Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. II - an intensive study of NGC 5548 at optical wavelengths

Peterson, B. M.; Balonek, T. J.; Barker, E. S.; Bechtold, Jill; Bertram, R.; Бочкарев, Н. Г.; Bolte, M.; Bond, Dick; Boroson, Todd A.; Carini, M. T.; Carone, T. E.; Christensen, J. A.; Clements, S. D.; Cochran, A. L.; Cohen, R. D.; Crampton, D.; Dietrich, M.; Elvis, M.; Ferguson, Annette M. N.; Filippenko, A. V.; Fricke, K. J.; Gaskell, C. M.; Halpern, J. P.; Huchra, J.; Hutchings, J. B.; Kollatschny, W.; Koratkar, Anuradha; Korista, K. T.; Krolik, Julian H.; Lame, N. J.; Laor, Ari; Leacock, R. J.; MacAlpine, G. M.; Malkan, M. A.; Maoz, Dan; Miller, H. R.; Morris, Simon L.; Netzer, H.; Oliveira, Claudia L. Mendes de; Penfold, J. E.; Penston, M. V.; Pérez, E.; Pogge, Richard W.; Richmond, M.; Romanishin, W.; Rosenblatt, E. I.; Saddlemyer, Les; Sadun, A. C.; Sawyer, S. R.; Shields, J. C.; Shapovalova, A. I.; Smith, Alex; Smith, H. A.; Smith, Paul S.; Sun, Wei‐Hsin; Thiele, U.; Turner, T. J.; Veilleux, Sylvain; Wagner, R. M.; Weymann, R. J.; Wilkes, B. J.; Wills, Beverley J.; Wills, D.; Younger, P. F.

doi:10.1086/169675

Cited by 220 publications

(53 citation statements)

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“…We use the time delay measurements of Hβ emission line summarized in Du et al (2015Du et al ( , 2016, which are compiled from the reverberation campaigns performed by different groups (Barth et al 2013, 2009b, 2014, Collier et al 1998, Dietrich et al 1993, 2015, Kaspi et al 2000, Pei et al 2014, Peterson et al 1991, 1992, 2002, 2014, Santos-Lleó et al 1997, 2001, Stirpe et al 1994, Wang et al 2014. The time delays represent the emissivity-weighted radii of the BLR in those RM objects.…”

Section: Observational Datamentioning

confidence: 99%

A Test of the Formation Mechanism of the Broad Line Region in Active Galactic Nuclei

Czerny

Wang

et al. 2016

ApJ

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The origin of the Broad Line Region (BLR) in active galaxies remains unknown. It seems to be related to the underlying accretion disk but an efficient mechanism is required to rise the material from the disk surface without giving too strong signatures of the outflow in the case of the low ionization lines. We discuss in detail two proposed mechanisms: (i) radiation pressure acting on dust in the disk atmosphere creating a failed wind (ii) the gravitational instability of the underlying disk. We compare the predicted location of the inner radius of the BLR in those two scenarios with the observed position obtained from the reverberation studies of several active galaxies. The failed dusty outflow model well represents the observational data while the predictions of the self-gravitational instability are not consistent with observations. The issue remains why actually we do not see any imprints of the underlying disk instability in the BLR properties.

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Section: Observational Datamentioning

confidence: 99%

A Test of the Formation Mechanism of the Broad Line Region in Active Galactic Nuclei

Czerny

Wang

et al. 2016

ApJ

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“…In this method the narrow emission-line flux can be taken as constant, since these lines arise in an extended, low-density region and are thus unaffected by short timescale variations in the ionizing continuum flux. Following this internal flux calibration, all subsets were scaled to the absolute [O iii] λ5007 line flux of 5.58 × 10 −13 erg s −1 cm −2 (Peterson et al 1991).…”

Section: Ngc 5548 Spectramentioning

confidence: 99%

Systematic Uncertainties in Black Hole Masses Determined From Single-Epoch Spectra

Denney¹,

Peterson²,

Dietrich³

et al. 2009

ApJ

154

198

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We explore the nature of systematic errors that can arise in measurement of black hole masses from singleepoch (SE) spectra of active galactic nuclei (AGNs) by utilizing the many epochs available for NGC 5548 and PG1229+204 from reverberation mapping (RM) databases. In particular, we examine systematics due to AGN variability, contamination due to constant spectral components (i.e., narrow lines and host galaxy flux), data quality (i.e., signal-to-noise ratio (S/N)), and blending of spectral features. We investigate the effect that each of these systematics has on the precision and accuracy of SE masses calculated from two commonly used line width measures by comparing these results to recent RM studies. We calculate masses by characterizing the broad Hβ emission line by both the full width at half maximum and the line dispersion, and demonstrate the importance of removing narrow emission-line components and host starlight. We find that the reliability of line width measurements rapidly decreases for S/N lower than ∼ 10-20 (per pixel), and that fitting the line profiles instead of direct measurement of the data does not mitigate this problem but can, in fact, introduce systematic errors. We also conclude that a full spectral decomposition to deblend the AGN and galaxy spectral features is unnecessary, except to judge the contribution of the host galaxy to the luminosity and to deblend any emission lines that may inhibit accurate line width measurements. Finally, we present an error budget which summarizes the minimum observable uncertainties as well as the amount of additional scatter and/or systematic offset that can be expected from the individual sources of error investigated. In particular, we find that the minimum observable uncertainty in SE mass estimates due to variability is 0.1 dex for high S/N ( 20 pixel −1 ) spectra.

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“…3 Consider, as an example, the UV and optical monitoring campaign on NGC 5548 undertaken with the International Ultraviolet Explorer (Clavel et al 1991) and ground-based telescopes (Peterson et al 1991) in 1989. The UV data were sampled at approximately regular 4 day intervals.…”

Section: Introductionmentioning

confidence: 99%

An Alternative Approach to Measuring Reverberation Lags in Active Galactic Nuclei

Kochanek

Peterson

2011

ApJ

376

543

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Motivated by recent progress in the statistical modeling of quasar variability, we develop a new approach to measuring emission-line reverberation lags to estimate the size of broad-line regions (BLRs) in active galactic nuclei. Assuming that all emission-line light curves are scaled, smoothed, and displaced versions of the continuum, this alternative approach fits the light curves directly using a damped random walk model and aligns them to recover the time lag and its statistical confidence limits. We introduce the mathematical formalism of this approach and demonstrate its ability to cope with some of the problems for traditional methods, such as irregular sampling, correlated errors, and seasonal gaps. We redetermine the lags for 87 emission lines in 31 quasars and reassess the BLR size-luminosity relationship using 60 Hβ lags. We confirm the general results from the traditional crosscorrelation methods, with a few exceptions. Our method, however, also supports a broad range of extensions. In particular, it can simultaneously fit multiple lines and continuum light curves which improves the lag estimate for the lines and provides estimates of the error correlations between them. Determining these correlations is of particular importance for interpreting emission-line velocity-delay maps. We can also include parameters for luminosity-dependent lags or line responses. We use this to detect the scaling of the BLR size with continuum luminosity in NGC 5548.

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Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. II - an intensive study of NGC 5548 at optical wavelengths

Cited by 220 publications

References 0 publications

A Test of the Formation Mechanism of the Broad Line Region in Active Galactic Nuclei

A Test of the Formation Mechanism of the Broad Line Region in Active Galactic Nuclei

Systematic Uncertainties in Black Hole Masses Determined From Single-Epoch Spectra

An Alternative Approach to Measuring Reverberation Lags in Active Galactic Nuclei

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