The morphological evolution of galaxy satellites

We study the evolution of galaxy satellites with high resolution N-body simulations. Satellites are modeled as replicas of typical low and high surface brightness galaxies (LSBs and HSBs). Encounters on high eccentricity orbits (as typical in hierarchical models of galaxy formation) strip LSBs of most of their stars and tend to decrease their surface brightness. On the contrary, bar instability in HSBs leads to substantial loss of angular momentum of the stellar component and to an increase of central surface brightness. In both cases the remnant resembles a spheroidal galaxy with an exponential surface brightness profile. A simple modeling of color evolution and interactions driven star formation gives M/L ratios for the remnants that are roughly consistent with observations. These results suggest an evolutionary scenario for the dwarf galaxies in our Local Group, faint dSphs being the descendents of LSBs and brighter dSphs/dEs being the final state of HSB satellites.