SIGNORINI, MatildeMatildeSIGNORINIMARCHESI, STEFANOSTEFANOMARCHESIGILLI, RobertoRobertoGILLIBrusa, MarcellaMarcellaBrusaCOMASTRI, AndreaAndreaCOMASTRID'AMATO, QuirinoQuirinoD'AMATOIwasawa, KazushiKazushiIwasawaLANZUISI, GiorgioGiorgioLANZUISIMAZZOLARI, GiovanniGiovanniMAZZOLARIMIGNOLI, MarcoMarcoMIGNOLIPECA, ALESSANDROALESSANDROPECAPRANDONI, ISABELLAISABELLAPRANDONITOZZI, PaoloPaoloTOZZIVIGNALI, CRISTIANCRISTIANVIGNALIVITO, FabioFabioVITONorman, ColinColinNorman2024-01-162024-01-1620230004-6361http://hdl.handle.net/20.500.12386/34540The 500ks Chandra ACIS-I observation of the field around the $z=6.31$ quasar SDSS J1030+0524 is currently the 5th deepest extragalactic X-ray survey. The rich multi-band coverage of the field allowed for 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 $z\approx0-6$ is available over a 355 arcmin$^2$ area. 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, measuring its nuclear column density $N_{\rm H}$ and intrinsic (de-absorbed) 2-10 keV rest-frame luminosity, $L_{2-10}$. 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 $z\sim 1.2$, we found $f_{22}\sim0.7-0.8$ and $f_{23}\sim0.5-0.6$, respectively, in broad agreement with the results from other X-ray surveys. No significant variations with X-ray luminosity were found within the limited luminosity range probed by our sample (log$L_{2-10}\sim 42.8-44.3$). When focusing on luminous AGN with log$L_{2-10}\sim44$ 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 $z\sim0.8-3$. Nonetheless, the obscured fractions we measure are significantly higher than ...STAMPAenArticle10.1051/0004-6361/2023463642-s2.0-85168151873https://www.aanda.org/articles/aa/full_html/2023/08/aa46364-23/aa46364-23.htmlhttp://arxiv.org/abs/2305.13368v1https://ui.adsabs.harvard.edu/abs/2023A%26A...676A..49S/abstract2023A&A...676A..49SFIS/02 - FISICA TEORICA, MODELLI E METODI MATEMATICIERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation