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

M. T. Huynh*, A. E. Kimball, R. P. Norris, Ian Smail, K. E. Chow, K. E. K. Coppin, B. H. C. Emonts, R. J. Ivison, V. Smolcic, A. M. Swinbank

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We present the detection of (CO)-C-12(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 mu m emission. Using the luminosity of the (CO)-C-12(2-1) emission, we estimate the gasmass to be M-gas similar to 1.7x10(10) M-circle dot. The gas depletion time-scale of ALESS65.1 is similar to 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], (CO)-C-12 and far-infrared luminosities implies a strong far-ultraviolet field of G(0) similar to 10(3.25), 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-[C II]/L-FIR = 1.0 x 10(-3) observed in ALESS65.1, combined with L-[C II]/L-CO similar to 2300, is consistent with ALESS65.1 having more extended regions of intense star formation than local ULIRGs.

Original languageEnglish
Pages (from-to)L54-L58
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Volume443
Issue number1
DOIs
Publication statusPublished - 1 Sep 2014

Keywords

  • galaxies: evolution
  • galaxies: formation
  • radio lines: galaxies
  • DEEP-FIELD-SOUTH
  • STAR-FORMING GALAXIES
  • C-II LINE
  • LARGE ARRAY OBSERVATIONS
  • REDSHIFT DISTRIBUTION
  • PHOTODISSOCIATION REGIONS
  • INTERSTELLAR-MEDIUM
  • STARBURST GALAXIES
  • EARLY UNIVERSE
  • COMPACT ARRAY

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