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The X-ray spectra of optically selected Seyfert 2 galaxies : are there any Seyfert 2 galaxies with no absorption?

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posted on 2009-12-08, 16:24 authored by A. Pappa, I. Georgantopoulos, A. L. Zezas, G. C. Stewart
We present an X-ray spectral analysis of a sample of eight bona fide Seyfert 2 galaxies, selected on the basis of their high [O iii]λ5007 flux, from the Ho et al. spectroscopic sample of nearby galaxies. We find that, in general, the X-ray spectra of our Seyfert 2 galaxies are complex, with some of our objects having spectra different from the ‘typical’ spectrum of X-ray selected Seyfert 2 galaxies. Two (NGC 3147 and 4698) show no evidence for intrinsic absorption. We suggest that this is a result of the fact that when the torus suppresses the intrinsic medium and hard energy flux, underlying emission from the host galaxy, originating in circumnuclear starbursts, and scattering from warm absorbers contributes in these energy bands more significantly. Our ASCA data alone cannot discriminate whether low-absorption objects are Compton-thick active galactic nuclei (AGNs) with a strong scattered component or lack an obscuring torus. The most striking example of our low absorption Seyfert 2 is NGC 4698. Its spectrum could be explained by either a dusty warm absorber or a lack of broad-line clouds so that its appearance as a Seyfert 2 is intrinsic and not a result of absorption.

History

Citation

Monthly Notices of the Royal Astronomical Society, 2001, 326 (3), pp. 995-1006

Version

  • VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Oxford University Press (OUP) on behalf of Royal Astronomical Society

issn

0035-8711

eissn

1365-2966

Copyright date

2001

Available date

2009-12-08

Publisher version

http://mnras.oxfordjournals.org/content/326/3/995

Notes

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2001 Royal Astronomical Society Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.

Language

en

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