Eight new luminous z &gt; 6 quasars selected via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 Observations
Creators: name: Reed, S. L.
name: McMahon, R. G.
name: Martini, P.
name: Banerji, M.
name: Auger, M.
name: Hewett, P. C.
name: Koposov, S. E.
name: Gibbons, S. L. J.
name: Gonzalez-Solares, E.
name: Ostrovski, F.
name: Tie, S. S.
name: Abdalla, F. B.
name: Allam, S.
name: Benoit-Levy, A.
name: Bertin, E.
name: Brooks, D.
name: Buckley-Geer, E.
name: Burke, D. L.
name: Rosell, A. Carnero
name: Kind, M. Carrasco
name: Carretero, J.
name: da Costa, L. N.
name: DePoy, D. L.
name: Desai, S.
name: Diehl, H. T.
name: Doel, P.
name: Evrard, A. E.
name: Finley, D. A.
name: Flaugher, B.
name: Fosalba, P.
name: Frieman, J.
name: Garcıa-Bellido, J.
name: Gaztanaga, E.
name: Goldstein, D. A.
name: Gruen, D.
name: Gruendl, R. A.
name: Gutierrez, G.
name: James, D. J.
name: Kuehn, K.
name: Kuropatkin, N.
name: Lahav, O.
name: Lima, M.
name: Maia, M. A. G.
name: Marshall, J. L.
name: Melchior, P.
name: Miller, C. J.
name: Miquel, R.
name: Nord, B.
name: Ogando, R.
name: Plazas, A. A.
name: Romer, A. K.
name: Sanchez, E.
name: Scarpine, V.
name: Schubnell, M.
name: Sevilla-Noarbe, I.
name: Smith, R. C.
name: Sobreira, F.
name: Suchyta, E.
name: Swanson, M. E. C.
name: Tarle, G.
name: Tucker, D. L.
name: Walker, A. R.
name: Wester, W.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present the discovery and spectroscopic confirmation with the ESO NTT and Gemini South telescopes of eight new 6.0 &lt; z &lt; 6.5 quasars with z$_{AB}$ &lt; 21.0. These quasars were photometrically selected without any star-galaxy morphological criteria from 1533 deg$^{2}$ using SED model fitting to photometric data from the Dark Energy Survey (g, r, i, z, Y), the VISTA Hemisphere Survey (J, H, K) and the Wide-Field Infrared Survey Explorer (W1, W2). The photometric data was fitted with a grid of quasar model SEDs with redshift dependent Lyman-α forest absorption and a range of intrinsic reddening as well as a series of low mass cool star models. Candidates were ranked using on a SED-model based $χ^{2}$-statistic, which is extendable to other future imaging surveys (e.g. LSST, Euclid). Our spectral confirmation success rate is 100% 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 over run by spurious false candidates. We also present a robust parametric redshift estimating technique that gives comparable accuracy to MgII and CO based redshift estimators. We find two z $\sim$ 6.2 quasars with HII near zone sizes &lt; 3 proper Mpc which could indicate that these quasars may be young with ages &lt; 10$^6$ - 10$^7$ years or lie in over dense regions of the IGM. The z = 6.5 quasar VDESJ0224-4711 has J$_{AB}$ = 19.75 is the second most luminous quasar known with z &gt; 6.5.
description: 19 pages, 15 figures