Implications on the origin of cosmic rays in light of 10 TV spectral softenings

TL;DR

Recent precise measurements of cosmic ray spectra around 10 TV reveal spectral softenings that challenge single-component models, favoring multi-source or nearby source scenarios for their origin.

Contribution

This paper analyzes new spectral softening data from DAMPE and ground-based experiments, proposing two multi-component models to explain cosmic ray origins.

Findings

Single component models cannot fit all data.

Multiple source and nearby source scenarios both fit the data.

Nearby source model is favored considering anisotropy observations.

Abstract

Precise measurements of the energy spectra of cosmic rays (CRs) show various kinds of features deviating from single power-laws, which give very interesting and important implications on their origin and propagation. Previous measurements from a few balloon and space experiments indicate the existence of spectral softenings around 10 TV for protons (and probably also for Helium nuclei). Very recently, the DArk Matter Particle Explorer (DAMPE) measurement about the proton spectrum clearly reveals such a softening with a high significance. Here we study the implications of these new measurements, as well as the groundbased indirect measurements, on the origin of CRs. We find that a single component of CRs fails to fit the spectral softening and the air shower experiment data simultaneously. In the framework of multiple components, we discuss two possible scenarios, the multiple source population scenario and the background plus nearby source scenario. Both scenarios give reasonable fits to the wide-band data from TeV to 100 PeV energies. Considering the anisotropy observations, the nearby source model is favored.