J/ApJS/235/26ivo://CDS.VizieR/J/ApJS/235/26doi:10.26093/cds/vizier.22350026CDSZhu Z.Li Z.Morris M.R.2018-12-03T14:38:11Z2018-09-25T09:44:07ZCDS support team

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

cds-question@unistra.frgalactic-centerx-ray-sourcesWe present an updated catalog of X-ray point sources in the inner 500" (~20pc) of the Galactic center (GC), where the nuclear star cluster (NSC) stands, based on a total of ~4.5Ms of Chandra observations taken from 1999 September to 2013 April. This ultradeep data set offers unprecedented sensitivity for detecting X-ray sources in the GC, down to an intrinsic 2-10keV luminosity of 1.0x10^31^erg/s. A total of 3619 sources are detected in the 2-8keV band, among which ~3500 are probable GC sources and ~1300 are new identifications. The GC sources collectively account for ~20% of the total 2-8keV flux from the inner 250" region where detection sensitivity is the greatest. Taking advantage of this unprecedented sample of faint X-ray sources that primarily traces the old stellar populations in the NSC, we revisit global source properties, including long-term variability, cumulative spectra, luminosity function, and spatial distribution. Based on the equivalent width and relative strength of the iron lines, we suggest that in addition to the arguably predominant population of magnetic cataclysmic variables (CVs), nonmagnetic CVs contribute substantially to the detected sources, especially in the lower-luminosity group. On the other hand, the X-ray sources have a radial distribution closely following the stellar mass distribution in the NSC, but much flatter than that of the known X-ray transients, which are presumably low-mass X-ray binaries (LMXBs) caught in outburst. This, together with the very modest long-term variability of the detected sources, strongly suggests that quiescent LMXBs are a minor (less than a few percent) population.2018ApJS..235...26Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/235/26CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2014)J/ApJ/502/558 : Catalog of ROSAT galaxy clusters (Vikhlinin+ 1998)J/ApJ/589/225 : Chandra X-ray sources toward Galactic Center (Muno+, 2003)J/ApJ/613/1179 : X-ray sources in Galactic Center (Muno+, 2004)J/ApJS/165/173 : Chandra sources in Galaxy central 150pc (Muno+, 2006)J/ApJS/169/401 : ChaMP X-ray point source catalog (Kim+, 2007)J/ApJ/685/958 : Spitzer and Chandra sources in galactic center (Arendt+ 2008)J/ApJ/703/30 : NIR counterparts to Chandra sources. I. (Mauerhan+, 2009)J/ApJ/703/1323 : Stars in the Galaxy's nuclear cluster spectroscopy (Do+ 2009)J/ApJ/706/223 : X-ray point sources near the Galactic Center (Hong+, 2009)J/ApJS/181/110 : Galactic center X-ray sources (Muno+, 2009)J/ApJ/721/1368 : X-ray emission from the Sombrero galaxy (Li+, 2010)J/ApJ/721/1663 : NIR matches of X-ray sources in Gal. Center (DeWitt+, 2010)J/ApJ/766/14 : Deep Chandra bulge field X-ray point sources (Morihana+, 2013)J/ApJ/821/44 : Star motions in the nuclear cluster of the MW (Fritz+, 2016)J/ApJS/224/40 : Catalog of Chandra ACIS point like sources (Wang+, 2016)http://cxc.cfa.harvard.edu/ : Chandra X-ray Center home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/235/26https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/235/26http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/235/26https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/235/26https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/235/26http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/235/26GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/235/26/table2 (Catalog of the R<500" sources detected in the 0.5-2keV band)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/235/26/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/235/26/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/235/26/table2?GETtext/xml+votable180.050000true266.26885-28.986690.005555555555555556Cone search capability for table J/ApJS/235/26/table1 (Chandra observation log)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/235/26/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/235/26/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/235/26/table1?GETtext/xml+votable180.050000true266.41399-29.012710.005555555555555556Cone search capability for table J/ApJS/235/26/table3 (Catalog of the R<500" sources detected in the 2-8keV band)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/235/26/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/235/26/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/235/26/table3?GETtext/xml+votable180.050000true266.26001-28.995710.005555555555555556Cone search capability for table J/ApJS/235/26/table5 (Positions of removed sources originally found by wavdetect)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/235/26/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/235/26/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/235/26/table5?GETtext/xml+votable180.050000true266.26906-28.964970.0055555555555555566/28822 28830https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/235/26?format=asciiX-raydefaultJ/ApJS/235/26/table2Catalog of the R<500" sources detected in the 0.5-2keV bandrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/421] Index numberphot.flux;em.X-ray.softintRAJ2000[266.26/266.6] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-29.2/-28.8] Declination (J2000)degpos.eq.dec;meta.mainePos[0.05/3.3] Positional errorarcsecstat.error;posdoubleCTot[9/12560] Total 0.5-2 keV band countsctphot.count;em.X-rayintCBck[3/198.5] Background 0.5-2keV band countsctinstr.background;em.X-ray.softfloatl_CNetLimit flag on CNetmeta.code.errorcharCNet[5.5/12391] Net 0.5-2keV band countsctphot.count;em.X-ray.soft;src.netfloatE_CNet[/107.7]? Upper 1{sigma} uncertainty in CNetctstat.error;stat.maxfloatnullablee_CNet[/112.2]? Lower 1{sigma} uncertainty in CNetctstat.errorfloatnullableS[0.01/262.8] Photon flux in 0.5-2keV band1e-07ph.cm**-1.s**-1phot.flux;em.X-ray.softfloatl_HR0Limit flag on HR0meta.code.errorcharHR0[-1/0.9] Soft color ratio (1)phot.flux;em.X-ray;arith.ratiofloatE_HR0[/0.6]? Upper 1{sigma} uncertainty in HR0stat.error;stat.maxfloatnullablee_HR0[/0.7]? Lower 1{sigma} uncertainty in HR0stat.errorfloatnullableJ/ApJS/235/26/table1Chandra observation logrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFieldGC = Galactic center or LW = Limiting Window (see the "Description" section above)obs.fieldcharObsIDChandra observation identifiermeta.id;obs.param;obsintm_ObsIDFlag on ObsID 1561 (1)meta.code.multipcharStartStarting time of observation (UT)time.start;obsnullableExp[4.5/189.3] Exposure timekstime.duration;obs.exposurefloatInstInstrumentmeta.id;instrcharRAJ2000Aim point right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Aim point declination (J2000)degpos.eq.dec;meta.mainRollRoll angledeginstr.offsetfloatJ/ApJS/235/26/table3Catalog of the R<500" sources detected in the 2-8keV bandl_HR0Limit flag on HR0meta.code.errorcharCNet[12.4/27371.5] Net 2-8keV band countsctphot.count;em.X-ray.soft;src.netfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/3619] Index numberphot.flux;em.X-ray.softintRAJ2000[266.26/266.58] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-29.2/-28.8] Declination (J2000)degpos.eq.dec;meta.mainePos[0.03/0.8] Positional errorarcsecstat.error;posfloatCTot[73/28299] Total 2-8 keV band countsctphot.count;em.X-rayintCBck[20.2/7012.5] Background 2-8keV band countsctinstr.background;em.X-ray.mediumfloatl_CNetLimit flag on CNetmeta.code.errorcharE_CNet[6.5/234.4]? Upper 1{sigma} uncertainty in CNetctstat.error;stat.maxfloatnullablee_CNet[6.7/167]? Lower 1{sigma} uncertainty in CNetctstat.errorfloatnullableS0.5-2[0.01/346.1]? Observed 0.5-2keV photon flux (1)1e-07ph.cm**-2.s**-1phot.flux;em.X-ray.softfloatnullableH2-8[0.3/455.4] Observed 2-8keV photon flux1e-07ph.cm**-2.s**-1phot.flux;em.X-ray.hardfloatF2-8[0.7/1083.7] Absorption-corrected 2-10keV energy flux1e-15mW.m**-2phot.flux;em.X-ray.hardfloatHR0Soft hardness ratio (2)phot.flux;em.X-ray;arith.ratiofloatE_HR0[0.003/1.1]? Upper 1{sigma} uncertainty in HR0stat.error;stat.maxfloatnullablee_HR0[0.003/1]? Lower 1{sigma} uncertainty in HR0stat.errorfloatnullablel_HR1Limit flag on HR1meta.code.errorcharHR1[-0.8/1] Medium hardness ratio (2)phot.flux;em.X-ray;arith.ratiofloatE_HR1[0.006/1]? Upper 1{sigma} uncertainty in HR1stat.error;stat.maxfloatnullablee_HR1[0.007/1]? Lower 1{sigma} uncertainty in HR1stat.errorfloatnullablel_HR2Limit flag on HR2meta.code.errorcharHR2[-0.9/1] Hard hardness ratio (2)phot.flux;em.X-ray;arith.ratiofloatE_HR2[0.006/1.1]? Upper 1{sigma} uncertainty in HR2stat.error;stat.maxfloatnullablee_HR2[0.006/1]? Lower 1{sigma} uncertainty in HR2stat.errorfloatnullablen_Seq[,fimrx] Specific source notes for Seq (3)meta.notecharM09Display the data from Muno+, 2009, J/ApJS/181/110 within 2"meta.ref.urlcharJ/ApJS/235/26/table5Positions of removed sources originally found by wavdetectrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/576] Index number (1)meta.id;meta.mainintRAJ2000[266.26/266.58] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-29.2/-28.8] Declination (J2000)degpos.eq.dec;meta.mainn_SeqS: spurious source or E: extended sourcemeta.notechar