Suzaku observations of a shock front tracing the western edge of the
  giant radio halo in the Coma Cluster
  We present the results of new Suzaku observations of the Coma Cluster, the
X-ray brightest, nearby, merging system hosting a well studied, typical giant
radio halo. It has been previously shown that, on the western side of the
cluster, the radio brightness shows a much steeper gradient compared to other
azimuths. XMM-Newton and Planck revealed a shock front along the southern half
of the region associated with this steep radio gradient, suggesting that the
radio emission is enhanced by particle acceleration associated with the shock
passage. Suzaku demonstrates for the first time that this shock front extends
northwards, tracing the entire length of the western edge of the Coma radio
halo. The shock is detected both in the temperature and X-ray surface
brightness distributions and has a Mach number of around $\mathcal{M}\sim1.5$.
The locations of the surface brightness edges align well with the edge of the
radio emission, while the obtained temperature profiles seem to suggest shocks
located 125-185 kpc further out in radius. In addition, the shock strengths
derived from the temperature and density jumps are in agreement when using
extraction regions parallel to the radio halo edge, but become inconsistent
with each other when derived from radial profiles centred on the Coma Cluster
core. It is likely that, beyond mere projection effects, the geometry of the
shock is more complex than a front with a single, uniform Mach number and an
approximately spherically symmetric shape.
