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Gamma-Ray Observations of the Interstellar Clouds in CepheusDuring the last six months of the period of performance, the diffuse gamma-ray emission from the Monoceros region was reanalyzed and one of the important conclusions was revised as a result. The reanalysis incorporated newly-available data from recent EGRET viewing periods and revealed a previously-uncataloged gamma-ray point source near the plane in Monoceros. The effect of incorporating this source in the diffuse emission model was significant, as its flux was comparable to that from a large interstellar cloud complex in the Perseus arm. In the updated model, a greatly reduced gamma-ray emissivity was found in the Perseus arm. This finding alters the previous conclusion that we had found evidence for an enhanced emissivity in the arm, which had supported the hypothesis that cosmic rays are coupled to the interstellar medium on the scale of spiral arms. Our updated findings are consistent with our previous results for the emissivity toward the Cepheus region (Digel et al. 1996), where a monotonic gradient of emissivity in the outer Galaxy was found. The updated analysis of Monoceros was presented at the June, 1998 meeting of the American Astronomical Society, and a journal publication should be ready for submission soon.
Document ID
19980237336
Acquisition Source
Goddard Space Flight Center
Document Type
Contractor or Grantee Report
Authors
Digel, S. (Raytheon STX Corp. Greenbelt, MD United States)
Thaddeus, Patrick (Smithsonian Astrophysical Observatory Cambridge, MA United States)
Date Acquired
September 6, 2013
Publication Date
September 17, 1998
Subject Category
Space Radiation
Funding Number(s)
CONTRACT_GRANT: NAG5-2823
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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