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Title: SIMULATION OF ENERGETIC PARTICLE TRANSPORT AND ACCELERATION AT SHOCK WAVES IN A FOCUSED TRANSPORT MODEL: IMPLICATIONS FOR MIXED SOLAR PARTICLE EVENTS

We use numerical solutions of the focused transport equation obtained by an implicit stochastic differential equation scheme to study the evolution of the pitch-angle dependent distribution function of protons in the vicinity of shock waves. For a planar stationary parallel shock, the effects of anisotropic distribution functions, pitch-angle dependent spatial diffusion, and first-order Fermi acceleration at the shock are examined, including the timescales on which the energy spectrum approaches the predictions of diffusive shock acceleration theory. We then consider the case that a flare-accelerated population of ions is released close to the Sun simultaneously with a traveling interplanetary shock for which we assume a simplified geometry. We investigate the consequences of adiabatic focusing in the diverging magnetic field on the particle transport at the shock, and of the competing effects of acceleration at the shock and adiabatic energy losses in the expanding solar wind. We analyze the resulting intensities, anisotropies, and energy spectra as a function of time and find that our simulations can naturally reproduce the morphologies of so-called mixed particle events in which sometimes the prompt and sometimes the shock component is more prominent, by assuming parameter values which are typically observed for scattering mean free paths of ions inmore » the inner heliosphere and energy spectra of the flare particles which are injected simultaneously with the release of the shock.« less
Authors:
;  [1] ;  [2]
  1. Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg (Germany)
  2. Department of Physics, Ben-Gurion Unversity of the Negev, Beer-Sheva (Israel)
Publication Date:
OSTI Identifier:
22518577
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 820; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; DIFFERENTIAL EQUATIONS; DISTRIBUTION FUNCTIONS; ENERGY LOSSES; ENERGY SPECTRA; HELIOSPHERE; MAGNETIC FIELDS; NUMERICAL SOLUTION; SCATTERING; SHOCK WAVES; SOLAR FLARES; SOLAR PROTONS; SOLAR WIND; STOCHASTIC PROCESSES; SUN; TIME DEPENDENCE; TRANSPORT THEORY