Estimating plasma parameters of solar coronal mass ejections at higher coronal heights using high fidelity low-frequency radio images

Coronal Mass Ejection (CMEs) are large scale explosive eruptions of magnetised plasma from Sun into Heliosphere. Measuring the physical parameters of CMEs is crucial for understanding their physics and for assessing their geoeffectiveness. Radio observations offer the most direct means for estimating these plasma parameters when gyrosynchrotron (GS) emission is detected from the CME. But only a handful of studies have successfully managed to detect this GS emissions (Bastian et al. 2001; Maia et al. 2007; and Demoulin et al. 2012).

We will show that it is now routinely possible to detect these GS emissions using high dynamic range radio images produced by an automated imaging pipeline (Mondal et al. 2019a) using the data from Murchison Widefield Array. We have detected the radio emission from CME plasma at the largest distance (8.3 solar radii) till date. We will show that magnetic field and energetic electron distribution inside CME plasma can be estimated directly at higher coronal heights by fitting a  model of GS emission to the observed spectra. On the other hand it is also observed that radio spectra always can not be represented by simple GS spectra. This indicates that a more complicated physics is involved for these radio emissions.