Luminosity function at different redshifts. We show here the minimum and maximum values, considering both 1σ statistical uncertainties, using Poissonian statistics, and the fraction of absorbed AGNs (La Franca et al. 2005). Orange (45° hatching): coherent accretion during the decline of the quasar phase. Gray (horizontal hatching): chaotic accretion during the decline of the quasar phase.