Temporal and Spatial Characteristics of Hard X-Ray Sources in Flare Model with a Vertical Current Sheet

TL;DR

This study investigates the spatial and temporal dynamics of hard X-ray sources in solar flares, revealing correlations and trends explained by a collapsing trap model with electron acceleration mechanisms.

Contribution

It introduces a detailed analysis of HXR source behavior in flares using observational data and a theoretical collapsing trap model with relativistic electron kinetics.

Findings

Downward motion and energy-dependent separation of HXR sources observed.

Negative correlation between HXR source area and flux during early flare stages.

Time delay spectra at footpoints show increasing trends, explained by magnetic loop dynamics.

Abstract

We analyzed changes in the height of the coronal hard X-ray (HXR) source for flares SOL2013-05-13T01:50 and SOL2013-05-13T15:51. Analysis of the Reuven Ramaty High Energy Solar Spectroscopic Imager data revealed the downward motion of the HXR source and the separation of the sources by energy and height. In the early stages of the flares, a negative correlation was found between the HXR source area in the corona and HXR flux. For the SOL2013-05-13T15:51 event, an increasing trend in the time delay spectra at the footpoints was obtained. For both events, the spectra of the time delays in the coronal HXR source showed a decreasing trend across the energies in certain flare phases. To interpret the observed phenomena, we considered a flare model of collapsing traps and calculated the distribution functions of accelerated electrons along the magnetic loop using a nonstationary relativistic kinetic equation. This approach considers betatron and Fermi first-order acceleration mechanisms. The increasing trend of the time delay spectra at the footpoints was explained by the high mirror ratio in the magnetic loop and betatron acceleration mechanism. The observed features in the spatial and temporal behavior of the HXR sources, such as the negative correlation between the HXR source area and HXR flux, can be interpreted by the collapsing trap model.