Acceleration of Solar-Energetic Particles by Shocks |
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Authors: | Joe Giacalone József Kóta |
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Institution: | (1) Lunar & Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA |
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Abstract: | Our current understanding of the acceleration of solar-energetic particles is reviewed. The emphasis in this paper is on analytic
theory and numerical modeling of the physics of diffusive shock acceleration. This mechanism naturally produces an energy
spectrum that is a power law over a given energy interval that is below a characteristic energy where the spectrum has a break,
or a rollover. This power law is a common feature in the observations of all types of solar-energetic particles, and not necessarily just those associated with shock waves (e.g. events associated with
impulsive solar flares which are often described in terms of resonant stochastic acceleration). Moreover, the spectral index
is observed to have remarkably little variability from one event to the next (about 50%). Any successful acceleration mechanism
must be able to produce this feature naturally and have a resulting power-law index that does not depend on physical parameters
that are expected to vary considerably. Currently, only diffusive shock acceleration does this. |
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Keywords: | solar energetic particles particle acceleration solar magnetic fields coronal mass ejections |
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