Abstract The gamma-ray emission of Geminga during five COS-B observations has been analysed to derive its spectral properties between 50 MeV and 5 GeV. In all observations but one, the spectrum presents a turnover between 100 and 200 MeV, the source becoming very weak at the lowest gamma- ray energies. During the remaining observation, the spectrum is consistent with a power-law spectrum with index −2.02 ± 0.10 over the whole energy range. So, Geminga exhibits long-term variability for energies below 200 MeV. Very similar spectral properties and variability have been found for one component of the Vela pulsar lightcurve, providing new evidence that Geminga might be a Vela-type pulsar.
The variable energy-distribution of the gamma-ray emission from Geminga
Advances in Space Research ; 11 , 8 ; 107-110
01.01.1991
4 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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