Merger Signatures in the Galaxy Cluster Abell 98
  We present results from Chandra and XMM-Newton observations of Abell 98
(A98), a galaxy cluster with three major components: a relatively bright
subcluster to the north (A98N), a disturbed subcluster to the south (A98S), and
a fainter subcluster to the far south (A98SS). We find evidence for surface
brightness and temperature asymmetries in A98N consistent with a shock-heated
region to the south, which could be created by an early stage merger between
A98N and A98S. Deeper observations are required to confirm this result. We also
find that A98S has an asymmetric core temperature structure, likely due to a
separate ongoing merger. Evidence for this is also seen in optical data. A98S
hosts a wide-angle tail (WAT) radio source powered by a central active galactic
nucleus (AGN). We find evidence for a cavity in the intracluster medium (ICM)
that has been evacuated by one of the radio lobes, suggesting that AGN feedback
is operating in this system. Examples of cavities in non-cool core clusters are
relatively rare. The three subclusters lie along a line in projection,
suggesting the presence of a large-scale filament. We observe emission along
the filament between A98N and A98S, and a surface brightness profile shows
emission consistent with the overlap of the subcluster extended gas haloes. We
find the temperature of this region is consistent with the temperature of the
gas at similar radii outside this bridge region. Lastly, we examine the cluster
dynamics using optical data. We conclude A98N and A98S are likely bound to one
another, with a 67% probability, while A98S and A98SS are not bound at a high
level of significance.
