Detection of molecular gas in an ALMA [C II]-identified submillimetre galaxy at z = 4.44

Huynh, M. T. and Kimball, A. E. and Norris, R. P. and Smail, Ian and Chow, K. E. and Coppin, K. E. K. and Emonts, B. H. C. and Ivison, R. J. and Smolčić, Vernesa and Swinbank, A. M. (2014) Detection of molecular gas in an ALMA [C II]-identified submillimetre galaxy at z = 4.44. Monthly Notices of the Royal Astronomical Society, 443 (1). L54-L58. ISSN 0035-8711

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We present the detection of 12CO(2–1) in the z = 4.44 submillimetre galaxy ALESS65.1 using the Australia Telescope Compact Array. A previous Atacama Large Millimeter/submillimeter Array study of submillimetre galaxies (SMGs) in the Extended Chandra Deep Field South determined the redshift of this optically and near-infrared undetected source through the measurement of [C II] 157.74 µm emission. Using the luminosity of the 12CO(2–1) emission, we estimate the gas mass to be Mgas ∼ 1.7 × 1010 M. The gas depletion time-scale of ALESS65.1 is ∼ 25 Myr, similar to other high-redshift SMGs and consistent with z > 4 SMGs being the progenitors of massive ‘red-and-dead’ galaxies at z > 2. The ratio of the [C II], 12CO and farinfrared luminosities implies a strong far-ultraviolet field of G0 ∼103.25, which is at the high end of the far-ultraviolet fields seen in local starbursts, but weaker than the far-ultraviolet fields of most nearby ultraluminous infrared galaxies (ULIRGs). The high ratio of L[CII]/LFIR = 1.0 × 10−3 observed in ALESS65.1, combined with L[CII]/LCO ∼ 2300, is consistent with ALESS65.1 having more extended regions of intense star formation than local LIRGs.

Item Type: Article
Keywords: galaxies: evolution,galaxies: formation, radio lines: galaxies
Date: 22 April 2014
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 May 27. Received 2014 May 21; in original form 2014 April 22. Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided.
Divisions: Faculty of Science > Department of Physics
Publisher: Oxford University Press
Depositing User: Vernesa Smolčić
Date Deposited: 19 Apr 2016 14:55
Last Modified: 20 Mar 2018 16:22

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