Publications of the MPIfR
Optical & Infrared
Interferometry Group
Hönig, S., Beckert, T., Ohnaka, K.,
Weigelt, G.
Radiative Transfer Modeling of
Three-Dimensional
Clumpy AGN Tori and its Application to NGC1068
Astronomy & Astrophysics, vol.452, pg. 459
(2006)
Abstract
Recent observations of NGC1068 and other AGN support the idea of a
geometrically and optically thick dust torus
surrounding the central supermassive black hole and accretion disk of
AGN. In type 2 AGN, the torus is seen roughly edge-on,
leading to obscuration of the central radiation source and a silicate
absorption feature near 10 µm. While most of the current
torus models distribute the dust smoothly, there is growing evidence
that the dust must be arranged in clouds. We describe a
new method for modeling near- and mid-infrared emission of
3-dimensional clumpy tori using Monte Carlo simulations. We
calculate the radiation fields of individual clouds at various
distances from the AGN and distribute these clouds within the torus
region. The properties of the individual clouds and their distribution
within the torus are determined from a theoretical approach
of self-gravitating clouds close to the shear limit in a gravitational
potential. We demonstrate that clumpiness in AGN tori can
overcome the problem of over-pronounced silicate features. Finally, we
present model calculations for the prototypical Seyfert
2 galaxy NGC1068 and compare them to recent high-resolution
measurements. Our model is able to reproduce both the SED
and the interferometric observations of NGC1068 in the near- and
mid-infrared.
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