Faint, Evolving Radio AGN in SDSS Luminous Red Galaxies
  We detect and study the properties of faint radio AGN in Luminous Red
Galaxies (LRGs). The LRG sample comprises 760,000 objects from a catalog of LRG
photometric redshifts constructed from the Sloan Digital Sky Survey (SDSS)
imaging data, and 65,000 LRGs from the SDSS spectroscopic sample. These
galaxies have typical 1.4 GHz flux densities in the 10s-100s of microJy, with
the contribution from a low-luminosity AGN dominating any contribution from
star formation. To probe the radio properties of such faint objects, we employ
a stacking technique whereby FIRST survey image cutouts at each optical LRG
position are sorted by the parameter of interest and median-combined within
bins. We find that median radio luminosity scales with optical luminosity
(L_opt) as L_1.4 GHz ~ L_opt^(beta), where beta appears to decrease from beta ~
1 at z = 0.4 to beta ~ 0 at z = 0.7, a result which could be indicative of AGN
cosmic downsizing. We also find that the overall LRG population, which is
dominated by low-luminosity AGN, experiences significant cosmic evolution
between z = 0.2 and z = 0.7. This implies a considerable increase in total AGN
heating for these massive ellipticals with redshift. By matching against the
FIRST catalog, we investigate the incidence and properties of LRGs associated
with double-lobed (FR I/II) radio galaxies. (Abridged)
