Molecular gas and star formation in local early-type galaxies
Proceedings of the International Astronomical Union 6:S277 (2010) 55-58
Authors:
M Bureau, TA Davis, K Alatalo, AF Crocker, L Blitz, LM Young, F Combes, M Bois, F Bournaud, M Cappellari, RL Davies, PT De Zeeuw, PA Duc, E Emsellem, S Khochfar, D Krajnovi膰, H Kuntschner, PY Lablanche, RM McDermid, R Morganti, T Naab, T Oosterloo, M Sarzi, N Scott, P Serra, A Weijmans
Abstract:
The molecular gas content of local early-type galaxies is constrained and discussed in relation to their evolution. First, as part of the ATLAS 3D survey, we present the first complete, large (260 objects), volume-limited single-dish survey of CO in normal local early-type galaxies. We find a surprisingly high detection rate of 22%, independent of luminosity and at best weakly dependent on environment. Second, the extent of the molecular gas is constrained with CO synthesis imaging, and a variety of morphologies is revealed. The kinematics of the molecular gas and stars are often misaligned, implying an external gas origin in over a third of the systems, although this behaviour is drastically diffferent between field and cluster environments. Third, many objects appear to be in the process of forming regular kpc-size decoupled disks, and a star formation sequence can be sketched by piecing together multi-wavelength information on the molecular gas, current star formation, and young stars. Last, early-type galaxies do not seem to systematically obey all our usual prejudices regarding star formation, following the standard Schmidt-Kennicutt law but not the far infrared-radio correlation. This may suggest a greater diversity in star formation processes than observed in disk galaxies. Using multiple molecular tracers, we are thus starting to probe the physical conditions of the cold gas in early-types. 漏 Copyright International Astronomical Union 2011.
