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arXiv · astro-ph/0311338

Inner Size of a Dust Torus in the Seyfert 1 Galaxy NGC 4151

T. Minezaki·Y. Yoshii·Y. Kobayashi·K. Enya·M. Suganuma·H. Tomita·T. Aoki·B. A. Peterson
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Abstract

The most intense monitoring observations yet made were carried out on the Seyfert 1 galaxy NGC 4151 in the optical and near-infrared wave-bands. A lag from the optical light curve to the near-infrared light curve was measured. The lag-time between the V and K light curves at the flux minimum in 2001 was precisely 48+2-3 days, as determined by a cross-correlation analysis. The correlation between the optical luminosity of an active galactic nucleus (AGN) and the lag-time between the UV/optical and the near-infrared light curves is presented for NGC 4151 in combination with previous lag-time measurements of NGC 4151 and other AGNs in the literature. This correlation is interpreted as thermal dust reverberation in an AGN, where the near-infrared emission from an AGN is expected to be the thermal re-radiation from hot dust surrounding the central engine at a radius where the temperature equals to that of the dust sublimation temperature. We find that the inner radius of the dust torus in NGC 4151 is $\sim $ 0.04 pc corresponding to the measured lag-time, well outside the broad line region (BLR) determined by other reverberation studies of the emission lines.

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T. Minezaki, Y. Yoshii, Y. Kobayashi, K. Enya, M. Suganuma, H. Tomita, T. Aoki, B. A. Peterson. 2003-11-18. Inner Size of a Dust Torus in the Seyfert 1 Galaxy NGC 4151. https://doi.org/10.1086/381364

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