Riding the wake of a merging galaxy cluster

TL;DR

This paper reports the discovery of a unique ionised gas plume in a merging galaxy cluster, linking it to the offset cool core and recent disruption of the brightest cluster galaxy, providing insights into cluster merger dynamics.

Contribution

It presents the first observation of a thin ionised gas plume in a merging galaxy cluster and links it to the cluster's dynamic merger process and BCG disruption.

Findings

Discovery of a 15 kpc ionised gas plume in Abell 2146

Evidence of recent disruption to the brightest cluster galaxy

Proposed link between the plume and the offset cool core

Abstract

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.