Quantitative study of the hardening in the Alpha Magnetic Spectrometer nuclei spectra at a few hundred GV

TL;DR

This study analyzes cosmic-ray nuclei spectra from AMS-02 data, revealing that spectral hardening at a few hundred GV has hybrid origins, influenced by source superposition and propagation effects, with differences across nuclei types.

Contribution

It provides a comprehensive quantitative analysis of spectral hardening across multiple CR nuclei species, distinguishing the roles of sources and propagation.

Findings

CR nuclei spectral hardening has hybrid origins.

Primary nuclei hardening mainly from source superposition.

Secondary nuclei hardening mainly from propagation effects.

Abstract

The most significant feature in the cosmic-ray (CR) nuclei spectra is the spectral hardening at a few hundred GV. It is important to know whether the hardening of different nuclei species is the same or not for constructing CR sources and propagation models. In this work, we collect the recently released AMS-02 CR nuclei spectra of primary species (proton, helium, carbon, oxygen, neon, magnesium, silicon, and iron), secondary species (lithium, beryllium, boron, and fluorine), and hybrid species (nitrogen, sodium, and aluminum) and study the break positions and the spectral index differences (less and greater than the break rigidity) of the spectral hardening quantitatively. The results show us that the CR nuclei spectral hardening at a few hundred GV has hybrid origins. In detail, the dominating factors of the spectral hardening for primary and secondary CR nuclei species are different: the former comes from the superposition of different kinds of CR sources, while the latter comes from the propagation process. Both of these factors influence all kinds of CR nuclei spectra, just with different weights.