Radiative hydrodynamic simulations of the spectral characteristics of solar white-light flares

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 Å and 4250 Å and also the Hα and Lyα lines during WLFs modeled using radiative hydrodynamic 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 clearly shows enhancements in the continua at 3600 Å and 4250 Å as well as in the Hα and Lyα lines. A larger electron beam flux, a smaller spectral index, or an initial penumbral atmosphere leads to a stronger emission increase at 3600 Å, 4250 Å and in the Hα line. The Lyα line, however, is more obviously enhanced in a quiet-Sun initial atmosphere with a larger electron beam spectral index. It is also notable that the continua at 3600 Å and 4250 Å and the Hα line exhibit a dimming at the start of heating and reach their peak emissions after the peak time of the heating function, while the Lyα line does not show such behaviors. These results can serve as a reference for the analysis of future WLF observations.