Energetic Electrons Accelerated and Trapped in a Magnetic Bottle above a Solar Flare Arcade

Fuente: arXiv
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Auteurs principaux: Chen, Bin, Kong, Xiangliang, Yu, Sijie, Shen, Chengcai, Li, Xiaocan, Guo, Fan, Zhang, Yixian, Glesener, Lindsay, Krucker, Säm
Format: Preprint
Publié: 2024
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author Chen, Bin
Kong, Xiangliang
Yu, Sijie
Shen, Chengcai
Li, Xiaocan
Guo, Fan
Zhang, Yixian
Glesener, Lindsay
Krucker, Säm
author_facet Chen, Bin
Kong, Xiangliang
Yu, Sijie
Shen, Chengcai
Li, Xiaocan
Guo, Fan
Zhang, Yixian
Glesener, Lindsay
Krucker, Säm
contents Where and how flares efficiently accelerate charged particles remains an unresolved question. Recent studies revealed that a "magnetic bottle" structure, which forms near the bottom of a large-scale reconnection current sheet above the flare arcade, is an excellent candidate for confining and accelerating charged particles. However, further understanding its role requires linking the various observational signatures to the underlying coupled plasma and particle processes. Here we present the first study combining multiwavelength observations with data-informed macroscopic magnetohydrodynamics and particle modeling in a realistic eruptive flare geometry. The presence of an above-the-loop-top magnetic bottle structure is strongly supported by the observations, which feature not only a local minimum of magnetic field strength but also abruptly slowing down plasma downflows. It also coincides with a compact hard X-ray source and an extended microwave source that bestrides above the flare arcade. Spatially resolved spectral analysis suggests that nonthermal electrons are highly concentrated in this region. Our model returns synthetic emission signatures that are well matched to the observations. The results suggest that the energetic electrons are strongly trapped in the magnetic bottle region due to turbulence, with only a small fraction managing to escape. The electrons are primarily accelerated by plasma compression and facilitated by a fast-mode termination shock via the Fermi mechanism. Our results provide concrete support for the magnetic bottle as the primary electron acceleration site in eruptive solar flares. They also offer new insights into understanding the previously reported small population of flare-accelerated electrons entering interplanetary space.
format Preprint
id arxiv_https___arxiv_org_abs_2406_00109
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Energetic Electrons Accelerated and Trapped in a Magnetic Bottle above a Solar Flare Arcade
Chen, Bin
Kong, Xiangliang
Yu, Sijie
Shen, Chengcai
Li, Xiaocan
Guo, Fan
Zhang, Yixian
Glesener, Lindsay
Krucker, Säm
Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
Space Physics
Where and how flares efficiently accelerate charged particles remains an unresolved question. Recent studies revealed that a "magnetic bottle" structure, which forms near the bottom of a large-scale reconnection current sheet above the flare arcade, is an excellent candidate for confining and accelerating charged particles. However, further understanding its role requires linking the various observational signatures to the underlying coupled plasma and particle processes. Here we present the first study combining multiwavelength observations with data-informed macroscopic magnetohydrodynamics and particle modeling in a realistic eruptive flare geometry. The presence of an above-the-loop-top magnetic bottle structure is strongly supported by the observations, which feature not only a local minimum of magnetic field strength but also abruptly slowing down plasma downflows. It also coincides with a compact hard X-ray source and an extended microwave source that bestrides above the flare arcade. Spatially resolved spectral analysis suggests that nonthermal electrons are highly concentrated in this region. Our model returns synthetic emission signatures that are well matched to the observations. The results suggest that the energetic electrons are strongly trapped in the magnetic bottle region due to turbulence, with only a small fraction managing to escape. The electrons are primarily accelerated by plasma compression and facilitated by a fast-mode termination shock via the Fermi mechanism. Our results provide concrete support for the magnetic bottle as the primary electron acceleration site in eruptive solar flares. They also offer new insights into understanding the previously reported small population of flare-accelerated electrons entering interplanetary space.
title Energetic Electrons Accelerated and Trapped in a Magnetic Bottle above a Solar Flare Arcade
topic Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
Space Physics
url https://arxiv.org/abs/2406.00109