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

K. Caputi (1) , H. Dole (1) , Guilaine Lagache (1) , J. Mclure (2) , J‐l. Puget (1) , G. H Rieke (3) , J. S Dunlop (2) , E. Le Floc’h (3) , C. Papovich (3) , P. G. Perez-Gonzalez (3)

1 IAS - Institut d'astrophysique spatiale
2 IfA - Institute for Astronomy [Edinburgh]
3 Steward Observatory

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 Sv µm (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 jdz = Zspec -- zphot j/ (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 zk 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 (10 10 L < L IR < 10 11 L) and low-to-intermediate as sembled stellar masses (10 9 M < M < 10 11) at z < 0.8, to massive (M > 10 11M) hyperluminous galaxies ( Lir > 10 12 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 ~ 10 10–10 11 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 X 10 10 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

Mots clés: infrared: galaxies; galaxies: statistics; galaxies: evolution

Domaines: Astrophysique [astro-ph]

K. Caputi, H. Dole, Guilaine Lagache, J. Mclure, J‐l. Puget, et al.. Linking stellar mass and star formation in Spitzer MIPS 24 µm galaxies. The Astrophysical Journal, 2006, 637 (2), pp.727 - 740. ⟨10.1086/498497⟩. ⟨hal-01840636⟩