Modelling Giant Radio Halos

TL;DR

This paper reviews theoretical models of giant radio halos in galaxy clusters, comparing hadronic and reacceleration models with observations, and finds reacceleration models better explain the observed phenomena.

Contribution

It provides a comparative analysis of hadronic and reacceleration models for giant radio halos, including new simulation results supporting reacceleration.

Findings

Hadronic models face severe problems when compared with observations.

Reacceleration models successfully explain key observables of giant radio halos.

First simulation results support the viability of reacceleration models.

Abstract

We review models for giant radio halos in clusters of galaxies, with a focus on numerical and theoretical work. After summarising the most important observations of these objects, we present an introduction to the theoretical aspects of hadronic models. We compare these models with observations using simulations and find severe problems for hadronic models. We give a short introduction to reacceleration models and show results from the first simulation of CRe reaccel- eration in cluster mergers. We find that in-line with previous theoretical work, reacceleration models are able to elegantly explain main observables of giant radio halos.