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arXiv · 1309.1468

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
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Abstract

The narrow [O III] 4959, 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 ~ 10^5 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 Hbeta emission-line light curves for the period 1988 to 2008.

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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. 2013-10-25. The Size of the Narrow-Line Emitting Region in the Seyfert 1 Galaxy NGC 5548 from Emission-Line Variability. https://doi.org/10.1088/0004-637x%2F779%2F2%2F109

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