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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 358637.0, MPI für Astronomie / Publikationen_mpia
Star formation in AEGIS field galaxies since z=1.1: staged galaxy formation and a model of mass-dependent gas exhaustion
Authors:Noeske, K. G.; Faber, S. M.; Weiner, B. J.; Koo, D. C.; Primack, J. R.; Dekel, A.; Papovich, C.; Conselice, C. J.; Le Floc'h, E.; Rieke, G. H.; Coil, A. L.; Lotz, J. M.; Somerville, R. S.; Bundy, K.
Date of Publication (YYYY-MM-DD):2007
Title of Journal:The Astrophysical Journal
Start Page:L47
End Page:L50
Audience:Not Specified
Abstract / Description:We analyze star formation (SF) as a function of stellar mass (M*) and redshift z in the All-Wavelength Extended Groth Strip International Survey, for star-forming field galaxies with M*>~1010 Msolar out to z=1.1. The data indicate that the high specific SF rates (SFRs) of many less massive galaxies do not represent late, irregular or recurrent, starbursts in evolved galaxies. They rather seem to reflect the onset (initial burst) of the dominant SF episode of galaxies, after which SF gradually declines on gigayear timescales to z=0 and forms the bulk of a galaxy's M*. With decreasing mass, this onset of major SF shifts to decreasing z for an increasing fraction of galaxies (staged galaxy formation). This process may be an important component of the ``downsizing'' phenomenon. We find that the predominantly gradual decline of SFRs described by Noeske et al. can be reproduced by exponential SF histories (tau models), if less massive galaxies have systematically longer e-folding times tau, and a later onset of SF (zf). Our model can provide a first parameterization of SFR as a function of M* and z, and quantify mass dependences of tau and zf, from direct observations of M* and SFRs up to z>1. The observed evolution of SF in galaxies can plausibly reflect the dominance of gradual gas exhaustion. The data are also consistent with the history of cosmological accretion onto dark matter halos.
Free Keywords:Galaxies: Evolution; Galaxies: Formation; Galaxies: High-Redshift; Galaxies: Starburst
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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