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A lower limit to the magnetic field in the Crab Nebula from cosmic γ-ray experiments at 1011 eV

Published online by Cambridge University Press:  14 August 2015

G. G. Fazio ,
H. F. Helmken ,
G. H. Rieke  and
T. C. Weekes
G. G. Fazio
Affiliation:
Smithsonian Astrophysical Observatory and Harvard College Observatory, Cambridge, Mass., U.S.A.
H. F. Helmken
Affiliation:
Smithsonian Astrophysical Observatory and Harvard College Observatory, Cambridge, Mass., U.S.A.
G. H. Rieke
Affiliation:
Mt. Hopkins Observatory, Smithsonian Astrophysical Observatory, Amado, Arizona, and Harvard University, Cambridge, Mass., U.S.A.
T. C. Weekes
Affiliation:
Mt. Hopkins Observatory, Smithsonian Astrophysical Observatory, Amado, Arizona, and Harvard University, Cambridge, Mass., U.S.A.

Abstract

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The 10-m optical reflector at Mt. Hopkins, Arizona, has been used to search for cosmic γ-Rays by the detection of atmospheric Čerenkov radiation from energetic particle showers. Approximately 100 drift scans of the Crab Nebula during 1968–69 have yielded no positive evidence of a γ-Ray flux. The upper limit to the flux at 1.7 × 1011 eV is 2.0 × 10−10 photons/cm2 sec. Assuming γ-Rays of this energy are produced by Compton scattering, a lower limit on the average magnetic field in the Crab Nebula is 1.5 × 10−4 gauss. This experiment also verifies previous evidence that the high-energy electrons in the Crab Nebula are not the secondary products of high-energy proton interactions but must have been accelerated from lower energies.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 37: Non-Solar X- and Gamma-Ray Astronomy , 1970 , pp. 250 - 256
Copyright
Copyright © Reidel 1970 

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