Shocked Narrow-Angle Tail Radio Galaxies: Simulations and Emissions
  We present a numerical study of the interactions between the elongated AGN
outflows representing an evolved, narrow-angle tail (NAT) radio galaxy and
planar, transverse ICM shock fronts characteristic of those induced by galaxy
cluster mergers (incident Mach numbers 2 - 4). The simulated NAT formation was
reported previously in \cite{on19a}. Our simulations utilize a
three-dimensional, Eulerian magnetohydrodynamic code along with
energy-dependent Eulerian transport of passive cosmic ray electrons. Our
analysis of the shock/NAT interaction applies a Riemann problem-based
theoretical model to interpret complex shock front behavior during passage
through the highly heterogeneous structures of the simulated NAT tails. In
addition to shock compression, shock-induced vortical motions are observed
within the tails that contribute to coherent turbulent dynamo processes that
continue to amplify the magnetic fields in the tails well after initial shock
compression. We analyze synthetic radio observations spanning the NAT-shock
interaction period, and examine the brightness, spectral and polarization
properties of our shock-rejuvenated radio tails, as well as the extent to which
the pre-shock states of the plasma and particle populations in our tails
influence post-shock observations. Finally, we evaluate our findings in the
possible context of a physical analogy to our simulated NAT providing the
precursor to a cluster ``radio relic'' associated with an impacting ICM shock.
