Wavelet-based characterization of small-scale solar emission features at low radio frequencies by A. Suresh et al.*15 Aug 2017, 11:08 UTC
The improved sensitivity provided by new-generation radio arrays has unveiled an enormous diversity of previously under-appreciated solar radio bursts. Observations in the 100-240 MHz band using the Murchison Widefield Array (MWA) have highlighted the presence of a myriad of weak, short-lived, narrow-band solar emission features (Fig. 1), even during calm solar periods. Their appearance in the MWA solar dynamic spectrum (DS) comes closest to miniature versions of type-III bursts with bandwidths and durations of order a few MHz and a second respectively. Their high occurrence rates (many thousands per hour in DS bandwidth) raise the possibility that they might be radio signatures of the widely-discussed nanoflares, expected to be responsible for coronal heating.
Since such features have been discovered only comparatively recently (Oberoi et al. 2011), their detailed observational characteristics in terms of their morphology in the DS and flux density are yet to be established. A statistical characterization of their properties is needed to understand them and evaluate their potential contribution towards coronal heating. However, their seemingly ubiquitous presence necessitates the use of an automated approach. Here, we employ an automated wavelet-based technique, which we have developed, for robust feature detection and characterization.
Figure 1. A sample flux-calibrated MWA ...