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Observation of H₂O in a strongly lensed Herschel-ATLAS source at z = 2.3🟉
David Hughes
Acceso Abierto
Galaxies: high-redshift
Galaxies: starburst
Galaxies: active
Infrared: galaxies
Submillimeter: galaxies
Radio lines: galaxie
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 2₀₂2-1₁₁ 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)/L🇫🇮🇷 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.
Astronomy & Astrophysics
Público en general
Omont, A., et al., (2011), Observation of H₂O in a strongly lensed Herschel-ATLAS source at z = 2.3🟉, Astronomy & Astrophysics, Vol.530(L3):1-5
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