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Variable Positron Annihilation Radiation from the Galactic Center Region

Riegler, Guenter R. and Ling, James C. and Mahoney, William A. and Wheaton, William A. and Willett, James B. and Jacobson, Allan S. and Prince, Thomas A. (1981) Variable Positron Annihilation Radiation from the Galactic Center Region. Astrophysical Journal Letters, 248 (1). L13-L16. ISSN 2041-8205. doi:10.1086/183613.

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The HEAO 3 Cosmic Gamma-Ray Spectrometer performed the first high spectral resolution survey of the entire sky at gamma-ray energies from 50 keV to 10 MeV. Studies of 511 keV positron annihilation radiation from the vicinity of the galactic center are reported here, based on data which were recorded during 1979 September/October and 1980 March/ April. The 1979 fall data show unshifted, narrow 511 keV line emission of intensity (1.85 ± 0.21) X 10^(-3) photons cm^(-2) s^(-1), consistent with earlier measurements. The 1980 spring measurement showed a statistically significant reduction in 511 keV emission from this region, thus requiring that a significant fraction of the flux originate in one or more compact sources of size ≾ 10^(18) cm. While distribution of sources within ~ 22° (at 90% confidence level) of the direction of the galactic center are allowed by the observations, the data rule out most extended models for positron production, such as by cosmic ray interaction in the interstellar medium or by distributions of many supernovae, novae, or pulsars. The data are well satisfied by assuming that the emission originates in a single compact source at the galactic center.

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Prince, Thomas A.0000-0002-8850-3627
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Additional Information:© 1981 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1981 March 23; accepted 1981 May 6. We wish to thank J. Bradley, J. Brown, A. Dunklee, B. Gokhman, and R. Radocinsky for the development of the processing and analysis software; B. Teegarden, R. Ramaty, and R. Lingenfelter for suggestions on the data handling and interpretation; and M. Neugebauer and A. Metzger for valuable comments on this Letter. We also express our appreciation to the many persons who have worked with great dedication during the long development of this successful experiment, notably R. Jorgensen at the Jet Propulsion Laboratory, and J. Lindner and his colleagues at TRW Systems. This work was carried out under NASA contract NAS7-100 at the Jet Propulsion Laboratory, California Institute of Technology, and under NASA grant NGR 05-002-160 at the California Institute of Technology. W. A. W. is a NAS/National Research Council Resident Research Associate. Space Radiation Laboratory SRL ID #: 1981-19.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASANGR 05-002-160
Subject Keywords:galaxies: Milky Way - gamma rays: general
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Space Radiation Laboratory1981-19
Issue or Number:1
Record Number:CaltechAUTHORS:20140417-153800339
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ID Code:45040
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Deposited On:23 Apr 2014 19:14
Last Modified:10 Nov 2021 16:59

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