These results provide new important insights into the nature of the AGN population and its evolution since $z\sim1$.

The nature of the AGN population {#sec:nature}
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At low X-ray luminosities (the faint end of the XLF), the number density of AGNs is dominated by moderately massive galaxies (${\mathcal{M}_*}\sim 10^{10.5-11} {\mathcal{M}_{\sun}}$) with a range of specific accretion rates given by the power-law distribution with slope $\approx-0.65$ measured by @Aird12. [[ The model predicts that X-ray flux limited samples (probing low X-ray luminosities at $z\lesssim1$) will identify AGNs with a distribution of host stellar masses that peaks at $\log {\mathcal{M}_*}/{\mathcal{M}_{\sun}}\sim 10.5-11$, with the majority of sources in moderately massive galaxies ($10<\log {\mathcal{M}_*}/{\mathcal{M}_{\sun}}<11.5$), consistent with observed samples [e.g. @Alonso-Herrero08; @Hickox09].]{}]{} However, the predominant contribution by moderate mass galaxies is due to the shape of the SMF. As shown in @Aird12, AGN activity does not appear to have a preference for a particular stellar mass range. In our model, galaxies with lower or higher stellar masses are just as likely to host an AGN with the same distribution of accretion rates, but these sources do not constitute a significant fraction of the overall AGN number density.

The bright end of the XLF probes a 