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

Journal Article · Mon Apr 10 00:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA689F· OSTI ID:22661153

Wang, Feige; Yang, Jinyi; Wu, Xue-Bing; Yang, Qian; Li, Zefeng ^[1]; Fan, Xiaohui; McGreer, Ian D.; Ding, Jiani; Green, Richard ^[2]; Bian, Fuyan ^[3]; Li, Jiang-Tao ^[4]; Dey, Arjun ^[5]; Dye, Simon ^[6]; Findlay, Joseph R.; Myers, Adam D. ^[7]; James, David ^[8]; Jiang, Linhua ^[9]; Lang, Dustin ^[10]; Lawrence, Andy; Ross, Nicholas P. ^[11] ; others, and

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1. Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China)
2. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
3. Research School of Astronomy and Astrophysics, Australian National University, Weston Creek, ACT 2611 (Australia)
4. Department of Astronomy, University of Michigan, 311 West Hall, 1085 S. University Avenue, Ann Arbor, MI, 48109 (United States)
5. National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States)
6. School of Physics and Astronomy, Nottingham University, University Park, Nottingham, NG7 2RD (United Kingdom)
7. Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States)
8. Cerro Tololo Inter-American Observatory, Casilla 603 La Serena (Chile)
9. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
10. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario, M5S 3H4 (Canada)
11. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom)

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 deg{sup 2} of sky down to z {sub AB} ∼ 23.0, and UKIDSS and UHS will map the northern sky at 0 < decl. < +60°, reaching J {sub 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 {sub 1450} = −25.83 and M {sub 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 {sub 1450} = −25.95. This demonstrates the potential of using the combined DECaLS and UKIDSS/UHS data sets to find z ≳ 7 quasars. Extrapolating from previous QLF measurements, we predict that these combined data sets will yield ∼200 z ∼ 6 quasars to z {sub AB} < 21.5, ∼1000 z ∼ 6 quasars to z {sub AB} < 23, and ∼30 quasars at z > 6.5 to J {sub VEGA} < 19.5.

• OSTI ID: 22661153
• Journal Information: Astrophysical Journal, Vol. 839, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
EMISSION
GALAXIES
QUASARS
RED SHIFT