Abstract
The COS-B gamma-ray survey is compared with 12CO and HI surveys in a region containing the Orion complex and in the outer Galaxy. The observed gamma-ray intensities in the Orion region (100 MeV<E<5 GeV) can be ascribed to the interaction of uniformly distributed cosmic rays with the interstellar gas. Calibration of the ratio between H2 column-density and integrated CO line intensity resulted in the value: (3.0±0.7)×1020 molecules cm −2K −1km −1s. In the outer Galaxy HI column-density maps in three galacto-centric distance ranges are used in combination with COS-B gamma- ray data to determine the radial distribution of the gamma-ray emissivity. A steep negative gradient of the emissivity for the 70 MeV−150 MeV range and an approximately constant (within ~20%) emissivity for the 300 MeV-5GeV range is found. The result is interpreted as a strong decrease in the cosmic-ray electron density and a near constancy of the nuclear component.
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Hermsen, W., Bloemen, J.B.G.M. (1985). High-Energy Gamma Rays and the Large-Scale Distribution of Gas and Cosmic Rays. In: Van Woerden, H., Allen, R.J., Burton, W.B. (eds) The Milky Way Galaxy. International Astronomical Union, vol 106. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-5291-1_44
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DOI: https://doi.org/10.1007/978-94-009-5291-1_44
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