What Determines the Depth of Broad Absorption Lines? Keck HIRES Observations of BALQSO 1603+3002
What Determines the Depth of Broad Absorption Lines? Keck HIRES Observations of BALQSO 1603+3002
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什么决定了宽吸收线的深度？
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
M. de Kool
中科院分区：
文献类型：
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作者：
N. Arav;R. Becker;S. Laurent;M. Gregg;R. White;M. Brotherton;M. de Kool
我们发现BALQSO 1603+3002中宽吸收线（巴尔斯）的深度和形状在很大程度上取决于被BAL流覆盖的发射源的分数。此外，巴尔斯的观测深度与其真实的光学深度的相关性很差。这一结果意味着，根据直接从吸收槽深度提取柱密度进行丰度研究是不可靠的。我们的结论是基于对来自同一离子的两条线（在这种情况下是Si IV双峰）的未混合吸收特征的分析，这允许明确分离覆盖因子和光学深度效应。覆盖因子作为速度的函数的复杂形态表明巴尔斯是由几个物理上分离的流出产生的。覆盖因子在深度和速度宽度上都与离子有关。我们还发现在BALQSO 1603+3002的流动不覆盖广泛的发射线区域的证据。
We find that the depth and shape of the broad absorption lines (BALs) in BALQSO 1603+3002 are determined largely by the fraction of the emitting source which is covered by the BAL flow. In addition, the observed depth of the BALs is poorly correlated with their real optical depth. The implication of this result is that abundance studies based on direct extraction of column densities from the depth of the absorption troughs are unreliable. Our conclusion is based on analysis of unblended absorption features of two lines from the same ion (in this case the Si IV doublet), which allows unambiguous separation of covering factor and optical depth effects. The complex morphology of the covering factor as a function of velocity suggests that the BALs are produced by several physically separated outflows. The covering factor is ion dependent in both depth and velocity width. We also find evidence that in BALQSO 1603+3002 the flow does not cover the broad emission line region.