Explanation for the Cosmic Ray Anisotropies at Small and Medium Angular Scales

Cosmic Ray Anisotropy Workshop 2013

Giacinti, G.^1

University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom^1

关键词: Anisotropy measurements;    Arrival direction;    Cosmic ray anisotropy;    Diffusion approximations;    Dipolar anisotropy;    Energy dependent;    Mean free path;    Spatial scale;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/531/1/012006/pdf
DOI  :  10.1088/1742-6596/531/1/012006

来源: IOP

【 摘 要 】

A dipolar anisotropy in the cosmic ray (CR) arrival directions on the sky is predicted by the diffusion approximation (DA). However, the DA is not designed to predict phenomena arising on spatial scales smaller than the cosmic ray mean free path. We demonstrate here that energy-dependent smaller scale anisotropies (higher order multipoles) must naturally appear on the sky and reflect the local concrete realization of the magnetic field within the CR mean free path [1, 2]. We show that it is a viable explanation for the observed medium and small scale anisotropies. We also discuss the perspectives and priorities for the near future, and suggest that CR anisotropy measurements should become a new way of probing local interstellar and, or heliospheric fields in the future.