The Relative Wavelength Independence of IR Time Lags in NGC4151 During the Years 2010-2015

Abstract

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 Schnulle et al. (2013, 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 Schnulle 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 re-emission 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).

arXiv comment28 pages, 7 figures

References in corpus (23)

• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• AGN Dusty Tori: II. Observational Implications of Clumpiness
• AGN Dusty Tori: I. Handling of Clumpy Media
• An Alternative Approach To Measuring Reverberation Lags in Active Galactic Nuclei
• Dusty winds in active galactic nuclei: reconciling observations with models
• Parsec-scale dust emission from the polar region in the type 2 nucleus of NGC 424
• Swift monitoring of NGC 4151: Evidence for a Second X-ray/UV Reprocessing
• High Spatial Resolution Imaging of NGC 1068 in the Mid Infrared
• Mid-infrared interferometry of 23 AGN tori: On the significance of polar-elongated emission
• A dust-parallax distance of 19 megaparsecs to the supermassive black hole in NGC 4151
• Variation of Inner Radius of Dust Torus in NGC4151
• New evidence for the dusty wind model: Polar dust and a hot core in the type-1 Seyfert ESO323-G77
• A New Method for Measuring Extragalactic Distances
• Evidence for a receding dust sublimation region around a supermassive black hole
• Constraining properties of dusty environments by infrared variability
• Partial dust obscuration in active galactic nuclei as a cause of broad-line profile and lag variability, and apparent accretion disc inhomogeneities
• Spitzer Space Telescope Measurements of Dust Reverberation Lags in the Seyfert 1 Galaxy NGC 6418
• Dust reverberation-mapping of the Seyfert 1 galaxy WPVS48
• Dust reverberation mapping in the era of big optical surveys and its cosmological application
• Modeling the Infrared Reverberation Response of the Circumnuclear Dusty Torus in AGN: The Effects of Cloud Orientation and Anisotropic Illumination
• Monitoring the temperature and reverberation delay of the circumnuclear hot dust in NGC 4151
• Calibration of AGN Reverberation Distance Measurements
• Optical Monitoring of the Seyfert Galaxy NGC 4151 and Possible Periodicities in the Historical Light Curve

Cited by in corpus (5)

• Reverberation Measurements of the Inner Radii of the Dust Tori in Quasars
• Multi-Wavelength Monitoring and Reverberation Mapping of a Changing Look Event in the Seyfert Galaxy NGC 3516
• The Dusty Heart of NGC 4151 Revealed by $\lambda \sim$1-40 $\mu$m Reverberation Mapping and Variability: A Challenge to Current Clumpy Torus Models
• The post-maximum behaviour of the changing-look Seyfert galaxy NGC 1566
• Changing looks of the nucleus of the Seyfert galaxy NGC 1566 compared with other changing-look AGNs