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Poster De Conférence Année : 2017

Non-thermal Power-Law Distributions in Solar and Space Plasmas

M. Kuhar
  • Fonction : Auteur
G. Livadiotis
  • Fonction : Auteur
Y. Miyoshi
Alessandro Retinò
M. Oka
  • Fonction : Auteur
M. Battaglia
  • Fonction : Auteur
Joachim Birn
  • Fonction : Auteur
C. C. Chaston
  • Fonction : Auteur
F. Effenberger
  • Fonction : Auteur
E. Eriksson
  • Fonction : Auteur
L. Fletcher
S. Hatch
  • Fonction : Auteur
S. Imada
  • Fonction : Auteur

Résumé

Particles are accelerated to very high, non-thermal energies in solar and space plasma environments. While energy spectra of accelerated particles often exhibit a power-law and are characterized by the power-law index delta, it remains unclear how particles are accelerated to high energies and how delta is determined. Here, we review previous observations of the power-law index delta in a variety of different plasma environments with a particular focus on sub-relativistic electrons. It appears that in regions more closely related to magnetic reconnection (such as the "above-the-looptop" solar hard X-ray source and the plasma sheet in Earth's magnetotail), the spectra are typically soft (delta> 4). This is in contrast to the typically hard spectra (delta< 4) that are observed in coincidence with shocks. The difference implies that shocks are more efficient in producing a larger fraction of non-thermal electron energies than magnetic reconnection. A caveat is that during active times in Earth's magnetotail, delta values seem spatially uniform in the plasma sheet, while power-law distributions still exist even in quiet times. The role of magnetotail reconnection in the electron power-law formation could therefore be confounded with these background conditions. Because different regions have been studied with different instrumentations and methodologies, we point out a need for more systematic and coordinated studies of power-law distributions for a better understanding of possible scaling laws in particle acceleration as well as their universality.
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Dates et versions

hal-02861298 , version 1 (08-06-2020)

Identifiants

  • HAL Id : hal-02861298 , version 1

Citer

M. Kuhar, G. Livadiotis, Y. Miyoshi, Alessandro Retinò, M. Oka, et al.. Non-thermal Power-Law Distributions in Solar and Space Plasmas. 2017 AGU Fall Meeting, Dec 2017, New Orleans, Louisiane, United States. pp.SH51C-2518, 2017. ⟨hal-02861298⟩
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