Riding the wake of a merging galaxy cluster
  Using WHT OASIS integral field unit observations, we report the discovery of
a thin plume of ionised gas extending from the brightest cluster galaxy in
Abell 2146 to the sub-cluster X-ray cool core which is offset from the BCG by
~37 kpc. The plume is greater than 15 kpc long and less than 3 kpc wide. This
plume is unique in that the cluster it is situated in is currently undergoing a
major galaxy cluster merger. The brightest cluster galaxy is unusually located
behind the X-ray shock front and in the wake of the ram pressure stripped X-ray
cool core and evidence for recent disruption to the BCG is observed. We examine
the gas and stellar morphology, the gas kinematics of the BCG and their
relation to the X-ray gas. We propose that a causal link between the ionised
gas plume and the offset X-ray cool core provides the simplest explanation for
the formation of the plume. An interaction or merger between the BCG and
another cluster galaxy is probably the cause of the offset.
