Molecular outflows in the most luminous ULIRGs

One of Herschel.s most important legacies will be the detection andsystematic study of largescale molecular outflows. Galaxy outflowsare a key ingredient in galaxy evolution: they regulate the growth ofgalaxies reducing the amount of molecular gas available for starformation, contribute to establish the observed correlation betweenthe black hole mass of a galaxy and the stellar velocity dispersionof its bulge, and play a critical role in the morphologicaltransformation of gasrich mergers into ellipticals. Before thelaunch of Herschel, our knowledge of the properties of galacticoutflows was mostly limited to the study of the ionized and neutralatomic gas. Little was known about the amount of molecular gasinvolved in the outflows, its velocity structure and spatialdistribution. Herschel revolutionized this field. Since 2009 our grouphas discovered powerful molecular outflows in the majority of theultraluminous infrared galaxies (ULIRG) studied. These outflows canbe easily identified in the form of strong blueshifted absorption andredshifted emission PCygni profiles in the OH 119, 79 and65micron lines. The outflows in some of these galaxies havemaximum velocities >1000km/s, mass outflow rates several timeslarger than the SFR in the galaxy, and molecular gas depletiontimes <10Myr. Objects with higher AGN luminosity appear to havehigher terminal outflow velocities and shorter gas depletiontimescales, which indicates that the molecular outflows in thesesystems might be mostly driven by the AGN. Here we propose tocomplement current Herschel molecular outflow studies observinga sample of 10 ULIRGs selected among the most IR luminousobjects in the local Universe. We will use the redshiftedOH 119micron doublet for this purpose. These observations willextend to higher SFR and AGN luminosities the outflow trends foundin our previous studies and will be an excellent comparisonsample for future A trun [truncated!, Please see actual data for full text]