THE EVOLUTION OF THE STAR FORMATION RATE OF GALAXIES AT 0.0 ≤ z ≤ 1.2

We present the 24 mu m rest-frame luminosity function (LF) of star-forming galaxies in the redshift range 0.0 <= z <= 0.6 constructed from 4047 spectroscopic redshifts from the AGN and Galaxy Evolution Survey of 24 mu m selected sources in the Bootes field of the NOAO Deep Wide-Field Survey. This sample provides the best available combination of large area (9 deg(2)), depth, and statistically complete spectroscopic observations, allowing us to probe the evolution of the 24 mu m LF of galaxies at low and intermediate redshifts while minimizing the effects of cosmic variance. In order to use the observed 24 mu m luminosity as a tracer for star formation, active galactic nuclei (AGNs) that could contribute significantly at 24 mu m are identified and excluded from our star-forming galaxy sample based on their mid-IR spectral energy distributions or the detection of X-ray emission. Optical emission line diagnostics are considered for AGN identification, but we find that 24 mu m emission from optically selected AGNs is usually from star-forming activity and therefore should not be excluded. The evolution of the 24 mu m LF of star-forming galaxies for redshifts of z <= 0.65 is consistent with a pure luminosity evolution where the characteristic 24 mu m luminosity evolves as (1 + z)(3.8 +/- 0.3). We extend our evolutionary study to encompass 0.0 <= z <= 1.2 by combining our data with that of the Far-Infrared Deep Extragalactic Legacy Survey. Over this entire redshift range, the evolution of the characteristic 24 mu m luminosity is described by a slightly shallower power law of (1 + z)(3.4 +/- 0.2). We find a local star formation rate density of (1.09 +/- 0.21) x 10(-2) M-circle dot yr(-1) Mpc(-3), and that it evolves as (1 + z)(3.5 +/- 0.2) over 0.0 <= z <= 1.2. These estimates are in good agreement with the rates using optical and UV fluxes corrected for the effects of intrinsic extinction in the observed sources. This agreement confirms that star formation at z <= 1.2 is robustly traced by 24 mu m observations and that it largely occurs in obscured regions of galaxies.