@article{5403bd6ab14146c99ca7b9bf986dad1d,
title = "The Discovery of a Gravitationally Lensed Quasar at z = 6.51",
abstract = "Strong gravitational lensing provides a powerful probe of the physical properties of quasars and their host galaxies. A high fraction of the most luminous high-redshift quasars was predicted to be lensed due to magnification bias. However, no multiple imaged quasar was found at z > 5 in previous surveys. We report the discovery of J043947.08+163415.7, a strongly lensed quasar at z = 6.51, the first such object detected at the epoch of reionization, and the brightest quasar yet known at z > 5. High-resolution Hubble Space Telescope imaging reveals a multiple imaged system with a maximum image separation θ ∼ 0.″2, best explained by a model of three quasar images lensed by a low-luminosity galaxy at z ∼ 0.7, with a magnification factor of ∼50. The existence of this source suggests that a significant population of strongly lensed, high-redshift quasars could have been missed by previous surveys, as standard color selection techniques would fail when the quasar color is contaminated by the lensing galaxy.",
keywords = "gravitational lensing: strong, quasars: individual (J0439+1634), quasars: supermassive black holes",
author = "Xiaohui Fan and Feige Wang and Jinyi Yang and Keeton, {Charles R.} and Minghao Yue and Ann Zabludoff and Fuyan Bian and Marco Bonaglia and Georgiev, {Iskren Y.} and Hennawi, {Joseph F.} and Jiangtao Li and McGreer, {Ian D.} and Rohan Naidu and Fabio Pacucci and Sebastian Rabien and David Thompson and Bram Venemans and Fabian Walter and Ran Wang and Wu, {Xue Bing}",
note = "Funding Information: We acknowledge the support of the staff at the MMT, Magellan, LBT, Keck, and Gemini Telescopes, and thank the Directors of LBTO, Gemini Observatory, JCMT, and STScI for granting us Director Discretionary time for follow-up observations of this object. X.F., J.Y., M.Y., and I.D.M. acknowledge support from US NSF grant AST-1515115, NASA ADAP grant NNX17AF28G, and HST-GO-13644 grant from the Space Telescope Science Institute. C.K. acknowledges support from US NSF grant AST-1716585. A.I.Z. acknowledges support from NSF grant AST-1211874. F.P. acknowledges support from the NASA Chandra award No. AR8-19021A and from the Yale Keck program No. Y144. B.P.V. and F.W. acknowledge funding through the ERC grants “Cosmic Dawn” and “Cosmic Gas.” R.W. and X.-B.W acknowledge support from NSFC grant No. 11533001. Publisher Copyright: {\textcopyright} 2019. The American Astronomical Society. All rights reserved..",
year = "2019",
month = jan,
day = "10",
doi = "10.3847/2041-8213/aaeffe",
language = "English (US)",
volume = "870",
journal = "Astrophysical Journal Letters",
issn = "2041-8205",
publisher = "IOP Publishing Ltd.",
number = "2",
}