Distribution of the 0.5–2 keV flux for the four mocks presented in this work: AGN from the Gilli et al. (2007) AGN population synthesis model (red solid line for the whole population; red dotted line for the z > 3 subsample); z > 3 AGN from the Vito et al. (2014) X-ray luminosity function (blue long-dashed line); nonactive galaxies (black short-dashed line); and clusters of galaxies (cyan long dashed line). All histograms refer to a 1 deg² field.