Abstract
view Abstract Citations (152) References (72) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galaxies and gamma-ray astronomy. Bignami, G. F. ; Fichtel, C. E. ; Hartman, R. C. ; Thompson, D. J. Abstract The nature of the high-energy spectra of several types of active galaxies and their contribution to the measured diffuse gamma-ray emission between 1 and 150 MeV are considered, using X-ray spectra of active galaxies and SAS 2 data regarding the intensity upper limits to the gamma-ray emission above 35 MeV. It is found that a substantial increase in slope of the photon energy spectrum must occur in the low energy gamma-ray region for Seyfert galaxies, BL Lac objects, and emission line galaxies; the power-law spectra observed in the X-ray range must steepen substantially between 50 keV and 50 MeV. In addition, a cosmological integration shows that Seyfert galaxies, BL Lac objects, and quasars may account for most of the 1-150 MeV diffuse background, even without significant evolution. Publication: The Astrophysical Journal Pub Date: September 1979 DOI: 10.1086/157323 Bibcode: 1979ApJ...232..649B Keywords: Bl Lacertae Objects; Cosmology; Gamma Ray Astronomy; Quasars; Seyfert Galaxies; Active Galaxies; Energy Spectra; Extraterrestrial Radiation; Radio Galaxies; X Ray Astronomy; Astrophysics; Cosmology:Gamma-Ray Background; Galaxies:Gamma-Ray Sources full text sources ADS | data products SIMBAD (28)
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