Vol. 551
In section 4. Extragalactic astronomy

H2O emission in high-z ultra-luminous infrared galaxies

Six lensed ultra-luminous galaxies at high redshift have been clearly detected with the IRAm interferometer in the H2O lines. The objects were selected from the Herschel key project H-ATLAS. H2O lines are revealed to be among the strongest molecular lines with intensities almost comparable to those of the high-J CO lines. Water line luminosity is found to have a strong dependence on the infrared luminosity, which might indicate a radiative infrared excitation of the lines.