J/A+A/676/A49ivo://CDS.VizieR/J/A+A/676/A49doi:10.26093/cds/vizier.36760049CDSSignorini M.Marchesi S.Gilli R.Brusa M.Comastri A.D'Amato Q.,Iwasawa K.Lanzuisi G.Mazzolari G.Mignoli M.Peca A.Prandoni I.,Tozzi P.Vignali C.Vito F.Norman C.2025-10-30T20:00:58Z2023-08-07T08:35:10ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleix-ray-sourcesredshiftedThe 500ks Chandra ACIS-I observation of the field around the z=6.31 quasar SDSS J1030+0524 is currently the fifth deepest extragalactic X-ray survey. The rich multi-band coverage of the field allowed an effective identification and redshift determination of the X-ray source counterparts; to date, a catalog of 243 extragalactic X-ray sources with either a spectroscopic or photometric redshift estimate in the range z~=0-6 is available over an area of 355 arcmin^2^. Given its depth and the multi-band information, this catalog is an excellent resource to investigate X-ray spectral properties of distant active galactic nuclei (AGN) and derive the redshift evolution of their obscuration. We performed a thorough X-ray spectral analysis for each object in the sample, and measured its nuclear column density NH and intrinsic (de-absorbed) 2-10keV rest-frame luminosity, L2-10. Whenever possible, we also used the presence of the Fe K{alpha} emission line to improve the photometric redshift estimates. We measured the fractions of AGN hidden by column densities in excess of 10^22^ and 10^23^cm^-2^ (f_22_ and f_23_, respectively) as a function of L_2-10_ and redshift, and corrected for selection effects to recover the intrinsic obscured fractions. At z~1.2, we found f_22_~0.7-0.8 and f_23_~0.5-0.6, respectively, in broad agreement with the results from other X-ray surveys. No significant variations in X-ray luminosity were found within the limited luminosity range probed by our sample (logL_2-10_~42.8-44.3). When focusing on luminous AGN with logL_2-10_~44 to maximize the sample completeness up to large cosmological distances, we did not observe any significant change in f_22_ or f_23_ over the redshift range z~0.8-3. Nonetheless, the obscured fractions we measure are significantly higher than is seen in the local Universe for objects of comparable intrinsic luminosity, pointing toward an increase in the average AGN obscuration toward early cosmic epochs, as also observed in other X-ray surveys. We finally compared our results with recent analytic models that ascribe the greater obscuration observed in AGN at high redshifts to the dense interstellar medium (ISM) of their hosts. When combined with literature measurements, our results favor a scenario in which the total column density of the ISM and the characteristic surface density of its individual clouds both increase toward early cosmic epochs as N_H,ISM_{prop.to}(1+z)^delta^, with delta~3.3-4 and {SIGMA}_c*_{prop.to}(1+ z)^2^, respectively.2023A&A...676A..49Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/676/A49CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/637/A52 : Deep Chandra survey in J1030+0524 field (Nanni+, 2020)J/A+A/656/A117 : Chandra J1030 redshift identification (Marchesi+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/676/A49https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/676/A49http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/676/A49https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/676/A49https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/676/A49http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/676/A49GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/676/A49/table3 (Chandra J1030 spectral catalog (corrected version, 30-Oct-2025))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/676/A49/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/676/A49/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/676/A49/table3?GETtext/xml+votable180.050000true157.6045.31927780.0055555555555555566/27440https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/676/A49?format=asciiX-raydefaultJ/A+A/676/A49/table3Chandra J1030 spectral catalog (corrected version, 30-Oct-2025)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintfigShow the NH probability distributionmeta.ref.urlcharXIDChandra J1030 ID (from Nanni et al., 2020A&A...637A..52N, Cat. J/A+A/637/A52) (XID)meta.id;meta.mainintRAJ2000Right Ascension, X-ray source (J2000) (RACORRX_H)pos.eq.ra;meta.mainDEJ2000Declination, X-ray source (J2000) (DECCORRX_D)pos.eq.dec;meta.mainf_z[0/1] 1 if spectroscopic, 0 if photometric redshift (1)meta.codecharl_z[>] Lower limit flag on z (if the photometric redshift probability curve is flat)meta.code.error;src.redshiftcharzSource redshift: spectroscopic when available, photometric otherwisesrc.redshiftdoublee_z? Lower error on the source redshift estimate (2)stat.error;src.redshiftdoublenullableE_z? Higher error on the source redshift estimatestat.error;stat.maxdoublenullablectSource counts in the 0.5-7keV rangectphot.count;em.X-ray.mediumfloatlog(NH)Logarithm of the source column densitylog(cm**-2)phys.columnDensitydoublee_log(NH)? Lower error on the logarithm of the source column density,log(cm**-2)stat.errordoublenullableE_log(NH)? Higher error on the logarithm of the source column densitylog(cm**-2)stat.error;stat.maxdoublenullableGammaPhoton index of the spectral power-law. Fixed to 1.9 if the source has less than 148 counts in the 0.5-7keV rangespect.index;em.X-ray.mediumfloate_Gamma? Lower error on the photon index Gamma (3)stat.errordoublenullableE_Gamma? Higher error on the photon index Gamma (3)stat.error;stat.maxdoublenullablelog(L2-10)dIntrinsic (de-absorbed) rest-frame 2-10keV luminosity in erg/slog(1e-07W)phys.luminosity;em.X-ray.mediumfloate_log(L2-10)d? Lower error on the intrinsic (de-absorbed) rest-frame 2-10keV luminosity in erg/slog(1e-07W)stat.errordoublenullableE_log(L2-10)d? Higher error on the intrinsic (de-absorbed) rest-frame 2-10keV luminosity in erg/slog(1e-07W)stat.error;stat.maxdoublenullableFileNameName of the file in subdirectory fig with NH probality distribution curvemeta.id;meta.filechar