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Positron annihilation in the interstellar mediumPositronium formation and annihilation are studied in a model for the interstellar medium consisting of cold cloud cores, warm partially ionized cloud envelopes, and hot intercloud gas. The gamma-ray spectra resulting from positron annihilation in these components of the interstellar medium are calculated. The spectra from the individual components are then combined, using two limiting assumptions for the propagation of the positrons, namely, that the positrons propagate freely throughout the interstellar medium, and that the positrons are excluded from the cold cloud cores. In the first case, the bulk of the positrons annihilate in the cloud cores and the annihilation line exhibits broad wings resulting from the annihilation of positronium formed by charge exchange in flight. In the second case, the positrons annihilate mainly in the warm envelopes, and the line wings are suppressed.
Document ID
19910065870
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Guessoum, Nidhal
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Ramaty, Reuven
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lingenfelter, Richard E.
(California, University La Jolla, United States)
Date Acquired
August 14, 2013
Publication Date
September 1, 1991
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 378
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
91A50493
Funding Number(s)
CONTRACT_GRANT: NAGW-1970
Distribution Limits
Public
Copyright
Other

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