Insights from Snapshot Spectroscopic Radio Observations of a Weak Type I Solar Noise Storm

Abstract

Abstract We present a high-fidelity snapshot spectroscopic radio imaging study of a weak type I solar noise storm that took place during an otherwise exceptionally quiet time. Using high-fidelity images from the Murchison Widefield Array, we track the observed morphology of the burst source for 70 minutes and identify multiple instances where its integrated flux density and area are strongly anticorrelated with each other. The type I radio emission is believed to arise due to electron beams energized during magnetic reconnection activity. The observed anticorrelation is interpreted as evidence for presence of MHD sausage wave modes in the magnetic loops and strands along which these electron beams are propagating. Our observations suggest that the sites of these small scale reconnections are distributed along the magnetic flux tube. We hypothesize that small scale reconnections produces electron beams which quickly get collisionally damped. Hence, the plasma emission produced by them span only a narrow bandwidth and the features seen even a few mehahertz apart must arise from independent electron beams.