Gamma radiation from the Crab Nebula above 35 MeV
Abstract
OBSERVATIONS of electromagnetic radiation from the Crab have been made to at least 1 GeV (ref. 1) and possibly as high as 1012 eV (refs 2 and 3). The Crab is unique among strong X-ray sources in that the major component in the low energy range (1-10 keV) shows little or no temporal variation. A small (<~ 10% at 10 keV) pulsed component from NP0532 is observed in the X-ray region, but its strength relative to the constant component increases with increasing X-ray energy. Gamma ray observations of the Crab in the 15-100 MeV range have yielded rather uncertain results with reported upper limits4,5 and fluxes6-10 in apparent or near conflict. As the reported intensities were just marginally detectable above atmospheric background with the balloon experiments which produced the observations, this seems understandable.
- Publication:
-
Nature
- Pub Date:
- October 1974
- DOI:
- 10.1038/251397a0
- Bibcode:
- 1974Natur.251..397K