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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 742554.0, MPI für Astronomie / Publikationen_mpia
Physical properties of 15 quasars at z > 6.5
Authors:Mazzucchelli, C.; Bañados, E.; Venemans, B. P.; Decarli, R.; Farina, E. P.; Walter, F.; Eilers, A. -. C.; Rix, H. -. W.; Simcoe, R.; Stern, D.; Fan, X.; Schlafly, E.; De Rosa, G.; Hennawi, J.; Chambers, K. C.; Greiner, J.; Burgett, W.; Draper, P. W.; Kaiser, N.; Kudritzki, R. -. P.; Magnier, E.; Metcalfe, N.; Waters, C.; Wainscoat, R. J.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:The Astrophysical Journal
Issue / Number:2
Start Page:id. 91 (26 pp)
Audience:Not Specified
Abstract / Description:Quasars 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.
Free Keywords:galaxies: high-redshift; quasars: general
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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