Ultra-low frequency LOFAR spectral indices of cluster radio halos
Ultra-low frequency LOFAR spectral indices of cluster radio halos
A fraction of galaxy clusters harbor diffuse radio sources known as radio halos. The currently adopted scenario for their formation is based on second-order Fermi re-acceleration of seed electrons that is driven by merger-driven turbulence in the intra-cluster medium. This mechanism is expected to be inefficient, which implies that a …