LOFAR and APERTIF surveys of the radio sky: probing shocks and magnetic fields in galaxy clusters

TL;DR

LOFAR and APERTIF are new radio telescopes enabling deep, wide surveys of the northern sky at low frequencies, revealing shocks and magnetic fields in galaxy clusters and advancing understanding of their formation and evolution.

Contribution

This paper introduces the capabilities of LOFAR and APERTIF for large-scale radio sky surveys and discusses their potential to study shocks and magnetic fields in galaxy clusters.

Findings

Diffuse radio emission traces shocks from cluster mergers.

LOFAR can detect thousands of cluster-related radio sources.

Preliminary LOFAR results provide insights into cluster magnetic fields.

Abstract

At very low frequencies, the new pan-European radio telescope LOFAR is opening the last unexplored window of the electromagnetic spectrum for astrophysical studies. The revolutionary APERTIF phased arrays that are about to be installed on the Westerbork radio telescope (WSRT) will dramatically increase the survey speed for the WSRT. Combined surveys with these two facilities will deeply chart the northern sky over almost two decades in radio frequency from \sim 15 up to 1400 MHz. Here we briefly describe some of the capabilities of these new facilities and what radio surveys are planned to study fundamental issues related the formation and evolution of galaxies and clusters of galaxies. In the second part we briefly review some recent observational results directly showing that diffuse radio emission in clusters traces shocks due to cluster mergers. As these diffuse radio sources are relatively bright at low frequencies, LOFAR should be able to detect thousands of such sources up to the epoch of cluster formation. This will allow addressing many question about the origin and evolution of shocks and magnetic fields in clusters. At the end we briefly review some of the first and very preliminary LOFAR results on clusters.