A novel algorithm for high fidelity spectro-polarimetric snapshot imaging of the low-frequency radio Sun using SKA-low precursor

TL;DR

This paper introduces a new polarization calibration algorithm for low-frequency solar radio observations, enabling routine measurements of coronal magnetic fields with high fidelity, crucial for understanding solar phenomena.

Contribution

The paper presents a novel calibration method that reduces instrumental polarization to below 1%, facilitating detection of weak polarized signals from the solar corona.

Findings

Instrumental polarization reduced to <1%.

Method enables detection of low-level polarized coronal emissions.

Applicable to future SKA observations for routine coronal magnetic field measurements.

Abstract

Magnetic field couples the solar interior to the solar atmosphere, known as the corona. The coronal magnetic field is one of the crucial parameters which determines the coronal structures and regulates the space weather phenomena like flares, coronal mass ejections, energetic particle events, and solar winds. Measuring the magnetic field at middle and higher coronal heights are extremely difficult problem and to date there is no single measurement technique available to measure the higher coronal magnetic fields routinely. polarization measurements of the low-frequency radio emissions are an ideal tool to probe the coronal magnetic fields at higher coronal heights ($>1R_\odot$). To date, most of the low-frequency polarization observations of the Sun were limited to bright solar radio bursts. Here we developed a novel algorithm for performing precise polarization calibration of the solar observations done with the Murchison Widefield Array, a future Square Kilometer Array (SKA) precursor. We have brought down the instrumental polarization $<1\%$. We anticipate this method will allow us to detect very low-level polarised emissions from coronal thermal emissions, which will become a tool for routine measurements of the global coronal magnetic fields at higher coronal heights. This method can be easily adapted for future SKA and open a window of new discoveries using high fidelity spectro-polarimetric snapshot imaging of the Sun at low radio frequencies.