The Planck clusters in the LOFAR sky V. LoTSS-DR2: Mass - radio halo power correlation at low frequency

TL;DR

This study investigates the relationship between radio halo power and galaxy cluster mass at low frequencies, revealing a correlation that extends to lower mass clusters and is influenced by cluster dynamics.

Contribution

It provides the first low-frequency analysis of the mass-radio power relation for a large, diverse sample of galaxy clusters, including lower mass systems.

Findings

Radio halo power correlates with cluster mass down to 3×10^14 Msun.

Cluster dynamical state contributes to scatter in the correlation.

Clusters without radio halos are distributed differently than those with halos.

Abstract

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 intra-cluster medium (ICM). There is general agreement 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. Previous studies have been limited to massive clusters and 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. We analysed the clusters from the second catalogue of Planck Sunyaev Zel'dovich sources that lie within the 5634 sq deg covered by the second Data Release of the LOFAR Two-meter Sky Survey. We derived the correlation between the radio power and the mass of the host clusters and we investigated the distribution of clusters without radio halos with respect to the correlation. We use X-ray observations to classify the dynamical state of clusters and investigate its role on the power of radio halos. We found a correlation between the power of radio halos at 150 MHz and the mass of the host clusters down to 3e14 Msun. This correlation has a large scatter, part of which can be attributed to the different dynamical states of host clusters. We used two statistical test 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 an upper envelope constituted by the correlation.