Star formation in distant red galaxies: Spitzer observations in the hubble deep field-south

Tracy M.A. Webb, Pieter Van Dokkum, Eiichi Egami, Giovanni Fazio, Marijn Franx, Eric Gawiser, David Herrera, Jiasheng Huang, Ivo Labbé, Paulina Lira, Danilo Marchesini, José Maza, Ryan Quadri, Gregory Rudnick, Paul Van Der Werf

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


We present Spitzer 24 μm 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 K AB < 23.2 mag at S24μm ≳ 40 μJy and conclude that the bulk of the DRG population is dusty active galaxies. A mid-infrared (MIR) color analysis with IRAC data suggests that the MIR fluxes are not dominated by buried AGNs, and we interpret the high detection rate as evidence for a high average star formation rate of (SFR) = 130 ±30 M⊙ yr -1. 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⊙ yr-1 Mpc-3 to our completeness limit of KAB = 22.9 mag.

Original languageEnglish (US)
Pages (from-to)L17-L20
JournalAstrophysical Journal
Issue number1 II
StatePublished - Jan 1 2006


  • Dust, extinction
  • Galaxies: evolution
  • Galaxies: high-redshift
  • Galaxies: starburst
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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