The Power of Low Frequencies: Faraday Tomography in the sub-GHz regime

TL;DR

This paper reviews how low-frequency radio observations (below 1 GHz) enhance Faraday tomography, revealing magnetic field structures in the interstellar medium with unique observational advantages and challenges.

Contribution

It provides a theoretical overview and recent results of Faraday tomography at sub-GHz frequencies, highlighting the potential of low-frequency arrays like LOFAR and MWA.

Findings

Low-frequency observations reveal complex magnetic field structures.

Faraday tomography at 100-200 MHz offers unique insights into the interstellar medium.

Future low-frequency surveys will improve magnetic field mapping.

Abstract

Faraday tomography, the study of the distribution of extended polarized emission by strength of Faraday rotation, is a powerful tool for studying magnetic fields in the interstellar medium of our Galaxy and nearby galaxies. The strong frequency dependence of Faraday rotation results in very different observational strengths and limitations for different frequency regimes. I discuss the role these effects take in Faraday tomography below 1 GHz, emphasizing the 100-200 MHz band observed by the Low Frequency Array and the Murchison Widefield Array. With that theoretical context, I review recent Faraday tomography results in this frequency regime, and discuss expectations for future observations.