EXPANDED VERY LARGE ARRAY OBSERVATIONS OF A PROTO-CLUSTER OF MOLECULAR GAS-RICH GALAXIES AT z = 4.05

Journal Article · Tue Sep 20 00:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/739/1/L33· OSTI ID:21565468

Carilli, C L ^[1]; Hodge, J; Walter, F; Dannerbauer, H ^[2]; Riechers, D ^[3]; Daddi, E ^[4]; Morrison, G E ^[5]

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1. National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801-0387 (United States)
2. Max-Planck Institute for Astronomy, Konigstuhl 17, 69117, Heidelberg (Germany)
3. Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
4. Laboratoire AIM, CEA/DSM-CNRS-University Paris Diderot, DAPNIA/Service Astrophysccique, CEA Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette (France)
5. Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

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{sub 2}) between 10{sup 10} and 10{sup 11} x ({alpha}/0.8) M{sub sun}. The emission from the brightest source, GN20, is resolved with a size {approx}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 x 10{sup 11} x ({alpha}/0.8) M{sub sun} and 2.3 x 10{sup 11} M{sub sun}, respectively), and the sum of gas plus stellar mass is comparable to the dynamical mass of the system ({approx}3.4 x 10{sup 11}[sin (i)/sin (45{sup 0})]{sup -2} M{sub sun}), 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 3{sigma} limit to the molecular gas mass of this galaxy of 1.1 x 10{sup 10} x ({alpha}/0.8) M{sub sun}.

• OSTI ID: 21565468
• Journal Information: Astrophysical Journal Letters, Vol. 739, Issue 1; Other Information: DOI: 10.1088/2041-8205/739/1/L33; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CARBON MONOXIDE
EMISSION
EVOLUTION
GALAXIES
GALAXY CLUSTERS
HYDROGEN
MASS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
ELEMENTS
NONMETALS
OXIDES
OXYGEN COMPOUNDS