Astronomy and Astrophysics, volume 538, L4-4 (2012/2-1)
A bright z = 5.2 lensed submillimeter galaxy in the field of Abell 773 - HLS J091828.6+514223.
COMBES F., REX M., RAWLE T.D., EGAMI E., BOONE F., SMAIL I., RICHARD J., IVISON R.J., GURWELL M., CASEY C.M., OMONT A., BERCIANO ALBA A., DESSAUGES-ZAVADSKY M., EDGE A.C., FAZIO G.G., KNEIB J.-P., OKABE N., PELLO R., PEREZ-GONZALEZ P.G., SCHAERER D., SMITH G.P., SWINBANK A.M. and VAN DER WERF P.
Abstract (from CDS):
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 (∼200mJy at 500µm) 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 LFIR=1.1x1014/µ*L☉, where µ is the magnification factor, likely ∼11. We report here the redshift identification through CO lines with the IRAM-30m, 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, 540km/s apart. Assuming the ultraluminous galaxy (ULIRG) CO-to-H2 conversion ratio, the H2 mass is 5.8x1011/µ*M☉, of which one third is in a cool component. From the CI(3P2-3P1) line we derive a CI/H2 number abundance of 6x10–5 similar to that in other ULIRGs. The H2Op(2,0,2-1,1,1) line is strong only in the red velocity component, with an intensity ratio I(H2O)/I(CO)∼0.5, suggesting a strong local FIR radiation field, possibly from an active nucleus (AGN) component. We detect the [NII]205µm 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.
galaxies: evolution - galaxies: high-redshift - galaxies: ISM - infrared: galaxies - submillimeter: galaxies - galaxies: individual: HLS J091828.6+514223
[CRR2012] HLS J091828.6+514223 N=1.
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