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dc.contributor.authorWang, Feige
dc.contributor.authorYang, Jinyi
dc.contributor.authorFan, Xiaohui
dc.contributor.authorWu, Xue-Bing
dc.contributor.authorYue, Minghao
dc.contributor.authorLi, Jiang-Tao
dc.contributor.authorBian, Fuyan
dc.contributor.authorJiang, Linhua
dc.contributor.authorBañados, Eduardo
dc.contributor.authorSchindler, Jan-Torge
dc.contributor.authorFindlay, Joseph R.
dc.contributor.authorDavies, Frederick B.
dc.contributor.authorDecarli, Roberto
dc.contributor.authorFarina, Emanuele P.
dc.contributor.authorGreen, Richard
dc.contributor.authorHennawi, Joseph F.
dc.contributor.authorHuang, Yun-Hsin
dc.contributor.authorMazzuccheli, Chiara
dc.contributor.authorMcGreer, Ian D.
dc.contributor.authorVenemans, Bram
dc.contributor.authorWalter, Fabian
dc.contributor.authorDye, Simon
dc.contributor.authorLyke, Brad W.
dc.contributor.authorMyers, Adam D.
dc.contributor.authorNunez, Evan Haze
dc.date.accessioned2020-02-01T00:43:28Z
dc.date.available2020-02-01T00:43:28Z
dc.date.issued2019-10-08
dc.identifier.citationFeige Wang et al 2019 ApJ 884 30en_US
dc.identifier.issn0004-637X
dc.identifier.doi10.3847/1538-4357/ab2be5
dc.identifier.urihttp://hdl.handle.net/10150/636845
dc.description.abstractThis 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 less than or similar to z less than or similar to 6.9 from an area of similar to 13,020 deg(2), and present the quasar luminosity function (QLF) at z similar to 6.7. The measured QLF follows Phi(L-1450) proportional to L-1450(-2.35) in the magnitude range 27.6 < M-1450 < 25.5. We determine the quasar comoving spatial density at < z > - 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 similar to 6 to z similar to 6.7, corresponding to a rapid decline by a factor of similar to 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 similar to 3 and 5. We measured quasar comoving emissivity at z similar to 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 greater than or similar to 6.5 is measured to be greater than or similar to 22%. In addition, we also report the discovery of six additional quasars at z similar to 6 in the Appendix.en_US
dc.description.sponsorshipNational Key R&D Program of China [2016YFA0400703]; National Science Foundation of ChinaNational Natural Science Foundation of China [11533001, 11721303]; US NSF grantNational Science Foundation (NSF) [AST-1515115]; NASA ADAP grant [NNX17AF28G]; National Science Foundation through REU grant [AST-1560461]; NOAO program [GN-2018A-C-1]; ESO Programme [179.A-2010, 179.A-2004]; National Aeronautics and Space AdministrationNational Aeronautics & Space Administration (NASA); National Astronomical Observatories, Chinese Academy of SciencesChinese Academy of Sciences; Special Fund for Astronomy from the Ministry of Finance in Chinaen_US
dc.language.isoenen_US
dc.publisherIOP PUBLISHING LTDen_US
dc.rightsCopyright © 2019. The American Astronomical Society. All rights reserved.en_US
dc.subjectearly universeen_US
dc.subjectgalaxies: activeen_US
dc.subjectgalaxies: high-redshiften_US
dc.subjectquasars: generalen_US
dc.titleExploring 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 ∼ 6.7en_US
dc.typeArticleen_US
dc.contributor.departmentUniv Arizona, Steward Observen_US
dc.identifier.journalASTROPHYSICAL JOURNALen_US
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en_US
dc.eprint.versionFinal published versionen_US
dc.source.volume884
dc.source.issue1
dc.source.beginpage30
refterms.dateFOA2020-02-01T00:43:29Z


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