New constraints on Galactic cosmic-ray propagation

TL;DR

This paper develops a comprehensive model for galactic cosmic-ray propagation, incorporating various particles and realistic interstellar conditions, and finds that reacceleration models better explain observed energy dependencies.

Contribution

It introduces an extensive, realistic cosmic-ray propagation model including reacceleration, and determines the halo size and source distribution consistent with recent measurements.

Findings

Reacceleration models reproduce the observed B/C energy dependence.

Halo height is greater than 4 kpc based on 10Be/9Be data.

Broader source distribution than current SNR estimates.

Abstract

An extensive program for the calculation of galactic cosmic-ray propagation has been developed. Primary and secondary nucleons, primary and secondary electrons, secondary positrons and antiprotons are included. Fragmentation and energy losses are computed using realistic distributions for the interstellar gas and radiation fields. Models with diffusion and convection only do not account naturally for the observed energy dependence of B/C, while models with reacceleration reproduce this easily. The height of the halo propagation region is determined, using recent 10Be/9Be measurements, as greater than 4 kpc. The radial distribution of cosmic-ray sources required is broader than current estimates of the SNR distribution for all halo sizes. Our results include an estimate of cosmic-ray antiproton and positron spectra, and the Galactic diffuse gamma-ray emission (see accompanying paper: Moskalenko 1998b).