GOODS Discovery of a Significant Population of Obscured AGN
  We analysed the optical and infrared properties of X-ray sources in the Great Observatories Origins Deep Survey (GOODS), a deep multiwavelength survey covering 0.1 square degrees in two fields. The HST ACS data are well explained by a unified AGN scheme that postulates roughly 3 times as many obscured as unobscured AGN, as are the spectroscopic and photometric redshift distributions once selection effects are considered. Our model predicts infrared number counts of AGN that agree well with the preliminary Spitzer data, confirming that large numbers of obscured AGN are present in the early Universe (z>1). 
C. M. Urry and E. Treister