Diffusive gamma-rays and antiprotons

Abstract

Based on our three-dimensional cosmic-ray (CR) propagation model in the Galaxy, we study the diffusive gamma-rays (Dγ's) and antiprotons (p̄'s), and compare our numerical results with recent experimental data, particularly those obtained by EGRET and BESS, each for Dγ data and p̄ data respectively. Galactic parameters such as the gas density and diffusion constant are determined from the most recent data for the CR energy spectra, particularly those for protons and helium nuclei from AMS and BESS with excellent accuracy over the 1–100 GeV per nucleon range, and from JACEE and RUNJOB covering the very high energy region up to 500 TeV per particle. Using these parameters, we find that the EGRET data are well reproduced in the energy region Eγ ≲ 2 GeV, in both the spectral shape and the absolute value, and also that the BESS data are compatible with our propagation model in the energy region ≳ 1 GeV. However, there are still two open questions in these components, 1) the intensity of the Dγ's gives a significant enhancement, by approximately the factor 2–3, at ≳ 2 GeV as compared to those expected from the CR spectrum, and 2) we could not confirm whether or not BESS data with the energies less than 1 GeV are consistent or not with those expected from other CR components.