Modeling Electron Acceleration and Transport in the Early Impulsive Phase of the 2017 September 10th Solar Flare

Abstract

The X8.2-class limb flare on 2017 September 10 is among the best studied solar flare events owing to its great similarity to the standard flare model and the broad coverage by multiple spacecraft and ground-based observations. These multiwavelength observations indicate that electron acceleration and transport are efficient in the reconnection and flare looptop regions. However, there lacks a comprehensive model for explaining and interpreting the multi-faceted observations. In this work, we model the electron acceleration and transport in the early impulsive phase of this flare. We solve the Parker transport equation that includes the primary acceleration mechanism during magnetic reconnection in the large-scale flare region modeled by MHD simulations. We find that electrons are accelerated up to several MeV and fill a large volume of the reconnection region, similar to the observations shown in microwaves. The electron spatial distribution and spectral shape in the looptop region agree well with those derived from the microwave and hard X-ray emissions before magnetic islands grow large and dominate the acceleration. Future emission modelings using the electron maps will enable direct comparison with microwave and hard X-ray observations. These results shed new light on the electron acceleration and transport in a broad region of solar flares within a data-constrained realistic flare geometry.

Numerical Study on Excitation of Turbulence and Oscillation in Above-the-loop-top Region of a Solar Flare

“…We expect that electrons can be accelerated to high energies via multiple energizations (similar to the diffusive shock acceleration) because such a field line helps electrons to cross termination shocks multiple times. This idea is similar to a picture of the multiple energizations of electrons based on 2D MHD plus kinetic models (e.g., Kong et al 2019;Li et al 2022).…”

Quantifying Energy Release in Solar Flares and Solar Eruptive Events: New Frontiers with a Next-Generation Solar Radio Facility

“…Fig. 4 demonstrates the superior imaging performance of FASR, based on realistic MHD and macroscopic particle simulations of the 2017 September 10 flare (Chen et al 2020b;Li et al 2022). In agreement with the observations shown in Fig.…”

Numerical Modeling of Energetic Electron Acceleration, Transport, and Emission in Solar Flares: Connecting Loop-top and Footpoint Hard X-Ray Sources

“…The Parker equation is a convective-diffusive equation including the effects of convection, diffusion, drift, and acceleration and assumes a nearly isotropic pitch-angle distribution. By coupling with MHD simulations, it has been applied to modeling electron acceleration by the flare TS in the loop top (Kong et al 2019(Kong et al , 2020(Kong et al , 2022 and large-scale compression in the reconnection layer (Li et al 2018b(Li et al , 2022. However, in the context where the anisotropy is large, one should use the focused transport equation, which retains the pitch-angle dependence of the distribution function (see the review of van den Berg et al 2020).…”

“…Recent modeling efforts have been successful in modeling particle acceleration in the loop-top and current sheet regions (e.g., Kong et al 2019;Arnold et al 2021;Li et al 2022). Although multiple acceleration mechanisms may be relevant for flare particle acceleration (see, e.g., Miller et al 1997;Zharkova et al 2011;Li et al 2021), in this study, we focus our discussion on the flare termination shock (TS), which is capable of directly accelerating particles in the loop-top region and producing loop-top emissions (Tsuneta & Naito 1998;Mann et al 2009;Warmuth et al 2009;Guo & Giacalone 2012;Li et al 2013;Chen et al 2015;Kong et al 2019).…”