Citation: Inglis , M D , Young , S , Hough , J , Axon , D J , Bailey , J & Ward , M J 1994 , Spatially Resolved Spectropolarimetry of NGC 1068 . in In: Procs of The First Stromlo Symposium: The Physics of Active Galaxies, ASP Conference Series 54 . Astronomical Society of the Pacific , pp. 313-4 .
A turning point in the study of AGN was the discovery of broad hydrogen lines seen in polarized light in the nucleus of NGC 1068 (Antonucci and Miller 1985). A model was developed whereby the scatterers responsible for continuum and broad line polarization are located above and below the optically and geometrically thick torus which obscures our direct view of the Seyfert 1 nucleus, and hence the object appears as a Seyfert 2 galaxy. A cone shaped region of high ionization gas aligned with the radio axis and emanating from the nucleus is seen clearly in an interference filter image (Pogge 1988a). It is now widely accepted that the gas is photoionized by nuclear radiation which only illuminates the conical zone.
Original paper can be found at: http://www.astrosociety.org/pubs/cs/035-069.html--Copyright Astronomical Society of the Pacific