Obscured AGN at z~0.5-1 in the CDFS

We identify a numerically significant population of heavily obscured AGNs at z~0.5-1 in the Chandra Deep Field-South (CDF-S) and Extended Chandra Deep Field-South by selecting 242 X-ray undetected objects with infrared-based star-formation rates (SFRs) substantially higher (a factor of 3.2 or more) than their SFRs determined from the UV after correcting for dust extinction. An X-ray stacking analysis of 23 candidates in the central CDF-S region using the 4Ms Chandra data reveals a hard X-ray signal with an effective power-law photon index of {Gamma}=0.6^+0.3^_-0.4_, indicating a significant contribution from obscured AGNs.

Based on Monte Carlo simulations, we conclude that 74%+/-25% of the selected galaxies host obscured AGNs, within which ~95% are heavily obscured and ~80% are Compton-thick (CT; N_H_>1.5x10^24^cm^-2^).