Atomic Carbon in M82
Abstract
We report observations of C I(^3P_1 - ^3P_0) emission at 492 GHz toward the starburst galaxy M82. Both the C I/C II intensity ratio and the C/CO column density ratio are a factor of 2-5 higher than observed toward Galactic photodissociation regions (PDRs) or predicted by PDR models. We argue that current PDR models are insufficient to explain the observations, and propose that some of the emission is due to atomic carbon existing within molecular clouds. Employing new chemical models, which use a fast H_3^+ dissociative recombination rate, we find that enhanced cosmic-ray flux supplied by supernova remnants in the M82 starburst lead to an enhanced atomic carbon abundance and elevated temperatures deep within the molecular clouds, resulting in a higher C I emissivity than found in previous PDR models.
Additional Information
© 1993 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1993 June 24; accepted 1993 August 30. We thank J. Le Bourlot, G. Pineau des Forets, and E. Roueff for the permission to use their PDR program and for interesting discussions, and D. Jaffe for help with the observations. This work was supported by NSF contract AST 90-15755 to the California Institute of Technology.Attached Files
Published - 1993ApJ___417L__67S.pdf
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Additional details
- Eprint ID
- 76074
- Resolver ID
- CaltechAUTHORS:20170408-154938446
- AST 90-15755
- NSF
- Created
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2017-05-23Created from EPrint's datestamp field
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2021-11-15Created from EPrint's last_modified field