Radioheliograph observations of microwave bursts with zebra structures

TL;DR

This study analyzes microwave zebra structures in solar radio bursts to infer plasma parameters in flare loops, supporting the double plasma resonance mechanism as the primary generation process.

Contribution

It provides new microwave observations of zebra structures and supports the double plasma resonance theory for their formation in solar flare regions.

Findings

Zebra structures are localized in flare regions.

Plasma parameters can be estimated from observations.

Double plasma resonance is the likely generation mechanism.

Abstract

The so-called zebra structures in radio dynamic spectra, specifically their frequencies and frequency drifts of emission stripes, contain information on the plasma parameters in the coronal part of flare loops. This paper presents observations of zebra structures in a microwave range. Dynamic spectra were recorded by Chinese spectro-polarimeters in the frequency band close to the working frequencies of the Siberian Solar Radio Telescope. The emission sources are localized in the flare regions, and we are able to estimate the plasma parameters in the generation sites using X-ray data. The interpretation of the zebra structures in terms of the existing theories is discussed. The conclusion has been arrived that the preferred generation mechanism of zebra structures in the microwave range is the conversion of plasma waves to electromagnetic emission on the double plasma resonance surfaces distributed across a flare loop.