Speaker
Timothy Davis
(ESO)
Description
The centres of early-type galaxies are extreme environments, with strong radiation fields from old stars, high metallicities, alpha-enhancements, deep potential wells, and a high incidence of AGN. It has been shown in recent years that despite these extreme conditions a sizeable proportion of these galaxies have a cold ISM, with atomic/molecular gas and dust reservoirs. We have carried out a comprehensive survey of the cold and warm ISM in the volume-limited ATLAS-3D sample of early-type galaxies; our data include CO and HI maps, detections of high density molecular tracers, optical emission line ratios, and Herschel spectroscopy of the [CII], [OI] 63micron, and [NII] 122 and 205 micron lines plus the high-J CO ladder. Our data also allow us to probe the influence of a galaxy's cluster or group environment, AGN activity, and its dynamical state on the properties of its ISM. I will show that environment has a strong effect on the kinematics and chemistry of gas in early-type galaxies. In addition, spatially resolved measures of the star formation rate and the gas depletion timescales show that these massive galaxies have lower star-formation efficiencies than one might expect based on canonical star-formation relations. These observations of ""normal"" early-type galaxies in the local universe provide a useful comparison sample for local spirals, radio galaxies, central galaxies of cooling flow clusters, and systems at higher redshift. All of this information can be combined with our knowledge of the galaxies' stellar populations (ages, metallicities & kinematics) for insights into the formation and evolution of early-type galaxies, and enable us to make predictions which will be directly testable in the era of ALMA, CCAT and the LMT.
Author
Timothy Davis
(ESO)