Study on the 3D anisotropic propagation of Galactic cosmic rays

Wei Liu, Su-jie Lin, Hong-bo Hu, Yi-Qing Guo

Published 2019-09-06Version 1

Conventional cosmic-ray propagation models usually assume an isotropic diffusion coefficient to account for the random deflection of cosmic rays by the turbulent interstellar magnetic field. Such a picture is very successful in explaining a lot of observational phenomena related to the propagation of galactic cosmic rays, such as broken power-law energy spectra, secondary-to-primary ratios, etc. However, the isotropic diffusion presupposition is facing severe challenges from observations. In particular, recent observations on the large-scale anisotropy of TeV cosmic rays show that the dipole direction differs from the prediction of the conventional model. One possible reason is that the large-scale regular magnetic field, which leads to an anisotropic diffusion of cosmic rays, has not been included in the model provided by the public numerical packages. In this work, we propose a pseudo source method to solve the 3-dimensional anisotropic transport equation. Based on a realistic configuration of Galactic magnetic field, both proton energy spectrum and B/C ratio are reproduced with proper transport parameters.