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arXiv · 1703.03526

Discovery of 16 New z ~ 5.5 Quasars : Filling in the Redshift Gap of Quasar Color Selection

Jinyi Yang·Xiaohui Fan·Xue-Bing Wu·Feige Wang·Fuyan Bian·Qian Yang·Ian D. McGreer·Weimin Yi·Linhua Jiang·Richard Green·Minghao Yue·Shu Wang·Zefeng Li·Jiani Ding·Simon Dye·Andy Lawrence
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Abstract

We present initial results from the first systematic survey of luminous $z\sim 5.5$ quasars. Quasars at $z \sim$ 5.5, the post-reionization epoch, are crucial tools to explore the evolution of intergalactic medium, quasar evolution and the early super-massive black hole growth. However, it has been very challenging to select quasars at redshifts 5.3 $\le z \le$ 5.7 using conventional color selections, due to their similar optical colors to late-type stars, especially M dwarfs, resulting in a glaring redshift gap in quasar redshift distributions. We develop a new selection technique for $z \sim$ 5.5 quasars based on optical, near-IR and mid-IR photometric data from Sloan Digital Sky Survey (SDSS), UKIRT InfraRed Deep Sky Surveys - Large Area Survey (ULAS), VISTA Hemisphere Survey (VHS) and Wide field Infrared Survey Explorer (WISE). From our pilot observations in SDSS-ULAS/VHS area, we have discovered 15 new quasars at 5.3 $\le z \le$ 5.7 and 6 new lower redshift quasars, with SDSS z band magnitude brighter than 20.5. Including other two $z \sim$ 5.5 quasars already published in our previous work, we now construct an uniform quasar sample at 5.3 $\le z \le$ 5.7 with 17 quasars in a $\sim$ 4800 square degree survey area. For further application in a larger survey area, we apply our selection pipeline to do a test selection by using the new wide field J band photometric data from a preliminary version of the UKIRT Hemisphere Survey (UHS). We successfully discover the first UHS selected $z \sim$ 5.5 quasar.

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Jinyi Yang, Xiaohui Fan, Xue-Bing Wu, Feige Wang, Fuyan Bian, Qian Yang, Ian D. McGreer, Weimin Yi, Linhua Jiang, Richard Green, Minghao Yue, Shu Wang, Zefeng Li, Jiani Ding, Simon Dye, Andy Lawrence. 2017-03-10. Discovery of 16 New z ~ 5.5 Quasars : Filling in the Redshift Gap of Quasar Color Selection. https://doi.org/10.3847/1538-3881%2Faa6577

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