MHD Simulations of AGN Jets in a Dynamic Galaxy Cluster Medium
  We present a pair of 3-d magnetohydrodynamical simulations of intermittent
jets from a central active galactic nucleus (AGN) in a galaxy cluster extracted
from a high resolution cosmological simulation. The selected cluster was chosen
as an apparently relatively relaxed system, not having undergone a major merger
in almost 7 Gyr. Despite this characterization and history, the intra-cluster
medium (ICM) contains quite active "weather". We explore the effects of this
ICM weather on the morphological evolution of the AGN jets and lobes. The
orientation of the jets is different in the two simulations so that they probe
different aspects of the ICM structure and dynamics. We find that even for this
cluster that can be characterized as relaxed by an observational standard, the
large-scale, bulk ICM motions can significantly distort the jets and lobes.
Synthetic X-ray observations of the simulations show that the jets produce
complex cavity systems, while synthetic radio observations reveal bending of
the jets and lobes similar to wide-angle tail (WAT) radio sources. The jets are
cycled on and off with a 26 Myr period using a 50% duty cycle. This leads to
morphological features similar to those in "double-double" radio galaxies.
While the jet and ICM magnetic fields are generally too weak in the simulations
to play a major role in the dynamics, Maxwell stresses can still become locally
significant.
