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Extended Cold Molecular Gas Reservoirs in z ≃ 3.4 Submillimeter Galaxies

Riechers, Dominik A. and Hodge, Jacqueline A. and Walter, Fabian and Carilli, Christopher L. and Bertoldi, Frank (2011) Extended Cold Molecular Gas Reservoirs in z ≃ 3.4 Submillimeter Galaxies. Astrophysical Journal Letters, 739 (1). Art. No. L31. ISSN 2041-8205.

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We report the detection of spatially resolved CO(J = 1→0) emission in the z ~ 3.4 submillimeter galaxies (SMGs) SMM J09431+4700 and SMM J13120+4242, using the Expanded Very Large Array (EVLA). SMM J09431+4700 is resolved into the two previously reported millimeter sources H6 and H7, separated by ~30 kpc in projection. We derive CO(J = 1→0) line luminosities of L'_(CO(1-0)) = (2.49 ± 0.86) and (5.82 ± 1.22) × 10^(10) K km s^–1 pc^2 for H6 and H7, and L'_(CO(1-0)) = (23.4 ± 4.1) × 10^(10) K km s^(–1) pc^2 for SMM J13120+4242. These are ~1.5-4.5 times higher than what is expected from simple excitation modeling of higher-J CO lines, suggesting the presence of copious amounts of low-excitation gas. This is supported by the finding that the CO(J = 1→0) line in SMM J13120+4242, the system with the lowest CO excitation, appears to have a broader profile and more extended spatial structure than seen in higher-J CO lines (which is less prominently seen in SMM J09431+4700). Based on L'_(CO(1-0)) and excitation modeling, we find M_(gas) = 2.0-4.3 and 4.7-12.7×10^(10) M _☉ for H6 and H7, and M_(gas) = 18.7-69.4×10^(10) M_☉ for SMM J13120+4242. The observed CO(J = 1→0) properties are consistent with the picture that SMM J09431+4700 represents an early-stage, gas-rich major merger and that SMM J13120+4242 represents such a system in an advanced stage. This study thus highlights the importance of spatially and dynamically resolved CO(J = 1→0) observations of SMGs to further understand the gas physics that drive star formation in these distant galaxies, which is possible only now that the EVLA is rising to its full capabilities.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Riechers, Dominik A.0000-0001-9585-1462
Hodge, Jacqueline A.0000-0001-6586-8845
Walter, Fabian0000-0003-4793-7880
Carilli, Christopher L.0000-0001-6647-3861
Bertoldi, Frank0000-0002-1707-1775
Additional Information:© 2011 The American Astronomical Society. Received 2011 April 14; accepted 2011 May 18; published 2011 August 29. We thank the referee, Dr. Laura Hainline, for a helpful report, and Christian Henkel for the original version of the LVG code. D.R. acknowledges support from NASA through a Spitzer Space Telescope grant. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
Funding AgencyGrant Number
NASA Spitzer Space TelescopeUNSPECIFIED
Subject Keywords:cosmology: observations; galaxies: active; galaxies: formation; galaxies: high-redshift; galaxies: starburst; radio lines: galaxies
Issue or Number:1
Classification Code:PACS: 98.54.Ep; 98.62.Bj; 95.85.Bh
Record Number:CaltechAUTHORS:20110926-082613201
Persistent URL:
Official Citation:Extended Cold Molecular Gas Reservoirs in z 3.4 Submillimeter Galaxies Dominik A. Riechers et al. 2011 ApJ 739 L31
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25430
Deposited By: Ruth Sustaita
Deposited On:26 Sep 2011 16:45
Last Modified:03 Oct 2019 03:05

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