Onsets and spectra of impulsive solar energetic electron events observed near the Earth

Kontar, E.P. and Reid, H.A.S. (2009) Onsets and spectra of impulsive solar energetic electron events observed near the Earth. Astrophysical Journal Letters, 695(2), pp. 140-144. (doi: 10.1088/0004-637X/695/2/L140)

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Impulsive solar energetic electrons are often observed in the interplanetary space near the Earth and have an attractive diagnostic potential for poorly understood solar flare acceleration processes. We investigate the transport of solar flare energetic electrons in the heliospheric plasma to understand the role of transport to the observed onset and spectral properties of the impulsive solar electron events. The propagation of energetic electrons in solar wind plasma is simulated from the acceleration region at the Sun to the Earth, taking into account self-consistent generation and absorption of electrostatic electron plasma (Langmuir) waves, effects of nonuniform plasma, collisions, and Landau damping. The simulations suggest that the beam-driven plasma turbulence and the effects of solar wind density inhomogeneity play a crucial role and lead to the appearance of (1) a spectral break for a single power-law injected electron spectrum, with the spectrum flatter below the break, (2) apparent early onset of low-energy electron injection, and (3) the apparent late maximum of low-energy electron injection. We show that the observed onsets, spectral flattening at low energies, and formation of a break energy at tens of keV is the direct manifestation of wave-particle interactions in nonuniform plasma of a single accelerated electron population with an initial power-law spectrum.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Kontar, Professor Eduard and Reid, Dr Hamish
Authors: Kontar, E.P., and Reid, H.A.S.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal Letters
ISSN (Online):2041-8213
Published Online:27 March 2009
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
398461Acceleration, propagation and emission of energetic particles from the sun to the earthEduard KontarParticle Physics & Astronomy Research Council (PPARC)PP/C001656/1Physics and Astronomy
465931Solar, stellar and cosmological plasmas: a synthesis of data, modelling and theory.Declan DiverScience & Technologies Facilities Council (STFC)ST/F002149/1Physics and Astronomy