A New Framework for Modeling Solar Flares from Magnetohydrodynamic to Kinetic Processes

Abstract Physical processes in solar flares span many orders of magnitude in spatiotemporal scales, so a single unified model accounting for all relevant processes remains computationally intractable. Instead, specialized codes have been developed, targeting specific domains that tackle specific aspects of the solar flare problem. Here, we present a comprehensive framework that links three models to capture flare initiation and energy release, the subsequent particle acceleration, the propagation and thermalization of those particles, and ultimately the heating of the lower solar atmosphere. We use the 2.5D ARMS magnetohydrodynamics (MHD) code to model stressing of the magnetic field in a simulated active region, the formation of a current sheet, magnetic reconnection, and the evolution of newly formed flare loops. We use the conditions in the ARMS current sheet to initialize the kglobal model, which predicts time-dependent nonthermal electron and proton distributions. Finally, we use RADYN+FP to inject these distributions into a newly reconnected ARMS loop and compute subsequent particle transport, atmospheric heating, and radiative emissions. This is the first detailed presentation of a RADYN+FP simulation tracking nonthermal electrons and protons in the same loop. As well as discussing the interesting physics that takes place, we note how this results in white-light flare emission height consistent with observations. This work is a first step toward building a fully 3D flare modeling framework.