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Astron. Astrophys. 331, 726-736 (1998)
The Orion Gamma-ray emission and the Orion-Eridanus bubble
Etienne M.G. Parizot
Service d'Astrophysique, CEA/DSM/DAPNIA, F-91191
Gif-sur-Yvette, France
Received 30 June 1997 / Accepted 13 October 1997
Abstract
We review the implications of the gamma-ray emission detected by COMPTEL in Orion, assuming that it is due to energetic particle (EP) interactions within the Orion clouds. We show that a series of independent arguments converge toward a model in which the EPs originate from the Orion-Eridanus bubble, located in front of the molecular cloud complex. We investigate in detail the question of energetics, introducing new indicators such as the total energy and the total mass of the EPs, and show that the average density of the EP confining region is a crucial parameter for any model of the Orion emission. Finally, we compare two extreme situations, where the EPs fill either the whole Orion-Eridanus bubble or a limited volume around the site of a recent supernova explosion in the Orion OB1 association. We conclude that the COMPTEL emission could be explained self-consistently by a hybrid solution in which a new supernova explodes within the energetic superbubble, propitious to particule acceleration. Possible generalisation to other Galactic sites is also investigated.
Key words: Gamma rays:
theory 
Nuclear
reactions
ISM: individual objects: Orion clouds, Orion-Eridanus
bubble
associations: individual: Orion OB1
Contents
- 1. Introduction
- 2. General analysis
- 3. Where do the EPs come from?
- 3.1. Internal source?
- 3.2. External source?
- 3.3. The Orion-Eridanus bubble
- 4. The energetics
- 5. Toward a solution of the Orion gamma-ray emission
puzzle - 6. Conclusion and discussion
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998
Online publication: February 16, 1998
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