Calibrating the Star Formation Rate at z=1 from Optical Data
  We present a star-formation rate calibration based on optical data that is
consistent with average observed rates in both the red and blue galaxy
populations at z~1. The motivation for this study is to calculate SFRs for
DEEP2 Redshift Survey galaxies in the 0.7<z<1.4 redshift range, but our results
are generally applicable to similar optically-selected galaxy samples without
requiring UV or IR data. Using SFRs fit from UV/optical SEDs in the AEGIS
survey, we explore the behavior of restframe B-band magnitude, observed [OII]
luminosity, and restframe (U-B) color with SED-fit SFR for both red sequence
and blue cloud galaxies. We find that a SFR calibration can be calculated for
all z~1 DEEP2 galaxies using a simultaneous fit in M_B and restframe colors
with residual errors that are within the SFR measurement error. The resulting
SFR calibration produces fit residual errors of 0.3 dex RMS scatter for the
full color-independent sample with minimal correlated residual error in L[OII]
or stellar mass. We then compare the calibrated z~1 SFRs to two diagnostics
that use L[OII] as a tracer in local galaxies and correct for dust extinction
at intermediate redshifts through either galaxy B-band luminosity or stellar
mass. We find that a L[OII] - M_B SFR calibration commonly used in the
literature agrees well with our calculated SFRs after correcting for the
average B-band luminosity evolution in L* galaxies. However, we find better
agreement with a local L[OII]-based SFR calibration that includes stellar mass
to correct for reddening effects, indicating that stellar mass is a better
tracer of dust extinction for all galaxy types and less affected by systematic
evolution than galaxy luminosity from z=1 to the current epoch.
