Testing the AGN Unification Model in the Infrared
  We present near-to-mid-infrared spectral energy distributions (SEDs) for 21
Seyfert galaxies, using subarcsecond resolution imaging data. Our aim is to
compare the properties Seyfert 1 (Sy1) and Seyfert 2 (Sy2) tori using clumpy
torus models and a Bayesian approach to fit the infrared (IR) nuclear SEDs.
These dusty tori have physical sizes smaller than 6 pc radius, as derived from
our fits. Active galactic nuclei (AGN) unification schemes account for a
variety of observational differences in terms of viewing geometry. However, we
find evidence that strong unification may not hold, and that the immediate
dusty surroundings of Sy1 and Sy2 nuclei are intrinsically different. The Type
2 tori studied here are broader, have more clumps, and these clumps have lower
optical depths than those of Type 1 tori. The larger the covering factor of the
torus, the smaller the probability of having direct view of the AGN, and
vice-versa. In our sample, Sy2 tori have larger covering factors
(C_T=0.95+/-0.02) and smaller escape probabilities than those of Sy1
(C_T=0.5+/-0.1). Thus, on the basis of the results presented here, the
classification of a Seyfert galaxy may depend more on the intrinsic properties
of the torus rather than on its mere inclination, in contradiction with the
simplest unification model.
