Figure 8: Ratio of obscured to total AGN as a function of hard X-ray luminosity. The black circles with dashed error bars show the obscured AGN fraction from the extended Chandra deep field south (ECDF-S) alone, while the gray circles show the results obtained using the meta-analysis by Treister and Urry . Black circles with solid error bars show the fraction obtained combining these two samples. The dependence in the AGN population synthesis model of Gilli et al.  for the intrinsic and observed fractions of obscured AGN is shown by the dashed and dotted red lines; the dependence used by Treister and Urry  is shown by the solid blue line. The dashed magenta line shows the expected dependence for a radiation-limited torus , while the dotted green line shows the expectation for the original “receding torus’’ , both normalized to the observed value in the erg s−1 bin. (b) Same as (a) but using an AGN sample at selected in hard X-rays from Swift/BAT observations . The fact that the same luminosity dependence is observed in both samples indicates that it is not due to selection effects.