Steps toward Determination of the Size and Structure of the Broad‐Line Region in Active Galactic Nuclei. XIV. Intensive Optical Spectrophotometric Observations of NGC 7469

Collier, S.; Horne, K.; Kaspi, S.; Netzer, H.; Peterson, B. M.; Wanders, I.; Alexander, Tal; Bertram, R.; Comastri, A.; Gaskell, C. Martin; Malkov, Yu. F.; Maoz, Dan; Mignoli, M.; Pogge, Richard W.; Pronik, V. I.; Сергеев, С. Г.; Snedden, Stephanie A.; Stirpe, G. M.; Бочкарев, Н. Г.; Burenkov, A. N.; Shapovalova, A. I.; Wagner, R. M.

doi:10.1086/305720

Cited by 197 publications

(190 citation statements)

References 34 publications

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“…With a resolution of $1 day, Peterson et al (1991) find no significant lag between the UVand optical continua in NGC 5548. A reanalysis of earlier data results in no UV-optical lag for NGC 5548, NGC 3783, and Fairall 9, while in NGC 7469 there is a UV-optical lag of $1-2 days (Peterson et al 1998;Collier et al 1998).…”

Section: X-ray/uv/optical Correlationsmentioning

confidence: 71%

Multiwavelength Monitoring of the Dwarf Seyfert 1 Galaxy NGC 4395. III. Optical Variability and X‐Ray/UV/Optical Correlations

Desroches¹,

Filippenko²,

Kaspi³

et al. 2006

ApJ

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We present optical observations of the low-luminosity Seyfert 1 nucleus of NGC 4395, as part of a multiwavelength reverberation-mapping program. Observations were carried out over two nights in 2004 April at Lick, Wise, and Kitt Peak Observatories. We obtained V-and B-band photometry, and spectra over the range 3500-6800 8. Simultaneous Hubble Space Telescope UV and Chandra X-ray observations are presented in companion papers. Even though NGC 4395 was in an extremely low state of activity, we detect significant continuum variability of 2%-10%, increasing toward shorter wavelengths. The continuum light curves, both spectroscopic and photometric, are qualitatively similar to the simultaneous UV and X-ray light curves. Interband cross-correlations suggest that the optical continuum emission lags behind the UV continuum emission by 24 þ7 À9 minutes, and that the optical continuum emission lags behind the X-ray continuum emission by 44 AE 13 minutes, consistent with a reprocessing model for active galactic nucleus emission. There are also hints of Balmer emission lines lagging behind the optical continuum by an amount slightly larger than the emission-line lag detected in the UV. These results are all similar to those of other Seyfert 1 nuclei. The emission-line lag yields a mass measurement of the central black hole, which although not very significant, is consistent with the value derived from the simultaneous UV data.

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Section: X-ray/uv/optical Correlationsmentioning

confidence: 71%

Multiwavelength Monitoring of the Dwarf Seyfert 1 Galaxy NGC 4395. III. Optical Variability and X‐Ray/UV/Optical Correlations

Desroches¹,

Filippenko²,

Kaspi³

et al. 2006

ApJ

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“…This distance might be larger by the order of two to four light-days because of the possibility that the observed continuum at 5180 Å does not correspond to the ionizing continuum in the UV below 1000 Å. Evidence of a wavelength-dependent continuum delay in the optical was found in the Seyfert galaxy NGC 7469 (Wanders et al 1997, Collier et al 1998. These observations were interpreted as reprocessing of high-energy radiation close to the center in an irradiated black-body accretion disk with a T ∝ R −4/3 temperature profile, which causes delays of τ ∝ λ 4/3 .…”

Section: The Blr Size In Mrk 926mentioning

confidence: 99%

Line profile and continuum variability in the very broad-line Seyfert galaxy Mrk 926

Kollatschny

Zetzl

2010

A&A

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Aims. We present results of an intensive spectroscopic variability campaign of the very broad-line Seyfert 1 galaxy Mrk 926. Our aim is to investigate the broad-line region (BLR) by studying the intensity and line profile variations of this galaxy on short timescales. Methods. High signal-to-noise ratio (S/N) spectra were taken with the 9.2 m Hobby-Eberly Telescope (HET) in identical conditions during two observing campaigns in 2004 and 2005. After the spectral reduction and internal calibration we achieved a relative flux accuracy of better than 1%. Results. The rms profiles of the very broad Balmer lines have shapes that differ from their mean line profiles, consisting of two inner (v ±6000 km s −1 ) and two outer (v ±6000 km s −1 ) line components in addition to a central component (v ±600 km s −1 ). These outer and inner line segments varied with different amplitudes during our campaign. The radius of the BLR is very small with an upper limit of 2 light-days for the Hβ BLR size. We derived an upper limit to the central black hole mass of M = 11.2 × 10 7 M . The 2-D cross-correlation functions CCF(τ, v) of Hβ and Hα are flat within the error limits. The response of the Balmer line segments with respect to continuum variations is different in the outer and inner wings of Hα and Hβ. This double structure in the response curves -of two separate inner and outer components -has also been seen in the rms line profiles. We conclude that the outer and inner line segments originate in different regions and/or under different physical conditions.

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“…Thus, the discrepancy originates from the improvement of fit with a top-hat smoothing kernel. The continuum of NGC 7469 was intensively monitored to search for time lags between the UV and optical continuum (Collier et al 1998), so its continuum light curve is densely sampled while the Hβ light curve is much less so. The model has to smooth the continuum light curve heavily (i.e., a broad top-hat width) to obtain a good fit, which at the same time shifts the time lag estimate to a longer value than it would be with a zero width (i.e., a delta function).…”

Section: Joint Analysis Of Multiple Linesmentioning

confidence: 99%

An Alternative Approach to Measuring Reverberation Lags in Active Galactic Nuclei

Kochanek

Peterson

2011

ApJ

370

541

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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. XIV. Intensive Optical Spectrophotometric Observations of NGC 7469

Cited by 197 publications

References 34 publications

Multiwavelength Monitoring of the Dwarf Seyfert 1 Galaxy NGC 4395. III. Optical Variability and X‐Ray/UV/Optical Correlations

Multiwavelength Monitoring of the Dwarf Seyfert 1 Galaxy NGC 4395. III. Optical Variability and X‐Ray/UV/Optical Correlations

Line profile and continuum variability in the very broad-line Seyfert galaxy Mrk 926

An Alternative Approach to Measuring Reverberation Lags in Active Galactic Nuclei

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