The Relative Wavelength Independence of Ir Lags in Active Galactic Nuclei: Implications for the Distribution of the Hot Dust

Gaskell, C. M.; Shimanovskaya, E. V.

doi:10.18524/1810-4215.2015.28.70710

Cited by 18 publications

(20 citation statements)

References 5 publications

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“…Significant, but small differences were found in some AGNs (Tomita 2005;Tomita et al 2006;Lira et al 2011;Jun et al 2015;Vazquez et al 2015;Lyu et al 2019), 3 and no significant difference was found in some other AGNs (Lira et al 2015;Pozo Nuñez et al 2015;Schnülle et al 2015;Ramolla et al 2018;Oknyansky et al 2019). In some studies, small differences between lag times for different near-infrared bands were found, although it may be difficult to attribute the observed differences in lag times conclusively to the wavelength dependence of the dust-reverberation lag, because the accretion-disk component had not been subtracted from the near-infrared fluxes (Clavel et al 1989;Sitko et al 1993;Glass 2004;Soldi et al 2008;Pozo Nuñez et al 2014;Oknyansky et al 2015Oknyansky et al , 2017Mandal et al 2018).…”

Section: Redshift Correction For the Dust-reverberation Lagmentioning

confidence: 99%

Reverberation Measurements of the Inner Radii of the Dust Tori in Quasars

Minezaki

Yoshii

Kobayashi

et al. 2019

ApJ

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We present the results of a dust-reverberation survey of quasars at redshifts z < 0.6. We found a delayed response of the K-band flux variation after the optical flux variation in 25 out of 31 targets, and obtained the lag time between them for 22 targets. Combined with the results for nearby Seyfert galaxies, we provide the largest homogeneous collection of K-band dust-reverberation data for 36 type 1 active galactic nuclei (AGNs). This doubles the sample and includes the most distant AGN and the largest lag so far measured. We estimated the optical luminosity of the AGN component of each target using three different methods: spectral decomposition, the flux-variation-gradient method, and image decomposition. We found a strong correlation between the reverberation radius for the innermost dust torus and the optical luminosity over a range of approximately four orders of magnitude in luminosity, as is already known for Seyfert galaxies. We estimated the luminosity distances of the AGNs based on their dust-reverberation lags, and found that the data in the redshift-distance diagram are consistent with the current standard estimates of the cosmological parameters. We also present the radiusluminosity relations for isotropic luminosity indicators such as the hard X-ray (14-195 keV), [OIV] 25.89 µm, and mid-infrared (12 µm) continuum luminosities, which are applicable to obscured AGNs.

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Section: Redshift Correction For the Dust-reverberation Lagmentioning

confidence: 99%

Reverberation Measurements of the Inner Radii of the Dust Tori in Quasars

Minezaki

Yoshii

Kobayashi

et al. 2019

ApJ

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“…The CCD observations were reduced to a system of photoelectric measurements with a 27 arcsec aperture. As in our previous papers (see [5,30,31]) B-band data were supplemented with published CCD B-band measurements of Roberts and Rumstey [1] and 17 nights from Guo et al [2]. In addition, we used 29 nights of optical measurements of Schnülle et al [3,4] in the red z band (29 dates) which were also reduced to our system B.…”

Section: Observational Datamentioning

confidence: 99%

“…були локалiзованi далi, нiж радiус областi можливої сублiмацiї. Вiдносна незалежнiсть IЧ запiзнення вiд довжини хвилi також узгоджується з моделлю порожнинного бiконiчного витоку пилових хмар [5]. Створення самоузгодженої моделі ІЧ-випромінювання поблизу активного ядра виходить за рамки даної статті.…”

Section: Introductionunclassified

Additional Support for Relative Wavelength Independence of Ir Lags in NGC 4151 Over the Past Decade

Шенаврин¹,

Metlova²,

Gaskell³

2018

OAP

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We present results of a study of the correlation between the infrared (JHKL) and optical (B) fluxes of the nucleus of the Seyfert galaxy NGC 4151 for the years 2010-2015 using our own data (partially published) in combination with published data [1, 2, 3, 4]. We find similar lags for each of the HKL passbands relative to the optical of 37 ± 3 days. The lags are the same to within the accuracy of measurement. We do not confirm a significant decrease in the lag for HKL in 2013-2014 previously reported by Schnülle et al. [4], but we find that the lag of the short-lag component of J increased. We discuss our results within the framework of the standard model, where the variable infrared radiation is mainly due to the thermal re-emission of shortwave radiation by dust clouds close to a variable central source. There is also some contribution to the IR emission from the accretion disk, and this contribution increases with decreasing wavelength. The variability in J and K is not entirely simultaneous, which may be due to the differing contributions of the radiation from the accretion disk in these bands. The absence of strong wavelength-dependent changes in infrared lag across the HKL passbands can be explained by having the dust clouds during 2010-2015 be located beyond the sublimation radius. The relative wavelength independence of the infrared lags is also consistent with the hollow bi-conical outflow model of Oknyansky et al. [5].

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“…We have proposed that the dusty clouds are located in a hollow bi-conical outflow of which we see only the near side (Oknyansky et al, 2015;. We have noted that this model can explain cases of changing Seyfert type.…”

Section: Discussionmentioning

confidence: 68%

Ulti-Wavelength Monitoring of the Changing-Look Agn NGC 2617 During State Changes

Gaskell¹,

Huseynov

Mikailov

et al. 2017

OAP

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ABSTRACT. Optical and near-infrared photometry, optical spectroscopy, and soft X-ray and UV monitoring of the changing-look active galactic nucleus NGC 2617 show that it continues to have the appearance of a type-1 Seyfert galaxy. An optical light curve for 2010-2017 indicates that the change of type probably occurred between 2010 October and 2012 February and was not related to the brightening in 2013. In 2016 and 2017 NGC 2617 brightened again to a level of activity close to that in 2013 April. However, in 2017 from the end of the March to end of July 2017 it was in very low level and starting to change back to a Seyfert 1.8. We find variations in all passbands and in both the intensities and profiles of the broad Balmer lines. A new displaced emission peak has appeared in Hβ. X-ray variations are well correlated with UV-optical variability and possibly lead by ~2-3 d. The K band lags the J band by about 21.5 ± 2.5 d and lags the combined B + J bands by ~25 d. J lags B by about 3 d. This could be because J-band variability arises predominantly from the outer part of the accretion disc, while Kband variability is dominated by thermal re-emission by dust. We propose that spectral-type changes are a result of increasing central luminosity causing sublimation of the innermost dust in the hollow bi-conical outflow. We briefly discuss various other possible reasons that might explain the dramatic changes in NGC 2617.

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The Relative Wavelength Independence of Ir Lags in Active Galactic Nuclei: Implications for the Distribution of the Hot Dust

Cited by 18 publications

References 5 publications

Reverberation Measurements of the Inner Radii of the Dust Tori in Quasars

Reverberation Measurements of the Inner Radii of the Dust Tori in Quasars

Additional Support for Relative Wavelength Independence of Ir Lags in NGC 4151 Over the Past Decade

Ulti-Wavelength Monitoring of the Changing-Look Agn NGC 2617 During State Changes

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