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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Abstract
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.
Item Type: | Article |
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Contact Email Address: | dmiles@caltech.edu |
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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. |
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Group: | Space Radiation Laboratory |
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Funders: | Funding Agency | Grant Number |
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NASA | NAS7-100 | NASA | NGR 05-002-160 |
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Subject Keywords: | galaxies: Milky Way - gamma rays: general |
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Other Numbering System: | Other Numbering System Name | Other Numbering System ID |
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Space Radiation Laboratory | 1981-19 |
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Issue or Number: | 1 |
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DOI: | 10.1086/183613 |
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Record Number: | CaltechAUTHORS:20140417-153800339 |
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Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20140417-153800339 |
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Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. |
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ID Code: | 45040 |
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Collection: | CaltechAUTHORS |
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Deposited By: |
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Deposited On: | 23 Apr 2014 19:14 |
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Last Modified: | 10 Nov 2021 16:59 |
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