Satellite Survival in Highly Resolved Milky Way Class Halos
  Surprisingly little is known about the origin and evolution of the Milky
Way's satellite galaxy companions. UV photoionisation, supernova feedback and
interactions with the larger host halo are all thought to play a role in
shaping the population of satellites that we observe today, but there is still
no consensus as to which of these effects, if any, dominates. In this paper, we
revisit the issue by re-simulating a Milky Way class dark matter (DM) halo with
unprecedented resolution. Our set of cosmological hydrodynamic Adaptive Mesh
Refinement (AMR) simulations, called the Nut suite, allows us to investigate
the effect of supernova feedback and UV photoionisation at high redshift with
sub-parsec resolution. We subsequently follow the effect of interactions with
the Milky Way-like halo using a lower spatial resolution (50pc) version of the
simulation down to z=0. This latter produces a population of simulated
satellites that we compare to the observed satellites of the Milky Way and M31.
We find that supernova feedback reduces star formation in the least massive
satellites but enhances it in the more massive ones. Photoionisation appears to
play a very minor role in suppressing star and galaxy formation in all
progenitors of satellite halos. By far the largest effect on the satellite
population is found to be the mass of the host and whether gas cooling is
included in the simulation or not. Indeed, inclusion of gas cooling
dramatically reduces the number of satellites captured at high redshift which
survive down to z=0.
