The unified model and the Seyfert 2 infrared dichotomy
The unified model and the Seyfert 2 infrared dichotomy
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DOI：
10.1046/j.1365-8711.2001.04131.x
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发表时间：
2000-10
影响因子：
4.8
通讯作者：
David Alexander
中科院分区：
文献类型：
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作者：
David Alexander
一项光学偏振光谱研究表明，塞弗特2星系中偏振宽H-α的可探测性与IRAS f60/f25通量比相关，其中只有那些具有“温暖”IRAS颜色的塞弗特2星系才会显示偏振宽线发射。有人认为，那些塞弗特2与“冷”的IRAS颜色有高度倾斜的环面，掩盖了广泛的线散射屏幕。我在这里提出的硬X射线观测与这张照片不一致，表明导出的柱密度的温暖和凉爽的塞弗特2星系是统计上相同的。我对亮星系样本进行分类，以产生非塞弗特比较。对这些星系的性质分析表明，IRAS f60/f25通量比与星系对Seyfert辐射的相对强度是一致的。我表明，这张新的图片可以解释没有极化广泛的H-α在凉爽的塞弗特2s。
An optical spectropolarimetric study has shown that the detectability of polarised broad H-alpha in Seyfert 2 galaxies is correlated to the IRAS f60/f25 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 f60/f25 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 H-alpha in the cool Seyfert 2s.