Radio emission from acceleration sites of solar flares

TL;DR

This paper investigates radio emissions from solar flare acceleration sites, comparing stochastic acceleration and collapsing magnetic traps, and finds observable differences that can help identify the acceleration mechanism.

Contribution

It provides the first detailed calculation of incoherent radio emission from the acceleration sites in two different solar flare models, highlighting their observational signatures.

Findings

Radio emission from acceleration sites is detectable with current instruments.

Spectral and temporal differences distinguish the two acceleration models.

Stochastic acceleration may produce narrowband microwave and decimeter bursts.

Abstract

The Letter takes up a question of what radio emission is produced by electrons at the very acceleration site of a solar flare. Specifically, we calculate incoherent radio emission produced within two competing acceleration models--stochastic acceleration by cascading MHD turbulence and regular acceleration in collapsing magnetic traps. Our analysis clearly demonstrates that the radio emission from the acceleration sites: (i) has sufficiently strong intensity to be observed by currently available radio instruments and (ii) has spectra and light curves which are distinctly different in these two competing models, which makes them observationally distinguishable. In particular, we suggest that some of the narrowband microwave and decimeter continuum bursts may be a signature of the stochastic acceleration in solar flares.