The origin of the positron excess in cosmic rays

Abstract

We show that the positron excess measured by the PAMELA experiment in the region between 10 and 100 GeV may well be a natural consequence of the standard scenario for the origin of Galactic cosmic rays. The 'excess' arises because of positrons created as secondary products of hadronic interactions inside the sources, but the crucial physical ingredient which leads to a natural explanation of the positron flux is the fact that the secondary production takes place in the same region where cosmic rays are being accelerated. Therefore secondary positrons (and electrons) participate in the acceleration process and turn out to have a very flat spectrum, which is responsible, after propagation in the Galaxy, for the observed positron 'excess'. This effect cannot be avoided though its strength depends on the values of the environmental parameters during the late stages of evolution of supernova remnants.

4 Pages, 2 figures. Some references and discussion added

References in corpus (2)

• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• Cosmic-ray positron fraction measurement from 1 to 30 GeV with AMS-01

Cited by in corpus (7)

• On possible interpretations of the high energy electron-positron spectrum measured by the Fermi Large Area Telescope
• High-energy antiprotons from old supernova remnants
• Inverse Compton constraints on the Dark Matter e+e- excesses
• Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas
• Testing astrophysical models for the PAMELA positron excess with cosmic ray nuclei
• Extended MSSM Neutralinos as the Source of the PAMELA Positron Excess
• Testing the Dark Matter Interpretation of the PAMELA Excess through Measurements of the Galactic Diffuse Emission