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

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.
Comment: 21 pages, 10figures, 1 table, accepted for publication in RAA