J/A+A/466/823ivo://CDS.VizieR/J/A+A/466/823doi:10.26093/cds/vizier.34660823CDSGeorgantopoulos I.Georgakakis A.Akylas A.2017-11-10T11:15:11Z2007-12-18T17:41:20ZCDS support team

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

cds-question@unistra.frx-ray-sourcesquasarsactive-galactic-nucleiredshiftedWe present Chandra and Spitzer data for the 186, extragalactic, hard 2-10keV X-ray selected sources, which lie in the central part of the Chandra Deep Field South (CDFS). For the vast majority of sources (99.5%), there is a spectroscopic or photometric redshift available. We classify 17 sources as X-ray obscured QSOs, strictly according to X-ray criteria, i.e. defined as having large hydrogen column densities (NH>10^22cm^-2^) and luminosities (LX>10^44^erg/s). The surface density of X-ray obscured QSOs is ~210{deg}^-2^. We find 18 candidate Compton-thick NH>10^24^cm^-2^ sources, of which three have QSO luminosities (LX>10^44^erg/s). The X-ray obscured QSO comprise a mixed bag of objects, covering the redshift range z=1.3-4.3. Eight of these show narrow-line optical spectra, two show no obscuration in their optical spectra that present broad lines, while for the other seven there is only a photometric redshift available. About half of the X-ray obscured QSOs show high X-ray to optical flux ratios, X/O>1, and red colours, I-3.6{mu}m>4. Combining the X-ray with the mid-IR 8{mu}m or 24{mu}m flux can be used as an additional diagnostic to sift out the heavily obscured AGN. All X-ray selected QSOs present red mid-IR colours and can be easily separated among mid-IR sources, demonstrating that mid-IR selection provides a powerful tool for detecting obscured QSOs.2007A&A...466..823Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/466/823CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/610/128 : NIR colors of hard X-ray-selected AGN (Watanabe+, 2004)J/ApJ/618/123 : Hard X-ray-emitting AGNs (Silverman+, 2005)J/A+A/467/73 : 3{sigma} hard sample of XMDS survey (Tajer+, 2007)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/466/823https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/466/823http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/466/823https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/466/823https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/466/823http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/466/823GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/466/823/table3 (Spectral fits)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/466/823/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/466/823/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/466/823/table3?GETtext/xml+votable180.050000true53.275-27.7808330.0055555555555555566/35935https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/466/823?format=asciiX-rayOpticaldefaultJ/A+A/466/823/table3Spectral fitsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[GZW2002]Sequential number, [GZW2002] XID NNN in Simbadmeta.recordintn_[GZW2002][*] *: Compton-thick sourcesmeta.notecharNameSource name from Giacconni et al. (2002, Cat. <J/ApJS/139/369>) JHHMMSS.s+DDMMSSmeta.idcharGammaBest fit model power-law photon indexmeta.code;spect.index;meta.modelledfloatE_Gamma? Error on Gamma (upper limit)stat.error;stat.maxfloatnullablee_Gamma? Error on Gamma (lower limit)stat.errorfloatnullablel_NHLimit flag on NHmeta.code.errorcharNHRest-frame column density1e+22cm**-2phys.columnDensityfloatf_NH[i] i when upper limit is infinitymeta.codecharE_NH? Error on NH (upper limit)1e+22cm**-2stat.error;stat.maxfloatnullablee_NH? Error on NH (lower limit)1e+22cm**-2stat.errorfloatnullablelogLX? logarithm of 2-10keV intrinsic luminosity1e-07Wphys.luminosity;em.X-rayfloatnullableClassOptical spectroscopic classification as given in Szokoly et al. (2004, J/ApJS/155/271) (1)meta.code.classcharz? Redshift from either Szokoly et al. (2004 <J/ApJS/155/271>) (spectroscopic) or Zheng et al. (2004, <J/ApJS/155/73>) (photometric)src.redshiftfloatnullableFluxObserved 2-10keV X-ray flux1e-17W.m**-2phot.flux;em.X-rayfloatchi2/dof? Reduced chi^2^stat.fit.chi2floatnullableSimbadSimbad column added by the CDSchar_RARight ascension (derived from Name) for Eq=J2000degpos.eq.ra;meta.main_DEDeclination (derived from Name) for Eq=J2000degpos.eq.dec;meta.main