Spectropolarimetry Surveys of Obscured AGNs

The results of spectropolarimetry surveys of obscured AGNs are reviewed, paying special attention to their implications for the existence of two populations of type 2 Seyfert galaxies – hidden Seyfert 1s and “true” Seyfert 2s. In this context, the results from our Keck spectropolarimetry survey are presented. Similar to previous work, we have detected hidden broad-line regions (HBLRs) in about half of our sample. However, owing to different selection methods, we find that differences in the properties of HBLR and non-HBLR objects are much less pronounced than prior reports have indicated. Spectropolarimetry studies continue to benefit AGN research, as illustrated by the discovery of double-peaked H-alpha emission in the polarized-flux spectrum of NGC 2110.