Xiao-Bo Dong, Luis C. Ho, Jian-Guo Wang, Ting-Gui Wang, Huiyuan Wang, Xiaohui Fan, Hongyan Zhou
Published 2010-09-12Version 1
From detailed spectral analysis of a large sample of low-redshift active galactic nuclei (AGNs) selected from the Sloan Digital Sky Survey, we demonstrate---statistically for the first time---that narrow optical Fe II emission lines, both permitted and forbidden, are prevalent in type 1 AGNs. Remarkably, these optical lines are completely absent in type 2 AGNs, across a wide luminosity range, from Seyfert 2 galaxies to type 2 quasars. We suggest that the narrow FeII-emitting gas is confined to a disk-like geometry in the innermost regions of the narrow-line region on physical scales smaller than the obscuring torus.
Comments: This Letter is separated from arXiv:0903.5020 (sumbitted to ApJ), with more tests on the robustness of the detection of narrow Fe II emission as well as more quantitative details and figures about narrow Fe II emission lines in AGNs. The implementation of the analytical narrow and broad Fe II templates in IDL is available at http://staff.ustc.edu.cn/~xbdong/Data_Release/FeII/Template/
Journal: The Astrophysical Journal Letters, 721, L143-L147 (2010)
What controls the Fe II strength in active galactic nuclei?
Active Galactic Nuclei
The different neighbours around Type-1 and Type-2 active galactic nuclei
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