Reproducing Type II White-Light Solar Flare Observations with Electron and Proton Beam Simulations

TL;DR

This study uses radiative hydrodynamic simulations to analyze how electron and proton beams influence spectral features and white-light emission in a solar flare, revealing that low-flux, high cut-off energy beams best match observations.

Contribution

It provides a detailed comparison of electron and proton beam effects on solar flare spectra, constraining beam parameters and clarifying their roles in white-light emission.

Findings

Proton beams penetrate deeper and cause less atmospheric disturbance.

Low-flux, high cut-off energy beams reproduce observed spectral features.

White-light emission is optically thin and minimally shifts the $ au=1$ surface.

Abstract

We investigate the cause of the suppressed Balmer series and the origin of the white-light continuum emission in the X1.0 class solar flare on 2014 June 11. We use radiative hydrodynamic simulations to model the response of the flaring atmosphere to both electron and proton beams which are energetically constrained using RHESSI and Fermi observations. A comparison of synthetic spectra with the observations allow us to narrow the range of beam fluxes and low energy cut-off that may be applicable to this event. We conclude that the electron and proton beams that can reproduce the observed spectral features are those that have relatively low fluxes and high values for the low energy cut-off. While electron beams shift the upper chromosphere and transition region to greater geometrical heights, proton beams with a similar flux leave these areas of the atmosphere relatively undisturbed. It is easier for proton beams to penetrate to the deeper layers and not deposit their energy in the upper chromosphere where the Balmer lines are formed. The relatively weak particle beams that are applicable to this flare do not cause a significant shift of the $\tau=1$ surface and the observed excess WL emission is optically thin.