J/ApJ/853/150ivo://CDS.VizieR/J/ApJ/853/150doi:10.26093/cds/vizier.18530150CDSSonbas E.Dhuga K.S.Gogus E.2019-01-09T14:00:16Z2018-12-04T07:58:45ZCDS support team

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

cds-question@unistra.frx-ray-binary-starsblack-holesneutron-starsx-ray-sourcesA recent study of a small sample of X-ray binaries (XRBs) suggests a significant softening of spectra of neutron star (NS) binaries as compared to black hole (BH) binaries in the luminosity range 10^34^-10^37^erg/s. This softening is quantified as an anticorrelation between the spectral index and the 0.5-10keV X-ray luminosity. We extend the study to significantly lower luminosities (i.e., ~a few x10^30^erg/s) for a larger sample of XRBs. We find evidence for a significant anticorrelation between the spectral index and the luminosity for a group of NS binaries in the luminosity range 10^32^-10^33^erg/s. Our analysis suggests a steep slope for the correlation i.e., -2.12+/-0.63. In contrast, BH binaries do not exhibit the same behavior. We examine the possible dichotomy between NS and BH binaries in terms of a Comptonization model that assumes a feedback mechanism between an optically thin hot corona and an optically thick cool source of soft photons. We gauge the NS-BH dichotomy by comparing the extracted corona temperatures, Compton-y parameters, and the Comptonization amplification factors: the mean temperature of the NS group is found to be significantly lower than the equivalent temperature for the BH group. The extracted Compton-y parameters and the amplification factors follow the theoretically predicted relation with the spectral index.2018ApJ...853..150Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/853/150CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2014)B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012)J/ApJ/376/161 : X-ray spectra of bursting neutron stars (Madej+, 1991)J/ApJ/719/L79 : BH spin-orbit misalignment in Galactic XRBs (Fragos+, 2010)J/ApJ/800/17 : Mass-transfer sequences in 16 Galactic LMXBs (Fragos+, 2015)J/A+A/587/A61 : BlackCAT, stellar-mass BHs. (Corral-Santana+, 2016)J/ApJS/222/15 : WATCHDOG: Galactic BHXBs all-sky database (Tetarenko+, 2016)J/A+A/606/A130 : List of 1254 X-ray bursts (in't Zand+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/853/150https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/853/150http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/853/150https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/853/150https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/853/150http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/853/150GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/853/150/table3 (Total number of observations analyzed for the sample of low-mass X-ray binaries (LMXBs))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/853/150/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/853/150/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/853/150/table3?GETtext/xml+votable180.050000true236.7844861-47.66952360.0055555555555555566/5609 14610 20537 22159 25690 28751 28798 28808 28827 28828 28877 29114 29267 29306 29416 29870 30299 37196 41583 41809 42159 42189 42196 42370 42387 42417 42533https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/853/150?format=asciiX-raydefaultJ/ApJ/853/150/table3Total number of observations analyzed for the sample of low-mass X-ray binaries (LMXBs)SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTypeBinary type (BH=Black hole or NH=Neutron star)meta.code.classcharNameName of the sourcemeta.id;meta.maincharObsID[95/744870201] ObsID numbermeta.id;obslongf_ObsID[CX] Facility flag of the ObsID (X=XMM or C=Chandra)meta.codecharExp[2.5/138.5] Exposure timekstime.duration;obs.exposurefloatGalNH[0.01/1.8] Galactic extinctioncm**-2phys.columnDensityfloatIntNH[0.01/11.6]? Intrinsic extinctioncm**-2phys.columnDensityfloatnullablee_IntNH[0.001/1]? Error in IntNHcm**-2stat.errorfloatnullableLum[2.5e+30/1.7e+37] Source 0.5-10 keV luminosity in erg/s units1e-07Wphys.luminosity;em.X-raydoublee_Lum[5e+29/8e+35] Error in Lum1e-07Wstat.errordoubleSpInd[0.3/5.8] Spectral indexspect.indexfloate_SpInd[0.01/1] Error in SpIndexstat.errorfloatTin/kTbb[0.1/4.0]? TemperaturekeVphys.temperaturefloatnullablee_Tin/kTbb[0.01/0.2]? Error in Tin/kTbbkeVstat.errorfloatnullablechi2[0.4/2.8] Model {chi}^2^ fitstat.fit.param;meta.modelledfloat_RAPositions from SIMBAD (right ascension part)degpos.eq.ra;meta.main_DEPositions from SIMBAD (declination part)degpos.eq.dec;meta.main