The AGN content of ROSAT and ASCA deep surveys

Abstract The results of ROSAT deep surveys were well established during the first few years of ROSAT operation (Papers I ‐ XV in this collaboration, and other papers in this Volume). They have allowed us to measure the AGN Luminosity Function and its evolution in soft X‐rays, both for AGN of Type I and for objects classified as AGN Type II/Narrow‐Line X‐ray Galaxy (NXLG). More recently, we have performep surveys with ASCA of some of these same ROSAT fields. Based on coincidences with ROSAT deep survey sources, and further optical spectroscopic identification, we discuss the optical identification content of five of our ASCA deep survey fields. Perhaps not surprisingly, we have observed significant cosmological evolution for Type I AGN in the 2–10 keV energy range, with an evolutionary rate which is consistent with that measured in other passbands. The predicted contribution of Type I AGN to the 2–10 keV X‐ray background (XRB) is about 60%, and the combined contribution from AGN of Types I & II is consistent with 100%.