On the Physics Connecting Cosmic Rays and Gamma Rays: Towards Determining the Interstellar Cosmic Ray Spectrum
Abstract
Secondary nuclear production physics is receiving increased attention given the high-quality measurements of the gamma-ray emissivity of local interstellar gas between ~50 MeV and ~40 GeV, obtained with the Large Area Telescope on board the Fermi space observatory. More than 90% of the gas-related emissivity above 1 GeV is attributed to gamma-rays from the decay of neutral pions formed in collisions between cosmic rays and interstellar matter, with lepton-induced processes becoming increasingly important below 1 GeV. The elementary kinematics of neutral pion production and decay are re-examined in light of two physics questions: does isobaric production follow a scaling behavior? and what is the minimum proton kinetic energy needed to make a gamma-ray of a certain energy formed through intermediate pi0 production? The emissivity spectrum will allow the interstellar cosmic-ray spectrum to be determined reliably, providing a reference for origin and propagation studies as well as input to solar modulation models. A method for such an analysis and illustrative results are presented.
Keywords
Cite
@article{arxiv.1303.6482,
title = {On the Physics Connecting Cosmic Rays and Gamma Rays: Towards Determining the Interstellar Cosmic Ray Spectrum},
author = {C. D. Dermer and J. D. Finke and R. J. Murphy and A. W. Strong and F. Loparco and M. N. Mazziotta and E. Orlando and T. Kamae and L. Tibaldo and J. Cohen-Tanugi and M. Ackermann and T. Mizuno and F. W. Stecker},
journal= {arXiv preprint arXiv:1303.6482},
year = {2013}
}
Comments
10 pages, 10 figures, 2012 Fermi Symposium proceedings - eConf C121028