COMPTEL observations of the Orion complex : evidence for cosmic-ray induced gamma-ray lines.
Abstract
We report the detection of gamma-ray emission from the Orion complex in the 3-7 MeV range by the Imaging Compton Telescope (COMPTEL) telescope aboard the Compton Gamma Ray Observatory (CGRO). This emission can be identified with the 4.44 MeV and 6.13 MeV nuclear de-excitation lines of C-12star and O-16star, respectively, which are predicted to be the strongest gamma-ray lines originating from the interaction of energetic particles with ambient matter. However, the observed flux of (1.0 +/- 0.15) x 10 -4 photon/sq cm/s (3-7 MeV) is much larger than anticipated. There is good circumstantial evidence that our findings indicate strongly enhanced abundances of C and O in low-energy cosmic rays (approximately 10 MeV/nucleon), rather than high fluxes of cosmic-ray protons and alpha-particles. The positrons resulting from energetic particle interactions in the Orion region should produce 511 keV annihilation radiation that is detectable by Oriented Scintillation Spectrometer Experiment (OSSE).
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1994
- Bibcode:
- 1994A&A...281L...5B
- Keywords:
-
- Cosmic Rays;
- Gamma Rays;
- Line Spectra;
- Molecular Clouds;
- Orion Constellation;
- Energy Spectra;
- Gamma Ray Observatory;
- Maximum Entropy Method;
- Maximum Likelihood Estimates;
- Astronomy