Infrared Luminosities and Dust Properties of Z ≈ 2 Dust-obscured Galaxies

We present SHARC-II 350μm imaging of twelve 24μm-bright (F24μm > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and CARMA 1mm imaging of a subset of 2 DOGs. These objects are selected from the Boötes field of the NOAO Deep Wide-Field Survey. Detections of 4 DOGs at 350μm imply infrared (IR) luminosities which are consistent to within a factor of 2 of expectations based on a warm dust spectral energy distribution (SED) scaled to the observed 24μm flux density. The 350μm upper limits for the 8 non-detected DOGs are consistent with both Mrk 231 and M82 (warm dust SEDs), but exclude cold dust (Arp 220) SEDs. The two DOGs targeted at 1mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: Tdust > 35− 60 K. Assuming these dust properties apply to the entire sample, we find dust masses of ≈ 3× 10 M⊙. In comparison to other dusty z ∼ 2 galaxy populations such as sub-millimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2×10L⊙ vs. 6×10L⊙ for the other galaxy populations) that are driven by warmer dust temperatures (>35-60 K vs. ∼30 K) and lower inferred dust masses (3 × 10 M⊙ vs. 3 × 10 9 M⊙). Wide-field Herschel and SCUBA-2 surveys should be able to detect hundreds of these power-law dominated DOGs. We use existing Hubble Space Telescope and Spitzer/IRAC data to estimate stellar masses of these sources and find that the stellar to gas mass ratio may be higher in our 24μm-bright sample of DOGs than in SMGs and other Spitzer-selected sources. Although much larger sample sizes are needed to provide a definitive conclusion, the data are consistent with an evolutionary trend in which the formation of massive galaxies at z ∼ 2 involves a sub-millimeter bright, cold-dust and star-formation dominated phase followed by a 24μm-bright, warm-dust and AGN-dominated phase. Subject headings: galaxies: evolution — galaxies: fundamental parameters — galaxies: high-redshift — submillimeter