Star Formation in Distant Red Galaxies: Spitzer Observations in the Hubble Deep Field South
نویسندگان
چکیده
We present Spitzer 24μm imaging of 1.5 < z < 2.5 Distant Red Galaxies (DRGs) in the 10×10 Extended Hubble Deep Field South of the Multiwavelength Survey by Yale-Chile. We detect 65% of the DRGs with KAB < 23.2 mag at S24μm & 40μJy, and conclude that the bulk of the DRG population are dusty active galaxies. A mid-infrared (MIR) color analysis with IRAC data suggests that the MIR fluxes are not dominated by buried AGN, and we interpret the high detection rate as evidence for a high average star formation rate of < SFR > = 130±30 M⊙yr. From this, we infer that DRGs are important contributors to the cosmic star formation rate density at z ∼ 2, at a level of ∼ 0.02 M⊙yrMpc to our completeness limit of KAB = 22.9 mag. Subject headings: galaxies: evolution — galaxies: high-redshift — galaxies: starburst — infrared: galaxies — (ISM:) dust, extinction
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