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EUV and Soft X-ray Evidence for Partially Ionized Gas in Active Galactic Nuclei

Published online by Cambridge University Press:  12 April 2016

J.P.D. Mittaz ,
R. Lieu ,
S. Bowyer ,
C.-Y. Hwang  and
J. Lewis
J.P.D. Mittaz
Affiliation:
Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, England
R. Lieu
Affiliation:
Center for EUV Astrophysics, 2150 Kittredge Street, Berkeley, University of California, CA 94720-5030, USA
S. Bowyer
Affiliation:
Center for EUV Astrophysics, 2150 Kittredge Street, Berkeley, University of California, CA 94720-5030, USA
C.-Y. Hwang
Affiliation:
Center for EUV Astrophysics, 2150 Kittredge Street, Berkeley, University of California, CA 94720-5030, USA
J. Lewis
Affiliation:
Center for EUV Astrophysics, 2150 Kittredge Street, Berkeley, University of California, CA 94720-5030, USA

Abstract

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We present a synoptic study of active galactic nuclei (AGN) detected by EUVE. We also present complementary ROSAT PSPC spectra for these sources and for other AGN in directions of low galactic absorption. It is found that the best-fit power-law photon indices of the X-ray spectra at 0.1–2.4 keV are anti-correlated with their galactic hydrogen columns. The indices for the 0.9–2.4 keV range do not show such a correlation, and are considerably smaller (i.e. flatter). We discuss a number of possible interpretations of this correlation but only one of these, the presence of a partially ionized absorbing gas in the AGN, explains the observations satisfactorily. The ubiquity of this effect suggests that this component be may very common in AGN.

Type
II. Extragalactic Sources in the EUV
Information
International Astronomical Union Colloquium , Volume 152: Astrophysics in the Extreme Ultraviolet , 1996 , pp. 45 - 49
Copyright
Copyright © Kluwer 1996

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