Mid-Infrared Galaxy Luminosity Functions from the AGN and Galaxy
  Evolution Survey
  We present galaxy luminosity functions at 3.6, 4.5, 5.8, and 8.0 micron
measured by combining photometry from the IRAC Shallow Survey with redshifts
from the AGN and Galaxy Evolution Survey of the NOAO Deep Wide-Field Survey
Bootes field. The well-defined IRAC samples contain 3800-5800 galaxies for the
3.6-8.0 micron bands with spectroscopic redshifts and z < 0.6. We obtained
relatively complete luminosity functions in the local redshift bin of z < 0.2
for all four IRAC channels that are well fit by Schechter functions. We found
significant evolution in the luminosity functions for all four IRAC channels
that can be fit as an evolution in M* with redshift, \Delta M* = Qz. While we
measured Q=1.2\pm0.4 and 1.1\pm0.4 in the 3.6 and 4.5 micron bands consistent
with the predictions from a passively evolving population, we obtained
Q=1.8\pm1.1 in the 8.0 micron band consistent with other evolving star
formation rate estimates. We compared our LFs with the predictions of
semi-analytical galaxy formation and found the best agreement at 3.6 and 4.5
micron, rough agreement at 8.0 micron, and a large mismatch at 5.8 micron.
These models also predicted a comparable Q value to our luminosity functions at
8.0 micron, but predicted smaller values at 3.6 and 4.5 micron. We also
measured the luminosity functions separately for early and late-type galaxies.
While the luminosity functions of late-type galaxies resemble those for the
total population, the luminosity functions of early-type galaxies in the 3.6
and 4.5 micron bands indicate deviations from the passive evolution model,
especially from the measured flat luminosity density evolution. Combining our
estimates with other measurements in the literature, we found (53\pm18)% of the
present stellar mass of early-type galaxies has been assembled at z=0.7.
