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Evidence for Large Scale Cosmic Ray Electron Gradients in the Galaxy

Published online by Cambridge University Press:  25 April 2016

W. R. Webber
W. R. Webber*
Affiliation:
Department of Physics, University of Tasmania
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Extract

In recent years observations of γ-ray emission from the disk of the galaxy have provided a new opportunity for research into the structure of the spiral arms of our own galaxy. In Figure 1 we show a map of the structure of the disk of the galaxy as observed for γ-rays of energy > 100 MeV by the SAS-2 satellite (Fichtel et al. 1975). The angular resolution of these measurements is ~ 3°, and besides two point sources at l = 190° and 265° several features related to the spiral structure of the galaxy are evident in the data. Most of these γ-rays are believed to arise from the decay of π° mesons produced by the nuclear interactions of cosmic rays (mostly protons) with the ambient interstellar gas. As a result, the γ-ray fluxes represent a measure of the line of sight integral of the product of the cosmic ray density N CR and the interstellar matter density N 1

Type
Invited Papers
Information
Publications of the Astronomical Society of Australia , Volume 3 , Issue 1 , September 1976 , pp. 1 - 6
Copyright
Copyright © Astronomical Society of Australia 1976

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