Carilli, C. L. and Hodge, J. and Walter, F. and Riechers, D. and Daddi, E. and Dannerbauer, H. and Morrison, G. E. (2011) Expanded Very Large Arrays Observations of a Proto-Cluster of Molecular Gas-Rich Galaxies at z = 4.05. Astrophysical Journal Letters, 739 (1). Art. No. L33. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20110923-105417000
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We present observations of the molecular gas in the GN20 proto-cluster of galaxies at z = 4.05 using the Expanded Very Large Array (EVLA). This group of galaxies is the ideal laboratory for studying the formation of massive galaxies via luminous, gas-rich starbursts within 1.6 Gyr of the big bang. We detect three galaxies in the proto-cluster in CO 2-1 emission, with gas masses (H_2) between 10^(10) and 10^(11) × (α/0.8) M_⊙. The emission from the brightest source, GN20, is resolved with a size ~2'' and has a clear north-south velocity gradient, possibly indicating ordered rotation. The gas mass in GN20 is comparable to the stellar mass (1.3 × 10^(11) × (α/0.8) M_⊙ and 2.3 × 10^(11) M_⊙, respectively), and the sum of gas plus stellar mass is comparable to the dynamical mass of the system (~3.4 × 10^(11)[sin (i)/sin (45°)]^(–2) M_⊙), within a 5 kpc radius. There is also evidence for a tidal tail extending another 2'' north of the galaxy with a narrow velocity dispersion. GN20 may be a massive, gas-rich disk that is gravitationally disturbed, but not completely disrupted. There is one Lyman-break galaxy (BD29079) in the GN20 proto-cluster with an optical spectroscopic redshift within our search volume, and we set a 3σ limit to the molecular gas mass of this galaxy of 1.1 × 10^(10) × (α/0.8) M_⊙.
|Additional Information:||© 2011 The American Astronomical Society. Received 2011 April 15; accepted 2011 May 17; published 2011 August 29. The Very Large Array of the National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. E.D. acknowledges the funding support of ERC-StGUPGAL-240039 and ANR-08-JCJC-0008. D.R. acknowledges support from NASA through Hubble Fellowship grant HST-HF-51235.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555.|
|Subject Keywords:||galaxies: evolution; galaxies: ISM; galaxies: starburst; submillimeter: galaxies|
|Classification Code:||PACS: 98.54.Ep; 95.85.Bh; 98.62.Qz; 98.62.Ai; 98.62.Bj|
|Official Citation:||Expanded Very Large Array Observations of a Proto-cluster of Molecular Gas-rich Galaxies at z = 4.05 C. L. Carilli et al. 2011 ApJ 739 L33|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||23 Sep 2011 18:56|
|Last Modified:||26 Dec 2012 13:42|
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