The XMM deep survey in the CDFS IV. Candidate Compton-thick AGN

Understand

The Chandra Deep Field is the region of the sky with the highest concentration of X-ray data available: 4Ms of Chandra and 3Ms of XMM data, allowing excellent quality spectra to be extracted even for faint sources.

• We take advantage of this in order to compile a sample of heavily obscured Active Galactic Nuclei (AGN) using X-ray spectroscopy.
• We select our sample among the 176 brightest XMM sources, searching for either a) flat X-ray spectra (Photon index<1.4 at the 90% confidence level) suggestive of a reflection dominated continuum or b) an absorption turn-over suggestive of a column density higher than ~10^{24} cm-2.
• We find a sample of nine candidate heavily obscured sources satisfying the above criteria.