Cosmic-ray protons, nuclei, electrons, and antiparticles under a two-halo scenario of diffusive propagation

TL;DR

This paper introduces a two-halo diffusion model for cosmic-ray propagation, predicting harder antiparticle spectra at high energies and implications for dark matter detection.

Contribution

It proposes a novel two-halo diffusion model that generalizes standard cosmic-ray transport models, supported by recent observational data.

Findings

Antiproton/proton ratio flattens above 10 GeV

Positron fraction increases with energy

Supports a two-halo diffusion scenario

Abstract

We report calculations of cosmic-ray proton, nuclei, antiproton, electron and positron energy spectra within a "two-halo model" of diffusive transport. The two halos represent a simple, physically consistent generalization of the standard diffusion models, which assume a unique type of diffusion for cosmic rays in the whole Galactic halo. We believe instead that cosmic rays may experience a smaller energy dependence of diffusion when they are in proximity of the Galactic disk. Our scenario is supported by recent observations of cosmic-ray protons, nuclei, anisotropy, and gamma-rays. We predict remarkably hard antiparticle spectra at high energy. In particular, at E>10 GeV, the antiproton/proton ratio is expected to flatten, while the positron fraction is found to increase with energy. We discuss the implications for cosmic-ray physics and dark matter searches via antimatter.