Spectropolarimetry of high-polarization Seyfert 2 galaxies and unified Seyfert theories
Spectropolarimetry was used to study eight high-polarization Seyfert 2galaxies. In four of them (Mrk 3, Mrk 348, Mrk 463E, and NGC 7674),evidence was found for a hidden broad-line region (BLR), visible only inthe polarized flux spectrum. The other four objects, Mrk 78, Mrk 1066,NGC 591, and NGC 7672, may also have hidden BLRs, but at a flux levelbelow the detection threshold. The properties of the hidden BLRs areconsistent with their normal Seyfert 1 nuclei. If all Seyfert 2 galaxiesare in reality Seyfert 1 galaxies in which the nuclei are hidden fromdirect view and seen only in scattered light, then one might expect thatmany Seyfert 2 galaxies have polarizations of their featureless continuagreater than 50 percent. Such high polarization are not seen, perhapsindicating a particular geometry, in which nearly edge-on obscuring torialso block light from the scattering region. This model predicts that,in edge-on cases, little or no featureless continua in the spectra ofthe objects will be detected. Arguments are presented that objects withhigh luminosity, such as QSOs, have geometrically thin tori and henceare much less likely to have obscured continua and BLRs.
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