|Title||Towards a new paradigm for early-type galaxies|
Traditionally, early-type galaxies (ETGs) are separated into elliptical and lenticular galaxies. This distinction is, however, not based on physical parameters, but mostly on their apparent shape. Panoramic, two-dimensional spectroscopic observations can be used to probe the class of ETGs in a way that is less sensitive to projection effects, hereby revealing new insights into their dynamics and evolution.
In this talk I will present the ATLAS3D project, a multi-wavelength survey combined with theoretical modeling, and its first results concerning the morphology, kinematics and stellar populations of nearby ETGs. The census of the apparent stellar angular momentum of all 260 ETGs within the volume-limited Atlas3D sample, reveals a separation of ETGs into Fast and Slow Rotators. I show that the vast majority (86%) of nearby ETGs are Fast Rotators with regular rotation, and spread over a large range of flattening, while Slow Rotators only represent about 14% of these ETGs, are rather round (E4 or rounder) with most of them having Kinematically Distinct Cores. I will also discuss the spatially resolved stellar population analysis of optical absorption line strength maps and conclude by connecting the observational results with the theoretical efforts to probe the evolution of these end-products of galaxy formation.