University of Hertfordshire

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From the same journal

By the same authors


  • 906142

    Accepted author manuscript, 981 KB, PDF document

  • A.I. Harris
  • A. J. Baker
  • D. T. Frayer
  • Ian Smail
  • A.M. Swinbank
  • D. A. Riechers
  • P. P. van der Werf
  • R. Auld
  • M. Baes
  • R. S. Bussmann
  • S. Buttiglione
  • A. Cava
  • D. L. Clements
  • A. Cooray
  • H. Dannerbauer
  • A. Dariush
  • G. De Zotti
  • L. Dunne
  • S. Dye
  • S. Eales
  • J. Fritz
  • J. Gonzalez-Nuevo
  • R. Hopwood
  • E. Ibar
  • R. J. Ivison
  • M.J. Jarvis
  • S. Maddox
  • M. Negrello
  • E. Rigby
  • P. Temi
  • J. Wardlow
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Original languageEnglish
Article number152
Number of pages14
JournalThe Astrophysical Journal
Journal publication date20 Jun 2012
Publication statusPublished - 20 Jun 2012


We report measurements of the carbon monoxide ground state rotational transition ((CO)-C-12-O-16 J = 1-0) with the Zpectrometer ultrawideband spectrometer on the 100 m diameter Green Bank Telescope. The sample comprises 11 galaxies with redshifts between z = 2.1 and 3.5 from a total sample of 24 targets identified by Herschel-ATLAS photometric colors from the SPIRE instrument. Nine of the CO measurements are new redshift determinations, substantially adding to the number of detections of galaxies with rest-frame peak submillimeter emission near 100 mu m. The CO detections confirm the existence of massive gas reservoirs within these luminous dusty star-forming galaxies (DSFGs). The CO redshift distribution of the 350 mu m selected galaxies is strikingly similar to the optical redshifts of 850 mu m-selected submillimeter galaxies in 2.1 <= z <= 3.5. Spectroscopic redshifts break a temperature-redshift degeneracy; optically thin dust models fit to the far-infrared photometry indicate characteristic dust temperatures near 34 K for most of the galaxies we detect in CO. Detections of two warmer galaxies, and statistically significant nondetections, hint at warmer or molecule-poor DSFGs with redshifts that are difficult to determine from Herschel-SPIRE photometric colors alone. Many of the galaxies identified by H-ATLAS photometry are expected to be amplified by foreground gravitational lenses. Analysis of CO linewidths and luminosities provides a method for finding approximate gravitational lens magnifications mu from spectroscopic data alone, yielding mu similar to 3-20. Corrected for magnification, most galaxy luminosities are consistent with an ultraluminous infrared galaxy classification, but three are candidate hyper-LIRGs with luminosities greater than 10(13) L-circle dot

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