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 language||English (US)|
|State||Published - Nov 28 2018|
- Galaxies: active
- Galaxies: high-redshift
- Quasars: emission lines
ASJC Scopus subject areas