A nonlinear Monte Carlo model of super-diffusive shock acceleration with magnetic field amplification

Abstract

Fast collisionless shocks in cosmic plasmas convert their kinetic energy flow into the hot downstream thermal plasma with a substantial fraction of energy going into a broad spectrum of superthermal charged particles and magnetic fluctuations. The superthermal particles can penetrate into the shock upstream region producing an extended shock precursor. The cold upstream plasma flow is decelerated by the force provided by the superthermal particle pressure gradient. In high Mach number collisionless shocks, efficient particle acceleration is likely coupled with turbulent magnetic field amplification (MFA) generated by the anisotropic distribution of accelerated particles. This anisotropy is determined by the fast particle transport making the problem strongly nonlinear and multi-scale. Here, we present a nonlinear Monte Carlo model of collisionless shock structure with super-diffusive propagation of high-energy Fermi accelerated particles coupled to particle acceleration and MFA which affords a consistent description of strong shocks. A distinctive feature of the Monte Carlo technique is that it includes the full angular anisotropy of the particle distribution at all precursor positions. The model reveals that the super-diffusive transport of energetic particles (i.e., Levy-walk propagation) generates a strong quadruple anisotropy in the precursor particle distribution. The resultant pressure anisotropy of the high-energy particles produces a non-resonant mirror-type instability which amplifies compressible wave modes with wavelengths longer than the gyroradii of the highest energy protons produced by the shock.

Published in Physical Review E, Vol. 95, p. 033207 (2017)

References in corpus (8)

• Lévy walks
• The microphysics of collisionless shock waves
• Simultaneous Acceleration of Protons and Electrons at Nonrelativistic Quasiparallel Collisionless Shocks
• The transport of cosmic rays in self-excited magnetic turbulence
• Magnetic field amplification in nonlinear diffusive shock acceleration including resonant and non-resonant cosmic-ray driven instabilities
• Parameter estimation of superdiffusive motion of energetic particles upstream of heliospheric shocks
• Highlights and Discoveries from the Chandra X-ray Observatory
• Electron and Ion Acceleration in Relativistic Shocks with Applications to GRB Afterglows

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• On application of stochastic differential equations for simulation of nonlinear wave-particle resonant interactions
• Constraints on the AGN flares as sources of ultra-high energy cosmic rays from the Fermi-LAT observations
• Plasmas in Gamma-Ray Bursts: particle acceleration, magnetic fields, radiative Processes and environments
• Merger-Driven Turbulence and Coherent Transport in the Intracluster Medium