Project Part A7: Radio relics and haloes

Persons involved


Clusters of galaxies frequently exhibit two conspicuous phenomena in the radio continuum: central haloes and peripheral relics. Their common property is that they are diffuse, synchrotron- emitting structures not associated to any sources. Their likely common origin are relativistic particles that are accelerated by shocks or turbulence produced by mergers between galaxy clus- ters. The goals of this proposal are a twofold: (1) In a case study, the relativistic plasma of the Coma Cluster of galaxies will be investigated via sensitive low-frequency radio continuum observations with LOFAR. These will disclose the full extent of the radiating electrons and magnetic field. With the presence of both, a central halo as well as a peripheral relic, it is thus possible to (i) pinpoint the nature of these phenomena and (ii) shed light on the question how particles and fields were deposited in the ICM/IGM. (2) In a statistical approach we will collect information on a large sample of galaxy clusters by exploiting the “Million Source Sky Survey”. This will shed light on the origin of relativistic particles and their acceleration mechanism. Finally, we will compile a luminosity function of diffuse radio sources in clusters of galaxies that can be compared to theoretical predictions.