AGN polarization models

We present model calculations for the scattered flux and polarization of nuclear radiation having in mind the AGN unification scheme. It is our aim to survey the influence of several model parameters, especially, the influence of the torus. Additionally, we considerably improved present models, for instance by including multiple instead of single scattering. For these purposes, we developed a Monte-Carlo radiative transfer code for both electron and dust scattering (Thomson and Rayleigh/Mie scattering). Irradiation from a point-like source can be treated as well as extended anisotropic radiation sources and dust re-emission. We found that the observed wavelength dependence of the linear polarization of some AGNi can be explained by dust scattering in optically thin cones, whereby the additional presence of electrons increases the absolute amount of polarization. The torus geometry and density profile as well as the thermal dust reemission also influence the polarization degree. Multiple scattering in the cones was found to be important for optical depths above ≈ 0.1.