The Synergy between Deep X-ray and Infrared Surveys: AGN and Star
  Formation Activity
  We explore the connections between the infrared and X-ray properties of AGNs.
Using the well constrained infrared SEDs of a sample of local (i.e., z < 0.1)
sample of X-ray AGNs, we develop new diagnostics that exploit 24um and 70um
flux densities to identify AGN-dominated systems at z<1.5 and measure their
total infrared luminosities. We apply these diagnostics to the X-ray detected
AGNs in the Chandra Deep Field South and, in doing so, reveal that the infrared
to X-ray luminosity ratio was a factor of ~12 higher in the early Universe
compared to today. We explore possible explanations for this dramatic evolution
and demonstrate how forthcoming Herschel observations will discriminate between
these scenarios and, while doing so, identify potential Compton-thick AGNs.
Summary of Mullaney et al., MNRAS, 401, 995 (2010).
