Probing the dusty environment of the Seyfert 1 nucleus in NGC 3783 with MIDI/VLTI interferometry
Beckert, T., Driebe, T., Hoenig, S., Weigelt, G.
Astronomy and Astrophysics, Volume 486, Issue 3, pp.L17-L20 (2008)
Abstract
We present mid-IR spectro-interferometry of the Seyfert type 1 nucleus of NGC 3783. The dusty circumnuclear environment is spatially resolved and the wavelength dependence
of the compact emission is discussed. The observations were carried out with the MIDI instrument at the Very Large Telescope Interferometer in the N-band. Spectra and
visibilities were derived with a spectral resolution of 30 in the wavelength range from 8 to 13 micron. For the interpretation we developed a simple dusty disk model with
small and variable covering factor. At baselines of 65 and 69 m, visibilities in the range of 0.4 to 0.7 were measured. The N-band spectra show a monotonic increase of the
measured flux with wavelength with no apparent silicate feature around 10 micron. We find that the mid-IR emission from the nucleus can be reproduced by an extended dust
disk or torus with a small covering factor of the radiating dust clouds. Our mid-IR observations of NGC 3783 are consistent with a clumpy circumnuclear dust environment.
The interpretation in terms of a dusty torus with low covering factor supports a clumpy version of the unified scheme for AGN. The inferred sizes and luminosities are in
good agreement with dust reverberation sizes and bolometric luminosities from optical and X-ray observations.
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