Cosmic-ray pitch-angle scattering in imbalanced mhd turbulence simulations

M.S. Weidl; F. Jenko; B. Teaca; R. Schlickeiser

doi:10.1088/0004-637X/811/1/8

Cosmic-ray pitch-angle scattering in imbalanced mhd turbulence simulations

M.S. Weidl, F. Jenko, B. Teaca, R. Schlickeiser

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Abstract

Pitch-angle scattering rates for cosmic-ray particles in MHD simulations with imbalanced turbulence are calculated for fully evolving electromagnetic turbulence. We compare with theoretical predictions derived from the quasilinear theory of cosmic-ray diffusion for an idealized slab spectrum and demonstrate how cross helicity affects the shape of the pitch-angle diffusion coefficient. Additional simulations in evolving magnetic fields or static field configurations provide evidence that the scattering anisotropy in imbalanced turbulence is not primarily due to coherence with propagating Alfvén waves, but an effect of the spatial structure of electric fields in cross-helical MHD turbulence.

Original language	English
Article number	8
Journal	Astrophysical Journal
Volume	811
Issue number	1
DOIs	https://doi.org/10.1088/0004-637X/811/1/8
Publication status	Published - 11 Sept 2015

Keywords

cosmic rays
diffusion
magnetohydrodynamics (MHD)
scattering

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10.1088/0004-637X/811/1/8

Cosmic Ray COMBAccepted author manuscript, 2.44 MB

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title = "Cosmic-ray pitch-angle scattering in imbalanced mhd turbulence simulations",

abstract = "Pitch-angle scattering rates for cosmic-ray particles in MHD simulations with imbalanced turbulence are calculated for fully evolving electromagnetic turbulence. We compare with theoretical predictions derived from the quasilinear theory of cosmic-ray diffusion for an idealized slab spectrum and demonstrate how cross helicity affects the shape of the pitch-angle diffusion coefficient. Additional simulations in evolving magnetic fields or static field configurations provide evidence that the scattering anisotropy in imbalanced turbulence is not primarily due to coherence with propagating Alfv{\'e}n waves, but an effect of the spatial structure of electric fields in cross-helical MHD turbulence.",

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AU - Weidl, M.S.

AU - Jenko, F.

AU - Teaca, B.

AU - Schlickeiser, R.

PY - 2015/9/11

Y1 - 2015/9/11

N2 - Pitch-angle scattering rates for cosmic-ray particles in MHD simulations with imbalanced turbulence are calculated for fully evolving electromagnetic turbulence. We compare with theoretical predictions derived from the quasilinear theory of cosmic-ray diffusion for an idealized slab spectrum and demonstrate how cross helicity affects the shape of the pitch-angle diffusion coefficient. Additional simulations in evolving magnetic fields or static field configurations provide evidence that the scattering anisotropy in imbalanced turbulence is not primarily due to coherence with propagating Alfvén waves, but an effect of the spatial structure of electric fields in cross-helical MHD turbulence.

AB - Pitch-angle scattering rates for cosmic-ray particles in MHD simulations with imbalanced turbulence are calculated for fully evolving electromagnetic turbulence. We compare with theoretical predictions derived from the quasilinear theory of cosmic-ray diffusion for an idealized slab spectrum and demonstrate how cross helicity affects the shape of the pitch-angle diffusion coefficient. Additional simulations in evolving magnetic fields or static field configurations provide evidence that the scattering anisotropy in imbalanced turbulence is not primarily due to coherence with propagating Alfvén waves, but an effect of the spatial structure of electric fields in cross-helical MHD turbulence.

KW - cosmic rays

KW - diffusion

KW - magnetohydrodynamics (MHD)

KW - scattering

U2 - 10.1088/0004-637X/811/1/8

DO - 10.1088/0004-637X/811/1/8

M3 - Article

SN - 1538-4357

VL - 811

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 8

ER -

Cosmic-ray pitch-angle scattering in imbalanced mhd turbulence simulations

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