On the knee of Galactic cosmic rays in light of sub-TeV spectral hardenings

作     者：Yi-Qing Guo1 2 Qiang Yuan1 3 1. Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China 2. Key Laboratory of Particle Astrophysics Institute of High Energy Physics 郭义庆;袁强

作者机构：Key Laboratory of Dark Matter and Space AstronomyPurple Mountain ObservatoryChinese Academy of Sciences Key Laboratory of Particle AstrophysicsInstitute of High Energy PhysicsChinese Academy of Sciences School of Astronomy and Space ScienceUniversity of Science and Technology of China 

出 版 物：《Chinese Physics C》 (中国物理C（英文版）)

年 卷 期：2018年第42卷第7期

页      面：113-122页

核心收录：

学科分类：0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 0804[工学-仪器科学与技术] 0827[工学-核科学与技术] 0703[理学-化学] 0704[理学-天文学] 070202[理学-粒子物理与原子核物理] 0702[理学-物理学] 

基　　金：Supported by National Key Research and Development Program of China(2016YFA0400200) the National Natural Science Foundation of China(11635011,11761141001,11663006,11722328) the 100 Talents program of Chinese Academy of Sciences 

主　　题：cosmic ray knee spectrum propagation 

摘      要：More than fifty years after the discovery of the knee in the cosmic ray （CR） spectra, its physical origin remains a mystery. This is partly due to the ambiguity of the energy spectra of individual components. Recently, direct measurements from several space experiments found significant spectral hardenings of CR nuclei at ~200 GV. A joint modeling of the direct and indirect measurements may help to understand the experimental systematics and the physics of the knee. In this work, we update the phenomenological ＂poly-gonato＂ model to include the spectral hardenings, with a changing spectral index of γ ＋ β·logE. This modification gives a reasonable description of the CR spectra in a wide energy range. However, the fits to different data sets give different results. We find that the fit to the AMS-02 and CREAM data slightly favors a relatively low energy knee of the light components. In such a case, the expected all-particle spectra under-shoot the data, which may require an extra component of CRs. The fits to AMS-02 data and the light component （H＋He） data from the Tibet ASγ/ARGO-YBJ/WFCTA and KASCADE experiments give consistent results with the all-particle spectra. We further propose a possible physical realization of such a ＂modified poly-gonato＂ model of spectral hardenings by means of spatially-dependent diffusion of CRs. We find reasonably good agreement between the model predictions and the data for CR spectra, the secondary-to-primary ratios, and the amplitude of anisotropies.