Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7
Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7
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DOI：
10.3847/1538-4357/ab2be5
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发表时间：
2018-10
期刊：
影响因子：
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通讯作者：
Feige Wang;Jinyi Yang;Xiaohui Fan;Xue-bing Wu;M. Yue;Jiangtao Li;F. Bian;Linhua Jiang;E. B
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文献类型：
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作者：
Feige Wang;Jinyi Yang;Xiaohui Fan;Xue-bing Wu;M. Yue;Jiangtao Li;F. Bian;Linhua Jiang;E. B
这是旨在通过结合DESI遗留成像测量(DELS)、泛STARRS1(PS1)测量和近红外成像测量(如UKIRT半球测量(UHS))以及广域红外测量探测器(WISE)中红外测量来发现再电离时代类星体的系列论文中的第三篇。在本文中，我们描述了最新的类星体候选选择过程，报道了在6.4≲z≲6.9时从∼13,020°2区域发现了16个类星体，并给出了z∼6.7时的类星体光度函数。测量到的类星体在−27.6 5星等范围内，这是前人发现的持续到z>；6的星等范围，其速率明显快于z∼3和z∼5之间的平均衰减率。我们测量了类星体在z∼6.7时的联合发射率，这表明高红移类星体不太可能对氢再电离做出重大贡献。在z≳6.5时测得宽吸收线类星体分数为≳22%。此外，我们还在附录中报告了在z∼6上发现的另外六个类星体。
This is the third paper in a series aimed at finding reionization-era quasars with the combination of DESI Legacy imaging Surveys (DELS), the Pan-STARRS1 (PS1) Survey, and near-infrared imaging surveys, such as the UKIRT Hemisphere Survey (UHS), as well as the Wide-field Infrared Survey Explorer (WISE) mid-infrared survey. In this paper, we describe the updated quasar candidate selection procedure, report the discovery of 16 quasars at 6.4 ≲ z ≲ 6.9 from an area of ∼13,020 deg2, and present the quasar luminosity function (QLF) at z ∼ 6.7. The measured QLF follows in the magnitude range −27.6 5 that was found by previous works continues to z > 6, at a rate significantly faster than the average decline rate between z ∼ 3 and 5. We measured quasar comoving emissivity at z ∼ 6.7, which indicates that high-redshift quasars are highly unlikely to make a significant contribution to hydrogen reionization. The broad absorption line quasar fraction at z ≳ 6.5 is measured to be ≳22%. In addition, we also report the discovery of six additional quasars at z ∼ 6 in the Appendix.