HIDDEN BROAD LINE SEYFERT 2 GALAXIES IN THE CfA AND 12μm SAMPLES

We report the results of a spectropolarimetric survey of the CfA and 12μm samples of Seyfert 2 galaxies (S2s). Polarized (hidden) broad line regions (HBLRs) are confirmed in a number of galaxies, and several new cases (F02581–1136, MCG -3-58-7, NGC 5995, NGC 6552, NGC 7682) are reported. The 12μm S2 sample shows a significantly higher incidence of HBLR (50%) than its CfA counterpart (30%), suggesting that the latter may be incomplete in hidden AGNs. Compared to the non-HBLR S2s, the HBLR S2s display distinctly higher radio power relative to their far-infrared output and hotter dust temperature as indicated by the f25/f60 color. However, the level of obscuration is indistinguishable between the two types of S2. These results strongly support the existence of two intrinsically different populations of S2: one harboring an energetic, hidden S1 nucleus with BLR, and the other, a “pure S2”, with weak or absent S1 nucleus and a strong, perhaps dominating starburst component. Thus, the simple purely orientation-based unification model is not applicable to all Seyfert galaxies. Subject headings: galaxies:active — galaxies: Seyfert — polarization