Agradecimentos: SLR would like to thank the reviewer for a very thorough proofreading. SLR and RGM would like to thank Laura Keating for an interesting and educational discussion on near zones. RGM, SLR, MB, MA, PH, SEK, SLJG and EGS acknowledge the support of UK Science and Technology Facilities Council (STFC). Support for RGM by ERC Advanced Grant 320596 ‘The Emergence of Structure During the Epoch of Reionization’ is gratefully acknowledged. MB acknowledges funding from STFC via an Ernest Rutherford Fellowship. Funding for the DES Projects has been provided by the US Department of Energy, the US National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of UK, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo á Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnologico and the Ministério da Ciência e Tecnologia, the Deutsche Forschungsgemeinschaft and ˆ the Collaborating Institutions in the DES. The Collaborating Institutions are Argonne National Laboratories, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the Eidgenossische Technische Hochschule (ETH) Zurich, Fermi National Accelerator Laboratory, the University of Edinburgh, the University of Illinois at Urbana-Champaign, the Institut de Ciencies de lEspai (IEEC/CSIC), the Institut de Fisica dAltes Energies, the Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, the Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Laboratory, Stanford University, the University of Sussex and Texas A&M University. The analysis presented here is based on observations obtained as part of the VHS, ESO Programme, 179.A-2010 (PI: McMahon). The analysis presented here is based on observations obtained as part of ESO Programme, 096.A-0411 (PI: McMahon) and GEMINI programme GS-2015B-Q-18 (PI: Martini). This analysis makes use of the cosmics.py algorithm based on Pieter van Dokkum's L.A. Cosmic algorithm detailed in van Dokkum (2001). This paper has gone through internal review by the DES collaboration Ver menos

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 z(AB) < 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 a 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 chi(2)-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 similar to 6.2 quasars with HII near zone sizes <= 3 proper Mpc that could indicate that these quasars may be young with ages less than or similar to 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 Ver menos