The mid-IR Luminosity Function at z<0.3 from 5MUSES: Understanding the
  Star-formation/AGN Balance from a Spectroscopic View
  We present rest-frame 15 and 24 um luminosity functions and the corresponding
star-forming luminosity functions at z<0.3 derived from the 5MUSES sample.
Spectroscopic redshifts have been obtained for ~98% of the objects and the
median redshift is ~0.12. The 5-35 um IRS spectra allow us to estimate
accurately the luminosities and build the luminosity functions. Using a
combination of starburst and quasar templates, we quantify the star-formation
and AGN contributions in the mid-IR SED. We then compute the star-formation
luminosity functions at 15 um and 24 um, and compare with the total 15 um and
24 um luminosity functions. When we remove the contribution of AGN, the bright
end of the luminosity function exhibits a strong decline, consistent with the
exponential cutoff of a Schechter function. Integrating the differential
luminosity function, we find that the fractional contribution by star formation
to the energy density is 58% at 15 um and 78% at 24 um, while it goes up to
~86% when we extrapolate our mid-IR results to the total IR luminosity density.
We confirm that the active galactic nuclei play more important roles
energetically at high luminosities. Finally, we compare our results with work
at z~0.7 and confirm that evolution on both luminosity and density is required
to explain the difference in the LFs at different redshifts.
