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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 358772.0, MPI für Astronomie / Publikationen_mpia
Multiwavelength study of massive galaxies at z~2. I. Star formation and galaxy growth
Authors:Daddi, E.; Dickinson, M.; Morrison, G.; Chary, R.; Cimatti, A.; Elbaz, D.; Frayer, D.; Renzini, A.; Pope, A.; Alexander, D. M.; Bauer, F. E.; Giavalisco, M.; Huynh, M.; Kurk, J.; Mignoli, M.
Date of Publication (YYYY-MM-DD):2007
Title of Journal:The Astrophysical Journal
Start Page:156
End Page:172
Audience:Not Specified
Abstract / Description:Examining a sample of massive galaxies at 1.4<z<2.5 with KVega<22 from GOODS, we compare photometry from Spitzer at mid- and far-IR to submillimeter, radio, and rest-frame UV wavelengths, to test the agreement between different tracers of star formation rates (SFRs) and to explore the implications for galaxy assembly. For z~2 galaxies with moderate luminosities (L8mum<1011 Lsolar), we find that the SFR can be estimated consistently from the multiwavelength data based on local luminosity correlations. However, 20%-30% of massive galaxies, and nearly all those with L8mum>1011 Lsolar, show a mid-IR excess that is likely due to the presence of obscured active nuclei, as shown in a companion paper. There is a tight and roughly linear correlation between stellar mass and SFR for 24 mum-detected galaxies. For a given mass, the SFR at z=2 was larger by a factor of ~4 and ~30 relative to that in star-forming galaxies at z=1 and 0, respectively. Typical ultraluminous infrared galaxies (ULIRGs) at z=2 are relatively ``transparent'' to ultraviolet light, and their activity is long lived (>~400 Myr), unlike that in local ULIRGs and high-redshift submillimeter-selected galaxies. ULIRGs are the common mode of star formation in massive galaxies at z=2, and the high duty cycle suggests that major mergers are not the dominant trigger for this activity. Current galaxy formation models underpredict the normalization of the mass-SFR correlation by about a factor of 4 and the space density of ULIRGs by an order of magnitude but give better agreement for z>1.4 quiescent galaxies.
Free Keywords:Cosmology: Observations; 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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