A Radio and X-ray Study of the Merging Cluster A2319
  A2319 is a massive, merging galaxy cluster with a previously detected radio
halo that roughly follows the X-ray emitting gas. We present the results from
recent observations of A2319 at 20 cm with the Jansky Very Large Array (VLA)
and a re-analysis of the X-ray observations from XMM-Newton, to investigate the
interactions between the thermal and nonthermal components of the ICM . We
confirm previous reports of an X-ray cold front, and report on the discovery of
a distinct core to the radio halo, 800 kpc in extent, that is strikingly
similar in morphology to the X-ray emission, and drops sharply in brightness at
the cold front. We detect additional radio emission trailing off from the core,
which blends smoothly into the 2 Mpc halo detected with the Green Bank
Telescope (GBT; Farnsworth et al., 2013). We speculate on the possible
mechanisms for such a two-component radio halo, with sloshing playing a
dominant role in the core. By directly comparing the X-ray and radio emission,
we find that a hadronic origin for the cosmic ray electrons responsible for the
radio halo would require a magnetic field and/or cosmic ray proton distribution
that increases with radial distance from the cluster center, and is therefore
disfavored.
