The properties of satellite galaxies in simulations of galaxy formation
  We investigate the properties of satellite galaxies in cosmological
N-body/SPH simulations of galaxy formation in Milky Way-sized haloes. Because
of their shallow potential wells, satellite galaxies are very sensitive to
heating processes which affect their gas content. Their properties can
therefore be used to constrain the nature of feedback processes that regulate
galaxy formation. In our simulations, we assume that all the energy produced by
supernovae is used as kinetic energy to drive galactic winds. Several of our
simulations produce bright, disc-dominated galaxies. We find that wind models
in which the wind speed, v_w, is proportional to local velocity dispersion of
dark matter, sigma, (and thus the wind mass-loading, eta_w \propto sigma^{-2})
have episodic star formation histories, reproduce the observed satellite
luminosity function reasonably well (down to M_v=-7) and match the
luminosity-metallicity relation observed in the Local Group satellites. By
contrast, models that assume a constant wind speed overproduce faint satellites
and predict an incorrect luminosity-metallicity relation. Our simulations
therefore suggest that the feedback processes that operate on the scale of
satellite galaxies should generate galactic outflows whose intensity varies
inversely with the depth of the potential.
