| Issue |
A&A
Volume 420, Number 3, June IV 2004
|
|
|---|---|---|
| Page(s) | 799 - 808 | |
| Section | Astrophysical processes | |
| DOI | https://doi.org/10.1051/0004-6361:20034304 | |
| Published online | 04 June 2004 | |
Cosmic ray transport in anisotropic magnetohydrodynamic turbulence*
III. Mixed magnetosonic and Alfvénic turbulence
1
Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany e-mail: rsch@tp4.ruhr-uni-bochum.de
2
now at: Bartol Research Institute, University of Delaware, Newark, DE 19716, USA
Corresponding author: A. Shalchi, andreasm4@yahoo.com
Received:
10
September
2003
Accepted:
2
February
2004
Observations of interstellar turbulence imply that
the power spectrum of the wave turbulence must
be highly anisotropic. This anisotropy has to be included
when transport of high energy cosmic rays in
the Galaxy is discussed. Here we evaluate the relevant cosmic ray
transport parameters in the presence of anisotropic plasma wave
turbulence, consisting of
a mixture of shear Alfvén waves and fast magnetosonic waves.
By averaging the respective Fokker-Planck coefficient over the particle
pitch-angle we calculate the momentum and spatial diffusion
coefficients for
different anisotropy parameters.
For strongly perpendicular turbulence (
) we obtain that
the momentum
diffusion coefficient is proportional to ![$\Lambda ^{-1/2} \left[ \ln \epsilon^{-1} + \ln \Lambda ^{1/2} \right]$](/articles/aa/abs/2004/24/aa0304/aa0304_tex_eq2.png)
,
whereas for strongly parallel turbulence (
) the momentum
diffusion
coefficient is a constant.
We also calculate the anisotropy dependence of the spatial diffusion
coefficient and
the parallel mean free path for the mixed turbulence.
For all coefficients we discuss the rigidity dependence for
different cosmic ray particles.
Key words: magnetohydrodynamics (MHD) / plasmas / turbulence / ISM: cosmic rays / ISM: magnetic fields / acceleration of particles
© ESO, 2004
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