Relationship between microwave and metre ranges during an impulsive solar flare

An analysis of solar flares with simple temporal structures can help us to understand the features and mechanisms of energy and particle propagation. A weak impulsive solar flare that occurred on 2021 June 3 provided such opportunity. For the purposes of the study, we used microwave observations with spatial resolution from the Siberian Radioheliograph (3–6 GHz) combined with various spectral radio and X-ray data. Flare topology analysis revealed a configuration consisting of a small loop or dome-like structure associated with a compact bright source, and a long high loop system associated with the diffuse source. This indicates a compact and relatively low-lying site of acceleration and initial energy release. The radio metre and the microwave emission demonstrated a peak-to-peak correlation in three of the four bursts. The delays obtained from comparing microwave and metre radio ranges are in good agreement with the delays from the metre dynamic spectrum analysis, but the different radio bursts had different delays. We found that the electron energies derived from metre dynamic spectrum analysis are lower than those shown by hard X-ray emissions. According to the results of theoretical simulations, this can be explained by the expansion of magnetic loops with altitude. The difference in drift velocities for various radio bursts can be the result of the different size of the loop where the electron beams are propagated. This can be a feature related to the configuration type of the studied flare.