Characterizing Quasar C iv Emission-line Measurements from Time-resolved Spectroscopy
Characterizing Quasar C iv Emission-line Measurements from Time-resolved Spectroscopy
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DOI：
10.3847/1538-4357/aba62c
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发表时间：
2020-07
期刊：
影响因子：
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通讯作者：
A. Rivera;G. Richards;P. Hewett;A. Rankine
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文献类型：
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作者：
A. Rivera;G. Richards;P. Hewett;A. Rankine
我们使用多历元类星体光谱来确定单历元光谱在发射线参数空间中定位类星体的准确度，以便为无法使用时间分辨光谱的研究提供信息。我们探讨了改进发射线表征，结果从使用非参数信息从许多线，而不是一个单一的线的参数数量少，利用重建的基础上应用到数据的独立分量分析从斯隆数字巡天混响映射项目。我们发现，大多数的类星体都很好地描述了只有两个组件，而更多的组件信号类星体可能会产生一个成功的混响映射分析。在单历元光谱学中，等效宽度的明显变化被夸大了，因为它依赖于连续谱。多历元光谱表明，单历元的结果并没有显着改变类星体位于C IV参数空间，并没有显着影响调查的全球鲍德温效应。类星体的发射线性能指示较高的L/LEdd是可变的，增强吸积盘密度与模型一致。系统红移处的窄吸收特征可能是方向的指示（包括射电宁静类星体），可能出现在多达20%的类星体样本中。未来的工作将这些技术应用于低光度类星体将是重要的了解吸积盘风的性质。
We use multiepoch quasar spectroscopy to determine how accurately single-epoch spectroscopy can locate quasars in emission-line parameter space in order to inform investigations where time-resolved spectroscopy is not available. We explore the improvements in emission-line characterization that result from using nonparametric information from many lines as opposed to a small number of parameters for a single line, utilizing reconstructions based on an independent component analysis applied to the data from the Sloan Digital Sky Survey Reverberation Mapping project. We find that most of the quasars are well described by just two components, while more components signal a quasar likely to yield a successful reverberation mapping analysis. In single-epoch spectroscopy the apparent variability of equivalent width is exaggerated because it is dependent on the continuum. Multiepoch spectroscopy reveals that single-epoch results do not significantly change where quasars are located in C iv parameter space and do not have a significant impact on investigations of the global Baldwin effect. Quasars with emission-line properties indicative of higher L/LEdd are less variable, consistent with models with enhanced accretion disk density. Narrow absorption features at the systemic redshift may be indicative of orientation (including radio-quiet quasars) and may appear in as much as 20% of the quasar sample. Future work applying these techniques to lower-luminosity quasars will be important for understanding the nature of accretion disk winds.