ThePlanckclusters in the LOFAR sky

Abstract

Context.Many galaxy clusters show diffuse cluster-scale emission in the form of radio halos, showing that magnetic fields and relativistic electrons are mixed in with the intracluster medium. There is in general agreement with the idea that the origin of radio halos is connected to turbulence generated during cluster mergers. Statistical studies of large samples of galaxy clusters in the radio band have the potential to unveil the connection between the properties of radio halos and the mass and dynamics of the host clusters.Aims.Previous studies were limited to massive clusters and were based on a small number of radio halos. The aim of this paper is to investigate the scaling relation between the radio power of radio halos and the mass of the host clusters at low frequencies and down to lower cluster masses.Methods.We analysed the clusters from the second catalogue ofPlanckSunyaev–Zel’dovich sources that lie within the 5634 deg2covered by the second Data Release of the LOFAR Two-meter Sky Survey. We derived the correlation between radio power and host cluster mass, and investigated the distribution of clusters without radio halos with respect to this correlation. We used X-ray observations to classify the dynamical state of clusters and investigated its effect on the power of radio halos.Results.Using different fitting methods, we found a correlation between the power of a radio halo at 150 MHz and the mass of its host cluster down to 3 × 1014 M⊙. For comparison with previous works, with the Bivariate Correlated Errors and intrinsic Scatter (BCES)Y|Xmethod, we obtained the slope of the correlationB = 3.55 ± 0.60 and the normalisationA = 1.1 ± 0.1. This correlation has a large scatter, part of which can be attributed to the different dynamical states of host clusters. We used two statistical tests to show that the distribution of clusters with and without (upper limits) radio halos in the mass–radio power diagram is not compatible with a single correlation and that it is also not compatible with clusters being uniformly distributed below the correlation.