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EP: Fachverband Extraterrestrische Physik

EP 7: Sun and heliosphere II

EP 7.5: Talk

Wednesday, March 22, 2023, 15:30–15:45, ZEU/0160

Nonlinear diffusive shock acceleration in a spherical geometry* — •Dominik Walter, Horst Fichtner, and Frederic Effenberger — Ruhr-Universität-Bochum Tp4, Bochum, Germany

Based on previous investigations in a Cartesian geometry, we now discuss the influence of a self-consistent diffusion coefficient on the transport of energetic particles in a spherical geometry. The formulation of the diffusion coefficient is motivated by taking into account the diffusing particles' influence on the scattering centers in the background medium. The resulting single transport equation is nonlinear due to a dependence of the diffusion coefficient on the gradient of the particle distribution. After trying to predict, based on insights from linear theory, the behaviour of the solutions of the nonlinear equation in a shock acceleration model in spherical geometry, numerical methods are applied to the equation to explore the time evolution of the solutions and to investigate the features of the steady-state shock spectra. The results are dicussed in the context of Cosmix Ray modulation in the heliosphere.

*Supported by DFG (SFB\,1491)