A Parameter Space Exploration of Galaxy Cluster Mergers I: Gas Mixing
  and the Generation of Cluster Entropy
  We present a high-resolution set of adiabatic binary galaxy cluster merger
simulations using FLASH. These are the highest-resolution simulations to date
of such mergers using an AMR grid-based code with Eulerian hydrodynamics. In
this first paper in a series we investigate the effects of merging on the
entropy of the hot intracluster gas, specifically with regard to the ability of
merging to heat and disrupt cluster "cool-cores." We find, in line with recent
works, that the effect of fluid instabilities that are well-resolved in
grid-based codes is to significantly mix the gases of the two clusters and to
significantly increase the entropy of the gas of the final merger remnant. This
result is characteristic of mergers over a range of initial mass ratio and
impact parameter. In line with this, we find that the kinetic energy associated
with random motions is higher in our merger remnants which have high entropy
floors, indicating the motions have efficiently mixed the gas and heated the
cluster core with gas of initially high entropy. We examine the implications of
this result for the maintenance of high entropy floors in the centers of galaxy
clusters and the derivation of the properties of dark matter from the thermal
properties of the X-ray emitting gas.
