Reed, SL;
McMahon, RG;
Martini, P;
Banerji, M;
Auger, M;
Hewett, PC;
Koposov, SE;
... Wester, W; + view all
(2017)
Eight new luminous z >= 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations.
Monthly Notices of the Royal Astronomical Society
, 468
(4)
pp. 4702-4718.
10.1093/mnras/stx728.
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Abstract
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 con- firmation 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.
| Type: | Article |
|---|---|
| Title: | Eight new luminous z >= 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stx728 |
| Publisher version: | http://doi.org/10.1093/mnras/stx728 |
| Language: | English |
| Additional information: | © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, galaxies: active, galaxies: formation, galaxies: high redshift, quasars individual: VDES J0224-4711, dark ages, reionization, first stars, DIGITAL SKY SURVEY, Z-SIMILAR-TO-6 QUASARS, SCIENCE ARCHIVE, FAINT GALAXIES, REDSHIFT, REIONIZATION, PERFORMANCE, SYSTEM, SAMPLE, FIELD |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1540492 |
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