Physical conditions of the gas in an ALMA [C II]-identified submillimetre galaxy at z = 4.44

Huynh, M. T. and Norris, R. P. and Coppin, K. E. K. and Emonts, B. H. C. and ivison, R. J. and Seymour, N. and Smail, I. and Smolčić, Vernesa and Swinbank, A. M. and Brandt, W. N. and Chapman, S. C. and Dannerbauer, H. and Breuck, C. De and Greve, T. R. and Hodge, J. A. and Karim, A. and Knudsen, K. K. and Menten, K. M. and van der Werf, P. P. and Walter, F. and Weiss, A. (2013) Physical conditions of the gas in an ALMA [C II]-identified submillimetre galaxy at z = 4.44. Monthly Notices of the Royal Astronomical Society, 431 (1). L88-L92. ISSN 0035-8711

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Abstract

We present 12CO(2-1) observations of the submillimetre galaxy ALESS65.1 performed with the Australia Telescope Compact Array (ATCA) at 42.3 GHz. A previous Atacama Large Millimeter Array study of submillimetre galaxies (SMGs) in the Extended Chandra Deep Field South detected [C II] 157.74 ?m emission from this galaxy at a redshift of z = 4.44. No 12CO(2-1) emission was detected but we derive a firm upper limit to the cold gas mass in ALESS65.1 of M_gas < 1.7 ? 10^{10} M_{{?}}. The estimated gas depletion time-scale is <50 Myr, which is similar to other high-redshift SMGs, and consistent with z > 4 SMGs being the likely progenitors of massive red-and-dead galaxies at z > 2. The ratio of the [C II], 12CO and far-infrared luminosities implies a strong far-ultraviolet field of G0 ? 103, as seen in Galactic star-forming regions or local ultraluminous infrared galaxies (ULIRGs). The observed L_{[C II]}/L_FIR = 2.3 ? 10^{-3} is high compared to local ULIRGs and, combined with L_{[C II]}/L_CO ? 2700, it is consistent with ALESS65.1 either having an extended (several kpc) [C II] emitting region or lower than solar metallicity.

Item Type: Article
Keywords: galaxies: evolution, galaxies: formation
Date: April 2013
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 January 30. Received 2013 January 29; in original form 2012 December 10. First published online March 7, 2013.
Divisions: Faculty of Science > Department of Physics
Publisher: Oxford University Press
Depositing User: Vernesa Smolčić
Date Deposited: 11 May 2016 18:56
Last Modified: 14 Oct 2016 07:07
URI: http://digre.pmf.unizg.hr/id/eprint/4817

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