The challenges of low-frequency radio polarimetry: lessons from the Murchison Widefield Array

TL;DR

This paper discusses calibration techniques for low-frequency radio polarimetry using the Murchison Widefield Array, enabling studies of polarized sources and media in the universe.

Contribution

It introduces novel calibration and correction methods for MWA low-frequency polarimetric observations, improving data quality and scientific potential.

Findings

Successful calibration and correction of MWA polarimetric data

Enhanced imaging techniques for wide field-of-view observations

Potential for new insights into cosmic magnetic fields and media

Abstract

We present techniques developed to calibrate and correct Murchison Widefield Array (MWA) low frequency (72-300 MHz) radio observations for polarimetry. The extremely wide field-of-view, excellent instantaneous (u, v)-coverage and sensitivity to degree-scale structure that the MWA provides enable instrumental calibration, removal of instrumental artefacts, and correction for ionospheric Faraday rotation through imaging techniques. With the demonstrated polarimetric capabilities of the MWA, we discuss future directions for polarimetric science at low frequencies to answer outstanding questions relating to polarised source counts, source depolarisation, pulsar science, low-mass stars, exoplanets, the nature of the interstellar and intergalactic media, and the solar environment.