A scenario for the anisotropy of galactic cosmic rays related to nearby source and local interstellar magnetic field

In our recent work, we build a propagation scenario to simultaneously explain the spectra and anisotropy of cosmic rays (CRs) by considering spatially dependent propagation (SDP) model and nearby Geminga supernova remnant (SNR) source. But the phase of anisotropy is still inconsistent with the experimental data. Recent observations of CR anisotropy show that the phase is consistent with local regular magnetic field (LRMF) observed by Interstellar Boundary Explorer (IBEX) below 100 TeV, which indicates that diffusion along LRMF is important. In this work, we further introduce the LRMF and take into account the effect of corresponding anisotropic diffusion to explain the anisotropy of CRs. We find that when the diffusion coefficient perpendicular to the LRMF is much smaller than the parallel one, the phase of anisotropy points to $\sim R.A.= 3^h$, which accords with experimental observation below 100 TeV. We also analyze the influence of the ratio of perpendicular and parallel diffusion coefficient on the anisotropy and the energy dependence of the ratio. The results illustrate that with the decrease of perpendicular diffusion, the anisotropic phase changes from the direction of nearby source to the LRMF below 100 TeV, meanwhile it changes from the galactic center (GC) to opposite direction of LRMF above 100 TeV. When the perpendicular diffusion coefficient grows faster than the parallel one with energy, the diffusion approaches to the isotropic at high energy, the phase of anisotropy shifts from the LRMF to the GC above 100 TeV. This could be helpful to ascertain the energy dependence of diffusion coefficients.