the growth of SMBHs and prompting periods of AGN activity. It is thus vital to understand how the rapid decline of SMBH accretion since $z\sim1$ is related to the co-evolving properties of their host galaxies.

The AGN luminosity function provides the principal tracer of the distribution of SMBH accretion over the history of the universe. A variety of wavebands and identification techniques have been used to measure the luminosity function of AGNs out to high redshifts ($z\sim6$) [e.g. @Boyle87; @Page97; @Richards06; @Assef11; @Ueda03; @Ebrero09; @Aird10]. These studies have revealed a “downsizing" behavior in the evolution of AGNs [e.g. @Barger05]. This downsizing is characterized by a rapid decline in the number density of the most luminous AGNs since a peak at $z\sim2$, while the number density of lower luminosity AGNs evolves much more weakly and peaks at lower $z$.

To understand the underlying physical processes that drive the observed evolution of the AGN luminosity function it is vital to connect the AGN population to the galaxies that host them. A number of studies have indicated that AGNs are preferentially found in the most massive galaxies [e.g. @Kauffmann03; @Dunlop03; @Schawinski07; @Nandra07; @Coil09; @Hickox09; @Georgakakis11b; @Bongiorno12]. These galaxies tend to have red optical 