Velocity decorrelation functions of high-energy cosmic rays propagating in magnetic fields

Abstract

Diffusion tensor coefficients play a central role in describing cosmic-ray transport in various astrophysical environments permeated with magnetic fields, which are usually modeled as a fluctuating field on top of a mean field. In this article, a formal derivation of these coefficients is presented by means of the calculation of velocity decorrelation functions of particles. It relies mainly on expanding the 2-pt correlation function of the (fluctuating) magnetic field experienced by the particles between two successive times in the form of an infinite Dyson series and retaining a class of terms that converge to a physical solution. Subsequently, the velocity decorrelation functions, themselves expressed as Dyson series, are deduced from an iteration procedure that improves on the partial summation scheme. The results are shown to provide approximate solutions compared to those obtained by Monte-Carlo simulations as long as the Larmor radius of the particles is larger than at least one tenth of the largest scale of the turbulence.

arXiv comment15 pages, 11 figures, accepted for publication in Phys. Rev. D

References in corpus (27)

• Origin and Propagation of Extremely High Energy Cosmic Rays
• Compressible Magnetohydrodynamic Turbulence: mode coupling, scaling relations, anisotropy, new regime and astrophysical implications
• Compressible Sub-Alfvenic MHD turbulence in Low-beta Plasmas
• Transport of Cosmic Rays in Chaotic Magnetic Fields
• Feedback Heating by Cosmic Rays in Clusters of Galaxies
• Wave damping by MHD turbulence and its effect upon cosmic ray propagation in the ISM
• Properties of the Circumgalactic Medium in Cosmic Ray-Dominated Galaxy Halos
• The Role of Cosmic Ray Transport in Shaping the Simulated Circumgalactic Medium
• Cosmic ray physics in calculations of cosmological structure formation
• Diffusive propagation of UHECR and the propagation theorem
• Propagation of high-energy cosmic rays in extragalactic turbulent magnetic fields: resulting energy spectrum and composition
• Diffusion and drift of cosmic rays in highly turbulent magnetic fields
• Anisotropies of ultra-high energy cosmic rays diffusing from extragalactic sources
• Reconciling cosmic ray diffusion with Galactic magnetic field models
• Global diffusion of cosmic rays
• Novel aspects of cosmic ray diffusion in synthetic magnetic turbulence
• Charged particle diffusion in isotropic random magnetic fields
• Simulating Gamma-ray Emission in Star-forming Galaxies
• Turbulence-Level Dependence of Cosmic-Ray Parallel Diffusion
• First Predicted Cosmic Ray Spectra, Primary-to-Secondary Ratios, and Ionization Rates from MHD Galaxy Formation Simulations
• GZK horizon and magnetic fields
• Particle Transport in intense small scale magnetic turbulence with a mean field
• The Physics of Galactic Winds Driven by Cosmic Rays II: Isothermal Streaming Solutions
• The impact of astrophysical dust grains on the confinement of cosmic rays
• Early-time velocity autocorrelation for charged particles diffusion and drift in static magnetic turbulence
• A Numerical Assessment of Cosmic-ray Energy Diffusion through Turbulent Media
• Numerical Study of Cosmic Ray Confinement through Dust Resonant Drag Instabilities