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Observation of H2O in a strongly lensed Herschel-ATLAS source at z=2.3.

Omont, A. and Neri, R. and Cox, P. and Lupu, R. and Guélin, M. and van der Werf, P. and Weiß, A. and Ivison, R. and Negrello, M. and Leeuw, L. and Lehnert, M. and Smail, I. and Verma, A. and Baker, A.J. and Beelen, A. and Aguirre, J.E. and Baes, M. and Bertoldi, F. and Clements, D.L. and Cooray, A. and Coppin, K. and Dannerbauer, H. and de Zotti, G. and Dye, S. and Fiolet, N. and Frayer, D. and Gavazzi, R. and Hughes, D. and Jarvis, M. and Krips, M. and Michałowski, M.J. and Murphy, E.J. and Riechers, D. and Serjeant, S. and Swinbank, A.M. and Temi, P. and Vaccari, M. and Vieira, J.D. and Auld, R. and Buttiglione, B. and Cava, A. and Dariush, A. and Dunne, L. and Eales, S.A. and Fritz, J. and Gomez, H. and Ibar, E. and Maddox, S. and Pascale, E. and Pohlen, M. and Rigby, E. and Smith, D.J.B. and Bock, J. and Bradford, C.M. and Glenn, J. and Scott, K.S. and Zmuidzinas, J. (2011) 'Observation of H2O in a strongly lensed Herschel-ATLAS source at z=2.3.', Astronomy & astrophysics., 530 . L3.


The Herschel survey, H-ATLAS, with its large areal coverage, has recently discovered a number of bright, strongly lensed high-z submillimeter galaxies. The strong magnification makes it possible to study molecular species other than CO, which are otherwise difficult to observe in high-z galaxies. Among the lensed galaxies already identified by H-ATLAS, the source J090302.9-014127B (SDP.17b) at z = 2.305 is remarkable because of its excitation conditions and a tentative detection of the H2O 202-111 emission line (Lupu et al. 2010, ApJ, submitted). We report observations of this line in SDP.17b using the IRAM interferometer equipped with its new 277–371 GHz receivers. The H2O line is detected at a redshift of z = 2.3049 ± 0.0006, with a flux of 7.8 ± 0.5 Jy km s-1 and a FWHM of 250 ± 60   km   s-1. The new flux is 2.4 times weaker than the previous tentative detection, although both remain marginally consistent within 1.6σ. The intrinsic line luminosity and ratio of H2O(202 − 111)/CO(8 − 7) are comparable with those of the nearby starburst/enshrouded-AGN Mrk 231, and the ratio I(H2O)/LFIR is even higher, suggesting that SDP.17b could also host a luminous AGN. The detection of a strong H2O 202 − 111 line in SDP.17b implies an efficient excitation mechanism of the water levels that must occur in very dense and warm interstellar gas probably similar to Mrk 231.

Item Type:Article
Keywords:Galaxies, High-redshift, Starburst, Active, Infrared, Submillimeter, Radio lines.
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Date accepted:No date available
Date deposited:14 June 2013
Date of first online publication:June 2011
Date first made open access:No date available

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