Simulations of the merging galaxy cluster Abell 3376
  Observed galaxy clusters often exhibit X-ray morphologies suggestive of
recent interaction with an infalling subcluster. Abell 3376 is a nearby
(z=0.046) massive galaxy cluster whose bullet-shaped X-ray emission indicates
that it may have undergone a recent collision. It displays a pair of Mpc-scale
radio relics and its brightest cluster galaxy is located 970 h_70^-1 kpc away
from the peak of X-ray emission, where the second brightest galaxy lies. We
attempt to recover the dynamical history of Abell 3376. We perform a set of
N-body adiabatic hydrodynamical simulations using the SPH code Gadget-2. These
simulations of binary cluster collisions are aimed at exploring the parameter
space of possible initial configurations. By attempting to match X-ray
morphology, temperature, virial mass and X-ray luminosity, we set approximate
constraints on some merger parameters. Our best models suggest a collision of
clusters with mass ratio in the range 1/6-1/8, and having a subcluster with
central gas density four times higher than that of the major cluster. Models
with small impact parameter (b<150 kpc), if any, are preferred. We estimate
that Abell 3376 is observed approximately 0.5 Gyr after core passage, and that
the collision axis is inclined by i~40 degrees with respect to the plane of the
sky. The infalling subcluster drives a supersonic shock wave that propagates at
almost 2600 km/s, implying a Mach number as high as M~4; but we show how it
would have been underestimated as M~3 due to projection effects.
