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Three new VHS-DES quasars at 6.7 < z < 6.9 and emission line properties at z > 6.5

Research output: Contribution to journalArticle

  • Sophie L. Reed
  • M. Banerji
  • G. D. Becker
  • Paul C. Hewett
  • Paul Martini
  • R. McMahon
  • E. Pons
  • M. Rauch
  • T. M. C. Abbott
  • Sahar S. Allam
  • James T. Annis
  • Santiago Javier Avila Perez
  • Emmanuel Bertin
  • D. Brooks
  • Elizabeth J. Buckley-Geer
  • Aurelio Carnero Rosell
  • Jorge Carretero
  • Francisco Javier Castander
  • C. E. Cunha
  • Christopher Brian D'Andrea
  • And 39 others
  • Luiz Alberto Nicolaci da Costa
  • Juan de Vicente
  • S. Desai
  • H. Thomas Diehl
  • Peter Doel
  • A. E. Evrard
  • B. Flaugher
  • Joshua A. Frieman
  • Juan García-Bellido
  • Enrique Gaztanaga
  • Daniel Gruen
  • Julia Gschwend
  • G. Gutierrez
  • Klaus Honscheid
  • Ben Hoyle
  • Derek James
  • Kyler Kuehn
  • O. Lahav
  • M. Lima
  • Marcio Antonio Geimba Maia
  • J. L. Marshall
  • Ramon Miquel
  • Ricardo L. C. Ogando
  • Andres A. Plazas
  • Aaron Roodman
  • Eusebio Sanchez
  • Vic Scarpine
  • Michael Schubnell
  • Santiago Serrano
  • Ignacio Sevilla-Noarbe
  • Mathew Smith
  • Robert Chris Smith
  • Flavia Sobreira
  • Eric Suchyta
  • Molly E. C. Swanson
  • Gregory Tarle
  • Daniel B. Thomas
  • Douglas L. Tucker
  • Vinu Vikram
We report the results from a search for z > 6.5 quasars using the Dark Energy Survey (DES) Year 3 data set combined with the VISTA Hemisphere Survey (VHS) and WISE All-Sky Survey. Our photometric selection method is shown to be highly efficient in identifying clean samples of high-redshift quasars, leading to spectroscopic confirmation of three new quasars – VDES J0244−5008 (z = 6.724), VDES J0020−3653 (z = 6.834), and VDES J0246−5219 (z = 6.90) – which were selected as the highest priority candidates in the survey data without any need for additional follow-up observations. We have obtained spectroscopic observations in the near-infrared for VDES J0244−5008 and VDES J0020−3653 as well as our previously identified quasar, VDES J0224−4711 at z = 6.50 from Reed et al. We use the near-infrared spectra to derive virial black hole masses from the full width at half-maximum of the Mg II line. These black hole masses are ≃1–2 × 109 M. Combined with the bolometric luminosities of these quasars of Lbol ≃ 1–3 × 1047, these imply that the Eddington ratios are high, ≃0.6–1.1. We consider the C IV emission line properties of the sample and demonstrate that our high-redshift quasars do not have unusual C IV line properties when compared to carefully matched low-redshift samples. Our new DES + VHS z > 6.5 quasars now add to the growing census of luminous, rapidly accreting supermassive black holes seen well into the epoch of reionization.
Original languageEnglish
Pages (from-to)1874-1885
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Volume487
Issue number2
Early online date29 May 2019
DOIs
Publication statusPublished - 1 Aug 2019

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    Rights statement: This article has been accepted for publication in MNRAS ©: The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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