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arXiv 1102.3955astro-ph.CO
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Seyfert星系:核射电结构和统一

Seyfert galaxies: Nuclear Radio Structure and Unification

Dharam V. Lal, Prajval Shastri, Denise Gabuzda

摘要:

无线电研究的一个精心挑选的样本的20个塞弗特星系匹配的方向无关的参数,这是措施的内在活动星系核(AGN)的功率和宿主星系的属性,以测试的统一计划假设的预测。由于可行性要求,我们的样品源在5 GHz的弧秒尺度上具有大于8 mJy的核心通量密度。这些pc尺度和kpc尺度的射电观测结果表明:(i)Seyfert 1和Seyfert 2星系在质量尺度上具有相同的致密射电结构的倾向;(ii)Seyfert 1和Seyfert 2星系的pc尺度和kpc尺度的射电光度分布相似;(iii)Seyfert 1和Seyfert 2星系中没有相对论性光束的证据,(iv)尽管Seyfert星系显示出核射电通量密度的变化,但它们的源谱指数分布相似;(v)Seyfert 1和Seyfert 2星系的投影线尺寸分布并不像统一方案中所预期的那样有显著差异。后者可能主要是由于内在尺寸的相对较大的分布。我们还发现,单独的星暴不能为这些射电源提供动力。最后,对CfA Seyfert星系样本的kpc尺度射电性质的分析表明,结果与统一方案的预测一致。

英文摘要:

A radio study of a carefully selected sample of 20 Seyfert galaxies that are matched in orientation-independent parameters, which are measures of intrinsic active galactic nuclei (AGN) power and host galaxy properties is presented to test the predictions of the unified scheme hypothesis. Our sample sources have core flux densities greater than 8 mJy at 5 GHz on arcsec-scales due to the feasibility requirements. These simultaneous pc-scale and kpc-scale radio observations reveal (i) that Seyfert 1 and Seyfert 2 galaxies have equal tendency to show compact radio structures on mas-scales, (ii) the distributions of pc-scale and kpc-scale radio luminosities are similar for both Seyfert 1 and Seyfert 2 galaxies, (iii) no evidence for relativistic beaming in Seyfert galaxies, (iv) similar distributions of source spectral indices in spite of the fact that Seyferts show nuclear radio flux density variations, and (v) the distributions of projected linear size for Seyfert 1 and Seyfert 2 galaxies are not significantly different as would be expected in the unified scheme. The latter could be mainly due to a relatively large spread in the intrinsic sizes. We also find that a starburst alone cannot power these radio sources. Finally, an analysis of the kpc-scale radio properties of the CfA Seyfert galaxy sample shows results consistent with the predictions of the unified scheme.

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