Filaments in and between galaxy clusters at low and mid-frequency with the SKA telescope

TL;DR

This paper explores the potential of the SKA telescope and its precursors in studying magnetic fields in galaxy clusters and filaments via diffuse synchrotron radio emission, emphasizing the importance of polarimetric observations across multiple frequencies.

Contribution

It provides theoretical predictions and simulations on radio properties of galaxy clusters and filaments, highlighting the effectiveness of polarimetric observations with upcoming radio telescopes.

Findings

Polarisation observations are highly effective for studying large-scale magnetic fields.

Intermediate frequency radio telescopes offer high sensitivity and resolution for diffuse emission analysis.

Low frequency instruments are valuable for observing synchrotron emission in total intensity and polarisation.

Abstract

Understanding the magnetised Universe is a major challenge in modern astrophysics, and cosmic magnetism has been acknowledged as one of the science key drivers of the most ambitious radio instrument ever planned, the SKA telescope. With this work, we aim to investigate the potential of the SKA telescope and its precursors and pathfinders in the study of magnetic fields in galaxy clusters and filaments through diffuse synchrotron radio emission. Galaxy clusters and filaments of the cosmic web are indeed unique laboratories to investigate turbulent fluid motions and large-scale magnetic fields in action and much of what is known about magnetic fields in galaxy clusters comes from sensitive radio observations. Based on cosmological MHD simulations, we predict radio properties (total intensity and polarisation) of a pair of galaxy clusters connected by a cosmic-web filament. We use our theoretical expectations to explore the potential of polarimetric observations to study large-scale structure magnetic fields in the frequency ranges 50-350MHz and 950-1760MHz. We also present predictions for galaxy cluster polarimetric observations with the SKA precursors and pathfinders (LOFAR2.0 and MeerKAT+). Our findings point out that polarisation observations are particularly powerful for the study of large-scale magnetic fields, since they are not significantly affected by confusion noise. The unprecedented sensitivity and spatial resolution of the intermediate frequency radio telescopes make them the favourite instruments for the study of these sources through polarimetric data, potentially allowing us to understand if the energy density of relativistic electrons is in equipartition with the magnetic field or coupled with the thermal gas density. Our results show that low frequency instruments represent as well a precious tool to study diffuse synchrotron emission in total intensity and polarisation.