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Title: Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations

Abstract

Here, we present the discovery and spectroscopic confirmation with the European Southern Observatory New Technology Telescope (NTT) and Gemini South telescopes of eight new, and the rediscovery of two previously known, 6.0 < z < 6.5 quasars with zAB < 21.0. These quasars were photometrically selected without any morphological criteria from 1533 deg2 using spectral energy distribution (SED) model fitting to photometric data from Dark Energy Survey (g, r, i, z, Y), VISTA Hemisphere Survey (J, H, K) and Wide-field Infrared Survey Explorer (W1, W2). The photometric data were fitted with a grid of quasar model SEDs with redshift-dependent Ly α forest absorption and a range of intrinsic reddening as well as a series of low-mass cool star models. Candidates were ranked using an SED-model-based χ2-statistic, which is extendable to other future imaging surveys (e.g. LSST and Euclid). Our spectral confirmation success rate is 100 per cent without the need for follow-up photometric observations as used in other studies of this type. Combined with automatic removal of the main types of non-astrophysical contaminants, the method allows large data sets to be processed without human intervention and without being overrun by spurious false candidates. We also present a robust parametric redshiftmore » estimator that gives comparable accuracy to Mg ii and CO-based redshift estimators. We find two z ~6.2 quasars with H ii near zone sizes ≤3 proper Mpc that could indicate that these quasars may be young with ages ≲ 10 6-10 7 years or lie in over dense regions of the IGM. The z = 6.5 quasar VDES J0224–4711 has JAB = 19.75 and is the second most luminous quasar known with z ≥ 6.5.« less

Authors:
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Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Org.:
DES; WISE; VISTA
OSTI Identifier:
1361377
Alternate Identifier(s):
OSTI ID: 1343963
Report Number(s):
FERMILAB-PUB-16-570-AE-PPD; arXiv:1701.04852
Journal ID: ISSN 0035-8711; KJ0402000; KJ0503000; ERKJ311; ERKJEPM; TRN: US1702458
Grant/Contract Number:  
AC05-00OR22725; AC02-07CH11359
Resource Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 468; Journal Issue: 4; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxies: active; galaxies: formation; galaxies: high redshift; quasars individual: VDES J0224−4711; dark ages; reionization; first stars

Citation Formats

Reed, S. L., McMahon, R. G., Martini, P., Banerji, M., Auger, M., Hewett, P. C., Koposov, S. E., Gibbons, S. L. J., Gonzalez-Solares, E., Ostrovski, F., Tie, S. S., Abdalla, F. B., Allam, S., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Burke, D. L., Carnero Rosell, A., Carrasco Kind, M., Carretero, J., da Costa, L. N., DePoy, D. L., Desai, S., Diehl, H. T., Doel, P., Evrard, A. E., Finley, D. A., Flaugher, B., Fosalba, P., Frieman, J., García-Bellido, J., Gaztanaga, E., Goldstein, D. A., Gruen, D., Gruendl, R. A., Gutierrez, G., James, D. J., Kuehn, K., Kuropatkin, N., Lahav, O., Lima, M., Maia, M. A. G., Marshall, J. L., Melchior, P., Miller, C. J., Miquel, R., Nord, B., Ogando, R., Plazas, A. A., Romer, A. K., Sanchez, E., Scarpine, V., Schubnell, M., Sevilla-Noarbe, I., Smith, R. C., Sobreira, F., Suchyta, E., Swanson, M. E. C., Tarle, G., Tucker, D. L., Walker, A. R., and Wester, W. Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations. United States: N. p., 2017. Web. doi:10.1093/mnras/stx728.
Reed, S. L., McMahon, R. G., Martini, P., Banerji, M., Auger, M., Hewett, P. C., Koposov, S. E., Gibbons, S. L. J., Gonzalez-Solares, E., Ostrovski, F., Tie, S. S., Abdalla, F. B., Allam, S., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Burke, D. L., Carnero Rosell, A., Carrasco Kind, M., Carretero, J., da Costa, L. N., DePoy, D. L., Desai, S., Diehl, H. T., Doel, P., Evrard, A. E., Finley, D. A., Flaugher, B., Fosalba, P., Frieman, J., García-Bellido, J., Gaztanaga, E., Goldstein, D. A., Gruen, D., Gruendl, R. A., Gutierrez, G., James, D. J., Kuehn, K., Kuropatkin, N., Lahav, O., Lima, M., Maia, M. A. G., Marshall, J. L., Melchior, P., Miller, C. J., Miquel, R., Nord, B., Ogando, R., Plazas, A. A., Romer, A. K., Sanchez, E., Scarpine, V., Schubnell, M., Sevilla-Noarbe, I., Smith, R. C., Sobreira, F., Suchyta, E., Swanson, M. E. C., Tarle, G., Tucker, D. L., Walker, A. R., & Wester, W. Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations. United States. doi:10.1093/mnras/stx728.
Reed, S. L., McMahon, R. G., Martini, P., Banerji, M., Auger, M., Hewett, P. C., Koposov, S. E., Gibbons, S. L. J., Gonzalez-Solares, E., Ostrovski, F., Tie, S. S., Abdalla, F. B., Allam, S., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Burke, D. L., Carnero Rosell, A., Carrasco Kind, M., Carretero, J., da Costa, L. N., DePoy, D. L., Desai, S., Diehl, H. T., Doel, P., Evrard, A. E., Finley, D. A., Flaugher, B., Fosalba, P., Frieman, J., García-Bellido, J., Gaztanaga, E., Goldstein, D. A., Gruen, D., Gruendl, R. A., Gutierrez, G., James, D. J., Kuehn, K., Kuropatkin, N., Lahav, O., Lima, M., Maia, M. A. G., Marshall, J. L., Melchior, P., Miller, C. J., Miquel, R., Nord, B., Ogando, R., Plazas, A. A., Romer, A. K., Sanchez, E., Scarpine, V., Schubnell, M., Sevilla-Noarbe, I., Smith, R. C., Sobreira, F., Suchyta, E., Swanson, M. E. C., Tarle, G., Tucker, D. L., Walker, A. R., and Wester, W. Fri . "Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations". United States. doi:10.1093/mnras/stx728. https://www.osti.gov/servlets/purl/1361377.
@article{osti_1361377,
title = {Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations},
author = {Reed, S. L. and McMahon, R. G. and Martini, P. and Banerji, M. and Auger, M. and Hewett, P. C. and Koposov, S. E. and Gibbons, S. L. J. and Gonzalez-Solares, E. and Ostrovski, F. and Tie, S. S. and Abdalla, F. B. and Allam, S. and Benoit-Lévy, A. and Bertin, E. and Brooks, D. and Buckley-Geer, E. and Burke, D. L. and Carnero Rosell, A. and Carrasco Kind, M. and Carretero, J. and da Costa, L. N. and DePoy, D. L. and Desai, S. and Diehl, H. T. and Doel, P. and Evrard, A. E. and Finley, D. A. and Flaugher, B. and Fosalba, P. and Frieman, J. and García-Bellido, J. and Gaztanaga, E. and Goldstein, D. A. and Gruen, D. and Gruendl, R. A. and Gutierrez, G. and James, D. J. and Kuehn, K. and Kuropatkin, N. and Lahav, O. and Lima, M. and Maia, M. A. G. and Marshall, J. L. and Melchior, P. and Miller, C. J. and Miquel, R. and Nord, B. and Ogando, R. and Plazas, A. A. and Romer, A. K. and Sanchez, E. and Scarpine, V. and Schubnell, M. and Sevilla-Noarbe, I. and Smith, R. C. and Sobreira, F. and Suchyta, E. and Swanson, M. E. C. and Tarle, G. and Tucker, D. L. and Walker, A. R. and Wester, W.},
abstractNote = {Here, we present the discovery and spectroscopic confirmation with the European Southern Observatory New Technology Telescope (NTT) and Gemini South telescopes of eight new, and the rediscovery of two previously known, 6.0 < z < 6.5 quasars with zAB < 21.0. These quasars were photometrically selected without any morphological criteria from 1533 deg2 using spectral energy distribution (SED) model fitting to photometric data from Dark Energy Survey (g, r, i, z, Y), VISTA Hemisphere Survey (J, H, K) and Wide-field Infrared Survey Explorer (W1, W2). The photometric data were fitted with a grid of quasar model SEDs with redshift-dependent Ly α forest absorption and a range of intrinsic reddening as well as a series of low-mass cool star models. Candidates were ranked using an SED-model-based χ2-statistic, which is extendable to other future imaging surveys (e.g. LSST and Euclid). Our spectral confirmation success rate is 100 per cent without the need for follow-up photometric observations as used in other studies of this type. Combined with automatic removal of the main types of non-astrophysical contaminants, the method allows large data sets to be processed without human intervention and without being overrun by spurious false candidates. We also present a robust parametric redshift estimator that gives comparable accuracy to Mg ii and CO-based redshift estimators. We find two z ~6.2 quasars with H ii near zone sizes ≤3 proper Mpc that could indicate that these quasars may be young with ages ≲ 106-107 years or lie in over dense regions of the IGM. The z = 6.5 quasar VDES J0224–4711 has JAB = 19.75 and is the second most luminous quasar known with z ≥ 6.5.},
doi = {10.1093/mnras/stx728},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 4,
volume = 468,
place = {United States},
year = {2017},
month = {3}
}

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Works referenced in this record:

Astropy: A community Python package for astronomy
journal, September 2013


The VISTA Science Archive
journal, December 2012


The Blanco Cosmology Survey: data Acquisition, Processing, Calibration, Quality Diagnostics, and data Release
journal, September 2012


Simultaneous Multicolor Detection of Faint Galaxies in the Hubble Deep Field
journal, January 1999

  • Szalay, Alexander S.; Connolly, Andrew J.; Szokoly, Gyula P.
  • The Astronomical Journal, Vol. 117, Issue 1
  • DOI: 10.1086/300689

Photometric brown-dwarf classification: I. A method to identify and accurately classify large samples of brown dwarfs without spectroscopy
journal, January 2015


SExtractor: Software for source extraction
journal, June 1996

  • Bertin, E.; Arnouts, S.
  • Astronomy and Astrophysics Supplement Series, Vol. 117, Issue 2
  • DOI: 10.1051/aas:1996164

The Gemini–North Multi‐Object Spectrograph: Performance in Imaging, Long‐Slit, and Multi‐Object Spectroscopic Modes
journal, May 2004

  • Hook, I. M.; Jørgensen, Inger; Allington‐Smith, J. R.
  • Publications of the Astronomical Society of the Pacific, Vol. 116, Issue 819
  • DOI: 10.1086/383624

Photometry of a complete sample of faint galaxies
journal, June 1980

  • Kron, R. G.
  • The Astrophysical Journal Supplement Series, Vol. 43
  • DOI: 10.1086/190669

A luminous quasar at a redshift of z = 7.085
journal, June 2011

  • Mortlock, Daniel J.; Warren, Stephen J.; Venemans, Bram P.
  • Nature, Vol. 474, Issue 7353
  • DOI: 10.1038/nature10159

DES J0454−4448: discovery of the first luminous z ≥ 6 quasar from the Dark Energy Survey
journal, October 2015

  • Reed, S. L.; McMahon, R. G.; Banerji, M.
  • Monthly Notices of the Royal Astronomical Society, Vol. 454, Issue 4
  • DOI: 10.1093/mnras/stv2031

IONIZATION NEAR ZONES ASSOCIATED WITH QUASARS AT z ∼ 6
journal, April 2010


DISCOVERY OF THREE z > 6.5 QUASARS IN THE VISTA KILO-DEGREE INFRARED GALAXY (VIKING) SURVEY
journal, November 2013


The nature and evolution of the highly ionized near-zones in the absorption spectra of z = 6 quasars
journal, January 2007


DISCOVERY OF A RADIO-SELECTED z ∼ 6 QUASAR
journal, July 2011

  • Zeimann, Gregory R.; White, Richard L.; Becker, Robert H.
  • The Astrophysical Journal, Vol. 736, Issue 1
  • DOI: 10.1088/0004-637X/736/1/57

Simulating wide-field quasar surveys from the optical to near-infrared
journal, April 2006


The Visible and Infrared Survey Telescope for Astronomy (VISTA): Design, technical overview, and performance
journal, February 2015


Probabilistic selection of high-redshift quasars: Probabilistic quasar selection
journal, October 2011

  • Mortlock, Daniel J.; Patel, Mitesh; Warren, Stephen J.
  • Monthly Notices of the Royal Astronomical Society, Vol. 419, Issue 1
  • DOI: 10.1111/j.1365-2966.2011.19710.x

unWISE: UNBLURRED COADDS OF THE WISE IMAGING
journal, April 2014


Methods for rapidly processing angular masks of next-generation galaxy surveys
journal, July 2008

  • Swanson, M. E. C.; Tegmark, Max; Hamilton, Andrew J. S.
  • Monthly Notices of the Royal Astronomical Society, Vol. 387, Issue 4
  • DOI: 10.1111/j.1365-2966.2008.13296.x

The dark Energy Camera
journal, October 2015


The Evolution of Optical Depth in the Lyα Forest: Evidence Against Reionization at z ∼6
journal, June 2007

  • Becker, George D.; Rauch, Michael; Sargent, Wallace L. W.
  • The Astrophysical Journal, Vol. 662, Issue 1
  • DOI: 10.1086/517866

How neutral is the intergalactic medium surrounding the redshift z = 7.085 quasar ULAS J1120+0641?: How neutral is the IGM around J1120+0641?
journal, July 2011

  • Bolton, J. S.; Haehnelt, M. G.; Warren, S. J.
  • Monthly Notices of the Royal Astronomical Society: Letters, Vol. 416, Issue 1
  • DOI: 10.1111/j.1745-3933.2011.01100.x

The UKIRT Infrared Deep Sky Survey ZY JHK photometric system: passbands and synthetic colours
journal, April 2006


Cosmic‐Ray Rejection by Laplacian Edge Detection
journal, November 2001

  • van Dokkum, Pieter G.
  • Publications of the Astronomical Society of the Pacific, Vol. 113, Issue 789
  • DOI: 10.1086/323894

The large area KX quasar catalogue - I. Analysis of the photometric redshift selection and the complete quasar catalogue: The large area KX quasar catalogue
journal, July 2012


THE FIRST HUNDRED BROWN DWARFS DISCOVERED BY THE WIDE-FIELD INFRARED SURVEY EXPLORER ( WISE )
journal, November 2011

  • Davy Kirkpatrick, J.; Cushing, Michael C.; Gelino, Christopher R.
  • The Astrophysical Journal Supplement Series, Vol. 197, Issue 2
  • DOI: 10.1088/0067-0049/197/2/19

THE CANADA-FRANCE HIGH- z QUASAR SURVEY: NINE NEW QUASARS AND THE LUMINOSITY FUNCTION AT REDSHIFT 6
journal, February 2010


Probing the end of reionization with the near zones of z ≳ 6 QSOs
journal, September 2015

  • Keating, Laura C.; Haehnelt, Martin G.; Cantalupo, Sebastiano
  • Monthly Notices of the Royal Astronomical Society, Vol. 454, Issue 1
  • DOI: 10.1093/mnras/stv2020

A SURVEY OF z ∼ 6 QUASARS IN THE SLOAN DIGITAL SKY SURVEY DEEP STRIPE. I. A FLUX-LIMITED SAMPLE AT z AB < 21
journal, February 2008


Planck 2015 results : XIII. Cosmological parameters
journal, September 2016


THE FINAL SDSS HIGH-REDSHIFT QUASAR SAMPLE OF 52 QUASARS AT z > 5.7
journal, December 2016


Systematic QSO emission-line velocity shifts and new unbiased redshifts
journal, March 1992

  • Tytler, David; Fan, Xiao-Ming
  • The Astrophysical Journal Supplement Series, Vol. 79
  • DOI: 10.1086/191642

THE SPITZER - WISE SURVEY OF THE ECLIPTIC POLES
journal, June 2011


A SURVEY OF z ∼ 6 QUASARS IN THE SLOAN DIGITAL SKY SURVEY DEEP STRIPE. II. DISCOVERY OF SIX QUASARS AT z AB >21
journal, June 2009


Automatic analysis of crowded fields
journal, June 1985


The Wide-Field Infrared Survey Explorer (Wise): Mission Description and Initial On-Orbit Performance
journal, November 2010


Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z  ~ 6 Quasars. II. A Sample of 19 Quasars
journal, June 2006

  • Fan, Xiaohui; Strauss, Michael A.; Becker, Robert H.
  • The Astronomical Journal, Vol. 132, Issue 1
  • DOI: 10.1086/504836

Two bright z > 6 quasars from VST ATLAS and a new method of optical plus mid-infrared colour selection
journal, May 2015

  • Carnall, A. C.; Shanks, T.; Chehade, B.
  • Monthly Notices of the Royal Astronomical Society: Letters, Vol. 451, Issue 1
  • DOI: 10.1093/mnrasl/slv057

A Survey of z  > 5.7 Quasars in the Sloan Digital Sky Survey. III. Discovery of Five Additional Quasars
journal, August 2004

  • Fan, Xiaohui; Hennawi, Joseph F.; Richards, Gordon T.
  • The Astronomical Journal, Vol. 128, Issue 2
  • DOI: 10.1086/422434

THE IDENTIFICATION OF z -DROPOUTS IN PAN-STARRS1: THREE QUASARS AT 6.5< z < 6.7
journal, February 2015


THE PAN-STARRS1 DISTANT z > 5.6 QUASAR SURVEY: MORE THAN 100 QUASARS WITHIN THE FIRST GYR OF THE UNIVERSE
journal, November 2016

  • Bañados, E.; Venemans, B. P.; Decarli, R.
  • The Astrophysical Journal Supplement Series, Vol. 227, Issue 1
  • DOI: 10.3847/0067-0049/227/1/11