J/A+A/638/A45ivo://CDS.VizieR/J/A+A/638/A45doi:10.26093/cds/vizier.36380045CDSMasoura V.A.Georgantopoulos I.Mountrichas G.Vignali C.,Koulouridis E.Chiappetti L.Fotopoulou S.Paltani S.Pierre M.2022-06-23T08:04:52Z2020-11-20T08:58:07ZCDS support team

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

cds-question@unistra.frx-ray-sourcesactive-galactic-nucleiThe combination of optical and mid-infrared (MIR) photometry has been extensively used to select red active galactic nuclei (AGNs). Our aim is to explore the obscuration properties of these red AGNs with both X-ray spectroscopy and spectral energy distributions (SEDs). In this study, we re-visit the relation between optical/MIR extinction and X-ray absorption. We use IR selection criteria, specifically the W1 and W2 WISE bands, to identify 4798 AGNs in the XMM-XXL area (~25deg^2^). Application of optical/MIR colours (r-W2>6) reveals 561 red AGNs (14%). Of these, 47 have available X-ray spectra with at least 50 net (background-subtracted) counts per detector. For these sources, we construct SEDs from the optical to the MIR using the CIGALE code. The SED fitting shows that 44 of these latter 47 sources present clear signs of obscuration based on the AGN emission and the estimated inclination angle. Fitting the SED also reveals ten systems (~20%) which are dominated by the galaxy. In these cases, the red colours are attributed to the host galaxy rather than AGN absorption. Excluding these ten systems from our sample and applying X-ray spectral fitting analysis shows that up to 76% (28/37) of the IR red AGNs present signs of X-ray absorption. Thus, there are nine sources (~20% of the sample) that although optically red, are not substantially X-ray absorbed. Approximately 50% of these sources present broad emission lines in their optical spectra. We suggest that the reason for this apparent discrepancy is that the r-W2 criterion is sensitive to smaller amounts of obscuration relative to the X-ray spectroscopy. In conclusion, it appears that the majority of red AGNs present considerable obscuration levels as shown by their SEDs. Their X-ray absorption is moderate with a mean of N_H_~10^22^cm^-2^.2020A&A...638A..45Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/638/A45CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIX/49 : XXL Survey: First results (Pierre+, 2016)IX/52 : XXL Survey. DR2 (Chiappetti+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/638/A45https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/638/A45http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/638/A45https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/638/A45https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/638/A45http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/638/A45GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/638/A45/table2 (General properties of the red AGN sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/638/A45/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/638/A45/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/638/A45/table2?GETtext/xml+votable180.050000true34.64883-5.632820.0055555555555555565/4419 6/17674 17681-17683 17685-17686 17689-17690 17692 17694-17697 17699-17700 17703 17705 17708 17712 17716 367982.85864675833786e-19 3.5010283109654867e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/638/A45?format=asciiX-raydefaultJ/A+A/638/A45/table3X-ray properties of the red AGN samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSequential numbermeta.recordint3XLSS3XLSS ID (JHHMMSS.s+DDMMSS)meta.id;meta.maincharn_3XLSS[ib] Note on 3XLSS (1)meta.notecharl_NHLimit flag on NHmeta.code.errorcharNHHydrogen column density1e+22cm**-2phys.columnDensityfloatNHG1.8? Hydrogen column density at GAMMA=1.8 (2)1e+22cm**-2phys.columnDensityfloatnullableGAMMAPhoton indexmeta.code;spect.indexfloatlogLXX-ray luminosity in 2-10keV bandlog(1e-07W)phys.luminosity;em.X-raydoubleC-statC statisticstat.fit.paramintdofDegree of freedomstat.fit.dofintJ/A+A/638/A45/table2General properties of the red AGN sampleSeqSequential numbermeta.recordintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint3XLSS3XLSS ID (JHHMMSS.s+DDMMSS)meta.id;meta.maincharzRedshiftsrc.redshiftfloatn_z[s/p] spectroscopic (s) or photometric (p) redshiftmeta.notecharrmagSDSS DR15 r magnitude (Vega)magphot.mag;em.opt.RfloatW2magW2 magnitude (Vega)magphot.mag;em.IR.4-8umfloat3xlssDisplay the 3XLSS data (XXL DR2, Cat. IX/52)meta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar_RApositions from 3XLSS catalog (right ascension part)degpos.eq.ra;meta.main_DEpositions from 3XLSS catalog (declination part)degpos.eq.dec;meta.mainJ/A+A/638/A45/table5SED properties of the red AGN samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSequential numbermeta.recordint3XLSS3XLSS ID (JHHMMSS.s+DDMMSS)meta.id;meta.maincharPSIViewing angle of the torus (1)degpos.posAngintfracAGNAGN fractionphot.flux;arith.ratiofloatchi2rReduced chi^2^ valuestat.fit.chi2floatJ/A+A/638/A45/table6Optical properties of the red AGN samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSequential numbermeta.recordint3XLSS3XLSS ID (JHHMMSS.s+DDMMSS)meta.id;meta.maincharOpticalOptical properties (1)meta.notecharJ/A+A/638/A45/table7Comparison of the X-ray, SED, and optical propertiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSequential numbermeta.recordint3XLSS3XLSS ID (JHHMMSS.s+DDMMSS)meta.id;meta.maincharn_3XLSS[b/i] Note on 3XLSS (1)meta.notecharXray[1/2] X-ray classification (2)src.classintSED[1/2] SED classification (2)src.classintOpt[0/3]? Optical-based classification (2)src.classintnullable