FLARED DUST DISKS AND THE IR EMISSION OF AGN

We describe an accelerated version of the two-dimensional (2D) ray-tra cing code for radiative transfer in disk configurations developed by M en'shchikov & Henning (1997). This new code enabled us to perform an e xtensive scan of the parameter space of flared dust disks around activ e galactic nuclei (AGN). Among the parameters influencing spectral ene rgy distributions, we varied the dust model, the density distribution, the opening angle, and the optical depth of the disks as well as the anisotropy of the radiation field of the central source. Our aim was t o find configurations that produce continuum spectra similar to the ob served ones which show no 10 mu m emission feature along lines of sigh t where the central source is not obscured. We found that optically th ick disks in combination with a strong anisotropic 7 radiation source can produce such spectral energy distributions. The best-fit models sh ow a very high optical depth of tau(200nm) approximate to 1000 (along the equatorial plane), an opening angle of 90 degrees, and a density d istribution proportional to r(-1). As the strong anisotropy of the sou rce radiation prevents significant silicate emission features from app earing, we see no need for the depletion of silicate grains by shocks or for the presence of compact cores.