TeV cosmic-ray proton and helium spectra in the myriad model

TL;DR

This paper explains the observed hardening in cosmic ray proton and helium spectra above a few hundred GeV by proposing a local sources model within a two-zone magnetic halo, aligning well with recent measurements.

Contribution

It introduces a local sources (myriad) model for cosmic ray propagation that accounts for spectral anomalies and fits observational data across a wide energy range.

Findings

Cosmic ray spectra are consistent with local source contributions.

Propagation parameters align with B/C measurements.

Model reproduces PAMELA and CREAM data over four decades.

Abstract

Recent measurements of cosmic ray proton and helium spectra show a hardening above a few hundreds of GeV. This excess is hard to understand in the framework of the conventional models of Galactic cosmic ray production and propagation. We propose here to explain this anomaly by the presence of local sources (myriad model). Cosmic ray propagation is described as a diffusion process taking place inside a two-zone magnetic halo. We calculate the proton and helium fluxes at the Earth between 50 GeV and 100 TeV. Improving over a similar analysis, we consistently derive these fluxes by taking into account both local and remote sources for which a unique injection rate is assumed. We find cosmic ray propagation parameters compatible with B/C measurements and for which the proton and helium spectra remarkably agree with the PAMELA and CREAM measurements over four decades in energy.