  Feedback from supermassive black holes is believed to be a critical driver of
the observed color bimodality of galaxies above the Milky Way mass scale. AGN
feedback has been modeled in many galaxy formation simulations, but most
implementations have involved simplified prescriptions or a coarse-grained
interstellar medium (ISM). We present the first set of FIRE-3 cosmological
zoom-in simulations with AGN feedback evolved to $z\sim0$, examining the impact
of AGN feedback on a set of galaxies with halos in the mass range
$10^{12}-10^{13} M_{\odot}$. These simulations combine detailed stellar and ISM
physics with multi-channel AGN feedback including radiative feedback,
mechanical outflows, and in some simulations, cosmic rays (CRs). We find that
massive (>L*) galaxies in these simulations can match local scaling relations
including the stellar mass-halo mass relation and the $M_{\rm BH}$-$\sigma$
relation; in the stronger model with CRs, they also match the size-mass
relation and the Faber-Jackson relation. Many of the massive galaxies in the
simulations with AGN feedback have quenched star formation and elliptical
morphologies, in qualitative agreement with observations. In contrast,
simulations at the massive end without AGN feedback produce galaxies that are
too massive and form stars too rapidly, are order-of-magnitude too compact, and
have velocity dispersions well above Faber-Jackson. Despite these successes,
the AGN models analyzed do not produce uniformly realistic galaxies when the
feedback parameters are held constant: while the stronger model produces the
most realistic massive galaxies, it tends to over-quench the lower-mass
galaxies. This indicates that further refinements of the AGN modeling are
needed.
