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Soft X-ray Variability and the Covering Fraction of Active Galactic Nuclei

Published online by Cambridge University Press:  07 August 2017

Michael A. Strauss ,
Kenneth W. Wachter  and
Alexei V. Filippenko
Michael A. Strauss
Affiliation:
Department of Astronomy, University of California, Berkeley, CA 94720 U.S.A.
Kenneth W. Wachter
Affiliation:
Department of Astronomy, University of California, Berkeley, CA 94720 U.S.A.
Alexei V. Filippenko
Affiliation:
Department of Astronomy, University of California, Berkeley, CA 94720 U.S.A.

Extract

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The variability of soft X-rays (0.2 – 2 keV) in some low-luminosity type 1 Seyferts may partly be due to an extrinsic mechanism: dense clouds of gas in the broad-line region, opaque to soft X-rays, move across our line of sight to the X-ray emitting portions of the accretion disk (Reichert, Mushotzky, and Holt 1986; Lawrence and Elvis 1982; Halpern 1984). As the clouds move, the covering fraction changes stochastically. Evidence for partial covering of the X-ray source in low-luminosity AGNs has been seen in soft X-ray spectra by Holt et al. (1980) and Reichert et al. (1985).

Type
Part 2: BLR and Variability
Information
Symposium - International Astronomical Union , Volume 134: Active Galactic Nuclei , 1989 , pp. 118 - 119
Copyright
Copyright © Kluwer 1989 

References

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