Speaker
Description
For nearly five decades, it has been widely assumed that linear polarization from the Sun at low radio frequencies would be entirely depolarized by strong Faraday rotation in the solar corona. As a result, most solar radio studies at these wavelengths either ignored linear polarization measurements or treated them as zero during calibration.
Here, we will present the first robust evidence of intrinsic linear polarization in solar emissions at meter wavelengths, based on simultaneous observations with two widely separated and fundamentally different instruments: the Murchison Widefield Array (MWA) and the upgraded Giant Metrewave Radio Telescope (uGMRT). Both datasets independently show consistent linear polarization fractions. The rapid temporal and spectral variability of the observed polarization further rules out instrumental effects. We will also explore and discuss the possible physical mechanisms that could give rise to such polarized emission.
Assuming absence of linear polarization in solar radio emissions can result in incorrect interpretation of solar observations and as well as those of other flare stars, which are often guided by learnings from solar studies. This discovery highlights the need for relaxing this assumption, and is essential for precise estimation of polarization signatures, ultimately leading to a better understanding of the plasma conditions in the Sun and other stars.
