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Title: The size of the narrow-line-emitting region in the Seyfert 1 galaxy NGC 5548 from emission-line variability

The narrow [O III] λλ4959, 5007 emission-line fluxes in the spectrum of the well-studied Seyfert 1 galaxy NGC 5548 are shown to vary with time. From this we show that the narrow-line-emitting region has a radius of only 1-3 pc and is denser (n {sub e} ∼ 10{sup 5} cm{sup –3}) than previously supposed. The [O III] line width is consistent with virial motions at this radius given previous determinations of the black hole mass. Since the [O III] emission-line flux is usually assumed to be constant and is therefore used to calibrate spectroscopic monitoring data, the variability has ramifications for the long-term secular variations of continuum and emission-line fluxes, though it has no effect on shorter-term reverberation studies. We present corrected optical continuum and broad Hβ emission-line light curves for the period 1988-2008.
Authors:
; ; ; ; ;  [1] ;  [2] ; ;  [3] ; ;  [4]
  1. Department of Astronomy, The Ohio State University, 140 W 18th Avenue, Columbus, OH 43210 (United States)
  2. Department of Physics and Astronomy, Georgia State University, 25 Park Place, Suite 610, Atlanta, GA 30303 (United States)
  3. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)
  4. Dipartimento di Fisica e Astronomia "G. Galilei," Università di Padova, Vicolo dell'Osservatorio 3 I-35122, Padova (Italy)
Publication Date:
OSTI Identifier:
22348471
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 779; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; EMISSION; GALAXIES; GALAXY NUCLEI; LINE WIDTHS; MASS; QUASARS; SPECTRA; VISIBLE RADIATION