The optical polarization signatures of fragmented equatorial dusty
  structures in Active Galactic Nuclei
  If the existence of an obscuring circumnuclear region around the innermost
regions of active galactic nuclei (AGN) has been observationally proven, its
geometry remains highly uncertain. The morphology usually adopted for this
region is a toroidal structure, but other alternatives, such as flared disks,
can be a good representative of equatorial outflows. Those two geometries
usually provide very similar spectroscopic signatures, even when they are
modeled under the assumption of fragmentation. In this lecture note, we show
that the resulting polarization signatures of the two models, either a torus or
a flared disk, are quite different from each other. We use a radiative transfer
code that computes the 2000 - 8000 angstrom polarization of the two
morphologies in a clumpy environment, and show that varying the sizes of a
toroidal region has deep impacts onto the resulting polarization, while the
polarization of flared disks is independent of the outer radius. Clumpy flared
disks also produce higher polarization degrees (about 10 % at best) together
with highly variable polarization position angles.
