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X-Ray Observations of Active Galactic Nuclei

Published online by Cambridge University Press:  04 August 2017

C. Megan Urry ,
Richard F. Mushotzky ,
Allyn F. Tennant ,
Elihu A. Boldt  and
Stephen S. Holt
C. Megan Urry
Affiliation:
NASA/Goddard Space Flight Center, Greenbelt, MD, USA Johns Hopkins University, Baltimore, MD, USA
Richard F. Mushotzky
Affiliation:
NASA/Goddard Space Flight Center, Greenbelt, MD, USA
Allyn F. Tennant
Affiliation:
NASA/Goddard Space Flight Center, Greenbelt, MD, USA University of Maryland, College Park, MD, USA
Elihu A. Boldt
Affiliation:
NASA/Goddard Space Flight Center, Greenbelt, MD, USA
Stephen S. Holt
Affiliation:
NASA/Goddard Space Flight Center, Greenbelt, MD, USA

Abstract

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HEAO 1 A2 and Einstein SSS spectral observations of Seyfert galaxies and BL Lac objects suggest that in both cases, the X-ray emission is due to relativistic particles. The five BL Lac objects have very soft spectra and at higher energies (above 10 keV) may have hard tails. Combining our X-ray data with radio, infrared, optical, and ultraviolet observations, we can fit the BL Lac spectra with the familiar synchrotron self-Compton model if we allow for relativistic beaming (Urry and Mushotzky 1982, Urry et al. 1982). We show that Doppler beaming of an underlying (Seyfert-like) source population flattens the observed luminosity function, and we emphasize that the relative numbers of BL Lacs and quasars in given spectral intervals are strong functions of selection effects, the degree of Doppler beaming, and the form of the intrinsic luminosity function.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 104: Early Evolution of the Universe and Its Present Structure , 1983 , pp. 347
Copyright
Copyright © Reidel 1983 

References

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