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Title: First Discoveries of z > 6 Quasars with the DECam Legacy Survey and UKIRT Hemisphere Survey

Journal Article · · The Astrophysical Journal (Online)
ORCiD logo [1];  [2]; ORCiD logo [1]; ORCiD logo [3];  [1]; ORCiD logo [4]; ORCiD logo [5];  [6];  [3]; ORCiD logo [5]; ORCiD logo [7]; ORCiD logo [8];  [9];  [5];  [10]; ORCiD logo [3]; ORCiD logo [11];  [12];  [9];  [13] more »; ORCiD logo [14];  [15] « less
  1. Peking Univ., Beijing (China); Univ. of Arizona, Tucson, AZ (United States)
  2. Univ. of Arizona, Tucson, AZ (United States); Peking Univ., Beijing (China)
  3. Peking Univ., Beijing (China)
  4. Australian National Univ., Canberra, ACT (Australia)
  5. Univ. of Arizona, Tucson, AZ (United States)
  6. Univ. of Michigan, Ann Arbor, MI (United States)
  7. National Optical Astronomy Observatory, Tucson, AZ (United States)
  8. Univ. of Nottingham (United Kingdom)
  9. Univ. of Wyoming, Laramie, WY (United States)
  10. Cerro Tololo Inter-American Observatory (CTIO), La Serena (Chile); Univ. of Washington, Seattle, WA (United States)
  11. Univ. of Toronto, ON (Canada)
  12. Univ. of Edinburgh, Scotland (United Kingdom). Royal Observatory
  13. Univ. of Edinburgh, Scotland (United Kingdom). Royal Observatory; Drexel Univ., Philadelphia, PA (United States)
  14. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  15. Durham Univ. (United Kingdom)
+ Show Author Affiliations

In this paper, we present the first discoveries from a survey of z ≳ 6 quasars using imaging data from the DECam Legacy Survey (DECaLS) in the optical, the UKIRT Deep Infrared Sky Survey (UKIDSS) and a preliminary version of the UKIRT Hemisphere Survey (UHS) in the near-IR, and ALLWISE in the mid-IR. DECaLS will image 9000 deg2 of sky down to z AB ~ 23.0, and UKIDSS and UHS will map the northern sky at 0 < decl. < +60°, reaching J VEGA ~ 19.6 (5-σ). The combination of these data sets allows us to discover quasars at redshift z ≳ 7 and to conduct a complete census of the faint quasar population at z ≳ 6. In this paper, we report on the selection method of our search, and on the initial discoveries of two new, faint z ≳ 6 quasars and one new z = 6.63 quasar in our pilot spectroscopic observations. The two new z ~ 6 quasars are at z = 6.07 and z = 6.17 with absolute magnitudes at rest-frame wavelength 1450 Å being M 1450 = -25.83 and M 1450 = -25.76, respectively. These discoveries suggest that we can find quasars close to or fainter than the break magnitude of the Quasar Luminosity Function (QLF) at z ≳ 6. The new z = 6.63 quasar has an absolute magnitude of M 1450 = -25.95. This demonstrates the potential of using the combined DECaLS and UKIDSS/UHS data sets to find z ≳ 7 quasars. Finally, extrapolating from previous QLF measurements, we predict that these combined data sets will yield ~200 z ~ 6 quasars to z AB < 21.5, ~1000 z ~ 6 quasars to z AB < 23, and ~30 quasars at z > 6.5 to J VEGA < 19.5.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE; National Science Foundation (NSF); National Natural Science Foundation of China (NSFC); National Key Basic Research Program of China; Ministry of Science and Technology of China; Strategic Priority Research Program (China); Science and Technology Facilities Council (STFC) (United Kingdom)
Grant/Contract Number:
AC02-05CH11231; AST 15-15115; 11373008; 11533001; 2014CB845700; 2016YFA0400703; XDB09000000
OSTI ID:
1379803
Journal Information:
The Astrophysical Journal (Online), Vol. 839, Issue 1; ISSN 1538-4357
Publisher:
Institute of Physics (IOP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 51 works
Citation information provided by
Web of Science

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79 ASTRONOMY AND ASTROPHYSICS
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