NGC 4151 and MCG 8-11-11: Two X-ray seyfert galaxies with strong soft γ-ray emission |
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| Authors: | L Bassani R C Butler A J Dean G Di Cocco N A Dipper F Perotti G Villa |
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| Institution: | (1) Department of Physics, University of Southampton, S09 5NH Southampton, UK;(2) Istituto TE.S.R.E./C.N.R., Via de' Castagnoli 1, 40126 Bologna, Italy;(3) Istituto Fisica Cosmica/C.N.R., Via Bassini, 15, 20133 Milano, Italy |
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| Abstract: | During a balloon flight of the MISO telescope on the 30th September 1979, the Seyfert galaxies NGC 4151 and MGC 8-11-11 were studied in the hard X-ray range (EX > 20 keV) and low-energy  -ray range up to 19 MeV. An emission at the 4.5  level above 20 keV (4 above 260 keV) was detected in the direction of NGC 4151. -ray emission at the 3.9 level above 90 keV was also observed from the direction of MCG 8-11-11. The emission photon spectrum shows a high-energy cutoff at about 3 MeV. A large amount of the observed low-energy -ray diffuse background could be produced by a few percent of the X-ray emitting Seyfert galaxies having a -ray luminosity comparable to that observed from the regions of NGC 4151 or MCG 8-11-11. |
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