The Star Formation and Nuclear Accretion Histories of Normal Galaxies in
  the AGES Survey
  We combine IR, optical and X-ray data from the overlapping, 9.3 square degree
NOAO Deep Wide-Field Survey (NDWFS), AGN and Galaxy Evolution Survey (AGES),
and XBootes Survey to measure the X-ray evolution of 6146 normal galaxies as a
function of absolute optical luminosity, redshift, and spectral type over the
largely unexplored redshift range 0.1 < z < 0.5. Because only the closest or
brightest of the galaxies are individually detected in X-rays, we use a
stacking analysis to determine the mean properties of the sample. Our results
suggest that X-ray emission from spectroscopically late-type galaxies is
dominated by star formation, while that from early-type galaxies is dominated
by a combination of hot gas and AGN emission. We find that the mean star
formation and supermassive black hole accretion rate densities evolve like
(1+z)^3, in agreement with the trends found for samples of bright, individually
detectable starburst galaxies and AGN. Our work also corroborates the results
of many previous stacking analyses of faint source populations, with improved
statistics.
