Galactic Gamma Radiation from Cosmic Rays Concentrated in Spiral Arms
Abstract
Extending the model proposed by Bignami et al. (1975), and by Fichtel et al. (1975a) for the production of the galactic high energy gamma ray distribution observed by SAS-2 to lower energies indicates the radiation is dominated by the bremsstrahlung emission of cosmic ray electrons traversing the interstellar gas. Although secondary electrons contribute only about 15% to the 10-30 MeV gamma ray emission in the solar vicinity, their contribution in the model is proportional to the third power of N, where N(r, gal. long., gal. lat.) is the total interstellar gas density, as compared to the square of N for the case of the primary components, and hence their relative importance increases in high density regions. Gamma-ray observations at these energies when compared to those at high energies (above 100 MeV) may provide a means for mapping the ratio of cosmic ray electrons to nucleons throughout the galaxy without the necessity of invoking models for the galactic magnetic field.
- Publication:
-
International Cosmic Ray Conference
- Pub Date:
- 1975
- Bibcode:
- 1975ICRC....1...40K
- Keywords:
-
- Cosmic Rays;
- Galactic Radiation;
- Gamma Rays;
- Radiation Distribution;
- Spatial Distribution;
- Spiral Galaxies;
- Astronomical Models;
- Bremsstrahlung;
- Energy Spectra;
- Gas Density;
- High Energy Electrons;
- Interstellar Gas;
- Radiation Sources;
- Radioactive Decay;
- Sas-2;
- Space Radiation