Are Seyfert 2 Galaxies without Polarized Broad Emission Lines More Obscured?
Abstract
New XMM-Newton data of seven Seyfert 2 galaxies with optical spectropolarimetric observations are presented. An analysis of the 0.5-10 keV spectra shows that four Seyfert 2 galaxies with polarized broad lines (PBLs) are absorbed by NH<1024 cm-2, while two of three Seyfert 2 galaxies without PBLs show evidence of Compton-thick obscuration, supporting the conclusion that Seyfert 2 galaxies without PBLs are more obscured than those with PBLs. Adding the measured obscuration indicators (NH, T ratio, and Fe Kα line EW) of six luminous AGNs to our previous sample improves the significance level of the difference in absorption from 92.3% to 96.3% for NH, 99.1% to 99.4% for T ratio, and 95.3% to 97.4% for Fe Kα line EW. The present results support and enhance the suggestions that the absence of PBLs in Seyfert 2 galaxies can be explained by larger viewing angles of the line of sight to the putative dusty torus, which leads to the obscuration of the broad-line scattering screen, as expected in the unification model.
- Publication:
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Chinese Journal of Astronomy and Astrophysics
- Pub Date:
- April 2008
- DOI:
- 10.1088/1009-9271/8/2/07
- arXiv:
- arXiv:0712.0352
- Bibcode:
- 2008ChJAA...8..204S
- Keywords:
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- Astrophysics
- E-Print:
- 9 pages with 3 figures, accepted by ChJAA