The morphological evolution of galaxy satellites

We study the evolution of galaxy satellites with high resolution N-body sim ulations. Satellites are modelled as replicas of typical low and high surfa ce brightness galaxies (LSBs and HSBs). Encounters on high eccentricity orb its (as typical in hierarchical models of galaxy formation) strip LSBs of m ost of their stars and tend to decrease their surface brightness. In contra st, bar instability in HSBs leads to substantial loss of angular momentum o f the stellar component and to an increase in central surface brightness. I n both cases the remnant resembles a spheroidal galaxy with an exponential surface brightness profile. A simple modelling of colour evolution and inte raction-driven star formation gives M/L ratios for the remnants that are ro ughly consistent with observations. These results suggest an evolutionary s cenario for the dwarf galaxies in our Local Group, faint dSphs being the de scendants of LSBs and brighter dSphs/dEs being the final state of HSB satel lites.