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

5 September 2017

The Murchison Widefield Array (MWA) has some unique features for a radio telescope. In a paper recently accepted for publication, Dr Emil Lenc , CAASTRO/SIFA Researcher and colleagues outline the techniques developed to calibrate and correct MWA observations for polarimetry.

Polarimetry studies the geometric orientation of the radio waves as they reach us. The amount and nature of the polarisation seen in the radio waves reveals details of the physical emission mechanism that can provide insight into processes occurring in systems that range from our own atmosphere (the ionosphere) to high-redshift galaxies.

The extremely wide field-of-view, excellent snapshot imaging capability and sensitivity to large diffuse structure that the MWA provides enable instrumental calibration, removal of instrumental artefacts, and correction for ionospheric effects through imaging techniques.

With the demonstrated polarimetric capabilities of the MWA, the new paper looks into future directions for polarimetric science and how it can be used to answer outstanding questions relating to polarised radio galaxies, pulsar science, low-mass stars, exoplanets, the nature of the interstellar and intergalactic media, and the solar environment.

The image above shows linearly polarised diffuse emission seen towards the South Galactic pole at 216 MHz over a region spanning over 1200 square degrees.

The paper is available on arxiv