Study of Quiet Sun Low Frequency Emission Using MWA

Rohit Sharma, University of Applied Sciences Northwestern Switzerland

The Sun is very dynamic at metrewavelengths along both frequency and time, even during periods of low solar activity. A possible reason for this observed variability can be the presence of weak energetic events or scattering of radio waves from density inhomogeneities. High sensitivity data from new generation instruments like the Murchison Widefield Array (MWA) provide an opportunity to study these weak emissions. The MWA, located in Western Australia, is an excellent instrument to study the Sun at metrewavelengths. MWA covers a good frequency range from 80 to 300 MHz spanning a large range in coronal heights from 0.08 to 0.65 R$_{sun}$ simultaneously in meterwaves. We study radio emission from the quietest time observed by MWA. Quiet Sun brightness temperature maps reveal the variability of the order of ~ 2-5%. The observed variability shows a spatial association with the structures seen at EUV wavelengths. The low-level temporal variability can be attributed to the scattering by density inhomogeneities present at various coronal heights or weak energetic nanoflare-like events. The coronal radio emission itself varies across height suggesting large scale structural variation or a transition from weak scattering to strong scattering regime. The results from the non-imaging and imaging analysis of quiet Sun observations from the MWA will be presented.