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Upper limits to the annihilation radiation luminosity of Centaurus A

Conference · · AIP Conf. Proc.; (United States)
OSTI ID:6095327
A high-resolution observation of the active nucleus galaxy Centaurus A (NGC 5128) was made by the GSFC Low Energy ..gamma..-ray Spectrometer (LEGS) during a balloon flight on 1981 November 19. The measured spectrum between 70 and 500 keV is well represented by a power law of the form 1.05 x 10/sup -4/ (E/100 keV)/sup -1/ /sup 59/ ph cm/sup -2/ s/sup -1/ with no breaks or line features observed. The 98% confidence (2sigma) flux upper limit for a narrow (< 3 keV) 511-keV positron annihilation line is 9.9 x 10/sup -4/ ph cm/sup -2/ s/sup -1/ Using this upper limit, the ratio of the narrow-line annihilation radiation luminosity to the intergral > 511 keV luminosity is estimated to be < 0.09 (2sigma upper limit). This is compared with the measured value for our galactic center in the Fall of 1979 of 0.10-0.13, indicating a difference in the emission regions in the nuclei of the two galaxies. 16 references, 1 figure.
Research Organization:
NASA/Goddard Space Flight Center, Greenbelt, MD
OSTI ID:
6095327
Report Number(s):
CONF-830136-
Conference Information:
Journal Name: AIP Conf. Proc.; (United States) Journal Volume: 101
Country of Publication:
United States
Language:
English