Unravelling the origin of large-scale magnetic fields in galaxy clusters and beyond through Faraday Rotation Measures with the SKA

TL;DR

This paper explores how the SKA can detect and analyze magnetic fields in galaxy clusters and their surroundings using Faraday Rotation Measures, providing insights into their strength, structure, and evolution.

Contribution

It introduces 3D magnetic field models and mock observations to predict SKA's capabilities in studying cluster magnetic fields across different masses and evolutionary stages.

Findings

SKA can infer magnetic field properties in clusters down to 10^13 solar masses.

Rotation measure enhancements can constrain magnetic fields after shock events.

SKA observations will shed light on magnetic field evolution over cosmic time.

Abstract

We investigate the possibility for the SKA to detect and study the magnetic fields in galaxy clusters and in the less dense environments surrounding them using Faraday Rotation Measures. To this end, we produce 3-dimensional magnetic field models for galaxy clusters of different masses and in different stages of their evolution, and derive mock rotation measure observations of background radiogalaxies. According to our results, already in phase I, we will be able to infer the magnetic field properties in galaxy clusters as a function of the cluster mass, down to $10^{13}$ solar-masses. Moreover, using cosmological simulations to model the gas density, we have computed the expected rotation measure through shock-fronts that occur in the intra-cluster medium during cluster mergers. The enhancement in the rotation measure due to the density jump will permit to constraint the magnetic field strength and structure after the shock passage. SKA observations of polarised sources located behind galaxy clusters will answer several questions about the magnetic field strength and structure in galaxy clusters, and its evolution with cosmic time.