Analysis of the impact of broad absorption lines on quasar redshift measurements with synthetic observations
Analysis of the impact of broad absorption lines on quasar redshift measurements with synthetic observations
复制标题
通过综合观测分析宽吸收线对类星体红移测量的影响
DOI：
10.1093/mnras/stad2993
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发表时间：
2023
影响因子：
4.8
通讯作者：
García L
中科院分区：
文献类型：
--
作者：
García L
准确的类星体分类和红移测量对于精密宇宙学实验越来越重要。宽吸收线 (BAL) 特征存在于 15-20% 的类星体中，这些特征可能会引入系统红移误差，在极端情况下会产生错误分类。我们使用合成光谱定量研究 BAL 特征对类星体分类和红移测量的影响，这些合成光谱旨在与暗能量光谱仪器 (DESI) 调查的观测结果相匹配。 DESI 的目标是在 5 年的时间里测量 4000 万个星系和类星体的光谱，其中包括近 300 万个类星体。我们的合成类星体光谱与 DESI 观测第一年的信噪比和红移分布相匹配，并且包括具有和不具有 BAL 特征的相同合成类星体光谱。我们证明，掩盖 BAL 特征的位置可将红移误差减少约 1%，并将灾难性红移误差的数量减少约 80%。我们得出的结论是，识别和掩盖 BAL 槽应该成为 DESI 和其他大规模类星体光谱调查的红移确定步骤的标准部分。
Accurate quasar classifications and redshift measurements are increasingly important to precision cosmology experiments. Broad absorption line (BAL) features are present in 15–20 per cent of all quasars, and these features can introduce systematic redshift errors, and in extreme cases produce misclassifications. We quantitatively investigate the impact of BAL features on quasar classifications and redshift measurements with synthetic spectra that were designed to match observations by the Dark Energy Spectroscopic Instrument (DESI) survey. Over the course of 5 yr, DESI aims to measure spectra for 40 million galaxies and quasars, including nearly three million quasars. Our synthetic quasar spectra match the signal-to-noise ratio and redshift distributions of the first year of DESI observations, and include the same synthetic quasar spectra both with and without BAL features. We demonstrate that masking the locations of the BAL features decreases the redshift errors by about 1 per cent and reduces the number of catastrophic redshift errors by about 80 per cent. We conclude that identifying and masking BAL troughs should be a standard part of the redshift determination step for DESI and other large-scale spectroscopic surveys of quasars.