Gas poor mergers and their impact on observed properties of galaxies
P. DiMatteo

The role that interactions and mergers play in the mass assembly and in the morphological signatures of present day galaxies
has been the subject of several observational and numerical studies. However less is known about the way angular momentum is redistributed
during these events,  between the different components (baryons and dark matter).
We have recently undertaken a numerical study to investigate how the angular momentum is redistributed from orbital into internal one, during major and minor mergers.
Our results show that a number of interesting observed kinematical features in galaxies can be explained in terms of this AM redistribution, as the presence of fast-rotating stellar halos in ellipticals (see Coccato et al. 2009, MNRAS, 394, 1249 and Di Matteo et al. 2009, A&A, 501, L9), counter-rotating old stellar components (Di Matteo et al. 2008, A&A, 477, 437) in early-type galaxies, etc.
At present, we are investigating the effect of minor mergers (mass ratio >= 10:1) on the kinematics of the stellar disk of the parent. For a variety of orbital parameters and initial conditions, we find that these minor interactions are always accompanied by a slowing down of the stellar disk, thus leading to a decrease in the disk line-of-sigh velocity (Qu et al, in preparation).
We plan to extend this study to gas-rich mergers in the near future.