Abstract :
Radio relics are Mpc-size synchrotron sources observed in the outskirts of some merging galaxy clusters. Their radio emission fills large volumes of the intracluster medium (ICM), unveiling the presence of a non-thermal component mixed with the thermal gas, i.e. relativistic electrons and magnetic fields. The origin of radio relics is recognized to be connected to shock waves injected in the ICM during cluster mergers. Yet, the details of particle acceleration processes leading to their emission are unclear. Furthermore, magnetic fields in radio relics, and in galaxy clusters in general, are difficult to measure and still poorly known. However, being highly polarized, radio relics offer a peculiar view of their magnetic fields by studying their polarization and Faraday rotation properties. In this talk, I will review recent advances in the knowledge of radio relics' origin, focusing on their polarized emission.
