发表机构
National Centre for Radio Astrophysics, Tata Institute of Fundamental Research; Department of Physics and Astronomy, National Institute of Technology, Rourkela（塔塔基础研究院国家射电天文中心; 鲁尔基拉国家技术理工学院物理与天文学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文检查SDSS DR16中655个高红移类星体，发现19.1%实为低红移源，因谱线误识别所致，推荐使用Z_FIT红移估计值。
AI 中文摘要
高红移类星体（$z>5$）对于研究早期黑洞增长和再电离至关重要。SDSS 数据发布16（DR16）目录列出了655个此类源，并提供了多种红移估计值。我们系统地检查了这一子样本，发现其中480个源（占73.2%）的管线红移（Z\\_DR16Q）与推导估计值（Z\\_FIT）存在显著差异。目视检查证实，其中125个源（占总数的19.1%）实际上是低红移活动星系核。在114个案例中，宽的 Mg\\,{\sc ii} 连同 C\\,{\sc iii} 和 C\\,{\sc iv} 被误识别为 Ly$\alpha$；在11个案例中，H$\alpha$ 被误识别为 Ly$\alpha$。这一错误可通过 Ly$\alpha$ 蓝端缺乏 Gunn--Peterson trough 立即显现。关键在于，在发射线显著的受影响源中，Z\\_FIT 能恢复正确的红移，表明该算法是可靠的；问题在于社区倾向于使用 Z\\_DR16Q 或 Z\\_SPEC。我们强烈呼吁对 $z>5$ DR16Q 源的管线红移不要不加批判地使用，并推荐 Z\\_FIT 作为首选估计值。
英文摘要
High-redshift quasars ($z>5$) are crucial for studying early black hole growth and reionisation. SDSS Data Release 16 catalogues 655 such sources with multiple redshift estimators. We systematically examined this subsample and found 480 sources (73.2\%) where pipeline redshift (Z\_DR16Q) disagrees with the derived estimate (Z\_FIT) significantly. Visual inspection confirms that 125 of these (19.1\% of the total) are actually low-redshift active galactic nuclei. In 114 cases, broad Mg\,{\sc ii} with C\,{\sc iii} and C\,{\sc iv} was misidentified as Ly$α$; in 11 cases, H$α$ was misidentified as Ly$α$. This error is immediately revealed by the absence of Gunn--Peterson trough blueward of Ly$α$. Crucially, Z\_FIT recovers correct redshift in the affected sources where emission lines are prominent, indicating the algorithm is sound; the issue lies in community preference for Z\_DR16Q or Z\_SPEC. We urge caution against uncritical use of pipeline redshifts for $z>5$ DR16Q sources and recommend Z\_FIT as the preferred estimator.
Comments3 pages, 1 figure, Published in RNAAS
