Cosmic ray Transport in Magnetohydrodynamic turbulence
arXiv:2108.01936 · doi:10.3847/1538-4357/ac46c8
Abstract
This paper studies cosmic ray (CR) transport in magneto hydrodynamic (MHD) turbulence. CR transport is strongly dependent on the properties of the magnetic turbulence. We perform test particle simulations to study the interactions of CR with both total MHD turbulence and decomposed MHD modes. The spatial diffusion coefficients and the pitch angle scattering diffusion coefficients are calculated from the test particle trajectories in turbulence. Our results confirm that the fast modes dominate the CR propagation, whereas Alfvén and slow modes are much less efficient and have shown similar pitch angle scattering rates. We investigate the cross field transport on large and small scales. On large/global scales, normal diffusion is observed and the diffusion coefficient is suppressed by compared to the parallel diffusion coefficients, with closer to 4 in Alfvén modes than that in total turbulence as theoretically expected. For the CR transport on scales smaller than the turbulence injection scale, both the local and global magnetic reference frames are adopted. Super diffusion is observed on such small scales in all the cases. Particularly, CR transport in Alfvén modes show clear Richardson diffusion in the local reference frame. Our results have broad applications to CRs in various astrophysical environments.
arXiv comment10 pages, 11 figures, Accepted to APJ
References in corpus (17)
- Compressible Magnetohydrodynamic Turbulence: mode coupling, scaling relations, anisotropy, new regime and astrophysical implications
- Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth
- Compressible Sub-Alfvenic MHD turbulence in Low-beta Plasmas
- Compressible MHD Turbulence in Interstellar Plasmas
- Scattering of Cosmic Rays by Magnetohydrodynamic Interstellar Turbulence
- Cosmic Ray Scattering and Streaming in Compressible Magnetohydrodynamic Turbulence
- Extending Big Power Law in the Sky with Turbulence Spectra from WHAM data
- Cosmic Ray Propagation: Nonlinear Diffusion Parallel and Perpendicular to Mean Magnetic Field
- Magnetic Field Structure and Stochastic Reconnection in a Partially Ionized Gas
- Superdiffusion of Cosmic Rays: Implications for Cosmic Ray Acceleration
- Cosmic Ray Parallel and Perpendicular Transport in Turbulent Magnetic Fields
- Understanding the multiwavelength observation of Geminga's TeV halo: the role of anisotropic diffusion of particles
- Numerical study of Cosmic Ray Diffusion in MHD turbulence
- Properties of magnetohydrodynamic modes in compressively driven plasma turbulence
- The divergence of neighboring magnetic field lines and fast-particle diffusion in strong magnetohydrodynamic turbulence, with application to thermal conduction in galaxy clusters
- Particle Acceleration by Fast Modes in Solar Flares
- Identification of plasma modes in Galactic turbulence with synchrotron polarization