Far-Infrared Properties of Spitzer-selected Luminous Starbursts
Abstract
We present SHARC-2 350 micron data on 20 luminous z~2 starbursts with S(1.2mm) > 2 mJy from the Spitzer-selected samples of Lonsdale et al. 2009 and Fiolet et al. 2009. All the sources were detected, with S(350um) > 25 mJy for 18. With the data we determine precise dust temperatures and luminosities for these galaxies, using on both single-temperature fits and models with powerlaw mass--temperature distributions. We derive appropriate formulae to use when optical depths are non-negligible. Our models provide an excellent fit to the 6um -- 2mm measurements of local starbursts. We find characteristic single-component temperatures T1 ~ 35.5 +- 2.2 K and integrated IR luminosities around 10^(12.9+-0.1) Lsun for the SWIRE-selected sources. Molecular gas masses are estimated at ~4*10^(10) Msun, assuming kappa(850um)=0.15 m^2/kg and an SMG-like gas-to-dust mass ratio. The best-fit models imply >~2 kpc emission scales. We also note a tight correlation between rest-frame 1.4 GHz radio and IR luminosities confirming star-formation as the predominant power source. The far-infrared properties of our sample are indistinguishable from the purely submillimeter-selected galaxy (SMG) populations from current surveys. We therefore conclude that our original selection criteria, based on mid-infrared IRAC colors and 24 micron flux densities, provides an effective means for the study of SMGs at z ~ 1.5--2.5.Keywords
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