J/ApJ/882/181ivo://CDS.VizieR/J/ApJ/882/181doi:10.26093/cds/vizier.18820181CDSBarrows R.S.Mezcua M.Comerford J.M.2022-09-02T08:54:35Z2021-03-08T09:43:10ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frx-ray-sourcesactive-galactic-nucleigalaxiesvisible-astronomyHyper-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.2019ApJ...882..181Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/882/181CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2014)VII/158 : Revised and Updated Catalog of Quasi-stellar Objects (Hewitt+ 1993)II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)IX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+, 2019)J/ApJS/154/519 : Properties of ultraluminous X-ray candidates (Swartz+, 2004)J/AJ/130/873 : Properties of BQS objects in the SDSS DR3 area (Jester+, 2005)J/ApJS/157/59 : Ultraluminous X-ray sources in nearby galaxies (Liu+, 2005)J/A+A/429/1125 : Catalog of Ultraluminous X-ray sources (Liu+, 2005)J/ApJ/670/92 : New sample of low-mass black holes in AGN (Greene+, 2007)J/ApJ/741/49 : ULX candidates in nearby galaxies (Swartz+, 2011)J/MNRAS/416/1844 : 2XMM ultraluminous X-ray source candidates (Walton+, 2011)J/ApJS/201/30 : The Chandra COSMOS survey. III. (Civano+, 2012)J/ApJ/756/27 : Classification of sources from the 2XMMi-DR3 cat. (Lin+, 2012)J/MNRAS/419/2095 : HMXBs in nearby galaxies (Mineo+, 2012)J/ApJ/772/26 : AGN with WISE. II. The NDWFS Bootes field (Assef+, 2013)J/ApJ/775/116 : z<0.06 active BH galaxies from SDSS-DR8 (Reines+, 2013)J/ApJ/813/82 : z<0.06 broad-line AGN emission-line measures (Reines+, 2015)J/ApJ/807/129 : X-ray to MIR luminosities relation of AGNs (Stern, 2015)J/ApJ/819/62 : The COSMOS-Legacy Survey (CLS) catalog (Civano+, 2016)J/ApJS/222/12 : Luminous X-ray candidates within D25 of galaxies (Gong+, 2016)J/ApJ/825/7 : Evolution of ~6Ms CDF-S galaxies (Lehmer+, 2016)J/ApJS/234/23 : The WISE AGN candidates catalogs (Assef+, 2018)J/MNRAS/479/807 : Catalogue of faint local radio AGN (Lofthouse+, 2018)J/MNRAS/483/5554 : Non-nuclear X-ray sources in nearby gal. (Earnshaw+, 2019)http://www.sdss.org/ : SDSS home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/882/181https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/882/181http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/882/181https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/882/181https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/882/181http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/882/181GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/882/181/hlx (Astrometric properties (Table 1), X-ray properties (Table 2) and galaxy properties and multi-wavelength detections (Table 3) of the HLX candidates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/882/181/hlx?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/882/181/hlx?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/882/181/hlx?GETtext/xml+votable180.050000true0.46333323.4997220.0055555555555555566/306 393 686 4718 4801 5327 5399 5439 5536 5633 5733 5816 5881 5927 5966 5975 5985 6073 6079 6098 7227 7309 7345 7768-7769 8195-8196 8220 8268 8282 8555 8557 8707 8906 8921 9009 9052 9168 9468 9633 9842 10182 10213 10271 10302 10354-10355 10379 10387 10391 10519 10544 10579 10589 10658 10761 10780 10911 10992 11029 11042 11080 11180 11194-11195 11263 11372 11424 11461 11467 11524 11802 12642 12719 15684 16184 16281 16702 16806 17237 17307 17343 17662 17699 17745 17921 18003 18096 18123 18227 18411 18642 18762 18779 18784 18878 18968 19036 19283 19449 19848 19857 19935 20014 20237 23339 25852 25919 25981 26002 26037 26177 26180 26189 26393 26440 26563 27095 27124 27247 27256 27258-27259 27344 27486 27515 27718 27764 27773 27955 28086 28149 28249 28356 28489 31158 31333 36785https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/882/181?format=asciiX-rayOpticaldefaultJ/ApJ/882/181/hlxAstrometric properties (Table 1), X-ray properties (Table 2) and galaxy properties and multi-wavelength detections (Table 3) of the HLX candidatesGamma[0.53/2.82] Intrinsic photon indexspect.indexfloatSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/169] Internal index numbermeta.idintz[0.05/0.87] Host galaxy redshiftsrc.redshiftfloatNavg[0/14] Average number of matches (1)meta.numberfloate_logM*HLX[5.9/11.6]? Uncertainty in logM*HLXlog(solMass)stat.errorfloatnullablelog(X/V)[-3.1/1] log X-ray to optical flux ratiophot.flux;arith.ratiofloatf_log(X/V)[a] a = lower limit on log(X/V); see Section 3.3.2meta.codecharLXXRB[0.02/395880] Hard (2-10keV) luminosity from XRBs in units of 10^39^erg/s1e+32Wphys.luminosity;em.X-raydoublee_LXXRB[0.01/215540] Lower uncertainty in LXXRB1e+32Wstat.errordoubleE_LXXRB[0.03/470490] Upper uncertainty in LXXRB1e+32Wstat.error;stat.maxdoubleLXISM[0.01/9800] Hard (2-10keV) luminosity from hot ISM gas in units of 10^37^erg/s1e+30Wphys.luminosity;em.X-rayfloatAngSep[0.8/12.2] HLX candidate angular offset from the host galaxy centerarcsecpos.angDistancefloate_AngSep[0.1/2] Uncertainty in AngSeparcsecstat.errorfloatPhySep[2.5/75.1] HLX candidate projected physical offset from the host galaxy centerkpcpos.distancefloate_PhySep[0.2/8.8] Uncertainty in PhySepkpcstat.errorfloatPA[2/359.2] HLX candidate offset position angle; East of Northdegpos.posAng;arith.difffloatsigma[0.4/5.3] 1{sigma} PSF size at HLX positionphys.angSizefloatLXS[0/585] Soft (0.5-2keV) band luminosity in units of 10^41^erg/s (2)1e+34Wphys.luminosity;em.X-rayfloate_LXS[0/318] Lower uncertainty in LXS1e+34Wstat.errorfloatE_LXS[0/658] Upper uncertainty in LXS1e+34Wstat.error;stat.maxfloatLXH[0.1/214] Hard (2-10keV) band luminosity in units of 10^42^erg/s (2)1e+35Wphys.luminosity;em.X-rayfloate_LXH[0.01/102] Lower uncertainty in LXH1e+35Wstat.errorfloatE_LXH[0.01/623] Upper uncertainty in LXH1e+35Wstat.error;stat.maxfloatLXF[0.14/238] Full (0.5-10keV) band luminosity in units of 10^42^erg/s (2)1e+35Wphys.luminosity;em.X-rayfloate_LXF[0.01/108] Lower uncertainty in LXF1e+35Wstat.errorfloatE_LXF[0.01/644.3] Upper uncertainty in LXF1e+35Wstat.error;stat.maxfloatf_Gamma[a] a=fixed value; see section 2.4.1meta.codechare_Gamma[0/1.1]? Lower uncertainty in Gammastat.errorfloatnullableE_Gamma[0.1/1.1]? Upper uncertainty in Gammastat.error;stat.maxfloatnullablenH[0/25.1] Intrinsic column density1e+22cm**-2phys.columnDensityfloatf_nH[a] a=fixed value; see section 2.4.1meta.codechare_nH[0/4]? Lower uncertainty in nH1e+22cm**-2stat.errorfloatnullableE_nH[0/5.1]? Upper uncertainty in nH1e+22cm**-2stat.error;stat.maxfloatnullableScts[1.5/331] Soft (0.5-2keV) band photon countsctphot.count;em.X-rayfloate_Scts[1.5/19] Lower uncertainty in Sctsctstat.errorfloatE_Scts[0.2/18] Upper uncertainty in Sctsctstat.error;stat.maxfloatHcts[9.4/515] Hard (2-10keV) band photon countsctphot.count;em.X-rayfloate_Hcts[3.6/25] Lower uncertainty in Hctsctstat.errorfloatE_Hcts[2.3/21] Upper uncertainty in Hctsctstat.error;stat.maxfloatHR[-0.54/0.96] Hardness ratio (HR=(H-S)/(H+S))phot.flux;arith.ratiofloate_HR[0.01/0.23] Lower uncertainty in HRstat.errorfloatE_HR[0.02/0.22] Upper uncertainty in HRstat.error;stat.maxfloatfc[0.2/86.3] Contamination rate%stat.fit.goodnessfloatfcind[0.2/36.4] LG06 contamination rate%stat.fit.goodnessfloatlogM*H[7.3/15.6] log host galaxy stellar masslog(solMass)phys.massfloate_logM*H[5/13.6] Uncertainty in logM*Hlog(solMass)stat.errorfloatlogM*HLX[7/13]? log HLX stellar counter part masslog(solMass)phys.massfloatnullablee_LXISM[0.01/5320] Lower uncertainty in LXISM1e+30Wstat.errorfloatE_LXISM[0.01/11640] Upper uncertainty in LXISM1e+30Wstat.error;stat.maxdoubleMIR-AGNHLX candidate is a detected MIR AGN?meta.codecharSloanDisplay the online SDSS-DR14 data for the nearest objectmeta.ref.urlchar_RAPositions from the 2CXO names (right ascension part)degpos.eq.ra;meta.main_DEPositions from the 2CXO names (declination part)degpos.eq.dec;meta.mainSDSSHost galaxy identifier (JHHMMSS.ss+DDMMSS.s)meta.id.parentchar2CXOHLX candidate identifier (JHHMMSS.s+DDMMSS) from the Chandra Source Catalog DR2 (IX/57)meta.id;meta.mainchar