Electron Spectral Breaking Caused by Magnetic Reconnection in Impulsive Flare Events

Using data from the Wind/3D Plasma and Energetic Particle (3DP) instrument, we have analyzed the energy spectral difference of low-energy electrons between the "impulsive" and "gradual" solar energetic particle (SEP) events during solar cycle 23. Since simulations reveal that in...

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Bibliographic Details
Published in:The Astrophysical journal 2018-05, Vol.858 (1), p.25
Main Author: Tan, Lun C.
Format: Article
Language:English
Subjects:
Astrophysics
Corona
Coronal loops
Current sheets
Electron energy
Energetic particles
Magnetic reconnection
Particle acceleration
Solar cycle
Solar wind
Solar wind effects
Spectra
Sun: corona
Sun: flares
Sun: heliosphere
Sun: particle emission
Sun: X-rays, gamma rays
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Summary:Using data from the Wind/3D Plasma and Energetic Particle (3DP) instrument, we have analyzed the energy spectral difference of low-energy electrons between the "impulsive" and "gradual" solar energetic particle (SEP) events during solar cycle 23. Since simulations reveal that in the exhaust of magnetic reconnection sites, electrons could form a beam structure in which the parallel speed is limited by the electron Alfvén speed (VAe), their spectral steepening should be observable at the electron energy Ee, corresponding to VAe. In addition, the analysis of transversely oscillating coronal loops shows that in the loop-top region, where the reconnection site is located, VAe corresponds to Ee < 15 keV. We hence search for the spectral steepening of electrons in this Ee range. In our search we have taken the effect of local particle acceleration at reconnecting current sheets into consideration. The effect may occur in the solar wind and impact the observed time-intensity profiles of SEPs. Our analysis shows that in the impulsive flare event, the electron spectral steepening occurs at Ee = 7 2 keV, whereas no steepening is seen in the gradual event. Therefore, the comparison between the impulsive and gradual SEP event lists provided by this work could be important for future investigations of particle acceleration in the corona and the solar wind.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aaba7e