Physical Properties of 15 Quasars at z ≳ 6.5

By C. Mazzucchelli, E. Bañados, B. Venemans, R. Decarli, E. Farina, F. Walter, Anna-Christina Eilers, Hans-Walter Rix, R. Simcoe, Daniel Stern and 14 more. 2017

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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 (<800 Myr after the big bang). In this work, we present six additional quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. We report four main results: (1) the majority of 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 ; (2) we estimate the quasars’ black hole masses ( (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 ) 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 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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7f0ff0f16215358ccac05d2c8d643759e1a8697e

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Citations in the corpus

The bolometric quasar luminosity function at z = 0–7 (2020, background): “In the last decade, the redshift frontier of the observations of quasars have been pushed up to z > 7 (Mortlock et al. 2011; Bañados et al. 2018; Wang et al. 2018b) and about ∼ 50 quasars are now known at z ∼ 6 − 7 (e.g., Willott et al. 2010; Venemans et al. 2013, 2015; Jiang et al. 2016; Reed et al”
An ALMA [C ii] Survey of 27 Quasars at z > 5.94 (2018, background): “The typical black hole mass is~ M109 , implying that these quasars radiate close to their Eddington limit (Jiang et al. 2007; De Rosa et al. 2011, 2014; Mazzucchelli et al. 2017).”
The Rise of Faint, Red Active Galactic Nuclei at z > 4: A Sample of Little Red Dots in the JWST Extragalactic Legacy Fields (2025, unknown): “…3 dex below that of bright quasars identi ﬁ ed by ground-based surveys at similar redshifts ( e.g., C. J. Willott et al. 2010; L. Jiang et al. 2016; C. Mazzucchelli et al. 2017; Y. Matsuoka et al. 2022; J. Yang et al. 2023 ) and are powered by black holes ( BHs ) with masses of ≈ 10 6 − 7 M e ,…”
Pōniuā‘ena: A Luminous z = 7.5 Quasar Hosting a 1.5 Billion Solar Mass Black Hole (2020, background): “…known quasars at z > 6.5: 47 luminous quasars at z > 6.5 have been discovered (e.g., Fan et al. 2019; Venemans et al. 2013, 2015; Wang et al. 2019; Mazzucchelli et al. 2017; Reed et al. 2019; Matsuoka et al. 2019a; Yang et al. 2019), although among them only six are at z ≥ 7 (Mortlock et al.…”