Linking Stellar Mass and Star Formation in Spitzer MIPS 24 μm Galaxies
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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. © 2006. The American Astronomical Society. All rights reserved.
author list (cited authors)
Caputi, K. I., Dole, H., Lagache, G., McLure, R. J., Puget, J., Rieke, G. H., ... Perez‐Gonzalez, P. G.