A combined JVLA and Chandra study of the Abell 2626 galaxy cluster

In this thesis work we carried out an accurate analysis of new observations of the galaxy cluster Abell 2626 in the radio and X-ray bands. Its radio emission is characterized by the presence of a system of peculiar radio sources, the arcs , whose properties differs from the properties of the common cluster diffuse radio sources. In the past years, several models have been proposed to explain their origin. Our work aims at investigating the origin of the arcs. We analyzed new JVLA observations of the cluster at 3.0 GHz and 5.5 GHz. During the radio analysis we detected the arcs at 3.0 GHz and possible evidences for extended emission inside them at 5.5 GHz. By combining archival maps at 1.4 GHz and the new ones at 3.0 GHz, we estimated that the arcs have a spectral index α ∼ -3. The analysis of a new CHANDRA observation of the cluster produced surprising results. We highlighted the a spatial connection between the radio arcs and a cold region inside the cluster core and, moreover, we discovered a cold front which coincides with the south-west junction of the radio arcs. It is well known that the turbulence inside the cold fronts is able to accelerate the relativistic particles, triggering radio emission in form of mini-halos. Under certain conditions, this emission results in form of collimated steep-spectrum arcs that traces the dynamics of the cold fronts. So we proposed a scenario, in which the arcs are not related to the precession of AGN jets, but instead are produced by non-thermal processes (particle acceleration and magnetic fled amplification) that are related to the formation and the evolution of the cold fronts in the core of Abell 2626. In this case the peculiar morphology of the arcs is the result of the dynamics of the cold fronts, that will be studied with future MHD simulations.