Propagation of coronal large-amplitude Alfvén-type waves to the solar photosphere

Abstract

Context. We present a study of the propagation of magnetohydrodynamic (MHD) Alfvén-type waves from the solar corona to the photosphere, generated by the large-amplitude velocity pulse.Aims. We aim to estimate the energy flux and the propagation time of Alfvén-type waves, which can be responsible for the white-light flare emission caused by solar photospheric heating.Methods. The ideal MHD equations were solved with the PLUTO code for the two-dimensional force-free magnetic configuration in the stratified solar atmosphere. We consider the evolution of the electromagnetic energy flux maximum caused by the non-linear large-amplitude velocity pulse launched in the solar corona.Results. We find that the Alfvén energy flux is about a few orders of magnitude less than the required values. It cannot heat the flare photosphere, due to the energy losses from the non-linear effects, the solar atmosphere stratification, and the influence of the magnetic configuration. The calculated characteristic propagation time of the energy flux from the corona to the photosphere was about 2 min which does not match some time delays between hard X-ray and white-light flare emissions. The results obtained suggest that Alfvén waves can make a significant contribution to the continuum optical emission generated in the chromosphere.