A Fully-Identified Sample of AEGIS20 Microjansky Radio Sources
  Infrared 3.6 to 8 micron images of the Extended Groth Strip yield plausible
counterpart identifications for all but one of 510 radio sources in the AEGIS20
S(1.4 GHz) > 50 micro-Jy sample. This is the first such deep sample that has
been effectively 100% identified. Achieving the same identification rate at
R-band would require observations reaching R_AB > 27. Spectroscopic redshifts
are available for 46% of the sample and photometric redshifts for an additional
47%. Almost all of the sources with 3.6 micron AB magnitudes brighter than 19
have spectroscopic redshifts z < 1.1, while fainter objects predominantly have
photometric redshifts with 1 \lapprox z \lapprox 3. Unlike more powerful radio
sources that are hosted by galaxies having large stellar masses within a
relatively narrow range, the AEGIS20 counterparts have stellar masses spanning
more than a factor of 10 at z \sim 1. The sources are roughly 10--15%
starbursts at z \lapprox 0.5 and 20--25% AGNs mostly at z > 1 with the
remainder of uncertain nature.
