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

¹ LAPTh, Université de Savoie, CNRS, BP 110, 74941 Annecy-le-Vieux, France
e-mail: taillet@lapp.in2p3.fr
² Instituto de Física Teórica UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
³ BK−21 Research Group, Department of Physics, Seoul National University, 157-742 Seoul, Republic of Korea
⁴ Institute of the Early Universe, Ewha Womans University, 120-750 Seoul, Republic of Korea
⁵ Cosmic Dark-Energy and Dark-Matter Research Group, National Astronomical Observatories, Chinese Academy of Science, 100012 Beijing, PR China

Received: 31 January 2013
Accepted: 3 May 2013

Abstract

Context. Recent measurements of cosmic ray proton and helium spectra show a hardening above a few hundred GeV. This excess is hard to understand in the framework of the conventional models of Galactic cosmic ray production and propagation.

Aims. We propose here to explain this anomaly by the presence of local sources (myriad model).

Methods. 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. As an improvement over a similar analysis, we consistently derive these fluxes by taking both local and remote sources for which a unique injection rate is assumed into account.

Results. We find cosmic ray propagation parameters compatible with B/C measurements for which the proton and helium spectra agree remarkably with the PAMELA and CREAM measurements over four decades in energy.