Karlsruhe 2024 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 83: Cosmic rays 6

T 83.9: Vortrag

Donnerstag, 7. März 2024, 18:00–18:15, Geb. 20.30: 2.059

Hybrid modeling of particle acceleration in MHD-jet simulations using stochastic differential equations — •Patrick Günther, Karl Mannheim, and Sarah Wagner — Julius-Maximilians-Universität Würzburg

Fluid-dynamical simulations of jets generated by accreting supermassive black holes have made great progress in recent years showing the evolution of the thermal particle parameters along the jets. The observed jets, however, show non-thermal emission from particles accelerated in situ at shock waves and magnetic reconnection sites. To connect the non-thermal particles with the simulated bulk of the thermal particles, we study the diffusive propagation and energy losses of energetic particles in the test-particle approximation. We use the equivalence to a set of stochastic differential equations to solve the underlying Fokker-Planck equation and apply the code to the case of both Fermi-type acceleration mechanisms (diffusive shock acceleration and stochastic acceleration). Integrating the stochastic differential equation with a basic Euler scheme does not lead to the analytically expected power-law indizes in the case of shock acceleration, but accuracy can be improved by applying a semi-implicit second-order scheme. This method enables us to calculate particle distributions emerging from arbitrary shock szenarios efficiently. We show first results and develop a perspective on the potential of hybrid simulations.

Keywords: Active Galactic Nuclei; Relativistic Jets; Numerical modeling; Stochastic differential equations