X-ray properties and obscured fraction of AGN in the J1030 Chandra field
| Autor: | Signorini, Matilde, Marchesi, Stefano, Gilli, Roberto, Brusa, Marcella, Comastri, Andrea, D'Amato, Quirino, Iwasawa, Kazushi, Lanzuisi, Giorgio, Mazzolari, Giovanni, Mignoli, Marco, Peca, Alessandro, Prandoni, Isabella, Tozzi, Paolo, Vignali, Cristian, Vito, Fabio, Norman, Colin |
|---|---|
| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | A&A 676, A49 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202346364 |
| Popis: | The 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 ... Comment: A&A, in press |
| Databáze: | arXiv |
| Externí odkaz: |
|