J/ApJ/766/14ivo://CDS.VizieR/J/ApJ/766/14doi:10.26093/cds/vizier.17660014CDSMorihana K.Tsujimoto M.Yoshida T.Ebisawa K.2014-12-20T05:43:55Z2014-12-04T16:04:10ZCDS support team

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

cds-question@unistra.frgalaxy-planesmilky-way-galaxyx-ray-sourcesApparently diffuse X-ray emission has been known to exist along the central quarter of the Galactic Plane since the beginning of X-ray astronomy; this is referred to as the Galactic Ridge X-ray emission (GRXE). Recent deep X-ray observations have shown that numerous X-ray point sources account for a large fraction of the GRXE in the hard band (2-8keV). However, the nature of these sources is poorly understood. Using the deepest X-ray observations made in the Chandra bulge field, we present the result of a coherent photometric and spectroscopic analysis of individual X-ray point sources for the purpose of constraining their nature and deriving their fractional contributions to the hard-band continuum and Fe K line emission of the GRXE. Based on the X-ray color-color diagram, we divided the point sources into three groups: A (hard), B (soft and broad spectrum), and C (soft and peaked spectrum). The group A sources are further decomposed spectrally into thermal and non-thermal sources with different fractions in different flux ranges. From their X-ray properties, we speculate that the group A non-thermal sources are mostly active galactic nuclei and the thermal sources are mostly white dwarf (WD) binaries such as magnetic and non-magnetic cataclysmic variables (CVs), pre-CVs, and symbiotic stars, whereas the group B and C sources are X-ray active stars in flares and quiescence, respectively. In the log N-log S curve of the 2-8 keV band, the group A non-thermal sources are dominant above {approx}10^-14^erg/cm2/s, which is gradually taken over by Galactic sources in the fainter flux ranges. The Fe K{alpha} emission is mostly from the group A thermal (WD binaries) and the group B (X-ray active stars) sources.2013ApJ...766...14Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/766/14CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2014)J/ApJS/210/18 : X-ray survey of the Galactic Bulge (CXOGBS) (Jonker+, 2014)J/ApJS/194/18 : The Galactic Bulge Survey: X-ray observations (Jonker+, 2011)J/ApJ/700/1702 : ChaMPlane deep galactic bulge survey. I. (van den Berg+, 2009)J/ApJ/685/463 : ChaMPlane X-ray sources in the Galactic bulge (Koenig+, 2008)J/A+A/468/353 : XMM-Newton Extended Survey of Taurus (Guedel+, 2007)J/A+A/451/457 : X-ray properties of AGN in CDFS (Tozzi+, 2006)J/ApJ/635/214 : Chandra X-ray sources and NIR identifications (Ebisawa+, 2005)J/MNRAS/351/31 : XMM-Newton Galactic Plane Survey (XGPS) (Hands+, 2004)J/ApJS/134/77 : ASCA Galactic Plane Survey X-ray sources (Sugizak+, 2001)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/766/14https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/766/14http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/766/14https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/766/14https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/766/14http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/766/14GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/766/14/table2 (Chandra catalog: basic source properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/766/14/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/766/14/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/766/14/table2?GETtext/xml+votable180.050000true267.68701-29.477113060.0055555555555555566/28822 28828https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/766/14?format=asciiX-raydefaultJ/ApJ/766/14/table2Chandra catalog: basic source propertiesSeq[1/2002] Sequence number; sorted by RAmeta.idintprimaryCXOUIAU designation (HHMMSS.ss+DDMMSS.s; J2000)meta.id;meta.maincharRAJ2000[267.68/268.03] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-29.74/-29.44] Declination (J2000)degpos.eq.dec;meta.mainePos[0/0.5] Positional uncertaintyarcsecstat.error;posfloatthetaOff-axis angle {theta}arcmininstr.offsetfloatCnet[5/6441] Estimated net 0.5-8 keV countsctphot.count;em.X-rayfloate_Cnet[3/83] Uncertainty in CNetctstat.errorfloatCbkg[1/503] Background 0.5-8 keV countsctphot.count;em.X-rayfloatChard[0/4337] Estimated net hard 2-8 keV countsctphot.count;em.X-rayfloatPSF[0/1] Fraction of PSF in extraction region (1)instr.det.psf;arith.ratiofloatSig[1/78] Photometric significancestat.fit.goodness;photfloatl_Pb[<] Limit flag on Pbmeta.code.errorcharPb[-5/-2] Log probability of background only (2)instr.backgroundfloatf_Pb[g] Source anomalies (3)meta.codecharVar[a-c] Variability characterization (4)meta.code;src.varcharExp[169/892] Effective exposure time (5)kstime.duration;obs.exposurefloatEmed[0.8/5.1] Background-corrected median photon energykeVem.energyfloatFxPhotometric 0.5-8 keV flux estimate; erg/s/cm^2^mW.m**-2phot.flux;em.X-rayfloatq1The q_1_ quantile value (hardness) (6)phot.flux;arith.ratiofloatq2The q_2_ quantile value (concentration) (6)stat.variancefloat