Three new VHS–DES quasars at 6.7 < z < 6.9 and emission line properties at z > 6.5. Issue 2 (29th May 2019)

• Record Type: Journal Article
• Authors: 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;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 487:Issue 2(2019)
• Page Start: 1874
• Page End: 1885
• Publication Date: 2019-05-29
• Subjects: galaxies: active -- galaxies: formation -- galaxies: high-redshift -- dark ages, reionization, first stars -- quasars: individual: VDES J0224−4711 -- quasars: individual: VDES J0244−5008 -- quasars: individual: VDES J0020−3653 -- quasars: individual: VDES J0246−5219; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz1341
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: 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. 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 × 10 9 M⊙ . Combined with the bolometric luminosities of these quasars of L bol ≃ 1–3 × 10 47, 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.