similar observational setting. For B-type stars, this sample provides ample spectral coverage in terms of subtype and luminosity class. For O-type stars, the ISO sample is coarse and therefore is complemented with 8 UKIRT Larcmin -band observations. In terms of the presence of diagnostic lines, the Larcmin -band is likely the most promising of the near-infrared atmospheric windows for the study of the physical properties of B stars. Specifically, this wavelength interval contains the Bralpha , Pfgamma , and other Pfund lines which are probes of spectral type, luminosity class and mass loss. Here, we present simple empirical methods based on the lines present in the 2.4 to 4.1 mu m interval that allow the determination of i) the spectral type of B dwarfs and giants to within two subtypes; ii) the luminosity class of B stars to within two classes; iii) the mass-loss rate of O stars and B supergiants to within 0.25 dex. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the UK) and with the participation of ISAS and NASA. The appendix is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin.qcat?J/A+A/384/473
We present phase-resolved spectroscopy and photometry of the optical counterpart to the X-ray binary IGR J19308+0530. Ellipsoidal
modulations in the light curve show that the F-type companion star in the system is Roche lobe filling. The optical spectra
are dominated by absorption features from the donor star, with ∼10–20 per cent disc contribution to the optical continuum.
We measure an orbital period of 14.662 ± 0.001 h, a radial velocity semi-amplitude for the companion star of K2 = 91.4 ± 1.4 km s− 1 and a rotational broadening of v sin i = 108.9 ± 0.6 km s− 1. From K2 and v sin i, given that the donor star is filling its Roche lobe, we derive a mass ratio of q = M2/M1 = 1.78 ± 0.04, which is typically considered to be too large for stable Roche lobe overflow. Our observations support an
inclination of ∼50°. The accretor in IGR J19308+0530 is most likely a white dwarf, although a neutron star cannot entirely
be excluded.
We present 2 μm (K band) spectra of 180 well-studied, optically
visible, luminous stars. Most of the stars are of OB spectral type, but
we have also included a number of Oe and Be stars, OBN and OBC stars,
cool hypergiant stars, and high-mass X-ray binary stars. Our aim in
studying normal OB stars is to develop an empirical relationship between
2 μm spectral features of these massive stars and their stellar
temperature and luminosity. We find the system of lines between 2.0 and
2.2 μm is particularly good for differentiating the early- and mid-O
type stars. In the late-O and early-B stars, differentiation becomes
more difficult, as the features show only moderate changes. We have
developed a spectral classification system for the K band to be used to
estimate effective temperatures of 0 and early-B stars. We demonstrate
that K-band spectroscopy is superior in estimating the temperature of
hot, luminous stars than the traditional methods of using infrared or
even optical photometric colors alone. The only requirements are that
adequate resolution (R > 1000) and signal-to-noise (S/N ˜70) be
achieved. With our classification system, stars behind large amounts of
visible extinction, such as in young, heavily reddened H II regions
throughout our Galaxy, may be identified and studied for the first time
through 2 μm spectroscopy.
Emission lines are commonly seen in the K-band spectra of supergiant
stars, however, the OBN super-giants, which have a higher ratio of some
processed materials at their surface, may be more likely to show line
emission, especially the He I singlet transition at 2.058 μm. This
has led us to propose an evolutionary scenario for some of the Galactic
center He I emission-line stars, which evokes rotational mixing (Maeder
1987; Langer 1992) to explain both the strong line emission and high
luminosity of these mysterious sources.
We have compared our spectroscopic database with the most recent stellar
atmosphere models. We are encouraged by the good match between the model
line profiles at 2 μm of Schaerer et al. (1996b) and those observed
in OB stars. Finally, we include a thorough discussion of the
observational and reduction methods employed to obtain the spectra shown
in this atlas for the benefit of those wishing to obtain similar,
classification-quality, near-infrared spectra.
We present moderate resolution (lambda / Delta lambda ~ 1380 and lambda
/ Delta lambda ~ 4830) spectra of 43 K0 to M6 III stars covering 2.19 -
2.34 mu m and measure equivalent widths of the strongest absorption
features - Na I, Ca I, and (12) CO(2,0) - present on the spectra. The
high resolution Wallace & Hinkle (1996) spectral atlas shows that
our moderate resolution measurements of the atomic features have
significant contributions from other species, such as Sc, S, Fe, Ti, Si,
and V. We also find that our measured equivalent widths are affected by
CN absorption present in the continuum bands. In spite of this, the
equivalent widths of Na I and Ca I features at moderate resolution still
show a strong dependence on effective temperature. The CO equivalent
width at moderate resolution is less affected by other lines and
continuum placement than the atomic features, because of its relatively
greater strength. We compare our data to similar data taken for
late-type dwarf stars (Ali et al. 1995) and find that a two dimensional
spectral classification can be constructed based on the near-IR spectra.
The quantity log[EW(CO)/(EW(Na)+EW(Ca))] is a strong luminosity
indicator independent of effective temperature, while the equivalent
width of (12) CO(2,0) has a well-defined dependence on effective
temperature for a given luminosity. This two dimensional spectral
classification is ideal for cool stars obscured by dust in, for example,
the central part of the Galactic bulge and regions of star formation.
We present an empirical infrared spectral library of medium-resolution (R ≈ 2000-3000) H (1.6 μm) and K (2.2 μm) band spectra of 218 red stars, spanning a range of [Fe/H] from ~-2.2 to ~+0.3. The sample includes Galactic disk stars, bulge stars from Baade's window, and red giants from Galactic globular clusters. We report the values of 19 indices covering 12 spectral features measured from the spectra in the library. Finally, we derive calibrations to estimate the effective temperature, and diagnostic relationships to determine the luminosity classes of individual stars from near-infrared spectra. This paper is part of a larger effort aimed at building a near-IR spectral library to be incorporated in population synthesis models, as well as at testing synthetic stellar spectra.
In this paper, we report on the fourth soft gamma-ray source catalog obtained with the IBIS gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 70 Ms of high-quality observations performed during the first five and a half years of the Core Program and public observations. Compared to previous IBIS surveys, this catalog includes a substantially increased coverage of extragalactic fields, and comprises more than 700 high-energy sources detected in the energy range 17-100 keV, including both transients and faint persistent objects that can only be revealed with longer exposure times. A comparison is provided with the latest Swift/BAT survey results.
Between 1997 June and 2001 February the Two Micron All Sky Survey (2MASS) collected 25.4 Tbytes of raw imaging data covering 99.998% of the celestial sphere in the near-infrared J (1.25 μm), H (1.65 μm), and Ks (2.16 μm) bandpasses. Observations were conducted from two dedicated 1.3 m diameter telescopes located at Mount Hopkins, Arizona, and Cerro Tololo, Chile. The 7.8 s of integration time accumulated for each point on the sky and strict quality control yielded a 10 σ point-source detection level of better than 15.8, 15.1, and 14.3 mag at the J, H, and Ks bands, respectively, for virtually the entire sky. Bright source extractions have 1 σ photometric uncertainty of <0.03 mag and astrometric accuracy of order 100 mas. Calibration offsets between any two points in the sky are <0.02 mag. The 2MASS All-Sky Data Release includes 4.1 million compressed FITS images covering the entire sky, 471 million source extractions in a Point Source Catalog, and 1.6 million objects identified as extended in an Extended Source Catalog.
In this paper we report on the third soft gamma-ray source catalog obtained with the IBIS/ISGRI gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 40 Ms of high-quality observations performed during the first 3.5 yr of Core Program and public IBIS/ISGRI observations. Compared to previous IBIS/ISGRI surveys, this catalog includes a substantially increased coverage of extragalactic fields, and comprises more than 400 high-energy sources detected in the energy range 17-100 keV, including both transients and faint persistent objects that can only be revealed with longer exposure times.
In this paper we report the second soft gamma-ray source catalog obtained with the IBIS/ISGRI gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 10 Ms of high-quality observations performed during the first 2 years of Core Program and public IBIS/ISGRI observations, and covers ~50% of the whole sky. The main aim of the first survey was to scan systematically, for the first time at energies above 20 keV, the whole Galactic plane to achieve a limiting sensitivity of ~1 mcrab in the central radian. The target of the second year of the INTEGRAL mission lifetime was to expand as much as possible our knowledge of the soft gamma-ray sky, with the same limiting sensitivity, to at least 50% of the whole sky, mainly by including a substantial coverage of extragalactic fields. This catalog comprises more than 200 high-energy sources detected in the energy range 20-100 keV, including new transients not active during the first year of operation, faint persistent objects revealed with longer exposure time, and several Galactic and extragalactic sources in sky regions not observed in the first survey. The mean position error for all the sources detected with significance above 10 σ is ~40'', enough to identify most of them with a known X-ray counterpart and to unveil the nature of most of the strongly absorbed ones, even though they are very difficult to detect in X-rays.
We report on Chandra observations of 18 hard X-ray (>20 keV) sources
discovered with the INTEGRAL satellite near the Galactic plane. For 14 of the
INTEGRAL sources, we have uncovered one or two potential Chandra counterparts
per source. These provide soft X-ray (0.3-10 keV) spectra and sub-arcsecond
localizations, which we use to identify counterparts at other wavelengths,
providing information about the nature of each source. Despite the fact that
all of the sources are within 5 degrees of the plane, four of the IGR sources
are AGN (IGR J01545+6437, IGR J15391-5307, IGR J15415-5029, and IGR
J21565+5948) and four others are likely AGN (IGR J03103+5706, IGR J09189-4418,
IGR J16413-4046, and IGR J16560-4958) based on each of them having a strong IR
excess and/or extended optical or near-IR emission. We compare the X-ray and
near-IR fluxes of this group of sources to those of AGN selected by their 2-10
keV emission in previous studies and find that these IGR AGN are in the range
of typical values. There is evidence in favor of four of the sources being
Galactic (IGR J12489-6243, IGR J15293-5609, IGR J16173-5023, and IGR
J16206-5253), but only IGR J15293-5609 is confirmed as a Galactic source as it
has a unique Chandra counterpart and a parallax measurement from previous
optical observations that puts its distance at 1.56+/-0.12 kpc. The 0.3-10 keV
luminosity for this source is 1.4e32 erg/s, and its optical/IR spectral energy
distribution is well described by a blackbody with a temperature of 4200-7000 K
and a radius of 12.0-16.4 Rsun. These values suggest that IGR J15293-5609 is a
symbiotic binary with an early K-type giant and a white dwarf accretor. We also
obtained likely Chandra identifications for IGR J13402-6428 and IGR
J15368-5102, but follow-up observations are required to constrain their source
types.
(abridged) Hard X-ray surveys performed by the INTEGRAL satellite have discovered a conspicuous fraction (up to 30%) of unidentified objects among the detected sources. Here we continue our identification program by selecting probable optical candidates using positional cross-correlation with soft X-ray, radio, and/or optical archives, and performing optical spectroscopy on them. As a result, we identified or more accurately characterized 44 counterparts of INTEGRAL sources: 32 active galactic nuclei, with redshift 0.019 < z < 0.6058, 6 cataclysmic variables (CVs), 5 high-mass X-ray binaries (2 of which in the Small Magellanic Cloud), and 1 low-mass X-ray binary. This was achieved by using 7 telescopes of various sizes and archival data from two online spectroscopic surveys. The main physical parameters of these hard X-ray sources were also determined using the available multiwavelength information. AGNs are the most abundant population among hard X-ray objects, and our results confirm this tendency when optical spectroscopy is used as an identification tool. The deeper sensitivity of recent INTEGRAL surveys enables one to begin detecting hard X-ray emission above 20 keV from sources such as LINER-type AGNs and non-magnetic CVs. Comment: 22 pages, 14 figures, 6 tables, accepted for publication on A&A, main journal
The IBIS imager on board INTEGRAL, with a sensitivity better than a mCrab in deep observations and a point source location accuracy of the order of few arcminutes, has localized so far 723 hard X-ray sources in the 17--100 keV energy band, of which a fraction of about 1/3 are still unclassified. The aim of this research is to provide sub-arcsecond localizations of the unidentified sources, necessary to pinpoint the optical and/or infrared counterpart of those objects whose nature is so far unknown. The cross-correlation between the new IBIS sources published within the fourth INTEGRAL/IBIS Survey catalogue and the CHANDRA/ACIS data archive resulted in a sample of 5 not yet identified objects. We present here the results of CHANDRA X-ray Observatory observations of these five hard X-ray sources discovered by the INTEGRAL satellite. We associated IGR J10447-6027 with IR source 2MASSJ10445192-6025115, IGR J16377-6423 with the cluster CIZA J1638.2-6420, IGR J14193-6048 with the pulsar with nebula PSR J1420-6048 and IGR J12562+2554 with the Quasar SDSSJ125610.42+260103.5. We suggest that the counterpart of IGR J12288+0052 may be an AGN/QSO type~2 at a confidence level of 90%. Comment: ApJ accepted
We report on 0.3-10 keV X-ray observations by the Chandra X-ray Observatory of the fields of 22 sources that were discovered as hard X-ray (20-100 keV) sources by the INTEGRAL satellite (IGR sources). The purpose of the Chandra observations is to localize the sources and to measure their soft X-ray spectra in order to determine the nature of the sources. We find very likely Chandra counterparts for 18 of the 22 sources. We discuss the implications for each source, considering previous results and new optical or IR identifications, and we identify or suggest identifications for the nature of 16 of the sources. Two of the sources, IGR J14003-6326 and IGR J17448-3232, are extended on arcminute scales. We identify the former as a pulsar wind nebula (PWN) with a surrounding supernova remnant (SNR) and the latter as a SNR. In the group of 242 IGR sources, there is only one other source that has previously been identified as a SNR. We confirm a previous identification of IGR J14331-6112 as an High-Mass X-ray Binary (HMXB), and we suggest that IGR J17404-3655, IGR J16287-5021, IGR J17354-3255, IGR J17507-2647, IGR J17586-2129, and IGR J13186-6257 are candidate HMXBs. Our results indicate or confirm that IGR J19267+1325, IGR J18173-2509, and IGR J18308-1232 are Cataclysmic Variables (CVs), and we suggest that IGR J15529-5029 may also be a CV. We confirm that IGR J14471-6414 is an Active Galactic Nucleus (AGN), and we also suggest that IGR J19443+2117 and IGR J18485-0047 may be AGN. Finally, we found Chandra counterparts for IGR J11098-6457 and IGR J18134-1636, but more information is required to determine the nature of these two sources. Comment: 14 pages, Accepted by ApJ
Context: The INTEGRAL hard X-ray observatory has revealed an emerging population of highly obscured X-ray binary systems through multi-wavelength observations. Previous studies have shown that many of these sources are high-mass X-ray binaries hosting neutron stars orbiting around luminous and evolved companion stars. Aims: To better understand this newly-discovered population, we have selected a sample of sources for which an accurate localisation is available to identify the stellar counterpart and reveal the nature of the companion star and of the binary system. Methods: We performed an intensive study of a sample of thirteen INTEGRAL sources, through multi-wavelength optical to NIR photometric and spectroscopic observations, using EMMI and SofI instruments at the ESO NTT telescope. We performed accurate astrometry and identified candidate counterparts for which we give the optical and NIR magnitudes. We detected many spectral lines allowing us to determine the spectral type of the companion star. We fitted with stellar black bodies the mid-infrared to optical spectral energy distributions of these sources. From the spectral analysis and SED fitting we identified the nature of the companion stars and of the binary systems. (abridged).
(abridged) We analysed data from observations of 17 INTEGRAL sources made with the Swift satellite. We refine the position of the hard X-ray sources to an accuracy of a few arcsec. We then browsed the online catalogs (e.g., NED, SIMBAD, 2MASS, 2MASX, USNO) to search for counterparts at other wavelengths. We also made use of the X-ray spectral parameters to try to identify the nature of those sources. We provide the X-ray position with arcsec accuracy, identify possible infrared and optical counterparts (when found), give the magnitudes in those bands and in the optical and UV as seen with the Swift/UVOT telescope when observations are available. We confirm the previously suggested associations and source types for IGR J03532-6829, J05346-5759, J10101-5654, J13000+2529, J13020-6359, J15479-4529, J18214-1318, and J23206+6431. We identify IGR J09025-6814 as an AGN for the first time, and we suggest that it may be a Seyfert 2. We suggest that IGR J05319-6601, J16287-5021, J17353-3539 and J17476-2253 are X-ray binaries, with J05319-6601 being located in the LMC and the other three possibly being HMXBs in our Galaxy. For IGR J15161-3827 and J20286+2544, we find several possible X-ray counterparts in the IBIS error region, and we discuss which, if any, are the likely counterparts. Both are likely AGNs, although the latter could be a blend of two AGNs. For IGR J03184-0014 and J19267+1325, we find X-ray sources slightly outside the IBIS error circle. In the former, we do not favour an association of the Swift and INTEGRAL source, while it is very likely that IGR J19267+1325 and the Swift source are the same. Comment: 12 pages, 3 figures, accepted for publication in A&A
USNO-B is an all-sky catalog that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations. The data were obtained from scans of 7,435 Schmidt plates taken for the various sky surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85% accuracy for distinguishing stars from non-stellar objects. A brief discussion of various issues is given here, but the actual data are available from http://www.nofs.navy.mil and other sites. Comment: Accepted by Astronomical Journal
Context : If relativistic particle acceleration takes place in colliding-wind binaries, hard X-rays and gamma-rays are expected through inverse Compton emission, but to date these have never been unambiguously detected. Aims : To detect this emission, observations of Eta Carinae were performed with INTEGRAL, leveraging its high spatial resolution. Methods : Deep hard X-ray images of the region of Eta Car were constructed in several energy bands. Results : The hard X-ray emission previously detected by BeppoSax around Eta Car originates from at least 3 different point sources. The emission of Eta Car itself can be isolated for the first time, and its spectrum unambiguously analyzed. The X-ray emission of Eta Car in the 22-100 keV energy range is very hard (photon index around 1) and its luminosity is 7E33 erg/s. Conclusions : The observed emission is in agreement with the predictions of inverse Compton models, and corresponds to about 0.1% of the energy available in the wind collision. Eta Car is expected to be detected in the GeV energy range.
(Abridged) We made use of X-ray observations with the X-ray telescope on-board the \swift observatory to refine the X-ray position to 3-5" accuracy of 12 INTEGRAL sources, so as to further identify their counterpart at optical, infrared, and radio wavelengths, to try to unveil their true nature. We then searched the online catalogues (e.g. NED, SIMBAD, 2MASS, 2MASX, and NVSS) to search for counterparts at other wavelengths. For all sources, we give a refined X-ray position, provide X-ray spectral parameters, identify infrared counterparts, and give magnitudes at optical and ultra violet wavelengths seen with UVOT when observations are available. We confirm the nature of six sources formerly suspected to be AGN (IGR J02343+3229, J13149+4422, J14579-4308, J16385-2057, J18559+1535, J19378-0617). Our analysis first leads us to suggest that IGR J09523-6231 and IGR J10147-6354 are AGN. While the former has recently been confirmed as a Seyfert 1.5 AGN, we suggest the latter is a Seyfert 2. All other sources may be Galactic sources, in which case their spectral shape may suggest that they are X-ray binaries. In one case (IGR J19308+0530), the Galactic nature is confirmed through the identification of an F8 star as the counterpart. We favour a distance to the source not greater than 1 kpc. The source is likely to be a neutron star XRB or a CV. We also report the discovery of six serendipitous sources of unknown nature. Comment: 7 pages, 2 figures, accepted for publication in A&A. Several changes since version 1 including referee's comments. Significant modifications in the case of IGR J18559+1535
Parameters from the literature, such as positions, photoelectric absorption (nH), spin and orbital periods, and distances or redshifts, were collected for all ~500 sources detected by INTEGRAL-ISGRI so far. We investigate where new and previously-known sources detected by ISGRI fit in the parameter space of high-energy objects, and we use the parameters to test correlations expected from theoretical predictions. For example, the influence of the local absorbing matter on periodic modulations is studied for Galactic High-Mass X-ray Binaries (HMXBs) with OB supergiant and Be companions. We examine the spatial distribution of different types of sources in the Milky Way using various projections of the Galactic plane, in order to highlight signatures of stellar evolution and to speculate on the origin of the group of sources whose classifications are still uncertain. ISGRI has detected similar numbers of X-ray Binaries and Active Galactic Nuclei (AGN). The former group contains new members of the class of HMXBs with supergiant stellar companions. Thanks to these additional systems, we are able to show that HMXBs are generally segregated in plots of intrinsic nH versus the orbital period of the system and versus the spin period of the pulsar, based on whether the companion is a Be or an OB supergiant star. We also find a tentative but expected anti-correlation between nH and the orbital period, and a possible and unexpected correlation between the nH and the spin period. While only a handful of new Low-Mass X-ray Binaries (LMXBs) have been discovered, there are many sources that remain unclassified and they appear to follow a spatial distribution typical of Galactic sources (especially LMXBs) rather than extragalactic sources.
Optical spectroscopic identification of the nature of 21 unidentified southern hard X-ray objects is reported here in the framework of our campaign aimed at determining the nature of newly-discovered and/or unidentified sources detected by INTEGRAL. Our results show that 5 of these objects are magnetic Cataclysmic Variables (CVs), 4 are High-Mass X-ray Binaries (HMXBs; one of which is in the Large Magellanic Cloud) and 12 are Active Galactic Nuclei (AGNs). When feasible, the main physical parameters for these hard X-ray sources are also computed using the multiwavelength information available in the literature. These identifications further underscore the importance of INTEGRAL in the study of the hard X-ray spectrum of AGNs, HMXBs and CVs, and the usefulness of a strategy of catalogues cross-correlation plus optical spectroscopy to securely pinpoint the actual nature of the X-ray sources detected with INTEGRAL. Comment: 14 pages, 7 figures, 6 tables, accepted for publication on A&A, main journal. Figures 1 and 2 and Table 1 will only appear on the on-line version of the paper
We report on the results of observations of hard X-ray sources in the Galactic plane with the Chandra X-ray Observatory. The hard X-ray IGR sources were discovered by the INTEGRAL satellite, and the goals of the Chandra observations are to provide sub-arcsecond localizations to obtain optical and infrared counterparts and to provide constraints on their 0.3-10 keV spectra. We obtained relatively short, ~5 ks, observations for 20 IGR sources and find a bright Chandra source in INTEGRAL error circles in 12 cases. In 11 of these cases, a cross-correlation with optical and/or infrared source catalogs yields a counterpart, and the range of J-band magnitudes is 8.1-16.4. Also, in 4 cases, the Chandra X-ray spectra show evidence for absorbing material surrounding the compact object with a column density of local material in excess of 5x10^22 cm^-2. We confirm that IGR J00234+6141 is a Cataclysmic Variable and IGR J14515-5542 is an Active Galactic Nucleus (AGN). We also confirm that IGR J06074+2205, IGR J10101-5645, IGR J11305-6256, and IGR J17200-3116 are High Mass X-ray Binaries (HMXBs). Our results (along with follow-up optical spectroscopy reported elsewhere) indicate that IGR J11435-6109 is an HMXB and IGR J18259-0706 is an AGN. We find that IGR J09026-4812, IGR J18214-1318, and IGR J18325-0756 may be HMXBs. In cases where we do not find a Chandra counterpart, the flux upper limits place interesting constraints on the luminosities of black hole and neutron star X-ray transients in quiescence. Comment: Accepted by ApJ
Here we report an all-sky soft gamma-ray source catalog based on IBIS observations performed during the first 1000 orbits of INTEGRAL. The database for the construction of the source list consists of all good-quality data available, from the launch in 2002, up to the end of 2010. This corresponds to ~110 Ms of scientific public observations, with a concentrated coverage on the Galactic Plane and extragalactic deep exposures. This new catalog includes 939 sources above a 4.5σ significance threshold detected in the 17–100 keV energy band, of which 120 sources represent previously undiscovered soft gamma-ray emitters. The source positions are determined, mean fluxes are provided in two main energy bands, and these are both reported together with the overall source exposure. Indicative levels of variability are provided, and outburst times and durations are given for transient sources. A comparison is made with previous IBIS catalogs and catalogs from other similar missions.
We present measurements of dust reddening using the colors of stars with spectra in the Sloan Digital Sky Survey. We measure reddening as the difference between the measured and predicted colors of a star, as derived from stellar parameters from the Sloan Extension for Galactic Understanding and Exploration Stellar Parameter Pipeline. We achieve uncertainties of 56, 34, 25, and 29 mmag in the colors u - g, g - r, r - i, and i - z, per star, though the uncertainty varies depending on the stellar type and the magnitude of the star. The spectrum-based reddening measurements confirm our earlier "blue tip" reddening measurements, finding reddening coefficients different by -3%, 1%, 1%, and 2% in u - g, g - r, r - i, and i - z from those found by the blue tip method, after removing a 4% normalization difference. These results prefer an RV = 3.1 Fitzpatrick reddening law to O'Donnell or Cardelli et al. reddening laws. We provide a table of conversion coefficients from the Schlegel et al. (SFD) maps of E(B - V) to extinction in 88 bandpasses for four values of RV , using this reddening law and the 14% recalibration of SFD first reported by Schlafly et al. and confirmed in this work.
1) Introduction. Cox 2)General Constants and Units. Cox 3) Atoms and Molecules. Dappen 4) Spectra. Cowley, et al 5) Radiation. Keady & Kilcrease 6) Radio and Microwave Astronomy. Hjellming 7) Infrared Astronomy. Tokunaga 8) Ultraviolet Astronomy. Teays 9) X-Ray Astronomy. Seward 10) Gamma-Ray and Neutrino Astronomy. Lingenfelter & Rothschild 11) Earth. Schubert & Walterscheid 12) Planets and Satellites. Tholen 13) Solar System Small Bodies. Binzel, et al 14) Sun. Livingston 15) Normal Stars. Drilling & Landolt 16) Stars with Special Characteristics. Fernie 17) Cataclysmic and Symbiotic Variables. Sparks, et al. 18) Supernovae. Wheeler & Bennetti 19) Star Populations and the Solar Neighborhood. Gilmore & Zeilik 20) Theoretical Stellar Evolution. Becker/Pensell/Cox 21) Circumstellar and Interstellar Material. Mathis 22) Star Clusters. Harris & Harris 23) Milky Way Galaxies. Trimble 24) Quasars and Active Galactic Nuclei. Wilkes 25) Clusters and Groups of Galaxies. Bahcall 26) Cosmology. Scott, et al 27) Incidental Tables. Fiala, et al.
The present atlas of K-band spectra for 26 near-solar abundance stars in
the F8 to M7 spectral type range and dwarf to supergiant luminosity
range is the basis of a comparison of the integrated absorption
strengths of selected features with narrowband filter photometry. The
comparison indicates that the filter photometric CO index of Frogel et
al. (1978) in dwarfs is significantly diminished by H2O absorption in
the reference band used to estimate the continuum. Temperature and
luminosity dependencies of the strong atomic and molecular features
reveal significant differences which are partly due to the higher
excitation of the atomic features and partly to the differences in
sensitivities of the atomic lines and molecular bands to
microturbulence.
By studying Swift X-ray spectra of an optically selected, non-magnetic sample of nearby cataclysmic variables (CVs), we show that there is
a population with X-ray luminosity much lower than accounted for in existing studies. We find an average 0.5–10.0 keV luminosity
of which is an order of magnitude lower than observed in previous samples. Looking at the co-added X-ray spectrum of 20 CVs,
we show that the spectral properties of this optically selected, low X-ray luminosity sample – likely characteristic of the
dominant population of CVs – resemble that of their brighter counterpart, as well as the X-ray emission originating in the
Galactic ridge. It is argued that if the space density of CVs is greater than the current estimates, as it is indeed predicted
by population synthesis models, then CVs can significantly contribute to the Galactic ridge emission.
We study the chemical evolution of population I and population II secondaries in cataclysmic variables (CVs) assuming that
during nova explosions a part of the high metallicity nova ejecta is intercepted by the secondary and mixed into its convective
envelope. We derive analytic expressions for the chemical composition of the envelope of the secondary as a function of the
chemical composition of the nova ejecta Xi,ej and the cross-section of the secondary σ. For population I CVs we find that the increase of the metallicity of the secondary is comparable to its initial metallicity
only if σ is larger by an order of magnitude than the geometrical cross-section. A significant accumulation is therefore possible only
in those species that are highly overabundant in the nova ejecta. Because the changes in the abundances of even those species
depend strongly on the poorly known cross-section σ, the predictive power of our model is weak for population I CVs as long as σ is not well determined. In the case of population II CVs the accumulation of heavy elements by this process dominates over
the initial metallicity of the secondary even for values of σ that are smaller by an order of magnitude than the geometrical cross-section. Thus, within a short time after turn-on of
mass transfer, the relative metal abundances in the envelope of the secondary reflect those in the nova ejecta. This is nearly
independent of the cross-section σ.
We investigate a sample of 11 Galactic X-ray sources recently discovered with INTEGRAL or RXTE with the goal of identifying their optical and/or near-infrared (NIR) counterpart. For this purpose, new Chandra positions of nine objects are presented together with follow-up observations of all the targets in the optical and NIR. For the four sources IGR J16194−2810, IGR J16479−4514, IGR J16500−3307 and IGR J19308+0530, the Chandra position confirms an existing association with an optical/NIR object, while for two sources, XTE J1716−389 and IGR J18490−0000, it rules out previously proposed counterparts indicating new ones. In the case of IGR J17597−220, a counterpart is selected out of the several possibilities proposed in the literature, and we present the first association with an optical/NIR source for IGR J16293−4603 and XTE J1743−363. Moreover, optical/NIR observations are reported for XTE J1710−281 and IGR J17254−3257; we investigate the counterpart to the X-ray sources based on their XMM–Newton positions. We discuss the nature of each system considering its optical/NIR and X-ray properties.
We analyze the images of the Sagittarius Arm tangent obtained with the IBIS telescope of the INTEGRAL observatory in the energy
range 18–120 keV during its observations in the spring of 2003. We detected 28 sources at a statistically significant level
with fluxes above 1.4 mCrab in the energy range 18–60 keV. Of these sources, 16 were previously identified as binaries of
various classes in our Galaxy, 3 were identified as extragalactic objects, 2 were identified as pulsars in supernova remnants,
and 7 sources were of an unknown nature. These observations revealed three new sources. A statistically significant flux in
the energy range 60–120 keV was recorded from 13 sources.
Results are presented for XMM-Newton observations of five hard X-ray sources discovered by INTEGRAL in the direction of the Scutum Arm. Each source received 20 ks of effective exposure time. We provide refined X-ray positions for all five targets enabling us to pinpoint the most likely counterpart in optical/infrared archives. Spectral and timing information (much of which is provided for the first time) allow us to give a firm classification for IGR J18462–0223 and to offer tentative classifications for the others. For IGR J18462–0223, we discovered a coherent pulsation period of 997 ± 1 s, which we attribute to the spin of a neutron star in a highly obscured (N
H =2 × 1023 cm–2) high-mass X-ray binary (HMXB). This makes IGR J18462–0223 the seventh supergiant fast X-ray transient candidate with a confirmed pulsation period. IGR J18457+0244 is a highly absorbed (N
H =8 × 1023 cm–2) source in which the possible detection of an iron line suggests an active galactic nucleus (AGN) of type Sey-2 situated at z = 0.07(1). A periodic signal at 4.4 ks could be a quasi-periodic oscillation which would make IGR J18457+0244 one of a handful of AGNs in which such features have been claimed, but a slowly rotating neutron star in an HMXB cannot be ruled out. IGR J18482+0049 represents a new obscured HMXB candidate with N
H =4 × 1023 cm–2. We tentatively propose that IGR J18532+0416 is either an AGN or a pulsar in an HMXB system. The X-ray spectral properties of IGR J18538–0102 are consistent with the AGN classification that has been proposed for this source.
The 4th IBIS/ISGRI survey lists 723 hard X-ray sources many still unidentified. We cross-correlated the list of the sources included in the 4th IBIS catalogue with the Swift/XRT data archive, finding a sample of 20 objects for which XRT data could help in the search for the X-ray and hence optical counterpart and/or in the study of the source spectral and variability properties below 10 keV. Four objects (IGR J00465-4005, LEDA 96373, IGR J1248.2-5828 and IGR J13107-5626) are confirmed or likely absorbed active galaxies, while two (IGR J14080-3023 and 1RXS J213944.3+595016) are unabsorbed AGN. We find three peculiar extragalactic objects, NGC 4728 being a Narrow Line Seyfert galaxy, MCG+04-26-006 a type 2 LINER and PKS 1143-693 probably a QSO; furthermore, our results indicate that IGR J08262+4051 and IGR J22234-4116 are candidate AGN, which require further optical spectroscopic follow-up observations to be fully classified. In the case of 1RXS J080114.6-462324 we are confident that the source is a Galactic object. For IGR J10447-6027, IGR J12123-5802 and IGR J20569+4940 we pinpoint one X-ray counterpart, although its nature could not be assessed despite spectral and sometimes variability information being obtained. Clearly, we need to perform optical follow-up observations in order to firmly assess their nature. There are five objects for which we find no obvious X-ray counterpart (IGR J07506-1547 and IGR J17008-6425) or even no detection (IGR J17331-2406, IGR J18134-1636 and IGR J18175-1530); apart from IGR J18134-1636, all these sources are found to be variable in the IBIS energy band, therefore it is difficult to catch them even in X-rays. Comment: 17 pages, including 20 figures and 4 tables. Accepted for publication in MNRAS
We present further results from our onging optical spectrophotometric campaign at the Astronomical Observatory of Bologna in Loiano (Italy) on unidentified hard X-ray sources detected by INTEGRAL. We observed spectroscopically the putative optical counterparts of the INTEGRAL sources IGR J00234+6141, IGR J01583+6713, IGR J06074+2205, IGR J13091+1137 and IGR J20286+2544. We find that the first two are Galactic objects, namely a Cataclysmic Variable at a distance pc and a Be/X transient High-Mass X-ray Binary (HMXB) located at ~6.4 kpc, respectively, whereas the last one is identified with MCG +04-48-002, a Starburst/H ii galaxy at redshift hiding a Seyfert 2 nucleus. We identify IGR J13091+1137 as the (likely Seyfert 2 type) active nucleus of galaxy NGC 4992, which we classify as an X-ray Bright, Optically Normal Galaxy; this is the first example of this type of object to be detected by INTEGRAL, and one of the closest of this class. We moreover confirm the possible Be/X nature of IGR J06074+2205, and we estimate it to be at a distance of ~1 kpc. We also reexamine the spectrum of the elliptical radio galaxy PKS 0352-686, the possible counterpart of the INTEGRAL source IGR J03532-6829, and we find that it is a BL Lac. Physical parameters for these sources are also evaluated by discussing our findings in the context of the available multiwavelength information. These identifications further stress the importance of INTEGRAL in the study of the hard X-ray spectrum of Active Galactic Nuclei, HMXBs and Cataclysmic Variables.
We present a new edition of the catalogue of high-mass X-ray binaries in the Galaxy. The catalogue contains source name(s), coordinates, finding chart, X-ray luminosity, system parameters, and stellar parameters of the components and other characteristic properties of 114 high-mass X-ray binaries, together with a comprehensive selection of the relevant literature. The aim of this catalogue is to provide the reader with some basic information on the X-ray sources and their counterparts in other wavelength ranges (-rays, UV, optical, IR, radio). About 60% of the high-mass X-ray binary candidates are known or suspected Be/X-ray binaries, while 32% are supergiant/X-ray binaries. Some sources, however, are only tentatively identified as high-mass X-ray binaries on the basis of their X-ray properties similar to the known high-mass X-ray binaries. Further identification in other wavelength bands is needed to finally determine the nature of these sources. In cases where there is some doubt about the high-mass nature of the X-ray binary this is mentioned. Literature published before 1 October 2005 has, as far as possible, been taken into account.
Context.During the first year in operation, INTEGRAL, the European Space Agency's -ray observatory, has detected more than 28 new bright sources in the galactic plane which emit the bulk of their emission above 10 keV.Aims.To understand the nature of those sources we have obtained follow-up observations in the X-ray band with XMM-Newton.Methods.We derive accurate X-ray positions, propose infrared counterparts and study the source high energy long and short term variability and spectra.Results.70% of the sources are strongly absorbed ( atom cm). More than half of these absorbed sources show pulsations with periods ranging from 139 to 1300 s, i.e., they are slow X-ray pulsars. The candidate infrared counterparts are not as strongly absorbed demonstrating that part of the absorbing matter is local to the sources. Conclusions.Many of these new sources are supergiant high-mass X-ray binaries (HMXB) in which the stellar wind of the companion star is accreted onto the compact object. The large local absorption in these new sources can be understood if the compact objects are buried deep in their stellar winds. These new objects represent half of the population of supergiant HMXB.
A linear relation between the hydrogen column density (N_H) and optical
extinction (A_V) in the Galaxy has long been observed. A number of studies
found differing results in the slope of this relation. Here, we utilize the
data on 22 supernova remnants that have been observed with the latest
generation X-ray observatories and for which optical extinction and/or
reddening measurements have been performed and find N_H (cm^-2) = (2.21
\pm0.09) x10^{21} A_V (mag). We compare our result with the previous studies
and assess any systematic uncertainties that may affect these results.
We present a new edition of the catalogue of the low-mass X-ray binaries in the Galaxy and the Magellanic Clouds. The catalogue contains source name(s), coordinates, finding chart, X-ray luminosity, system parameters, and stellar parameters of the components and other characteristic properties of 187 low-mass X-ray binaries, together with a comprehensive selection of the relevant literature. The aim of this catalogue is to provide the reader with some basic information on the X-ray sources and their counterparts in other wavelength ranges (-rays, UV, optical, IR, and radio). Some sources, however, are only tentatively identified as low-mass X-ray binaries on the basis of their X-ray properties similar to the known low-mass X-ray binaries. Further identification in other wavelength bands is needed to finally determine the nature of these sources. In cases where there is some doubt about the low-mass nature of the X-ray binary this is mentioned. Literature published before 1 October 2006 has, as far as possible, been taken into account.
Two symbiotic stars in the Small Magellanic Cloud (SMC), Lin 358 and SMC 3,
have been supersoft X-ray sources (SSS) for more than 10 years. We fit
atmospheric and nebular models to their X-ray, optical and UV spectra obtained
at different epochs. The X-ray spectra are extremely soft, and appear to be
emitted by the white dwarf atmosphere and not by the nebula like in some other
symbiotics. The white dwarf of SMC 3, the hottest of the two sources, had a
constant effective temperature ~500,000 K at various epochs during 12 years. No
nova-like outbursts of these systems have been recorded in the last 50 years,
despite continuous optical monitoring of the SMC, and there are no indications
of cooling of the white dwarf, expected after a thermonuclear flash. The
bolometric luminosity of this system in March of 2003 was more than an order of
magnitude lower than three years later, however the time of the observation is
consistent with a partial eclipse of the white dwarf, previously found in ROSAT
and optical observations. The red giant wind is either very asymmetric or very
clumpy. The conpact object of Lin 358 has been at T>~180,000 K since 1993,
perhaps with a moderate increase. Atmospheric fits are obtained with log(g)>=9,
appropriate only for WD mass >1.18 M(sol). The two systems are probably
accreting and burning hydrogen steadily at the high rate required for type Ia
supernova progenitors.
We report on the discovery of the optical counterpart to the neutron star soft X-ray transient (SXT) XTE J1709-267 in outburst and quiescence. We further report the detection of type I bursts in RXTE data obtained during an outburst of the source in 2002. These bursts show a precursor event before the onset of the main burst event, reminiscent of photospheric radius expansion bursts. Sifting through the archival RXTE data for the burster 4U 1636-53 we found a nearly identical burst with precursor in 4U 1636-53. A comparison of this burst to true photospheric radius expansion bursts in 4U 1636-53 leads us to conclude that these bursts-with-precursor do not reach the Eddington limit. We further report on the analysis of a 22.4 ksec observation of XTE J1709-267 obtained with the Chandra satellite when the source was in quiescence. We found that the source has a soft quiescent spectrum which can be fit well by an absorbed black body or neutron star atmosphere model. A power law contributes less than 10 per cent to the 0.5-10 keV unabsorbed flux of (1.0+-0.3)x10^-13 erg cm^-2 s^-1. This flux is the same within the errors as the flux measured right after the outburst in 2002, indicating that the quiescent flux was reached within a few weeks after the outburst. Finally, we compared the power-law fractional contribution to the unabsorbed 0.5-10 keV luminosity for neutron star SXTs in quiescence for which the distance is well-known. We find that the power-law contribution is low only when the source quiescent luminosity is close to \~1-2x10^33 erg s^-1. Both at higher and lower values the power-law contribution to the 0.5-10 keV luminosity increases. We discuss how models for the quiescent X-ray emission can explain these trends.(Abridged) Comment: 10 pages, 5 Figures, 1 color Fig, accepted for publication by MNRAS, added Globular Cluster sources to Figure 5
We present moderate resolution (R > 1,800) infrared K-band spectra of twelve long-period (Porb > 6 hr) cataclysmic variables. We detect absorption lines from the photospheres of the secondary stars in every system, even though two of the m were undergoing outubrsts. We have attempted to assign spectral types to each of the secondary stars, and these classifications are generally consistent with previous determinations/estimates. We find evidence for abundance anomalies that include enhancements and/or deficits for all of the species commonly found in the K-band spectra of G- and K-type dwarfs. There is, however, only one common abundance anomaly: extremely weak CO features. Only two of the twelve objects appeared to have normal levels of CO absorption. We interpret this as evidence for low carbon abundances. In addition, we detect 13CO absorption in four of the twelve objects. Depleted levels of 12C and enhanced levels of 13C indicate that material that has been processed in the CNO cycle is finding its way into the photospheres of CV secondary stars. In systems with luminous accretion disks, we find that the spectrum of the secondary star is contaminated by a source that flattens (reddens) the continuum. While free-free or classical accretion disk spectra are flatter than the blackbody-like spectra of G and K dwarfs, removal of such contamination from the K-band data results in spectra in which the absorption features become too strong to be consistent with those of G and K dwarfs. Comment: 43 pages, 20 figures
We report on analysis of the poorly studied source 2RXP J130159.6-635806 at different epochs with ASCA, BeppoSAX, XMM-Newton and INTEGRAL. The source shows coherent X-ray pulsations at a period ~700 s with an average spin-up rate of about . A broad-band (1-60 keV) spectral analysis of 2RXP J130159.6-635806 based on almost simultaneous XMM-Newton and INTEGRAL data demonstrates that the source has a spectrum typical of an accretion-powered X-ray pulsar, i.e. an absorbed power law
with a high-energy cut-off with a photon index G~0.5–1.0 and a cut-off energy of ~25 keV. The long-term behaviour of the source,
its spectral and timing properties, tend to indicate a high-mass X-ray binary with a Be companion. We also report on the identification
of the likely infrared counterpart to 2RXP J130159.6-635806. The interstellar reddening does not allow us to strongly constrain
the spectral type of the counterpart. The latter is, however, consistent with a Be star, the kind of which is often observed
in accretion-powered X-ray pulsars.
VizieR Online Data Catalog
- A Fresneau
- A E Vaughan
- R W Argyle
Fresneau, A., Vaughan, A. E., & Argyle, R. W. 2007, VizieR Online Data
Catalog: III/46
- A J Bird
- E J Barlow
- L Bassani
Bird, A. J., Barlow, E. J., Bassani, L., et al. 2006, ApJ, 636, 765