Determining Star Formation Rates for Infrared Galaxies

We show that measures of star formation rates (SFRs) for infrared galaxies using either singleband 24μm or extinction-corrected Paα luminosities are consistent in the total infrared luminosity = L(TIR) ∼ 10 L⊙ range. MIPS 24μm photometry can yield star formation rates accurately from this luminosity upward: SFR(M⊙ yr )=7.8×10 L(24μm, L⊙) from L(TIR) = 5× 10 9 L⊙ to 10 11 L⊙ and SFR = 7.8 × 10 −10 L(24μm, L⊙)(7.76 × 10 −11 L(24)) for higher L(TIR). For galaxies with L(TIR) ≥ 10 L⊙, these new expressions should provide SFRs to within 0.2 dex. For L(TIR) ≥ 10 L⊙, we find that the SFR of infrared galaxies is significantly underestimated using extinctioncorrected Paα (and presumably using any other optical or near infrared recombination lines). As a part of this work, we constructed spectral energy distribution (SED) templates for eleven luminous and ultraluminous purely star forming infrared galaxies (LIRGs and ULIRGs) and over the spectral range 0.4μm to 30 cm. We use these templates and the SINGS data to construct average templates from 5μm to 30 cm for infrared galaxies with L(TIR) = 5 × 10 to 10 L⊙. All of these templates are made available on line. Subject headings: galaxies: fundamental parameters galaxies: starburst galaxies: stellar content