| Radio relics are enormous Mpc-sized synchrotron emitting sources found in the outskirts of merging galaxy clusters. It is thought that these so-called relics trace cluster merger shock waves. In this talk I will present the latest observational results on several unique new relics. The properties of these relics provide unprecedented insights into the physical properties of extremely dilute cosmic plasmas, magnetic fields, and particle acceleration in shocks. Together with simulations of cluster mergers I will demonstrate how relics can be used to probe the intracluster medium at large distances from the cluster center and reconstruct the mass ratio, impact parameter and orientation, of cluster merger events. In addition, I will present high angular resolution LOFAR observations of the cluster Abell 2256.
Combined radio and X-ray image of the merging galaxy cluster CIZA J2242.8+5301. Red: radio continuum image at 610 MHz from the GMRT. Blue: ROSAT X-ray emission from the hot thermal intracluster medium.
|R. van Weeren/Leiden Observatory