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Observing Cold Gas in Submillimeter Galaxies: Detection of CO (1→0) Emission in SMM J13120+4242 with the Green Bank Telescope

Hainline, Laura J. and Blain, A. W. and Greve, T. R. and Chapman, S. C. and Smail, Ian and Ivison, R. J. (2006) Observing Cold Gas in Submillimeter Galaxies: Detection of CO (1→0) Emission in SMM J13120+4242 with the Green Bank Telescope. Astrophysical Journal, 650 (2). pp. 614-623. ISSN 0004-637X. doi:10.1086/507443.

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We report the first detection of CO (1→0) emission from a submillimeter-selected galaxy, using the Green Bank Telescope. We identify the line in the spectrum of SMM J13120+4242 as a broad emission feature at z = 3.408, with ΔV_(FWHM) = 1040 ± 190 km s^(-1). If the observed CO (1→0) line profile arises from a single object and not several merging objects, then the CO (4 → 3)/CO (1 → 0) brightness temperature ratio of ~0.26 suggests n(H_2) > (3-10) × 10^2 cm^(-3) and the presence of subthermally excited gas. The integrated line flux implies a cold molecular gas mass M(H_2) = 1.6 × 10^(11) M_☉, comparable to the dynamical mass estimate and 4 times larger than the H_2 mass predicted from the CO (4→3) line, assuming a brightness temperature ratio of 1.0. While our observations confirm that this submillimeter galaxy is massive and gas-rich, they also suggest that extrapolating gas masses from J_(upper) ≥ 3 transitions of CO leads to considerable uncertainties. We also report an upper limit to the mass of cold molecular gas in a second submillimeter galaxy, SMM J09431+4700, of M(H_2) ≲ 4 × 10^(10) M_☉.

Item Type:Article
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URLURL TypeDescription
Blain, A. W.0000-0001-7489-5167
Smail, Ian0000-0003-3037-257X
Ivison, R. J.0000-0001-5118-1313
Additional Information:© 2006 American Astronomical Society. Received 2006 May 2; accepted 2006 July 2. We gratefully acknowledge the assistance and advice of R. Maddalena and A. Minter at NRAO-Green Bank in developing tools to calibrate the GBT K-band data. We also thank C. Borys for providing HST images of SMM 13120 and E. Fomalont for providing VLA and Subaru images of SMM 13120. We wish to thank the anonymous referee for helpful comments that improved the manuscript. L. J. H. acknowledges the support of the GBT Graduate Funding program during this work. A. W. B. acknowledges support from the Alfred P. Sloan Foundation and the Research Corporation. I. R. S. acknowledges support from the Royal Society. The Green Bank Telescope is a facility of the National Radio Astronomy Observatory, operated by Associated Universities, Inc., under a cooperative agreement with the National Science Foundation.
Funding AgencyGrant Number
GBT Graduate Funding programUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Research CorporationUNSPECIFIED
Subject Keywords:galaxies: evolution; galaxies: formation; galaxies: high-redshift; galaxies: ISM; infrared: galaxies; radio lines: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20110428-151623031
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Official Citation:Observing Cold Gas in Submillimeter Galaxies: Detection of CO (1→0) Emission in SMM J13120+4242 with the Green Bank Telescope Laura J. Hainline et al. 2006 ApJ 650 614
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23495
Deposited On:28 Apr 2011 22:44
Last Modified:09 Nov 2021 16:15

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