Physical properties of 15 quasars at $z\gtrsim 6.5$

Abstract

Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only few quasars have been reported at $z>6.5$ ($<$800 Myr after the Big Bang). In this work, we present six additional $z\gtrsim 6.5$ quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 $z\gtrsim 6.5$ quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. We report four main results: (1) the majority of $z\gtrsim$6.5 quasars show large blueshifts of the broad CIV 1549Åemission line compared to the systemic redshift of the quasars, with a median value $\sim$3$\times$ higher than a quasar sample at $z\sim$1; (2) we estimate the quasars' black hole masses (M${}_{\mathrm{BH}}\sim$0.3$-$5 $\times$ 10${}^9$ M${}_{\odot }$) via modeling of the MgII 2798Åemission line and rest-frame UV continuum; we find that quasars at high redshift accrete their material (with $⟨(L_{\mathrm{bol}}/L_{\mathrm{Edd}})⟩=0.39$) 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 FeII/MgII abundance ratio with cosmic time; (4) we derive near zone sizes; together with measurements for $z\sim 6$ quasars from recent work, we confirm a shallow evolution of the decreasing quasar near zone sizes with redshift. Finally, we present new millimeter observations of the [CII] 158 $\mu$m emission line and underlying dust continuum from NOEMA for four quasars, and provide new accurate redshifts and [CII]/infrared luminosities estimates. The analysis presented here shows the large range of properties of the most distant quasars.

arXiv comment29 pages, 18 figures; accepted by ApJ

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• Unveiling the warm dense ISM in $z>6$ quasar host galaxies via water vapor emission
• What do observations tell us about the highest-redshift supermassive black holes?
• The missing FeII bump in faint JWST AGN: possible evidence for metal-poor broad-line regions at early cosmic times
• No redshift evolution in the rest-frame UV emission line properties of quasars from z=1.5 to z=4.0
• The LOFAR Two Metre Sky Survey Data Release 2: Probabilistic Spectral Source Classifications and Faint Radio Source Demographics
• A lack of LAEs within 5Mpc of a luminous quasar in an overdensity at z=6.9: potential evidence of quasar negative feedback at protocluster scales
• Molecular gas and dust properties in $z>7$ quasar hosts
• Investigating the nuclear properties of highly accreting active galactic nuclei with XMM-Newton
• A powerful (and likely young) radio-loud quasar at z=5.3
• VLT/SINFONI study of black hole growth in high redshift radio-loud quasars from the CARLA survey
• Testing the paradigm: First spectroscopic evidence of a quasar-galaxy Mpc-scale association at cosmic dawn
• The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei
• ALMA 300 pc resolution imaging of a z=6.79 quasar: no evidence for supermassive black hole influence on the [C II] kinematics
• The impact of faint AGN discovered by JWST on reionization
• Probing quasar lifetimes with proximate $21$-centimetre absorption in the diffuse intergalactic medium at redshifts $z\ge 6$
• Discovery and characterization of 25 new quasars at 4.6 < z < 6.9 from wide-field multi-band surveys
• Predictions for LISA and PTA based on SHARK galaxy simulations
• An X-ray fading, UV brightening QSO at $z\approx 6$
• Formation of the First Black Holes: Current observational status
• High Star Formation Rates of Low Eddington Ratio Quasars at $z\gtrsim 6$
• The host galaxies of radio-loud quasars at z>5 with ALMA
• Possible evolution of the circum-galactic medium around QSOs with QSO age and cosmic time revealed by Ly$\alpha$ halos
• Characterising SMSS J2157--3602, the most luminous known quasar, with accretion disc models
• The benefit of simultaneous seven-filter imaging: 10 years of GROND observations
• A Closer Look at Two of the Most Luminous Quasars in the Universe
• When Spectral Modeling Meets Convolutional Networks: A Method for Discovering Reionization-era Lensed Quasars in Multi-band Imaging Data
• Comprehensive view on a $z\sim 6.5$ radio-loud QSO: from the radio to the optical/NIR to the X-ray band
• Optical and near-infrared spectroscopy of quasars at $z>6.5$: public data release and composite spectrum
• The Decoupled Kinematics of high-z QSO Host Galaxies and their Lya halos
• The Infrared Medium-deep Survey. IX. Discovery of Two New $z\sim 6$ Quasars and Space Density down to $M_{1450}\sim -23.5$ mag
• Subaru medium-resolution spectra of a QSO at z=6.62: Three reionization tests
• The near-infrared SED of blue quasars: what drives the evolution of the dusty torus?
• High-redshift quasar selection from the CFHQSIR survey
• HYPERION: broad-band X-ray-to-near-infrared emission of Quasars in the first billion years of the Universe
• Monster radio jet (>66 kpc) observed in quasar at z$\sim$5
• Hungry or Not: How Stellar-Mass Black Holes Grow (or Don't) in Dark Matter Mini-Haloes at High-Resolution
• ALMA 360 pc high-frequency observations reveal warm dust in the center of a $z=6.9$ quasar
• Are there more galaxies than we see around high-$z$ quasars?
• Is the X-ray bright z = 5.5 quasar SRGE J170245.3+130104 a blazar?
• HYPERION. Shedding light on the first luminous quasars: A correlation between UV disc winds and X-ray continuum
• The Dawn of Black Holes
• A unique window into the Epoch of Reionisation: A double-peaked Lyman-$\alpha$ emitter in the proximity zone of a quasar at $z\sim 6.6$
• A luminous molecular gas pair beyond redshift 7
• Rapidly accreting black hole of the Lyα-luminous quasar PSO J006.1240+39.2219
• Effects of spin on constraining the seeds and growth of $\gtrsim 10^9{M}_{\odot }$ supermassive black holes in $z>6.5$ Quasars
• The quasar luminosity function at $z\sim 5$ via deep learning and Bayesian information criterion
• Exploring the radio spectral energy distribution of the ultraluminous radio-quiet quasar SDSS J0100+2802 at redshift 6.3
• AGN radiative feedback in the early growth of massive black holes
• Discovery of two quasars at $z=5$ from the OGLE Survey
• A scaling relation in [C II]-detected galaxies and its likely application in cosmology
• Lensing in the Darkness: A Bayesian Analysis of 22 Chandra Sources at $z\gtrsim 6$ Shows No Evidence of Lensing
• X-HESS: a large sample of highly accreting serendipitous AGN under the XMM-Newton microscope
• Quasar clustering at redshift 6
• Strong correlation between FeII/MgII ratio and Eddington ratio of type 1 Active galactic nuclei
• The Impact of Powerful Jets on the Far-infrared Emission of an Extreme Radio Quasar at z~6
• Mass transport in galaxy discs limits black hole growth to sub-Eddington rates
• Estimating the spins of supermassive black holes in distant ultraluminous quasars
• Molecular gas content of gravitational-lensed quasars at cosmic noon
• A new model of quasar mass evolution
• Tilsotua: Reproducing Slitmask Sky Positions for use with the LRIS Multislit Archive
• The Contribution of AGN Accretion Disks to Hydrogen Reionization
• Top-heavy stellar mass distribution in galactic nuclei inferred from the universally high abundance ratio of [Fe/Mg]