A New Class of Weak Radio Bursts: Nanoflares and Coronal Heating?

Abstract:

The newly commissioned Murchison Widefield Array (MWA) has revealed the presence of a numerous weak and short lived low frequency radio solar bursts. These emission features have duration of order a second, have relatively narrow spectral widths and are surprisingly numerous even during quiet solar conditions. Their appearance in the time-frequency plane is unlike that of the any of the known classes of radio bursts, and they at least an order of magnitude weaker than the weakest type III bursts routinely monitored and reported (e.g. by Automated Radio Burst Identification System operational at the Learmonth Radioheliograph in Australia). For the few bursts which have been studied in detail, we have not found a counterpart at X-Ray or EUV bands. There is an exciting possibility that these bursts are associated with the widely hypothesized "nanoflares" thought to play a role in coronal heating through magnetic reconnection on small scales in coronal loops. A systematic and detailed characterization of the statistical properties of these bursts over large temporal and spectral spans is necessary for investigating the role these bursts might play in coronal heating. To enable this, we have developed a novel system using region-growing, wavelet decompositions, and thresholding techniques for event recognition and parameter extraction in an automated manner for the voluminous MWA interferometric data. We will present and describe the statistical properties of these weak radio bursts based on a large number of events detected and parameterized by these automated methods.