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

M. T. Huynh*, R. P. Norris, N. Seymour, K. E K Coppin, R. J. Ivison, Smail Ian, A. M. Swinbank, A. Karim, C. De Breuck, V. Smolčić, W. N. Brandt, S. C. Chapman, H. Dannerbauer, T. R. Greve, J. A. Hodge, K. K. Knudsen, K. M. Menten, P. P. van der Werf, Axel Weiss

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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 μmemission 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 Mgas >1.7 × 1010M . 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 [CII], 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]/LFIR = 2.3 × 10-3 is high compared to local ULIRGs and, combined withL[C II]/LCO 2700, it is consiste×nt with ALESS65.1 either having an extended (several kpc) [C II] emitting region or lower than solar metallicity.

Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
Publication statusPublished - 7 Mar 2013


  • Galaxies: Evolution
  • Galaxies: Formation


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