Correlation of near-infrared and optical variability of NGC 4151 in 2008–2013

Metlova, N. V.; Taranova, O. G.; Шенаврин, В. И.; Артамонов, Б. П.; Gaskell, C. Martin

doi:10.1134/s1063773714090011

Cited by 17 publications

(36 citation statements)

References 28 publications

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“…This paper is a continuation of our series of studies on the correlation between infrared and optical variability in NGC 4151, as well as the variability of the IR lag values and their dependence on the wavelength (Oknyaskii, 1993; Oknyansky et al, 1999Oknyansky et al, , 2006Oknyansky et al, , 2008Oknyansky et al, , 2014aOknyansky et al, , 2014b. In these studies we found that the delay in the K band is different in different activity states of the AGN, and also that the ratio of the lag values in the bands L and K varies considerably in the range 1-3.…”

Section: Discussionmentioning

confidence: 79%

“…A detailed historical review and discussion of the obtained results was carried out in a previous paper (Oknyansky et al, 2014a). In the present paper, using more complete observational material and using two independent methods of analysis, we confirmed the relative independence of infrared lags from the wavelength during 2010-2015.…”

Section: Discussionmentioning

confidence: 99%

“…To estimate the errors in the lags derived by the MCCF, we applied the same Monte Carlo procedure as before (Oknyansky et al, 1999(Oknyansky et al, , 2014a. Our estimates of the errors in the lags gave a value of about 3 days.…”

Section: Evaluation Of Errorsmentioning

confidence: 96%

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The Relative Wavelength Independence of IR Time Lags in NGC 4151 during the Years 2010–2015

2019

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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 of Roberts and Rumstey (2012), Guo et al. (2014) and Schnülle et al. (2013Schnülle et al. ( , 2015.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. (2015), 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 reemission of short-wave 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. (2015).

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Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

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The Relative Wavelength Independence of IR Time Lags in NGC 4151 during the Years 2010–2015

2019

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“…It should be noted that there are several pieces of evidence from the studies of hot-dust-poor AGNs, dust reverberation mapping and infrared polarimetry, suggesting that emission from quasar accretion discs extends well into near-infrared wavelengths, which means that an accretion disc does not truncate even at a few thousands of RS (e.g., Kishimoto, Antonucci & Blaes 2005;Tomita et al 2006;Kishimoto et al 2007Kishimoto et al , 2008Hönig & Kishimoto 2010;Hao et al 2010;Lira et al 2011;Koshida et al 2014;Oknyansky et al 2014, and references therein). Therefore, we fix the disc outer radius as xout = 2 16 for convenience of the model calculations.…”

Section: Dexter and Agol's Formalizationmentioning

confidence: 99%

Constraints on the temperature inhomogeneity in quasar accretion discs from the ultraviolet-optical spectral variability

Kokubo

2015

Monthly Notices of the Royal Astronomical Society

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The physical mechanisms of the quasar ultraviolet (UV)-optical variability are not well understood despite the long history of observations. Recently, Dexter & Agol presented a model of quasar UV-optical variability, which assumes large local temperature fluctuations in the quasar accretion discs. This inhomogeneous accretion disc model is claimed to describe not only the single-band variability amplitude, but also microlensing size constraints and the quasar composite spectral shape. In this work, we examine the validity of the inhomogeneous accretion disc model in the light of quasar UV-optical spectral variability by using five-band multi-epoch light curves for nearly 9 000 quasars in the Sloan Digital Sky Survey (SDSS) Stripe 82 region. By comparing the values of the intrinsic scatter σ int of the two-band magnitude−magnitude plots for the SDSS quasar light curves and for the simulated light curves, we show that Dexter & Agol's inhomogeneous accretion disc model cannot explain the tight inter-band correlation often observed in the SDSS quasar light curves. This result leads us to conclude that the local temperature fluctuations in the accretion discs are not the main driver of the several years' UV-optical variability of quasars, and consequently, that the assumption that the quasar accretion discs have large localized temperature fluctuations is not preferred from the viewpoint of the UV-optical spectral variability.

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“…It is a very compact region (see for example Wandel et al, 1999;Peterson et al, 2004;Kaspi et al, 2005;Bentz et al, 2009;Bentz & Katz, 2015), nested in a small dusty torus (see for example Koshida et al, 2009;Kishimoto et al, 2011;Stalevski et al, 2012;Koshida et al, 2014;Oknyansky et al, 2014) at the core of AGN, where the optical and ultraviolet BELs originate (see for example Sulentic et al, 2002;Gaskell, 2009;Marziani et al, originating from galaxy mergers, the accretion rate is modulated by the SMBBHS, and shows 1-3 distinct periods, while for Q < 0.05 the rate shows no variability. They also pointed out that for smaller mass ratios (about Q < 0.3), the radius of the cavity is smaller.…”

Section: Introductionmentioning

confidence: 99%

Line Shapes Emitted from Spiral Structures around Symmetric Orbits of Supermassive Binary Black Holes

Smailagic

Bon

2015

J Astrophys Astron

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Correlation of near-infrared and optical variability of NGC 4151 in 2008–2013

Cited by 17 publications

References 28 publications

The Relative Wavelength Independence of IR Time Lags in NGC 4151 during the Years 2010–2015

The Relative Wavelength Independence of IR Time Lags in NGC 4151 during the Years 2010–2015

Constraints on the temperature inhomogeneity in quasar accretion discs from the ultraviolet-optical spectral variability

Line Shapes Emitted from Spiral Structures around Symmetric Orbits of Supermassive Binary Black Holes

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