Cosmic evolution of AGN obscuration in the j1030 field
Abstract
The field around the z∼6 quasar SDSS J1030+0524 has been observed in many different bands in recent years, including the X-rays with a 2015 Chandra survey, which is the 5th deepest X-ray survey in general. The dense multi-band coverage allowed the identification of the X-ray sources and their redshift determination: we now have a catalog of 243 identified AGNs in the J1030 field with a photometric or a spectroscopic redshift estimate for all of them (Marchesi+21), in the wide redshift range z∼0-6. Given its depth and the multi-band information, this Chandra catalog is an excellent resource to investigate for the redshift evolution of AGN obscuration. To derive information on the obscuration level of these sources, we performed a thorough X-ray spectral analysis for each of them, derived the column density parameter N_H, and refined these N_H estimates by means of additional optical and near-IR diagnostics. Whenever possible, we also used X-ray spectral features such as the Fe Kα emission line to put better constrains on the photometric redshift estimates. We found a significant trend of the obscuration level with the redshift, with objects at higher redshift showing on average higher column densities. In this talk I will discuss the methods and the results of this analysis performed in the J1030 field and compare the results with those found in other fields and with theoretical models of AGN obscuration and evolution.
- Publication:
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44th COSPAR Scientific Assembly. Held 16-24 July
- Pub Date:
- July 2022
- Bibcode:
- 2022cosp...44.1819S