Source density distribution with intrinsic X-ray luminosity distribution for CDFS (upper panel, ~140 arcmin²) and COSMOS (lower panel, 1.8   deg²) samples (note the y-axes are different). The distributions were obtained with a moving bin of width log (L_X) = 0.6, with measurements taken each log (L_X) = 0.2. The overall X-ray population is represented by the dotted line, the AGN by the solid line. The AGN population is further separated into the type-1 (light shaded region, log (N_H [cm^-2] ) ≤ 22), type-2 (dark shaded region, log (N_H [cm^-2] ) > 22), and unknown-type (white region) subpopulations. The regions do not overlap. The unknown-type AGN are those for which data was not enough to allow for an obscuration determination.