Understanding the galactic cosmic ray dipole anisotropy with a nearby single source under the spatially-dependent propagation scenario

Abstract

Recently studies of the dipole anisotropy in the arrival directions of Galactic cosmic rays indicate that the TeV-PeV dipole anisotropy amplitude is not described by a simple power law, moreover a rapid phase change exists at an energy of $0.1\sim0.3$ PeV. In this work we argue that the dipole anisotropy amplitude and phase evolution with energies can be reproduced under the spatially-dependent propagation scenario with a nearby single source added. Our results indicate a nearby single source have significant influence to the cosmic ray gradient below $0.1\sim0.3$ PeV under the spatially-dependent propagation scenario, which leads the dipole anisotropy phase change at this energy region. The dipole anisotropy amplitude of the galactic cosmic rays can also be maintained at a lower level, which are consistent with observations by underground muons and air shower experiments.