Sloshing of the Magnetized Cool Gas in the Cores of Galaxy Clusters
  X-ray observations of many clusters of galaxies reveal the presence of edges
in surface brightness and temperature, known as "cold fronts". In relaxed
clusters with cool cores, these edges have been interpreted as evidence for the
"sloshing" of the core gas in the cluster's gravitational potential. The
smoothness of these edges has been interpreted as evidence for the stabilizing
effect of magnetic fields "draped" around the front surfaces. To check this
hypothesis, we perform high-resolution magnetohydrodynamics simulations of
magnetized gas sloshing in galaxy clusters initiated by encounters with
subclusters. We go beyond previous works on the simulation of cold fronts in a
magnetized intracluster medium by simulating their formation in realistic,
idealized mergers with high resolution ({\Delta}x ~ 2 kpc). Our simulations
sample a parameter space of plausible initial magnetic field strengths and
field configurations. In the simulations, we observe strong velocity shears
associated with the cold fronts amplifying the magnetic field along the cold
front surfaces, increasing the magnetic field strength in these layers by up to
an order of magnitude, and boosting the magnetic pressure up to
near-equipartition with thermal pressure in some cases. In these layers, the
magnetic field becomes strong enough to stabilize the cold fronts against
Kelvin-Helmholtz instabilities, resulting in sharp, smooth fronts as those seen
in observations of real clusters. These magnetic fields also result in strong
suppression of mixing of high and low-entropy gas in the cluster, seen in our
simulations of mergers in the absence of a magnetic field. As a result, the
heating of the core due to sloshing is very modest and is unable to stave off a
cooling catastrophe.
