Evolution of optically faint AGN from COMBO-17 and GEMS
  We have mapped the AGN luminosity function and its evolution between z=1 and z=5 down to apparent magnitudes of $R<24$. Within the GEMS project we have analysed HST-ACS images of many AGN in the Extended Chandra Deep Field South, enabling us to assess the evolution of AGN host galaxy properties with cosmic time. 
L. Wisotzki, K. Jahnke, S.F. Sanchez, C. Wolf, M. Barden, E.F. Bell,   A. Borch, B. HaeUssler, K. Meisenheimer, H.-W. Rix, S...