Spatial-Dependent Diffusion of Cosmic Rays and the Ratio of pbar/p, B/C
Abstract
Recent precise measurements of cosmic ray spectral revealed an anomalous hardening at ~200 GV for nuclei from PAMELA, CREAM, ATIC, AMS02 experiments and at tens of GeV for primary electron derived from AMS02 experiment. Particularly, the latest observation of pbar/p ratio by AMS02 demonstrated a flat distribution, which further validated the spectrum anomalies of secondary particles. All those new phenomena indicated that the conventional propagation model of cosmic rays meet challenge. In this work, the spatial-dependent propagation coefficient D(r,z,) is employed by tracing the source distribution under the physical picture of two-halo model in DRAGON package. Under such scenario, the model calculation will result in a two-component spectral for primary nuclei and electron. Simultaneously, due to the smaller rigidity dependence of D(r,z,) in galactic disk, the ratio of secondary-to-primary will be inevitablly flatter than the calculation in the conventional propagation model. As a result, we can reproduce the spectral hardening of proton, electron and the flat ratio of pbar/p and B/C by only adopting the spatial-dependent propagation coefficient D(r,z,) in galactic disk.
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