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Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ? z ? 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ? 6.7

Myers, Adam D.; Wang, Feige; Yang, Jinyi; Fan, Xiaohui; Wu, Xue-Bing; Yue, Minghao; Li, Jiang-Tao; Bian, Fuyan; Jiang, Linhua; Ba�ados, Eduardo; Schindler, Jan-Torge; Findlay, Joseph R.; Davies, Frederick B.; Decarli, Roberto; Farina, Emanuele P.; Green, Richard; Hennawi, Joseph F.; Huang, Yun-Hsin; Mazzuccheli, Chiara; McGreer, Ian D.; Venemans, Bram; Walter, Fabian; Dye, Simon; Lyke, Brad W.; Nunez, Evan Haze

Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ? z ? 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ? 6.7 Thumbnail


Authors

Adam D. Myers

Feige Wang

Jinyi Yang

Xiaohui Fan

Xue-Bing Wu

Minghao Yue

Jiang-Tao Li

Fuyan Bian

Linhua Jiang

Eduardo Ba�ados

Jan-Torge Schindler

Joseph R. Findlay

Frederick B. Davies

Roberto Decarli

Emanuele P. Farina

Richard Green

Joseph F. Hennawi

Yun-Hsin Huang

Chiara Mazzuccheli

Ian D. McGreer

Bram Venemans

Fabian Walter

SIMON DYE Simon.Dye@nottingham.ac.uk
Associate Professor

Brad W. Lyke

Evan Haze Nunez



Abstract

This is the third paper in a series aimed at finding reionization-era quasars with the combination of DESI Legacy imaging Surveys (DELS), the Pan-STARRS1 (PS1) Survey, and near-infrared imaging surveys, such as the UKIRT Hemisphere Survey (UHS), as well as the Wide-field Infrared Survey Explorer (WISE) mid-infrared survey. In this paper, we describe the updated quasar candidate selection procedure, report the discovery of 16 quasars at 6.4 z 6.9 from an area of ~13,020 deg2, and present the quasar luminosity function (QLF) at z ~ 6.7. The measured QLF follows in the magnitude range −27.6 < M 1450 < −25.5. We determine the quasar comoving spatial density at = 6.7 and M 1450 < −26.0 to be 0.39 ± 0.11 Gpc−3 and find the exponential density evolution parameter to be k = −0.78 ± 0.18 from z ~ 6 to z ~ 6.7, corresponding to a rapid decline by a factor of ~6 per unit redshift toward earlier epochs. This indicates that the rapid decline of quasar spatial density at z > 5 that was found by previous works continues to z > 6, at a rate significantly faster than the average decline rate between z ~ 3 and 5. We measured quasar comoving emissivity at z ~ 6.7, which indicates that high-redshift quasars are highly unlikely to make a significant contribution to hydrogen reionization. The broad absorption line quasar fraction at z 6.5 is measured to be 22%. In addition, we also report the discovery of six additional quasars at z ~ 6 in the Appendix.

Citation

Myers, A. D., Wang, F., Yang, J., Fan, X., Wu, X., Yue, M., …Nunez, E. H. (2019). Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7. Astrophysical Journal, 884(1), Article 30. https://doi.org/10.3847/1538-4357/ab2be5

Journal Article Type Article
Acceptance Date Jun 20, 2019
Online Publication Date Oct 8, 2019
Publication Date Oct 10, 2019
Deposit Date Oct 29, 2019
Publicly Available Date Mar 28, 2024
Journal Astrophysical Journal
Print ISSN 1538-4357
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 884
Issue 1
Article Number 30
DOI https://doi.org/10.3847/1538-4357/ab2be5
Keywords Early universe; Galaxies: active; Galaxies: high-redshift; Quasars
Public URL https://nottingham-repository.worktribe.com/output/2987443
Publisher URL https://iopscience.iop.org/article/10.3847/1538-4357/ab2be5
Additional Information Journal title: The Astrophysical Journal; Article type: paper; Article title: Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7; Copyright information: © 2019. The American Astronomical Society. All rights reserved.; Date received: 2018-10-28; Date accepted: 2019-06-20; Online publication date: 2019-10-08

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