Three new VHS-DES quasars at 6.7 < z < 6.9 and emission line properties at z > 6.5 Academic Article uri icon


  • 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. 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 holemasses from the full width at half-maximum of the MgII line. These black hole masses are 1-2 109M. 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 highredshift 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.

published proceedings


altmetric score

  • 7.33

author list (cited authors)

  • Reed, S. L., Banerji, M., Becker, G. D., Hewett, P. C., Martini, P., McMahon, R. G., ... Vikram, V.

citation count

  • 48

complete list of authors

  • Reed, SL||Banerji, M||Becker, GD||Hewett, PC||Martini, P||McMahon, RG||Pons, E||Rauch, M||Abbott, TMC||Allam, S||Annis, J||Avila, S||Bertin, E||Brooks, D||Buckley-Geer, E||Carnero Rosell, A||Carrasco Kind, M||Carretero, J||Castander, FJ||Cunha, CE||D’Andrea, CB||da Costa, LN||De Vicente, J||Desai, S||Diehl, HT||Doel, P||Evrard, AE||Flaugher, B||Frieman, J||García-Bellido, J||Gaztanaga, E||Gruen, D||Gschwend, J||Gutierrez, G||Hollowood, DL||Honscheid, K||Hoyle, B||James, DJ||Kuehn, K||Lahav, O||Lima, M||Maia, MAG||Marshall, JL||Miquel, R||Ogando, RLC||Plazas, AA||Roodman, A||Sanchez, E||Scarpine, V||Schubnell, M||Serrano, S||Sevilla-Noarbe, I||Smith, M||Smith, RC||Sobreira, F||Suchyta, E||Swanson, MEC||Tarle, G||Thomas, D||Tucker, DL||Vikram, V

publication date

  • May 2019