A Multi-wavelength Analysis of Spitzer Selected Coma Cluster Galaxies: Star Formation Rates and Masses

We present a thorough study of the specific star formation rates (sSFRs) for MIPS 24 μm selected galaxies in the Coma cluster. We build galaxy spectral energy distributions using optical (u', g', r', i', z'), near-infrared (J, H, K_s ), and mid- to far-infrared (Infrared Array Camera and MIPS) photometry. New and archival spectra confirm 210 cluster members. Subsequently, the total infrared luminosity, galaxy stellar mass, and sSFR for the members are determined by measuring best-fit templates. Using an array of complementary diagnostics, we search for any contaminating active galactic nuclei, but find few. We compare obscured SFRs to unobscured rates derived from extinction-corrected Hα emission line measurements. The agreement between these two values leads us to conclude that there is no evidence for an additionally obscured component. In our spectroscopic sample, complete to 80% for r' < 19.5, we find that all starbursts are blue and are dwarfs, having masses <10⁹ M _⊙. Examining the location of these starbursts within the cluster, we confirm that there is a lower fraction in the cluster core.