Old stellar counter-rotating components in early-type galaxies from elliptical-spiral mergers

Abstract

We use numerical simulations to investigate the possibility of forming counter-rotating old stellar components by major mergers between an elliptical and a spiral galaxy. We show that counterrotation can appear both in dissipative and dissipationless retrograde mergers, and it is mostly associated to the presence of a disk component, which preserves part of its initial spin. In turn, the external regions of the two interacting galaxies acquire part of the orbital angular momentum, from the action of tidal forces exerted on each galaxy by the companion. © ESO 2007.