Predicted Fe II Emission-Line Strengths from Active Galactic Nuclei
Predicted Fe II Emission-Line Strengths from Active Galactic Nuclei
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DOI：
10.1086/345498
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发表时间：
2002-06
期刊：
影响因子：
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通讯作者：
T. Sigut;Anil K. Pradhan
中科院分区：
文献类型：
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作者：
T. Sigut;Anil K. Pradhan
我们提出的理论Fe II发射线强度的物理条件下典型的活动星系核宽线区域。Fe II线强度是使用来自铁项目的广泛而准确的原子数据，通过精确处理辐射传递计算出来的。Fe Ⅱ发射的激发机制包括连续荧光、碰撞激发、Fe Ⅱ跃迁间的自荧光以及Lyα和Lyβ的荧光激发。一个包含827个精细结构能级（包括到E = 15 eV的态）的大型Fe II原子模型被用来预测大约23，000个Fe II跃迁的通量，涵盖了大多数天体物理学感兴趣的紫外、光学和红外波长。给出了1600 ~ 1.2 μm波段的光谱合成。本文介绍了现有理论模板在观测分析中的应用。特别地，我们讨论了最近在8500 nm-1 μm区域的近红外Fe II线的观测，这些线是由Lyα荧光机制预测的。我们还比较了我们的紫外光谱合成与经验铁模板的原型，窄线塞弗特星系我ZW 1。在这项工作中提出的理论Fe II模板也应该适用于各种对象的Fe II光谱形成类似的激发条件下，如超新星和共生星。
We present theoretical Fe II emission line strengths for physical conditions typical of active galactic nuclei with broad-line regions. The Fe II line strengths were computed with a precise treatment of radiative transfer using extensive and accurate atomic data from the Iron Project. Excitation mechanisms for the Fe II emission included continuum fluorescence, collisional excitation, self-fluorescence among the Fe II transitions, and fluorescent excitation by Lyα and Lyβ. A large Fe II atomic model consisting of 827 fine structure levels (including states to E ≈ 15 eV) was used to predict fluxes for approximately 23,000 Fe II transitions, covering most of the UV, optical, and IR wavelengths of astrophysical interest. Spectral synthesis for wavelengths from 1600 Å to 1.2 μm is presented. Applications of present theoretical templates to the analysis of observations are described. In particular, we discuss recent observations of near-IR Fe II lines in the 8500 Å-1 μm region which are predicted by the Lyα fluorescence mechanism. We also compare our UV spectral synthesis with an empirical iron template for the prototypical, narrow-line Seyfert galaxy I Zw 1. The theoretical Fe II template presented in this work should also be applicable to a variety of objects with Fe II spectra formed under similar excitation conditions, such as supernovae and symbiotic stars.