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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
Evidence for a clumpy, rotating gas disk in a submillimeter galaxy at z = 4
Astrophysical Journal, Volume 760, No. 1, Article 11, Year 2012
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Description
We present Karl G. Jansky Very Large Array observations of the CO(2-1) emission in the z = 4.05 submillimeter galaxy (SMG) GN20. These high-resolution data allow us to image the molecular gas at 1.3kpc resolution just 1.6Gyr after the big bang. The data reveal a clumpy, extended gas reservoir, 14 ± 4kpc in diameter, in unprecedented detail. A dynamical analysis shows that the data are consistent with a rotating disk of total dynamical mass 5.4 ± 2.4 × 1011 M⊙. We use this dynamical mass estimate to constrain the CO-to-H2 mass conversion factor (αCO), finding αCO = 1.1 ± 0.6 M⊙(K kms-1 pc2)-1. We identify five distinct molecular gas clumps in the disk of GN20 with masses a few percent of the total gas mass, brightness temperatures of 16-31K, and surface densities of >3200-4500 × (αCO/0.8) M⊙ pc-2. Virial mass estimates indicate they could be self-gravitating, and we constrain their CO-to-H2 mass conversion factor to be <0.2-0.7 M ⊙(K kms-1 pc2)-1. A multiwavelength comparison demonstrates that the molecular gas is concentrated in a region of the galaxy that is heavily obscured in the rest-frame UV/optical. We investigate the spatially resolved gas excitation and find that the CO(6-5)/CO(2-1) ratio is constant with radius, consistent with star formation occurring over a large portion of the disk. We discuss the implications of our results in the context of different fueling scenarios for SMGs. © 2012. The American Astronomical Society. All rights reserved.
Authors & Co-Authors
Hodge, Jacqueline A.
Germany, Heidelberg
Max Planck Institute for Astronomy
Chris L. Carilli, Christopher L.
United States, Socorro
National Radio Astronomy Observatory Socorro
United Kingdom, Cambridge
Department of Physics
Walter, Fabian W.
Germany, Heidelberg
Max Planck Institute for Astronomy
United States, Socorro
National Radio Astronomy Observatory Socorro
de Blök, Willem J.G.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
South Africa, Cape Town
University of Cape Town
Riechers, Dominick A.
United States, Pasadena
California Institute of Technology
Daddi, Emmanuele
France, Gif-sur-yvette
Institut de Recherche Sur Les Lois Fondamentales de L'univers
Lentati, Lindley T.
United Kingdom, Cambridge
Department of Physics
Statistics
Citations: 137
Authors: 7
Affiliations: 7
Identifiers
Doi:
10.1088/0004-637X/760/1/11
ISSN:
0004637X
e-ISSN:
15384357
Research Areas
Environmental