X-ray Source Heights in a Solar Flare: Thick-target versus Thermal Conduction Front Heating

TL;DR

This study uses RHESSI observations of solar flare X-ray source motions to differentiate between non-thermal electron beam heating and in situ thermal conduction heating, favoring the former based on source morphology and height dispersion.

Contribution

The paper introduces a numerical approach to constrain heating mechanisms in solar flares using X-ray source height observations, distinguishing between non-thermal and thermal heating scenarios.

Findings

Both heating models can fit light curves

Non-thermal heating aligns better with observed source morphology

In situ heating predicts opposite height dispersion behavior

Abstract

Observations of solar flares with RHESSI have shown X-ray sources traveling along flaring loops, from the corona down to the chromosphere and back up. The 28 November 2002 C1.1 flare, first observed with RHESSI by Sui et al. 2006 and quantitatively analyzed by O'Flannagain et al. 2013, very clearly shows this behavior. By employing numerical experiments, we use these observations of X-ray source height motions as a constraint to distinguish between heating due to a non-thermal electron beam and in situ energy deposition in the corona. We find that both heating scenarios can reproduce the observed light curves, but our results favor non-thermal heating. In situ heating is inconsistent with the observed X-ray source morphology and always gives a height dispersion with photon energy opposite to what is observed.