Journal ArticleEnergetic Nonthermal Electrons within the Above-the-looptop Regions in Solar Flares: Acceleration, Feedback, and Quasiperiodic PulsationsSeo, Jeongbhin (ORCID:0000000255508667); Guo, Fan (ORCID:0000000343153755); Li, Xiaocan (ORCID:0000000152788029); Chen, Bin (ORCID:0000000206603350); Shen, Chengcai (ORCID:0000000292584490); Li, Hui (ORCID:0000000335566568)Solar flares are among the most dramatic events in the solar system, releasing substantial magnetic energy and accelerating a large number of electrons to high energies. Notably, in certain events, the above-the-looptop region may contain a significant population of nonthermal electrons, both in number and energy. For the first time, we adopt a novel numerical method that combines magnetohydrodynamics with energetic particles incorporating feedback from nonthermal electrons to investigate electron acceleration and transport in solar flares. We find that a large fraction of energetic electrons are accelerated via the current sheet and termination shock regions. Most energetic electrons are concentrated in the above-the-looptop region, carrying a sizable amount of the released energy. We observe that greater feedback of nonthermal electrons leads to steeper energy spectra. The energy density of the nonthermal electrons oscillates due to the periodic impact of magnetic islands into the above-the-looptop region, which may help explain the observed quasiperiodic pulsations. Our simulations provide new insights into the origin of nonthermal electrons and associated emissions in the above-the-looptop region.IOP2026-01-2910676663The Astrophysical Journal99723130004-637Xhttps://doi.org/10.3847/1538-4357/ae2de62108853National Science Foundation