Tracing the origin of diffuse radio emission in galaxy clusters

Abstract

In the hierarchy of structure formation, galaxy clusters emerge as the largest gravitationally bound structures formed by the accreting galaxies and groups of galaxies. Cluster mergers are among the highest-energy events since the Big Bang, where about 1063 − 1064 ergs of energy is released from the collision of two sub-clusters of mass around 1014M⊙ (Sarazin, 2002). This enormous energy is dissipated in the intra-cluster medium (ICM), increasing the overall ICM temperature and affecting the gas dynamics in the ICM. The supersonic gas flow from two sub-clusters generates turbulence and shock waves in the ICM. Additionally, during cluster mergers, particles can be accelerated to relativistic speeds along with enhancement in the magnetic field, resulting in the production of non-thermal emissions from clusters. Thus, merging clusters are ideal laboratories for studying several astrophysical interaction processes and large-scale structure formation. The hot baryonic intra-cluster gas radiates through the thermal bremsstrahlung process. This emission is visible through X-ray observations and gives significant insight into the internal dynamics of the cluster (Brunetti & Jones 2014).