Herschel reveals a molecular outflow in a z = 2.3 ULIRG

We report the results from a 19-h integration with the SPIRE Fourier Transform Spectrometer aboard the Herschel Space Observatory which has revealed the presence of a molecular outflow from the Cosmic Eyelash (SMM J2135-0102) via the detection of blueshifted OH absorption. Detections of several fine-structure emission lines indicate low-excitation HII regions contribute strongly to the [CII] luminosity in this z = 2.3 ULIRG. The OH feature suggests a maximum wind velocity of 700 km/s, which is lower than the expected escape velocity of the host dark matter halo, ~1000 km/s. A large fraction of the available molecular gas could thus be converted into stars via a burst protracted by the resulting gas fountain, until an AGN-driven outflow can eject the remaining gas.