Radiative Hydrodynamic Simulations of the Spectral Characteristics of Solar White-light Flares

TL;DR

This study uses radiative hydrodynamic simulations to analyze how white-light flares produce spectral emissions at specific wavelengths, revealing how different initial conditions and electron beam parameters influence these emissions.

Contribution

It introduces detailed modeling of spectral responses during white-light flares with non-thermal electron beams, highlighting the effects of various initial atmospheres and beam parameters on emission enhancements.

Findings

Enhanced continua at 3600Å and 4250Å during WLFs.

Stronger emissions with higher electron flux or smaller spectral index.

Different initial atmospheres affect Lyα and continuum emissions.

Abstract

As one of the most violent activities in the solar atmosphere, white-light flares (WLFs) are generally known for their enhanced white-light (or continuum) emission, which primarily originates in the solar lower atmosphere. However, we know little about how white-light emission is produced. In this study, we aim to investigate the response of the continua at 3600\AA\ and 4250\AA\ and also the H$\alpha$ and Ly$\alpha$ lines during WLFs modeled with radiative hydrodynamics simulations. We take non-thermal electron beams as the energy source for the WLFs in two different initial atmospheres and vary their parameters. Our results show that the model with non-thermal electron beam heating can clearly show enhancements in the continua at 3600\AA\ and 4250\AA\ as well as in the H$\alpha$ and Ly$\alpha$ lines. A larger electron beam flux, a smaller spectral index, or a penumbral initial atmosphere leads to a stronger emission increase at 3600\AA, 4250\AA\ and in the H$\alpha$ line. For the Ly$\alpha$ line, however, it is more preferably enhanced in a quiet-Sun initial atmosphere with a larger spectral index of the electron beam. It is also notable that the continua at 3600\AA\ and 4250\AA\ and the H$\alpha$ line exhibit a dimming at the beginning of the heating and reach their peak emissions later than the peak time of the heating function, while the Ly$\alpha$ line does not show such behaviors. These results can be served as a reference for analyzing future WLF observations.