Herschel reveals a molecular outflow in a z = 2.3 ULIRG

Abstract

We report the results from a 19-h integration with the Spectral and Photometric Imaging REceiver (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-excitationHII regions contribute strongly to the [C II] luminosity in this z = 2.3 ultra-luminous infrared galaxy (ULIRG). The OH feature suggests a maximum wind velocity of 700 km s-1, which is lower than the expected escape velocity of the host dark matter halo, ≈1000 km s-1. 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 active galactic nucleus (AGN)-driven outflow can eject the remaining gas. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.