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  • Three new VHS–DES quasars a...
    Reed, S L; Banerji, M; Becker, G D; Hewett, P C; Martini, P; McMahon, R G; Pons, E; Rauch, M; Abbott, T M C; Allam, S; Annis, J; Avila, S; Bertin, E; Brooks, D; Buckley-Geer, E; Carnero Rosell, A; Carrasco Kind, M; Carretero, J; Castander, F J; Cunha, C E; D’Andrea, C B; da Costa, L N; De Vicente, J; Desai, S; Diehl, H T; Doel, P; Evrard, A E; Flaugher, B; Frieman, J; García-Bellido, J; Gaztanaga, E; Gruen, D; Gschwend, J; Gutierrez, G; Hollowood, D L; Honscheid, K; Hoyle, B; James, D J; Kuehn, K; Lahav, O; Lima, M; Maia, M A G; Marshall, J L; Miquel, R; Ogando, R L C; Plazas, A A; Roodman, A; Sanchez, E; Scarpine, V; Schubnell, M; Serrano, S; Sevilla-Noarbe, I; Smith, M; Smith, R C; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thomas, D; Tucker, D L; Vikram, V

    Monthly Notices of the Royal Astronomical Society, 08/2019, Letnik: 487, Številka: 2
    Journal Article

    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. Here, 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.