Simulations of the merging cluster of galaxies Cygnus A
  The archetype FR-II galaxy Cygnus A lies in a moderately rich cluster about
to undergo a major merger. We study the pre-merger Cygnus cluster environment
using smoothed particle hydrodynamics simulations constrained by 2Ms of Chandra
observations of the hot intracluster medium. The observations constrain the
total gravitating mass and concentration parameter, and the simulations provide
the quiescent and merger-enhanced temperature profiles of the pre- and post
merger of the cluster excluding the central active galactic nucleus. We present
the first detailed model of the sub cluster north west of Cygnus A, named
CygNW. We find a lower baryon fraction and higher concentration parameter for
CygA than expected from known scaling relations in the literature. The model
suggests the Cygnus cluster hosts a pre-merger with a progenitor mass ratio of
about 1.5:1 at the virial radius. We notice that the intra cluster medium is
heated as a result of the merger, but we find no evidence for a (pre-)merger
shock in the interstitial region between both cluster haloes. We attribute the
merger-induced heating to compression of the cluster outskirts. The smooth
model obtained from our simulations is subtracted from the observed cluster
state and shows residual temperature structure that is neither hydrostatic nor
merger-heated cluster gas. We speculate that this residual heating may result
from previous AGN activity over the last ~100 Myr.
