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

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; Andy Lawrence; Adam D. Myers; Nicholas P. Ross; David J. Schlegel; Tom Shanks

doi:10.3847/1538-4357/aa689f

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

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, Andy Lawrence, Adam D. Myers, Nicholas P. RossDavid J. Schlegel, Tom Shanks

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Abstract

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. < +607deg;, 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. 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.

Original language	English
Article number	27
Journal	Astrophysical Journal
Volume	839
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/aa689f
Publication status	Published - 10 Apr 2017

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Wang, F., Fan, X., Yang, J., Wu, X. B., Yang, Q., Bian, F., McGreer, I. D., Li, J. T., Li, Z., Ding, J., Dey, A., Dye, S., Findlay, J. R., Green, R., James, D., Jiang, L., Lang, D., Lawrence, A., Myers, A. D., ... Shanks, T. (2017). First Discoveries of z > 6 Quasars with the DECam Legacy Survey and UKIRT Hemisphere Survey. Astrophysical Journal, 839(1), Article 27. https://doi.org/10.3847/1538-4357/aa689f

@article{c8eab2ab711d4a18ba6ff04400e49d82,

title = "First Discoveries of z > 6 Quasars with the DECam Legacy Survey and UKIRT Hemisphere Survey",

abstract = "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. < +607deg;, 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 {\AA} 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. 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.",

keywords = "galaxies: active, galaxies: high-redshift, quasars: emission lines, quasars: general",

author = "Feige Wang and Xiaohui Fan and Jinyi Yang and Wu, {Xue Bing} and Qian Yang and Fuyan Bian and McGreer, {Ian D.} and Li, {Jiang Tao} and Zefeng Li and Jiani Ding and Arjun Dey and Simon Dye and Findlay, {Joseph R.} and Richard Green and David James and Linhua Jiang and Dustin Lang and Andy Lawrence and Myers, {Adam D.} and Ross, {Nicholas P.} and Schlegel, {David J.} and Tom Shanks",

year = "2017",

month = apr,

day = "10",

doi = "10.3847/1538-4357/aa689f",

language = "English",

volume = "839",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

}

Wang, F, Fan, X, Yang, J, Wu, XB, Yang, Q, Bian, F, McGreer, ID, Li, JT, Li, Z, Ding, J, Dey, A, Dye, S, Findlay, JR, Green, R, James, D, Jiang, L, Lang, D, Lawrence, A, Myers, AD, Ross, NP, Schlegel, DJ & Shanks, T 2017, 'First Discoveries of z > 6 Quasars with the DECam Legacy Survey and UKIRT Hemisphere Survey', Astrophysical Journal, vol. 839, no. 1, 27. https://doi.org/10.3847/1538-4357/aa689f

TY - JOUR

T1 - First Discoveries of z > 6 Quasars with the DECam Legacy Survey and UKIRT Hemisphere Survey

AU - Wang, Feige

AU - Fan, Xiaohui

AU - Yang, Jinyi

AU - Wu, Xue Bing

AU - Yang, Qian

AU - Bian, Fuyan

AU - McGreer, Ian D.

AU - Li, Jiang Tao

AU - Li, Zefeng

AU - Ding, Jiani

AU - Dey, Arjun

AU - Dye, Simon

AU - Findlay, Joseph R.

AU - Green, Richard

AU - James, David

AU - Jiang, Linhua

AU - Lang, Dustin

AU - Lawrence, Andy

AU - Myers, Adam D.

AU - Ross, Nicholas P.

AU - Schlegel, David J.

AU - Shanks, Tom

PY - 2017/4/10

Y1 - 2017/4/10

N2 - 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. < +607deg;, 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. 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.

AB - 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. < +607deg;, 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. 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.

KW - galaxies: active

KW - galaxies: high-redshift

KW - quasars: emission lines

KW - quasars: general

UR - http://www.scopus.com/inward/record.url?scp=85018464235&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aa689f

DO - 10.3847/1538-4357/aa689f

M3 - Article

SN - 0004-637X

VL - 839

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 27

ER -

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

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