Recently, the existence of geometrically thick dust structures in Active
Galactic Nuclei (AGN) has been directly proven with the help of mid-infrared
interferometry. The observations are consistent with a two-component model made
up of a geometrically thin and warm central disk, surrounded by a colder,
fluffy torus component. In an exploratory study, we investigate one possible
physical mechanism, which could produce such a structure, namely the effect of
stellar feedback from a young nuclear star cluster on the interstellar medium
in centres of AGN. The model is realised with the help of the hydrodynamics
code TRAMP. We follow the evolution of the interstellar medium by taking
discrete mass loss and energy ejection due to stellar processes, as well as
optically thin radiative cooling into account. In a post-processing step, we
calculate observable quantities (spectral energy distributions and images) with
the help of the radiative transfer code MC3D. The interplay between injection
of mass, supernova explosions and radiative cooling leads to a two-component
structure made up of a cold geometrically thin, but optically thick and very
turbulent disk residing in the vicinity of the angular momentum barrier,
surrounded by a filamentary structure. The latter consists of cold long radial
filaments flowing towards the disk and a hot tenuous medium in between, which
shows both inwards and outwards directed motions. This modelling is able to
reproduce the range of observed neutral hydrogen column densities of a sample
of Seyfert galaxies as well as the relation between them and the strength of
the silicate 10 micron spectral feature. Despite being quite crude, our mean
Seyfert galaxy model is even able to describe the SEDs of two intermediate type
Seyfert galaxies observed with the Spitzer Space Telescope.Comment: 16 pages, 11 figures, accepted by MNRAS, high resolution version can
be downloaded from:
http://www.mpe.mpg.de/~mschartm/papers/schartmann_2008b.pd