Mazzucchelli, C.C.MazzucchelliBanados, E.E.BanadosVenemans, BramBramVenemansDECARLI, ROBERTOROBERTODECARLIFarina, E.P.E.P.FarinaWalter, f.f.WalterEilers, A.-C.A.-C.EilersRix, H.-W.H.-W.RixSimcoe, R.R.SimcoeStern, D.D.SternFan, X.X.FanSchlafly, E.E.SchlaflyDe Rosa, G.G.De RosaHennawi, J.J.HennawiChambers, K.C.K.C.ChambersGreiner, J.J.GreinerBurgett, W.W.BurgettDraper, P.W.P.W.DraperKaiser, N.N.KaiserKudritzki, R.-P.R.-P.KudritzkiMagnier, E.E.MagnierMetcalfe, N.N.MetcalfeWaters, C.C.WatersWainscoat, R.J.R.J.Wainscoat2021-01-152021-01-1520170004-637Xhttp://hdl.handle.net/20.500.12386/29784Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only a few quasars have been reported at z> 6.5 (<800 Myr after the big bang). In this work, we present six additional z≳ 6.5 quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 z≳ 6.5 quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. We report four main results: (1) the majority of z≳ 6.5 quasars show large blueshifts of the broad C IV λ1549 emission line compared to the systemic redshift of the quasars, with a median value ∼3× higher than a quasar sample at z∼ 1; (2) we estimate the quasars’ black hole masses ({M}{BH} ∼ (0.3-5) × 109 M ☉) via modeling of the Mg II λ2798 emission line and rest-frame UV continuum and find that quasars at high redshift accrete their material (with < ({L}{bol}/{L}{Edd})> =0.39) at a rate comparable to a luminosity-matched sample at lower redshift, albeit with significant scatter (0.4 dex); (3) we recover no evolution of the Fe II/Mg II abundance ratio with cosmic time; and (4) we derive near-zone sizes and, together with measurements for z∼ 6 quasars from recent work, confirm a shallow evolution of the decreasing quasar near-zone sizes with redshift. Finally, we present new millimeter observations of the [C II] 158 μm emission line and underlying dust continuum from NOEMA for four quasars and provide new accurate redshifts and [C II]/infrared luminosity estimates. The analysis presented here shows the large range of properties of the most distant quasars.STAMPAenArticle10.3847/1538-4357/aa91852-s2.0-85034447832000414587300011https://iopscience.iop.org/article/10.3847/1538-4357/aa91852017ApJ...849...91MFIS/05 - ASTRONOMIA E ASTROFISICA