Exploring Reionization-Era Quasars IV: Discovery of Six New z & 6.5 Quasars with DES, VHS and unWISE Photometry

Jinyi Yang, Feige Wang, Xiaohui Fan, Minghao Yue, Xue Bing Wu, Jiang Tao Li, Fuyan Bian, Linhua Jiang, Eduardo Bañados, Yuri Beletsky

Research output: Contribution to journalArticlepeer-review


This is the fourth paper in a series of publications aiming at discovering quasars at the epoch of reionization. In this paper, we expand our search for z ∼ 7 quasars to the footprint of the Dark Energy Survey (DES) Data Release One (DR1), covering ∼ 5000 deg2 of new area. We select z ∼ 7 quasar candidates using deep optical, near-infrared(near-IR) and mid-IR photometric data from the DES DR1, the VISTA Hemisphere Survey (VHS), the VISTA Kilo-degree Infrared Galaxy (VIKING) survey, the UKIRT InfraRed Deep Sky Surveys – Large Area Survey (ULAS) and the unblurred coadds from the Wide-field Infrared Survey Explore (WISE) images (unWISE). The inclusion of DES and unWISE photometry allows the search to reach ∼ 1 magnitude fainter, comparing to our z & 6.5 quasar survey in the northern sky (Wang et al. 2018b). We report the initial discovery and spectroscopic confirmation of six new luminous quasars at z > 6.4, including an object at z = 7.02, the fourth quasar yet known at z > 7, from a small fraction of candidates observed thus far. Based on the recent measurement of z ∼ 6.7 quasar luminosity function using the quasar sample from our survey in the northern sky, we estimate that there will be & 55 quasars at z > 6.5 at M1450 < −24.5 in the full DES footprint.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Nov 28 2018


  • Galaxies: active
  • Galaxies: high-redshift
  • Quasars: emission lines

ASJC Scopus subject areas

  • General

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