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

Research output: Contribution to journalArticle

  • Feige Wang
  • Xiaohui Fan
  • Jinyi Yang
  • Xue-Bing Wu
  • Qian Yang
  • Fuyan Bian
  • Ian D. McGreer
  • Jiang-Tao Li
  • Zefeng Li
  • Jiani Ding
  • Arjun Dey
  • Simon Dye
  • Joseph R. Findlay
  • Richard Green
  • David James
  • Linhua Jiang
  • Dustin Lang
  • Adam D. Myers
  • David J. Schlegel
  • Tom Shanks

Related Edinburgh Organisations

Original languageEnglish
Article number27
Number of pages8
JournalAstrophysical Journal
Volume839
Issue number1
DOIs
Publication statusPublished - 11 Apr 2017

Abstract

We present the first discoveries from a survey of z greater than or similar to 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(2) of sky down to z(AB) similar to 23.0, and UKIDSS and UHS will map the northern sky at 0 <decl. <+ 60 degrees, reaching J(VEGA) similar to 19.6 (5-sigma). The combination of these data sets allows us to discover quasars at redshift z greater than or similar to 7 and to conduct a complete census of the faint quasar population at z greater than or similar to 6. In this paper, we report on the selection method of our search, and on the initial discoveries of two new, faint z greater than or similar to 6 quasars and one new z = 6.63 quasar in our pilot spectroscopic observations. The two new z similar to 6 quasars are at z = 6.07 and z = 6.17 with absolute magnitudes at rest-frame wavelength 1450 angstrom 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 greater than or similar to 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 greater than or similar to 7 quasars. Extrapolating from previous QLF measurements, we predict that these combined data sets will yield similar to 200 z similar to 6 quasars to z(AB) <21.5, similar to 1000 z similar to 6 quasars to z(AB) <23, and similar to 30 quasars at z > 6.5 to J(VEGA) <19.5.

    Research areas

  • galaxies: active, galaxies: high-redshift, quasars: emission lines, quasars: general, DIGITAL SKY SURVEY, FIELD SPECTROGRAPH WIFES, INFRARED-SURVEY-EXPLORER, Z-GREATER-THAN-5.7 QUASARS, LUMINOSITY FUNCTION, ADDITIONAL QUASARS, REDSHIFT, PAN-STARRS1, Z-SIMILAR-TO-6, STRIPE

ID: 54802440