Ahlers M. Anomalous anisotropies of cosmic rays from turbulent magnetic fields.
PHYSICAL REVIEW LETTERS 2014;
112:021101. [PMID:
24484000 DOI:
10.1103/physrevlett.112.021101]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Indexed: 06/03/2023]
Abstract
The propagation of cosmic rays (CRs) in turbulent interstellar magnetic fields is typically described as a spatial diffusion process. This formalism predicts only a small deviation from an isotropic CR distribution in the form of a dipole in the direction of the CR density gradient or relative background flow. We show that the existence of a global CR dipole moment necessarily generates a spectrum of higher multipole moments in the local CR distribution. These anomalous anisotropies are a direct consequence of Liouville's theorem in the presence of a local turbulent magnetic field. We show that the predictions of this model are in excellent agreement with the observed power spectrum of multi-TeV CRs.
Collapse