Three-dimensional radiative transfer modeling of AGN dusty tori as a
  clumpy two-phase medium
  We investigate the emission of active galactic nuclei (AGN) dusty tori in the
infrared domain. Following theoretical predictions coming from hydrodynamical
simulations, we model the dusty torus as a 3D two-phase medium with
high-density clumps and low-density medium filling the space between the
clumps. Spectral energy distributions (SED) and images of the torus at
different wavelengths are obtained using 3D Monte Carlo radiative transfer code
SKIRT. Our approach of generating clumpy structure allows us to model tori with
single clumps, complex structures of merged clumps or interconnected
sponge-like structure. A corresponding set of clumps-only models and models
with smooth dust distribution is calculated for comparison. We found that dust
distribution, optical depth, clump size and their actual arrangement in the
innermost region, all have an impact on the shape of near- and mid-infrared
SED. The 10 micron silicate feature can be suppressed for some parameters, but
models with smooth dust distribution are also able to produce a wide range of
the silicate feature strength. Finally, we find that having the dust
distributed in a two-phase medium, might offer a natural solution to the lack
of emission in the near-infrared, compared to observed data, which affects
clumpy models currently available in the literature.
