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Recent Results on the Search for 1011 eV Gamma Rays from the Crab Nebula

Published online by Cambridge University Press:  14 August 2015

G. G. Fazio
Affiliation:
Smithsonian Astrophysical Observatory, Cambridge, Mass. U.S.A.
H. F. Helmken
Affiliation:
Smithsonian Astrophysical Observatory, Cambridge, Mass. U.S.A.
G. H. Rieke
Affiliation:
Smithsonian Astrophysical Observatory, Cambridge, Mass. U.S.A.
T. C. Weekes
Affiliation:
Smithsonian Astrophysical Observatory, Cambridge, Mass. U.S.A.

Abstract

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The detection of Čerenkov light emitted by cosmic-ray air showers was used to search for cosmic gamma rays from the Crab Nebula. By use of the 10-m optical reflector at Mt. Hopkins, Arizona, the Crab Nebula was observed during the winter of 1969–1970 for approximately 112 hours, which was a significant increase in exposure time over previous experiments. Above a gamma-ray energy of 2.2 × 1011 eV, no significant flux was detected, resulting in an upper limit to the flux of 8.1 × 10-11 photon/cm2 sec. In the synchrotron-Compton-scattering model of gamma-ray production in the Crab Nebula, this limit on the flux indicates the average magnetic field in the nebula must be greater than 3 × 10-4 G.

Type
Session 1
Copyright
Copyright © Reidel 1971 

References

Fazio, G. G., Helmken, H. F., Rieke, G. H., and Weekes, T. C.: 1970, in Gratton, L., (ed.), ‘Non-Solar X- and Gamma-Ray Astronomy’, IAU Symp. 37, 250.Google Scholar
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Rieke, G. H. and Weekes, T. C.: 1969, Astrophys. J. 155, 429.CrossRefGoogle Scholar