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Hot Accretion Disks and the High Energy Background

Published online by Cambridge University Press:  04 August 2017

M. Kafatos  and
Jean A. Eilek
M. Kafatos
Affiliation:
Department of Physics, George Mason University, Fairfax, VA and Laboratory for Astronomy and Solar Physics, NASA, Goddard Space Flight Center, Greenbelt, MD, U.S.A.
Jean A. Eilek
Affiliation:
Physics Department, New Mexico Tech, Socorro, NM, U.S.A.

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The origin of the high energy (X-ray and gamma-ray) background may be attributed to discrete sources, which are usually thought to be active galactic nuclei (AGN) (cf. Rothschild et al. 1982, Bignami et al. 1979). At X-rays a lot of information has been obtained with HEAO-1 in the spectral range 2–165 keV. At gamma-rays the background has been estimated from the Apollo 15 and 16 (Trombka et al. 1977) and SAS-2 (Bignami et al. 1979) observations. A summary of some of the observations (Rothschild et al. 1982) is shown in Figure 1. The contribution of AGN to the diffuse high energy background is uncertain at X-rays although it is generally estimated to be in the 20–30% range (Rothschild et al. 1982). At gamma-rays, in the range 1–150 MeV, AGN (specifically Seyfert galaxies) could account for all the emission.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 104: Early Evolution of the Universe and Its Present Structure , 1983 , pp. 345 - 346
Copyright
Copyright © Reidel 1983 

References

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