The size of the narrow-line-emitting region in the Seyfert 1 galaxy NGC 5548 from emission-line variability
- Department of Astronomy, The Ohio State University, 140 W 18th Avenue, Columbus, OH 43210 (United States)
- Department of Physics and Astronomy, Georgia State University, 25 Park Place, Suite 610, Atlanta, GA 30303 (United States)
- Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)
- Dipartimento di Fisica e Astronomia "G. Galilei," Università di Padova, Vicolo dell'Osservatorio 3 I-35122, Padova (Italy)
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.
- OSTI ID:
- 22348471
- Journal Information:
- Astrophysical Journal, Vol. 779, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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