A bright z = 5.2 lensed submillimeter galaxy in the field of Abell 773: HLSJ091828.6+514223

F. Combes, M. Rex, T. D. Rawle, E. Egami, F. Boone, I. Smail, J. Richard, R. J. Ivison, M. Gurwell, C. M. Casey, A. Omont, A. Berciano Alba, M. Dessauges-Zavadsky, A. C. Edge, G. G. Fazio, J. P. Kneib, N. Okabe, R. Pelló, P. G. Pérez-González, D. SchaererG. P. Smith, A. M. Swinbank, P. Van Der Werf

Research output: Contribution to journalReview articlepeer-review

117 Scopus citations


During our Herschel Lensing Survey (HLS) of massive galaxy clusters, we have discovered an exceptionally bright source behind the z = 0.22 cluster Abell 773, which appears to be a strongly lensed submillimeter galaxy (SMG) at z = 5.2429. This source is unusual compared to most other lensed sources discovered by Herschel so far, because of its higher submm flux (~200 mJy at 500 μm) and its high redshift. The dominant lens is a foreground z = 0.63 galaxy, not the cluster itself. The source has a far-infrared (FIR) luminosity of L FIR = 1.1 × 10 14/μ L , where μ is the magnification factor, likely ∼11. We report here the redshift identification through CO lines with the IRAM-30 m, and the analysis of the gas excitation, based on CO(7-6), CO(6-5), CO(5-4) detected at IRAM and the CO(2-1) at the EVLA. All lines decompose into a wide and strong red component, and a narrower and weaker blue component, 540 km s -1 apart. Assuming the ultraluminous galaxy (ULIRG) CO-to-H 2 conversion ratio, the H 2 mass is 5.8 × 10 11/μ M , of which one third is in a cool component. From the C I( 3P 2- 3P 1) line we derive a C I/H 2 number abundance of 6 × 10 -5 similar to that in other ULIRGs. The H 2O p(2,0,2-1,1,1) line is strong only in the red velocity component, with an intensity ratio I(H 2O)/I(CO) ∼ 0.5, suggesting a strong local FIR radiation field, possibly from an active nucleus (AGN) component. We detect the [NII]205 μm line for the first time at high-z. It shows comparable blue and red components, with a strikingly broad blue one, suggesting strong ionized gas flows.

Original languageEnglish (US)
Article numberL4
JournalAstronomy and astrophysics
StatePublished - 2012


  • galaxies: ISM
  • galaxies: evolution
  • galaxies: high-redshift
  • galaxies: individual: HLSJ091828.6+514223
  • infrared: galaxies
  • submillimeter: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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