Constraints on thermal conductivity in the fascinating merging cluster Abell 2146

The cluster of galaxies Abell 2146 is undergoing a major merger, which renders it an ideal system for studying the intracluster medium (ICM) physics. With the merger axis oriented in the plane of the sky, the cluster’s proximity and simple geometry allow us to resolve features at the relevant scales. Furthermore, the ICM temperature lies within Chandra’s peak sensitivity range. In particular, A2146 serves as a perfect target for studying thermal conduction within clusters of galaxies - a physical process only studied to a slight extent in the context of ICM physics in the literature. One of the most striking features of Abell 2146 is the partial stripping of its cool subcluster core. The resulting tail of gas creates a unique opportunity for studying thermal conductivity in the ICM, by analysing survival time of cool gas within the intracluster medium. Here we present our study of A2146, using deep 2.4-Ms Chandra observations in the 0.5-7 keV energy band. By fitting the absorbed thermal plasma emission model to the X-ray emission, we produce a high spatial resolution map of the temperature structure along a plume in the ram-pressure stripped tail, which is clearly distinguishable from the hot ambient gas. Previous studies of conduction in the ICM typically rely on estimates of the survival time for key structures, such as cold fronts. Here we use a suite of high-resolution hydrodynamical simulations of the A2146 system, measuring the flow velocities along the stripped plume and the timescales associated with the temperature increase along its length. We find that thermal conductivity is suppressed by multiple orders of magnitude with respect to the Spitzer rate in Abell 2146. With only 1% of the available energy budget needed to heat the cold, stripped gas, our results deliver important constraints on physical processes in clusters of galaxies.