Hybrid Origins of the Cosmic-Ray Nucleus Spectral Hardening at a Few Hundred GV

Abstract

Abstract Many experiments have confirmed the spectral hardening at a few hundred GV of cosmic-ray (CR) nucleus spectra, and three general different origins have been proposed: the primary source acceleration, the propagation, and the superposition of different kinds of sources. The AMS-02 CR nucleus spectra of He, C, N, O, Ne, Mg, Si, and B (which includes B and its dominating parent species) are collected to study the necessity of employing a break in diffusion coefficient and independent breaks in primary source injection spectra to reproduce the spectral hardening at a few hundred GV. For comparison, three different schemes are introduced to do the global fitting. The fitting results show that both the break in diffusion coefficient and the independent breaks in primary source injection spectra are needed, which correspond to the spatially dependent propagation and the superposition of different kinds of sources, respectively. Consequently, the nucleus spectral hardening in a few hundred GV should have hybrid origins. Moreover, the CR spectral indices of He and Ne show large deviations from other species in the low-rigidity region, which indicates their different CR origins.