Mid-Infrared Determination of Total Infrared Luminosity and Star
  Formation Rates of Local and High-Redshift Galaxies
  We demonstrate estimating the total infrared luminosity, LIR, and star
formation rates (SFRs) of star-forming galaxies at redshift 0 < z < 2.8 from
single-band 24 micron observations, using local spectral energy distributions
(SED) templates without introducing additional free parameters. Our method is
based on characterizing the SEDs of galaxies as a function of their LIR surface
density, which is motivated by the indications that the majority of IR luminous
star-forming galaxies at 1 < z < 3 have extended star-forming regions, in
contrast to the strongly nuclear concentrated, merger-induced starbursts in
local luminous and ultraluminous IR galaxies. We validate our procedure for
estimating LIR by comparing the resulting LIRs with those measured from far-IR
observations at 0 < z < 2.8. AGNs were excluded using X-ray and 3.6-8.0 micron
observations, which are generally available in deep cosmological survey fields.
The Gaussian fits to the distribution of the discrepancies between the LIR
measurements from single-band 24 micron and Herschel observations have sigma <
0.1 dex, with ~10% of objects disagreeing by more than 0.2 dex. Since the 24
micron estimates are based on SEDs for extended galaxies, this agreement
suggests that ~90% of IR galaxies at high z are indeed much more physically
extended than local counterparts of similar LIR, consistent with recent
independent studies of the fractions of galaxies forming stars in the
main-sequence and starburst modes, respectively. Because we have not introduced
empirical corrections to enhance these estimates, in principle, our method
should be applicable to lower luminosity galaxies. This will enable use of the
21 micron band of the Mid-Infrared Instrument (MIRI) on board the JWST to
provide an extremely sensitive tracer of obscured SFR in individual
star-forming galaxies across the peak of the cosmic star formation history.
