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. Pello, P. G. Perez-Gonzalez, D. Schaerer, G. P. Smith, A. M. Swinbank, P. van der Werf
During our Herschel Lensing Survey (HLS) of massive galaxy clusters, we have
discovered an exceptionally bright submillimeter 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, both for its higher submm flux (\sim 200mJy at
500micron) and its high redshift. The dominant lens is a foreground z=0.63
galaxy, not the cluster itself. From the continuum detected, we derive a
far-infrared luminosity of LFIR= 1.1E14 /\mu Lo, where \mu is the magnification
factor, likely \sim 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) detected with the
EVLA. All lines decompose in a wide and strong red component, and a narrower
and weaker blue component, 540\kms apart. Assuming the local ULIRG CO-to-H2
conversion ratio, the H2 mass derived is 5.8E11/\mu Mo, of which one third is
contained in a cool component. From the CI line we derive a CI/H2 number
abundance of 0.6E-4 similar to that in other ULIRGs. We detect the water line,
with an intensity ratio I(H2O)/I(CO) \sim 0.5, suggesting a strong local FIR
radiation field, possibly from an AGN component. The water line is strong only
in the red velocity component. We detect for the first time at high-z the
[NII]205micron line. It shows comparable blue and red components, with a
strikingly broad blue one, suggesting strong ionized gas flows.
View original:
http://arxiv.org/abs/1201.2908
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