Shocks and cold fronts in merging and massive galaxy clusters: new detections with Chandra

TL;DR

This study uses Chandra X-ray observations to identify 22 new surface brightness and temperature discontinuities in merging galaxy clusters, enhancing understanding of ICM physics and cosmic ray acceleration.

Contribution

The paper introduces new detection methods and reports 22 previously unknown shocks and cold fronts in massive galaxy clusters, expanding the catalog of ICM discontinuities.

Findings

Detected 6 shocks with Mach number < 2

Identified 8 cold fronts and 8 uncertain features

Demonstrated the effectiveness of combined imaging and spectral techniques

Abstract

A number of merging galaxy clusters shows the presence of shocks and cold fronts, i.e. sharp discontinuities in surface brightness and temperature. The observation of these features requires an X-ray telescope with high spatial resolution like Chandra, and allows to study important aspects concerning the physics of the intra-cluster medium (ICM), such as its thermal conduction and viscosity, as well as to provide information on the physical conditions leading to the acceleration of cosmic rays and magnetic field amplification in the cluster environment. In this work we search for new discontinuities in 15 merging and massive clusters observed with Chandra by using different imaging and spectral techniques of X-ray observations. Our analysis led to the discovery of 22 edges: six shocks, eight cold fronts and eight with uncertain origin. All the six shocks detected have $\mathcal{M} < 2$ derived from density and temperature jumps. This work contributed to increase the number of discontinuities detected in clusters and shows the potential of combining diverse approaches aimed to identify edges in the ICM. A radio follow-up of the shocks discovered in this paper will be useful to study the connection between weak shocks and radio relics.