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The contribution from extragalactic objects to the cosmic gamma-ray background

E C M Young and K N Yu

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The authors have used the SAS-2 gamma -ray data and the Lick survey galaxy count data to determine the functional relationships between the absolute gamma -ray luminosities Ly and the absolute optical or X-ray luminosities of different classes of extragalactic objects such as quasars, Seyfert galaxies and X-ray clusters. From these, the authors are able to derive their contribution to the extragalactic gamma -ray background. They have shown that quasars (B<20) and Seyfert (type 1 and 1.5) galaxies together contribute to a substantial part (59-26+55%) of the diffuse gamma -ray background in the 35-100 MeV range, while X-ray clusters are negligible contributors. Therefore they conclude that the extragalactic gamma -ray background is likely to be generated by active galaxies such as quasars and Seyfert galaxies.


PACS

98.70.Vc Background radiations

98.54.Aj Quasars

98.70.Qy X-ray sources; X-ray bursts

98.70.Rz &ggr;-ray sources; &ggr;-ray bursts

98.54.Cm Active and peculiar galaxies and related systems (including BL Lacertae objects, blazars, Seyfert galaxies, Markarian galaxies, and active galactic nuclei)

Subjects

Astrophysics and astroparticles

Dates

Issue 7 (July 1989)



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