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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 421705.0, MPI für Astronomie / Publikationen_mpia
Vigorous star formation with low efficiency in massive disk galaxies at z = 1.5
Authors:Daddi, E.; Dannerbauer, H.; Elbaz, D.; Dickinson, M.; Morrison, G.; Stern, D.; Ravindranath, S.
Date of Publication (YYYY-MM-DD):2008
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Start Page:L21
End Page:L24
Review Status:not specified
Audience:Experts Only
Abstract / Description:We present the first detection of molecular gas cooling CO emission lines from ordinary massive galaxies at z=1.5. Two sources were observed with the IRAM Plateau de Bure Interferometer, selected to lie in the mass-star formation rate correlation at their redshift, thus being representative of massive high-z galaxies. Both sources were detected with high confidence, yielding L'CO~2×1010 K km s-1 pc2. For one of the sources we find evidence of velocity shear, implying CO sizes of ~10 kpc. With an infrared luminosity of LFIR~1012 Lsolar, these disklike galaxies are borderline ULIRGs but with star formation efficiency similar to that of local spirals, and an order of magnitude lower than that in submillimeter galaxies. This suggests a CO to total gas conversion factor similar to local spirals, gas consumption timescales approaching 1 Gyr or longer, and molecular gas masses reaching ~1011 Msolar, comparable to or larger than the estimated stellar masses. These results support a major role of in situ gas consumption over cosmological timescales and with relatively low star formation efficiency, analogous to that of local spiral disks, for the formation of today's most massive galaxies and their central black holes. Given the high space density of similar galaxies, ~10-4 Mpc-3, this implies a widespread presence of gas-rich galaxies in the early universe, many of which might be within reach of detailed investigations of current and planned facilities. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).
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
Identifiers:URL:http://adsabs.harvard.edu/abs/2008ApJ...673L..21D [ID No:1]
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