| Description: | I will show how two dimensional observations of nearby early-type galaxies can be used to constrain the formation mechanisms of these objects, and, specifically, the evolution of galaxies along the red sequence. Early-type galaxies appear in two broad flavours, depending on whether they exhibit clear large scale rotation or not. We define a parameter, a proxy for specific angular momentum, which can be used to quantify the classification of early-types into slow and fast rotators, and show that slow and fast rotators are physically distinct classes of galaxies. Analysis of their stellar kinematic maps, which is based on a generalisation of surface photometry to the higher-moments of the line-of-sight velocity distribution, traces the differences between the two classes. I will show evidence that fast rotators are axisymmetric and slow rotators weakly triaxial objects. Specifically, fast rotators contain flattened fast rotating components, which can be also traced in their stellar populations, and this dynamical property differentiates them from slow rotators. I will conclude my talk with a preview of the results of the ATLAS3D project which provides multi-wavelength observations of a volume-limited sample of about 250 early-type galaxies, offering tight constraints on the origin of slow and fast rotators, their intrinsic structure, and more generally on scenarios for the formation and evolution of red sequence galaxies. |
