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

B. M. Peterson, K. D. Denney, G. De Rosa, C. J. Grier, R. W. Pogge, M. C. Bentz, C. S. Kochanek, M. Vestergaard, E. Kilerci-Eser, E. Dalla Bontà, S. Ciroi

Research output: Contribution to journalArticlepeer-review

96 Scopus citations

Abstract

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 e 105 cm-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.

Original languageEnglish (US)
Article number109
JournalAstrophysical Journal
Volume779
Issue number2
DOIs
StatePublished - Dec 20 2013
Externally publishedYes

Keywords

  • galaxies: Seyfert
  • galaxies: active
  • galaxies: individual (NGC 5548)
  • galaxies: nuclei
  • quasars: emission lines

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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