Simultaneous Modeling of the Stellar and Dust Emission in Distant
  Galaxies: Implications for Star Formation Rate Measurements
  We have used near-ultraviolet (NUV) to mid-infrared (MIR) composite spectral
energy distributions (SEDs) to simultaneously model the attenuated stellar and
dust emission of 0.5 < z < 2.0 galaxies. These composite SEDs were previously
constructed from the photometric catalogs of the NEWFIRM Medium-Band Survey, by
stacking the observed photometry of galaxies that have similar rest-frame
NUV-to-NIR SEDs. In this work, we include a stacked MIPS 24 micron measurement
for each SED type to extend the SEDs to rest-frame MIR wavelengths. Consistent
with previous studies, the observed MIR emission for most SED types is higher
than expected from only the attenuated stellar emission. We fit the NUV-to-MIR
composite SEDs by the Flexible Stellar Population Synthesis (SPS) models, which
include both stellar and dust emission. We compare the best-fit star formation
rates (SFRs) to the SFRs based on simple UV+IR estimators. Interestingly, the
UV and IR luminosities overestimate SFRs - compared to the model SFRs - by more
than ~ 1 dex for quiescent galaxies, while for the highest star-forming
galaxies in our sample the two SFRs are broadly consistent. The difference in
specific SFRs also shows a gradually increasing trend with declining specific
SFR, implying that quiescent galaxies have even lower specific SFRs than
previously found. Contributions from evolved stellar populations to both the UV
and the MIR SEDs most likely explain the discrepancy. Based on this work, we
conclude that SFRs should be determined from modeling the attenuated stellar
and dust emission simultaneously, instead of employing simple UV+IR-based SFR
estimators.
