The Unified model and the Seyfert 2 infrared dichotomy 3

نویسنده

  • D. M. Alexander
چکیده

An optical spectropolarimetric study has shown that the detectability of polarised broad Hα in Seyfert 2 galaxies is correlated to the IRAS f 60 /f 25 flux ratio where only those Seyfert 2s with " warm " IRAS colours show polarised broad line emission. It was suggested that those Seyfert 2s with " cool " IRAS colours have highly inclined tori which obscure the broad line scattering screen. I present here hard X-ray observations inconsistent with this picture showing that the derived column densities of warm and cool Seyfert 2 galaxies are statistically the same. I classify the Bright Galaxy Sample to produce a non-Seyfert comparison. The analysis of the properties of these galaxies with the Seyfert 2s suggest that the IRAS f 60 /f 25 flux ratio is consistent with implying the relative strength of galactic to Seyfert emission. I show that this new picture can account for the absence of polarised broad Hα in the cool Seyfert 2s.

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تاریخ انتشار 2000