Two Phases of Particle Acceleration of a Solar Flare Associated with in situ Energetic Particles

Fuente: arXiv
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Main Authors: Wang, Meiqi, Chen, Bin, Knuth, Trevor, Cohen, Christina, Lee, Jeongwoo, Wang, Haimin, Yu, Sijie
Format: Preprint
Published: 2025
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author Wang, Meiqi
Chen, Bin
Knuth, Trevor
Cohen, Christina
Lee, Jeongwoo
Wang, Haimin
Yu, Sijie
author_facet Wang, Meiqi
Chen, Bin
Knuth, Trevor
Cohen, Christina
Lee, Jeongwoo
Wang, Haimin
Yu, Sijie
contents How impulsive solar energetic particle (SEP) events are produced by magnetic-reconnection-driven processes during solar flares remains an outstanding question. Here we report a short-duration SEP event associated with an X-class eruptive flare on July 03, 2021, using a combination of remote sensing observations and in situ measurements. The in situ SEPs were recorded by multiple spacecraft including the Parker Solar Probe. The hard X-ray (HXR) light curve exhibits two impulsive periods. The first period is characterized by a single peak with a rapid rise and decay, while the second period features a more gradual HXR light curve with a harder spectrum. Such observation is consistent with in situ measurements: the energetic electrons were first released during the early impulsive phase when the eruption was initiated. The more energetic in situ electrons were released several minutes later during the second period of the impulsive phase when the eruption was well underway. This second period of energetic electron acceleration also coincides with the release of in situ energetic protons and the onset of an interplanetary type III radio burst. We conclude that these multi-messenger observations favor a two-phase particle acceleration scenario: the first, less energetic electron population was produced during the initial reconnection that triggers the flare eruption, and the second, more energetic electron population was accelerated in the above-the-looptop region below a well-developed, large-scale reconnection current sheet induced by the eruption.
format Preprint
id arxiv_https___arxiv_org_abs_2503_05987
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Two Phases of Particle Acceleration of a Solar Flare Associated with in situ Energetic Particles
Wang, Meiqi
Chen, Bin
Knuth, Trevor
Cohen, Christina
Lee, Jeongwoo
Wang, Haimin
Yu, Sijie
Solar and Stellar Astrophysics
How impulsive solar energetic particle (SEP) events are produced by magnetic-reconnection-driven processes during solar flares remains an outstanding question. Here we report a short-duration SEP event associated with an X-class eruptive flare on July 03, 2021, using a combination of remote sensing observations and in situ measurements. The in situ SEPs were recorded by multiple spacecraft including the Parker Solar Probe. The hard X-ray (HXR) light curve exhibits two impulsive periods. The first period is characterized by a single peak with a rapid rise and decay, while the second period features a more gradual HXR light curve with a harder spectrum. Such observation is consistent with in situ measurements: the energetic electrons were first released during the early impulsive phase when the eruption was initiated. The more energetic in situ electrons were released several minutes later during the second period of the impulsive phase when the eruption was well underway. This second period of energetic electron acceleration also coincides with the release of in situ energetic protons and the onset of an interplanetary type III radio burst. We conclude that these multi-messenger observations favor a two-phase particle acceleration scenario: the first, less energetic electron population was produced during the initial reconnection that triggers the flare eruption, and the second, more energetic electron population was accelerated in the above-the-looptop region below a well-developed, large-scale reconnection current sheet induced by the eruption.
title Two Phases of Particle Acceleration of a Solar Flare Associated with in situ Energetic Particles
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2503.05987