Linking stellar mass and star formation in Spitzer MIPS 24 μm galaxies

K. I. Caputi, H. Dole, G. Lagache, R. J. McLure, J. L. Puget, G. H. Rieke, J. S. Dunlop, E. Le Floc'h, C. Papovich, P. G. Pérez-González

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76 Scopus citations


We present deep Ks < 21.5 (Vega) identifications, redshifts, and stellar masses for most of the sources composing the bulk of the 24 μm background in the GOODS/CDFS. Our identified sample consists of 747 Spitzer MIPS 24 μm objects and includes ∼94% of all the 24 μm sources in the GOODS-South field that have fluxes Sν(24 μm) > 83 μJy (the ∼80% completeness limit of the Spitzer/GTO 24 μm catalog); 36% of our galaxies have spectroscopic redshifts (mostly at z < 1.5), and the remaining ones have photometric redshifts of very good quality, with a median of |dz| = |zspec - zphot|/(1 + zspec) = 0.02. We find that MIPS 24 μm galaxies span the redshift range z ∼ 0-4 and that a substantial fraction (28%) lie at high redshifts z ≳ 1.5. We determine the existence of a bump in the redshift distribution at z ∼ 1.9, indicating the presence of a significant population of galaxies with PAH emission at these redshifts. The 24 μm galaxy population ranges from sources with intermediate luminosities (1010 L < LIR < 1011 L) and low-to-intermediate assembled stellar masses (109 M ≲ M ≲ 1011 M ) at z ≲ 0.8, to massive (M ≳ 1011 M ) hyperluminous galaxies (LIR > 1012 L) at redshifts z ∼ 2-3. Massive star-forming galaxies at redshifts 2 ≲ z ≲ 3 are characterized by very high star formation rates (SFR > 500 M yr-1), and some of them are able to construct a mass of ≈ 1010-1011 M in a single burst lifetime (∼0.01-0.1 Gyr). At lower redshifts z ≲ 2, massive star-forming galaxies are also present but appear to be building their stars on long timescales, either quiescently or in multiple modest burstlike episodes. At redshifts z ∼ 1-2, the ability of the burstlike mode to produce entire galaxies in a single event is limited to some lower (M ≲ 7 × 1010 M) mass systems, and it is basically negligible at z ≲ 1. Our results support a scenario in which star formation activity is differential with assembled stellar mass and redshift, and where the relative importance of the burstlike mode proceeds in a downsizing way from high to low redshifts.

Original languageEnglish (US)
Pages (from-to)727-740
Number of pages14
JournalAstrophysical Journal
Issue number2 I
StatePublished - Feb 1 2006


  • Galaxies: evolution
  • Galaxies: statistics
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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