Implications from the optical to UV flux ratio of FeII emission in quasars
Implications from the optical to UV flux ratio of FeII emission in quasars
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DOI：
10.1111/j.1365-2966.2010.17498.x
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发表时间：
2010-08
期刊：
影响因子：
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通讯作者：
H. Sameshima;K. Kawara;Y. Matsuoka;S. Oyabu;N. Asami;N. Ienaka
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文献类型：
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作者：
H. Sameshima;K. Kawara;Y. Matsuoka;S. Oyabu;N. Asami;N. Ienaka
我们通过分析斯隆数字巡天 (SDSS) 类星体目录中 884 个类星体的 Fe II(UV)、Fe II(�4570) 和 Mg II 发射线，研究红移范围为 0:727 < z < 0:804 的 AGN 宽线区 (BLR) 中的 Fe II 发射线。 Fe II(�4570)/Fe II(UV)用于推断Fe II发射云的柱密度并探索Fe II发射线的激发机制。正如之前在各种工作中所建议的，经典光电离模型无法将 Fe II(�4570)/Fe II(UV) 解释为 10 倍，这可能表明 UV Fe II 发射的各向异性；否则，另一种加热机制（如电击）正在发挥作用。由 Fe II(�4570)/Fe II(UV) 得出的柱密度分布表明辐射压在 BLR 气体动力学中起着重要作用。我们发现 Fe II(�4570)/Fe II(UV) 与爱丁顿比率之间呈正相关。我们还发现，几乎所有 Fe II 发射云都处于超爱丁顿条件下，除非电离光子分数比之前建议的小得多。最后，我们提出了对各种发射线特性之间一组引人注目的相关性的物理解释，称为“特征向量 1”。
We investigate Fe II emission in Broad Line Region (BLR) of AGNs by analyzing the Fe II(UV), Fe II(�4570) and Mg II emission lines in 884 quasars in the Sloan Digital Sky Survey (SDSS) Quasar catalog in a redshift range of 0:727 < z < 0:804. Fe II(�4570)/Fe II(UV) is used to infer the column density of Fe II-emitting clouds and explore the excitation mechanism of Fe II emission lines. As suggested before in various works, the classical photoionization models fail to account for Fe II(�4570)/Fe II(UV) by a factor of 10, which may suggest anisotropy of UV Fe II emission; otherwise, an alternative heating mechanism like shock is working. The column density distribution derived from Fe II(�4570)/Fe II(UV) indicates that radiation pressure plays an important role in BLR gas dynamics. We find a positive correlation between Fe II(�4570)/Fe II(UV) and the Eddington ratio. We also find that almost all Fe IIemitting clouds are to be under super-Eddington conditions unless ionizing photon fraction is much smaller than that previously suggested. Finally we propose a physical interpretation of a striking set of correlations between various emission-line properties, known as “Eigenvector 1”.