Large Microwave Flare Sources with multi-loop Magnetic Reconnection observed by EOVSA Imaging Spectroscopy

We present the imaging spectroscopy of C-class flare SOL2017-04-04 observed by Expanded Owens Valley Solar Array (EOVSA) to investigate the source morphology and the behavior of the accelerated particles through the low-frequency microwave emission. Unlike the usually observed flare emission that neatly fit the “standard solar model” from a simple, straightforward loop system/arcade, we report that the low-frequency sources have shown an extended emission over the flaring active region and are spatially almost ten times as large as the other associated observations. These sources cannot be entirely explained by a standard two-dimensional model but with a “three-dimensional loop-loop interaction” scenario as observed from the contributions of multiple loop systems with different sizes. This scenario leads to observational evidence for a more realistic flare model consisting of a multi-polar magnetic field configuration with the accelerated particles having large access to travel over the flaring region, where other wavelength emissions are almost invisible. Thus, the study highlights the diagnostic potential of the observed microwave frequencies through which the physical conditions of the secondary emission observed in the low-frequency sources are presented.