A fully self-consistent model for solar flares

TL;DR

This paper introduces a fully self-consistent model of solar flares combining MHD and an analytic fast electron approach, enabling detailed study of flare dynamics, X-ray emissions, and reconnection processes.

Contribution

It presents the first integrated MHD and fast electron model that captures all key aspects of the standard solar flare scenario.

Findings

Reveals the relationship between hard X-ray flux and magnetic reconnection rate.

Shows that looptop hard X-ray sources can result from electron trapping.

Demonstrates the model's ability to reproduce observed flare features.

Abstract

The 'standard solar' flare model collects all physical ingredients identified by multi-wavelength observations of our Sun: magnetic reconnection, fast particle acceleration and the resulting emission at various wavelengths, especially in soft to hard X-ray channels. Its cartoon representation is found throughout textbooks on solar and plasma astrophysics, and guides interpretations of unresolved energetic flaring events on other stars, accretion disks and jets. To date, a fully self-consistent model that reproduces the standard scenario in all its facets is lacking, since this requires the combination of a large scale, multi-dimensional magnetohydrodynamic (MHD) plasma description with a realistic fast electron treatment. Here, we demonstrate such a novel combination, where MHD combines with an analytic fast electron model, adjusted to handle time-evolving, reconnecting magnetic fields and particle trapping. This allows to study (1) the role of fast electron deposition in the triggering of chromospheric evaporation flows; (2) the physical mechanisms that generate various hard X-ray sources at chromospheric footpoints or looptops; and (3) the relationship between soft X-ray and hard X-ray fluxes throughout the entire flare loop evolution. For the first time, this self-consistent solar flare model demonstrates the observationally suggested relationship between flux swept out by the hard X-ray footpoint regions, and the actual reconnection rate at the X-point, which is a major unknown in flaring scenarios. We also demonstrate that a looptop hard X-ray source can result from fast electron trapping.