The importance of anisotropic interstellar turbulence and molecular-cloud magnetic mirrors for galactic cosmic-ray propagation
Author: Chandran, B.D.G.
Source: Space Science Reviews, Volume 99, Numbers 1-4, October 2001 , pp. 271-280(10)
Abstract:Recent studies suggest that when magnetohydrodynamic (MHD) turbulence is excited by stirring a plasma at large scales, the cascade of energy from large to small scales is anisotropic, in the sense that small-scale fluctuations satisfy the inequality k_∥⋘k_⊥, where k_∥ and k_⊥ are, respectively, the components of a fluctuation's wave vector ∥ and ⊥ to the background magnetic field. Such anisotropic fluctuations are very inefficient at scattering cosmic rays. Results based on the quasilinear approximation for scattering of cosmic rays by anisotropic MHD turbulence are presented and explained. The important role played by molecular-cloud magnetic mirrors in confining and isotropizing cosmic rays when scattering is weak is also discussed.
Document Type: Regular Paper
Affiliations: Dept. of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, U.S.A.
Publication date: 2001-10-01