X-ray Spectral Features of the Crab Nebula and NP0532

Abstract

IN view of the pulsar ‘glitches’, the optical activity and the multi-component nature of its radiation1,2, there must be a level of sensitivity at which it becomes an oversimplification to state that a constant intensity and single spectral index characterise the total X-ray emission from the Crab Nebula. Here we present spectra of the total nebula and NP0532 obtained in the 15 to 300 keV range during balloon flights on September 9 and 25, 1970. These spectra are both statistically and systematically more accurate than previous hard X-ray measurements and together with other data show previously unknown or uncertain spectral features.