The Sloan Digital Sky Survey Reverberation Mapping Project: Systematic Investigations of Short-timescale C IV Broad Absorption Line Variability-猫眼课题宝

DOI：

10.3847/1538-4357/aaf1bf

发表时间：

2018-10

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

Z. Hemler;C. Grier;W. Brandt;P. Hall;K. Horne;Yue Shen;J. Trump;D. P. Schneider;M. Vivek;D. Bizyaev;D. Bizyaev;A. Oravetz;D. Oravetz;K. Pan

我们系统地研究了短时间尺度（<10天的休息框架）Civ宽吸收线（BAL）的变化，以限制类星体风的属性，并提供见解BAL变化机制的类星体。我们采用斯隆数字巡天混响映射项目的数据，因为这些观测的快速节奏提供了一个新的机会，在较短的休息帧时间尺度上探测BAL变异性比以前探索。在27个类星体的样本中，每个类星体的平均光谱历元为58个，我们已经确定了15个类星体（%），37个C iv BAL谷中的19个（%），1460个历元对中的54个（3.7% ± 0.5%），在类星体静止框架中，在小于10天的时间尺度上表现出显着的C iv BAL等效宽度变化。这些频率表明，这种变化在类星体和巴尔斯中很常见，尽管在历元对中有些罕见。因此，描述巴尔斯及其行为的模型必须考虑到类星体静止框架中时间尺度的变化，这种变化小于一天。我们还研究了各种光谱特性，并发现，在某些情况下，BAL的变异性是最好的电离状态的变化，而其他情况下更符合覆盖分数或列密度的变化。我们采用了一个简单的模型来约束的密度和径向距离的两个外流出现不同的电离状态的变化，产生外流密度下限与以前的工作一致。

We systematically investigate short-timescale (<10 day rest-frame) C iv broad absorption-line (BAL) variability to constrain quasar-wind properties and provide insights into BAL-variability mechanisms in quasars. We employ data taken by the Sloan Digital Sky Survey Reverberation Mapping project, as the rapid cadence of these observations provides a novel opportunity to probe BAL variability on shorter rest-frame timescales than have previously been explored. In a sample of 27 quasars with a median of 58 spectral epochs per quasar, we have identified 15 quasars ( %), 19 of 37 C iv BAL troughs ( %), and 54 of 1460 epoch pairs (3.7% ± 0.5%) that exhibit significant C iv BAL equivalent-width variability on timescales of less than 10 days in the quasar rest frame. These frequencies indicate that such variability is common among quasars and BALs, though somewhat rare among epoch pairs. Thus, models describing BALs and their behavior must account for variability on timescales down to less than a day in the quasar rest frame. We also examine a variety of spectral characteristics and find that, in some cases, BAL variability is best described by ionization-state changes, while other cases are more consistent with changes in covering fraction or column density. We adopt a simple model to constrain the density and radial distance of two outflows appearing to vary by ionization-state changes, yielding outflow density lower limits consistent with previous work.

The Sloan Digital Sky Survey Reverberation Mapping Project: Systematic Investigations of Short-timescale C IV Broad Absorption Line Variability

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