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Ultraviolet variability of NGC 5548 - Dynamics of the continuum production region and geometry of the broad-line regionData from the 1989-1990 IUE monitoring of the Seyfert galaxy NGC 5548 are used here to analyze the continuum variability properties of the galaxy and to derive the structure or its emission-line region. The mean shape of the UV continuum is well fit by an accretion disk model with a given black hole mass and an additional component required to reproduce the observed soft X-ray flux. The continuum fluctuation power spectrum is very steep, with most of the variance coming from about 1 yr time scales. The entire optical/UV continuum rises and falls almost simultaneously, so that the logarithmic slope of the power spectrum is nearly the same for all bands, but the flux at higher photon frequencies varies with larger amplitude. The emission-line material around the nucleus may best be described by a highly ionized inner zone of high and nearly constant pressure that stretches about 4-14 light-days from the center and an outer, more weakly ionized zone of considerably lower ionization at least 20-30 light-days out.
Document ID
19910048937
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Krolik, J. H.
(Johns Hopkins University Baltimore, MD, United States)
Horne, Keith
(Space Telescope Science Institute Baltimore, MD, United States)
Kallman, T. R.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Malkan, M. A.
(California, University Los Angeles, United States)
Edelson, R. A.
(Colorado, University Boulder, United States)
Date Acquired
August 14, 2013
Publication Date
April 20, 1991
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 371
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
91A33560
Funding Number(s)
CONTRACT_GRANT: NAGW-1194
CONTRACT_GRANT: NAGW-1017
CONTRACT_GRANT: NAGW-2012
Distribution Limits
Public
Copyright
Other

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