The polarization of reprocessed optical and UV emission in thermal Active Galactic Nuclei
Résumé
An important unknown for Seyfert Galaxies is the exact geometry and nature of their inner regions. In particular we still need to learn a lot about the transfer of mass from the dusty torus to the accretion disc and broad line region. Spectropolarimetry is a powerful tool for probing the structure of Seyfert nuclei, but the non-trivial radiative coupling between different reprocessing regions is a major challenge in interpreting the data. Using STOKES, a multi-wavelength, Monte Carlo radiative transfer code for modeling polarization spectra and images, we investigate the polarization signature produced by complex reprocessing in AGNs. We combine several, individual scattering regions that are assumed to exist in AGNs (e.g. the equatorial dusty torus or ionized polar winds). The resulting polarization properties are explored for different viewing angles, geometries, and scattering optical depths. The model puts important constraints on the causes of the observed polarization dichotomy of Seyfert galaxies. We present models to explain the UV and optical polarization spectra and morphology of well-studied Seyfert galaxies.