Origin of hardening in spectra of cosmic ray nuclei at a few hundred GeV using AMS-02 data
Many experiments have confirmed spectral hardening at a few hundred GeV in the spectra of cosmic ray(CR) nuclei. Three different origins have been proposed: primary source acceleration, propagation, and the superposition of different kinds of sources. In this work, a broken power law has been employed to fit each of the spectra of cosmic ray nuclei from AMS-02 directly, for rigidities greater than 45 GeV. The fitting results of the break rigidity and the spectral index differences less than and greater than the break rigidity show complicated relationships among different nuclear species, which cannot be reproduced naturally by a simple primary source scenario or a propagation scenario. However, with a natural and simple assumption, the superposition of different kinds of sources could have the potential to explain the fitting results successfully. Spectra of CR nuclei from a single future experiment,such as DAMPE, will provide us the opportunity to do cross checks and reveal the properties of the different kinds of sources.