  We post-process galaxy star formation histories in cosmological hydrodynamics
simulations to test quenching mechanisms associated with AGN. By comparing
simulation results to color-magnitude diagrams and luminosity functions of SDSS
galaxies, we examine whether "quasar mode" or "radio mode" AGN feedback can
yield a realistic red sequence. Both cases yield red sequences distinct from
the blue cloud, decent matches to the luminosity function, and galaxies that
are too blue by about 0.1 magnitudes in g-r. Our merger-based prescription for
quasar mode feedback, however, yields a red sequence build-up inconsistent with
observations: the luminosity function lacks a characteristic knee, and the
brightest galaxies include a small number of young stars.

Cosmology and Nongalactic Astrophysics