91福利

Timothy Davis (Oxford University)

Title: Red but not dead! Molecular gas in early-type galaxies

Abstract: Over the past few years, early-type galaxies (ETGs) have shed their red-and-dead moniker, thanks to the discovery that many host low-level residual star formation. As part of the Atlas3D project we are conducting a complete, volume limited survey of the stellar properties and ISM of 260 local early-type galaxies (with the SAURON IFU, WSRT, IRAM-30m telescope and CARMA). With this data we are attempting to understand the origin of the ISM in these galaxies, and study its distribution, kinematics and star formation properties.

I will outline the major results of this survey, and explain why the Hubble tuning fork view of ETGs should be discarded. I will also discuss the ISM in these systems (Which until about 10 years ago was thought not to exist!) We detect molecular gas in approximately 22% of early-type galaxies in the local volume, and this detection rate is independent of galaxy luminosity and environment, but does depend on the galaxy kinematics. Morphologically this molecular gas is most usually distributed in relaxed central discs, polar structures and rings. The origin of the molecular and ionised gas does however seem to depend strongly on environment, with misaligned gas (indicative of externally acquired material) being common in the field but almost completely absent in Virgo and group environments. I will discuss these results, which imply that environment has a strong impact on the properties of ETGs, and touch on implications for the formation and evolution of red sequence galaxies.