Revealing AGN by Polarimetry
  Polarimetric study in the UV and optical has been one of the keys to reveal the structure and nature of active galactic nuclei (AGN). Combined with the HST's high spatial resolution, it has directly confirmed the predicted scattering geometry of ~100 pc scale and accurately located the hidden nuclear position in some nearby active galaxies. Recently, we are using optical spectropolarimetry to reveal the nature of the accretion flow in the central engine of quasars. This is to use polarized light to de-contaminate the spectrum and investigate the Balmer edge spectral feature, which is otherwise buried under the strong emission from the outer region surrounding the central engine. 
Makoto Kishimoto (1), Robert Antonucci (2), Catherine Boisson (3),   Omer Blaes (2) ((1) Univ of Edinburgh, (2) UCSB, (3) Pa...