- ID:
- ivo://CDS.VizieR/J/ApJ/882/181
- Title:
- Hyper-luminous X-ray sources from SDSS and CSC2
- Short Name:
- J/ApJ/882/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hyper-luminous X-ray sources (HLXs; L_X_>10^41^erg/s) are off-nuclear X-ray sources in galaxies and strong candidates for intermediate-mass black holes (IMBHs). We have constructed a sample of 169 HLX candidates by combining X-ray detections from the Chandra Source Catalog (Version 2) with galaxies from the Sloan Digital Sky Survey and registering individual images for improved relative astrometric accuracy. The spatial resolution of Chandra allows for the sample to extend out to z~0.9. Optical counterparts are detected among one-fourth of the sample, one-third of which are consistent with dwarf galaxy stellar masses. The average intrinsic X-ray spectral slope indicates efficient accretion, potentially driven by galaxy mergers, and the column densities suggest one-third of the sample has significant X-ray absorption. We find that 144 of the HLX candidates have X-ray emission that is significantly in excess of the expected contribution from star formation and hot gas, strongly suggesting that they are produced by accretion onto black holes more massive than stars. After correcting for an average background or foreground contamination rate of 8%, we estimate that at least ~20 of the HLX candidates are consistent with IMBH masses, and this estimate is potentially several times higher assuming more efficient accretion. This catalog currently represents the largest sample of uniformly selected, off-nuclear IMBH candidates. These sources may represent scenarios in which a low-mass galaxy hosting an IMBH has merged with a more massive galaxy and provide an excellent sample for testing models of low-mass BH formation and merger-driven growth.
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- ID:
- ivo://CDS.VizieR/J/ApJS/182/12
- Title:
- ICM entropy profiles (ACCEPT)
- Short Name:
- J/ApJS/182/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial entropy profiles of the intracluster medium (ICM) for a collection of 239 clusters taken from the Chandra X-ray Observatory's Data Archive. We find that most ICM entropy profiles are well fitted by a model which is a power law at large radii and approaches a constant value at small radii: K(r)=K_0_+K_100_(r/100kpc)^{alpha}^, where K_0_ quantifies the typical excess of core entropy above the best-fitting power law found at larger radii. For completeness, we include previously unpublished optical spectroscopy of H{alpha} and [NII] emission lines discussed in Cavagnolo et al. (2008ApJ...683L.107C). All data and results associated with this work are publicly available via the project Web site (ACCEPT: Archive of Chandra Cluster Entropy Profile Tables).
- ID:
- ivo://CDS.VizieR/J/A+A/319/33
- Title:
- Identification of X-ray sources around Seyferts
- Short Name:
- J/A+A/319/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Excess numbers of X-ray sources around bright Seyfert galaxies have been demonstrated with significances of association up to 7.4-sigma (Radecke, 1997A&A...319...18R). The optical identification of these sources is shown here to be predominantly blue stellar objects (BSO's) of which some are already catalogued as quasars. Excluding the two brightest Seyferts, a subset of 24 with apparent magnitudes between 8.04<=B_T_^o,i^<=12.90mag. show a minimum excess of >46 bright X-ray sources. These excess X-ray sources are generally distributed between 10'<r<40' and 12 of the Seyferts show conspicuous pairs of X-ray sources across their active nuclei. Additional pairing and alignment of sources is seen for the remaining Seyferts. Among the paired X-ray sources, 53 have been identified as BSO's. Some double and multiple BSO's have been identified which are candidates for groups and associations of quasars. Some groups are well aligned and some centered on small blue galaxies. Four previously known BL Lac objects fall close enough to the Seyferts in this sample to confirm, at a significance level of 1-2x10^-9^, a previously reported association of BL Lac objects with bright, low redshift galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/15
- Title:
- Improved 2Ms and 250ks Chandra catalogs
- Short Name:
- J/ApJS/224/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present improved point-source catalogs for the 2Ms Chandra Deep Field-North (CDF-N) and the 250ks Extended Chandra Deep Field-South (E-CDF-S) Surveys, implementing a number of recent improvements in Chandra source-cataloging methodology. For CDF-N/E-CDF-S, we provide a main catalog that contains 683/1003 X-ray sources detected with wavdetect at a false-positive probability threshold of 10^-5^ that also satisfy a binomial-probability source-selection criterion of P<=0.004/P<0.002. Such an approach maximizes the number of reliable sources detected: a total of 196/275 main-catalog sources are new compared to the Alexander+ (2003, J/AJ/126/539) CDF-N/Lehmer+ (2005, J/ApJS/161/21) E-CDF-S main catalogs. We also provide CDF-N/E-CDF-S supplementary catalogs that consist of 72/56 sources detected at the same wavdetect threshold and having P of 0.004-0.1/0.002-0.1 and Ks<=22.9/Ks<=22.3mag counterparts. For all ~1800 CDF-N and E-CDF-S sources, including the ~500 newly detected ones (these being generally fainter and more obscured), we determine X-ray source positions utilizing centroid and matched-filter techniques; we also provide multiwavelength identifications, apparent magnitudes of counterparts, spectroscopic and/or photometric redshifts, basic source classifications, and estimates of observed active galactic nucleus and galaxy source densities around respective field centers. Simulations show that both the CDF-N and E-CDF-S main catalogs are highly reliable and reasonably complete. Background and sensitivity analyses indicate that the on-axis mean flux limits reached represent a factor of ~1.5-2.0 improvement over the previous CDF-N and E-CDF-S limits. We make our data products publicly available.
- ID:
- ivo://CDS.VizieR/J/A+A/475/775
- Title:
- INTEGRAL all-sky survey of hard X-ray sources
- Short Name:
- J/A+A/475/775
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an all-sky hard X-ray survey based on almost four years of observations with the IBIS telescope onboard the INTEGRAL observatory. The dead time-corrected exposure of the survey is about 33Ms. Approximately 12% and 80% of the sky has been covered to limiting fluxes lower than 1 and 5mCrab, respectively. Our catalog of detected sources includes 403 objects, 316 of which exceed a 5{sigma} detection threshold on the time-averaged map of the sky, and the rest were detected in various subsamples of exposures.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A61
- Title:
- INTEGRAL all-sky survey of hard X-ray sources
- Short Name:
- J/A+A/523/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper is the second in a series devoted to the hard X-ray (17-60keV) whole sky survey performed by the INTEGRAL observatory over seven years. Here we present a catalog of detected sources that includes 521 objects, 449 of which exceed a 5{sigma} detection threshold on the time-averaged map of the sky, and 53 were detected in various subsamples of exposures. Among the identified sources with known and suspected nature, 262 are Galactic (101 low-mass X-ray binaries, 94 high-mass X-ray binaries, 37 cataclysmic variables, and 30 of other types) and 221 are extragalactic, including 217 active galactic nuclei (AGNs) and 4 galaxy clusters. The extragalactic (|b|>5deg) and Galactic (|b|<5deg) persistently detected source samples have high identification completeness (respectively ~96% and ~93%) and are valuable for population studies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/1750
- Title:
- INTEGRAL/IBIS AGN catalogue
- Short Name:
- J/MNRAS/426/1750
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we present the most comprehensive INTEGRAL active galactic nucleus (AGN) sample. It lists 272 AGN for which we have secure optical identifications, precise optical spectroscopy and measured redshift values plus X-ray spectral information, i.e. 2-10 and 20-100keV fluxes plus column density. Here we mainly use this sample to study the absorption properties of active galaxies, to probe new AGN classes and to test the AGN unification scheme.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A27
- Title:
- INTEGRAL/IBIS 9-year Galactic hard X-ray survey
- Short Name:
- J/A+A/545/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present sky images, sensitivity maps, and catalogs of detected sources in the three energy bands 17-60, 17-35, and 35-80keV in the Galactic plane at |b|<17.5 degrees. The total number of sources in the reference 17-60keV band includes 402 objects exceeding a 4.7{sigma} detection threshold on the nine-year time-averaged map. Among the identified sources with known and tentatively identified natures, 253 are Galactic objects (108 low-mass X-ray binaries, 82 high-mass X-ray binaries, 36 cataclysmic variables, and 27 are of other types), and 115 are extragalactic objects, including 112 active galactic nuclei (AGNs) and 3 galaxy clusters. The sample of Galactic sources with S/N>4.7 sigma has an identification completeness of ~92%, which is valuable for population studies. Since the survey is based on the nine-year sky maps, it is optimized for persistent sources and may be biased against finding transients.
- ID:
- ivo://CDS.VizieR/J/A+A/411/L59
- Title:
- INTEGRAL reference catalog
- Short Name:
- J/A+A/411/L59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the INTEGRAL reference catalog which classifies previously known bright X-ray and gamma-ray sources before the launch of INTEGRAL. These sources are, or have been at least once, brighter than ~1mCrab above 3keV, and are expected to be detected by INTEGRAL. This catalog is being used in the INTEGRAL Quick Look Analysis to discover new sources or significantly variable sources. We compiled several published X-ray and gamma-ray catalogs, and surveyed recent publications for new sources. Consequently, there are 1122 sources in our INTEGRAL reference catalog. In addition to the source positions, we show an approximate spectral model and expected flux for each source, based on which we derive expected INTEGRAL counting rates. Assuming the default instrument performances and at least ~10^5^s exposure time for any part of the sky, we expect that INTEGRAL will detect at least ~700 sources below 10keV and ~400 sources above 20keV over the mission life.
- ID:
- ivo://CDS.VizieR/J/PAZh/30/430
- Title:
- INTEGRAL X-ray source in Galactic center
- Short Name:
- J/PAZh/30/430
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From August 23 through September 24, 2003, the INTEGRAL Observatory conducted a deep survey of Galactic-Center region with a record-breaking sensitivity at energies above 20keV. We detected a total of 60 sources with fluxes above 1.5mCrab in the range 18-60keV.
