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HUT Observations of the Lyman Limit in AGN: Implications for Unified Models

Published online by Cambridge University Press:  12 April 2016

G. Kriss ,
J. Krolik ,
J. Grimes ,
Z. Tsvetanov ,
B. Espey ,
W. Zheng  and
A. Davidsen
G. Kriss
Affiliation:
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
J. Krolik
Affiliation:
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
J. Grimes
Affiliation:
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
Z. Tsvetanov
Affiliation:
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
B. Espey
Affiliation:
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
W. Zheng
Affiliation:
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
A. Davidsen
Affiliation:
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA

Abstract

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We observed a total of 13 low-redshift AGN with the Hopkins Ultraviolet Telescope (HUT) during the course of the Astro-1 and Astro-2 missions. Of these, 4 show intrinsic Lyman-limit absorption — NGC 1068, NGC 4151, NGC 3516 and NGC 3227. AU galaxies with optically thick Lyman limits have extended narrow-line regions with bi-polar morphologies. All AGN with no absorption are Seyfert Is with compact NLRs. These observations support geometrical shadowing as the means for collimating the ionizing radiation in unified models of AGN, most likely in a photoionized atmosphere above the obscuring torus.

Type
X. Unification of Active Galaxies and Other Global Issues
Information
International Astronomical Union Colloquium , Volume 159: Emission Lines in Active Galaxies: New Methods and Techniques , 1997 , pp. 453 - 456
Copyright
Copyright © Astronomical Society of the Pacific 1997

References

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