The Canada-France High-z Quasar Survey: nine new quasars and the luminosity function at redshift 6

Abstract

We present discovery imaging and spectroscopy for nine new z ~ 6 quasars found in the Canada-France High-z Quasar Survey (CFHQS) bringing the total number of CFHQS quasars to 19. By combining the CFHQS with the more luminous SDSS sample we are able to derive the quasar luminosity function from a sample of 40 quasars at redshifts 5.74 < z < 6.42. Our binned luminosity function shows a slightly lower normalisation and flatter slope than found in previous work. The binned data also suggest a break in the luminosity function at M_1450 approx -25. A double power law maximum likelihood fit to the data is consistent with the binned results. The luminosity function is strongly constrained (1 sigma uncertainty < 0.1 dex) over the range -27.5 < M_1450 < -24.7. The best-fit parameters are Phi(M_1450^*) = 1.14 x 10^-8 Mpc^-3 mag^-1, break magnitude M_1450^* = -25.13 and bright end slope beta = -2.81. However the covariance between beta and M_1450^* prevents strong constraints being placed on either parameter. For a break magnitude in the range -26 < M_1450^* < -24 we find -3.8 < beta < -2.3 at 95% confidence. We calculate the z = 6 quasar intergalactic ionizing flux and show it is between 20 and 100 times lower than that necessary for reionization. Finally, we use the luminosity function to predict how many higher redshift quasars may be discovered in future near-IR imaging surveys.

15 pages, 9 figures, AJ in press

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• New Radio-Loud QSOs at the end of the Re-ionisation Epoch
• WISE detections of known QSOs at redshifts greater than six
• On the Prevalence of Super-Massive Black Holes over Cosmic Time
• Effects of turbulence and rotation on protostar formation as a precursor to seed black holes
• Evolution of growing black holes in axisymmetric galaxy cores
• Boosting hierarchical structure formation with scalar-interacting dark matter
• The Infrared Medium-deep Survey. VI. Discovery of Faint Quasars at $z\sim 5$ with a Medium-band-based Approach
• An extremely X--ray weak blazar at z=5
• Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). IX. Identification of Two Red Quasars at z > 5.6
• The imprint of the cosmic supermassive black hole growth history on the 21 cm background radiation
• Distinctive 21 cm structures of the first stars, galaxies, and quasars
• Accretion History of AGN III: Radiative Efficiency and AGN Contribution to Reionization
• SCUBA2 High Redshift Bright Quasar Survey: Far-infrared Properties and Weak-line Features
• The Infrared Medium-deep Survey. IV. Low Eddington Ratio of A Faint Quasar at $z\sim 6$: Not Every Supermassive Black Hole is Growing Fast in the Early Universe
• Truth or delusion? A possible gravitational lensing interpretation of the ultra-luminous quasar SDSS J010013.02+280225.8 at $z=6.30$
• Radio Jet Proper-motion Analysis of Nine Distant Quasars above Redshift 3.5
• Constraining the epoch of reionization from the observed properties of the high-z Universe
• The most massive Population III stars
• Selection constraints on high redshift quasar searches in the VISTA kilo-degree infrared galaxy survey
• Pure Density Evolution of the Ultraviolet Quasar Luminosity Function at $2\lesssim z\lesssim 6$
• Cosmological Tests with the FSRQ Gamma-ray Luminosity Function
• Milli-arcsecond imaging of the radio emission from the quasar with the most massive black hole at reionization
• Probing the faint end Luminosity Function of Lyman Alpha Emitters at 3<z<7 behind 17 MUSE lensing clusters
• On the effect of Lyman alpha trapping during the initial collapse of massive black hole seeds
• Identifying quasars with astrometric and mid-infrared methods from APOP and ALLWISE
• The ALHAMBRA survey: Discovery of a faint QSO at z = 5.41
• The Infrared Medium-deep Survey. \Romannum{7}. Faint Quasars at $z\sim 5$ in the ELAIS-N1 Field
• Radiation-driven turbulent accretion onto massive black holes
• Observations by GMRT at 323 MHz of radio-loud quasars at $z>5$
• UV spectral diagnostics for low redshift quasars: estimating physical conditions and radius of the Broad Line Region
• Dark-ages reionization and galaxy formation simulation -- XVIII. The high-redshift evolution of black holes and their host galaxies
• Ionizing radiation from AGNs at z>3.3 with the Subaru Hyper Suprime-Cam Survey and the CFHT Large Area U-band Deep Survey (CLAUDS)
• AGNs at the cosmic dawn: predictions for future surveys from a $\Lambda$CDM cosmological model
• Cosmic Textures and Global Monopoles as Seeds for Super-Massive Black Holes
• The Infrared Medium-deep Survey. III. Survey of Luminous Quasars at 4.7 $\le$ z $\le$ 5.4
• Detecting the Highest Redshift (z > 8) QSOs in a Wide, Near Infrared Slitless Spectroscopic Survey
• The infrared-luminous progenitors of high-z quasars
• What do observations tell us about the highest-redshift supermassive black holes?
• Radio Emission from the First Quasars at $z\sim$ 6-15
• Revisiting the Completeness and the Luminosity Function in High-Redshift Low-Luminosity Quasar Surveys
• High-resolution radio imaging of two luminous quasars beyond redshift 4.5
• 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
• Extreme Galaxies During Reionization: Testing ISM and Disk Models
• Neural-network selection of high-redshift radio quasars, and the luminosity function at z~4
• High-Redshift Galaxy Surveys and the Reionization of the Universe
• The extremely X-ray luminous radio-loud quasar CFHQS J142952+544717 at $z=6.18$ under Chandra high-angular resolution lens
• Radio-loud fraction of z>6 quasars
• Eddington accreting Black Holes in the Epoch of Reionization
• The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk Anisotropy
• AGN jets versus accretion as reionization sources
• Extending Semi-numeric Reionisation Models to the First Stars and Galaxies
• The impact of faint AGN discovered by JWST on reionization
• On the Evolution of High-Redshift Active Galactic Nuclei
• The properties of primordially-seeded black holes and their hosts in the first billion years: implications for JWST
• SMBH growth parameters in the early Universe of Millennium and Millennium-II simulations
• Finding of a population of active galactic nuclei showing a significant luminosity decline in the past $\sim 10^{3-4}$ yrs
• Formation of the First Black Holes: Current observational status
• Evolution of the mass relation between supermassive black holes and dark matter halos across the cosmic time
• Prospects for Observing High-redshift Radio-loud Quasars in the SKA Era: Paving the Way for 21-cm Forest Observations
• J1342+0928 Supports the Timeline in the R_h=ct Cosmology
• High Star Formation Rates of Low Eddington Ratio Quasars at $z\gtrsim 6$
• Radiation hydrodynamics simulations of line-driven AGN disc winds: metallicity dependence and black hole growth
• No strong radio absorption detected in the low-frequency spectra of radio-loud quasars at z > 5.6
• Submillimeter signatures from growing supermassive black holes before reionization
• Recovering Density Fields inside Quasar Proximity Zones at $z\sim 6$
• 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
• Structure of the super-Eddington outflow and itsimpact on the cosmological scale
• 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
• An Optically Faint Quasar Survey at z~5 in the CFHTLS Wide Field: Estimates of the Black Hole Masses and Eddington Ratios
• Radio recombination lines from obscured quasars with the SKA
• Cosmic reionization of hydrogen and helium: contribution from both mini-quasars and stars
• Monster radio jet (>66 kpc) observed in quasar at z$\sim$5
• High-redshift quasar selection from the CFHQSIR survey
• Demography of high redshift AGN
• The optical luminosity function of LOFAR radio-selected quasars at $1.4\le z\le 5.0$ in the NDWFS-Boötes field
• Constraining Dynamical Dark Energy Models through the Abundance of High-Redshift Supermassive Black Holes
• The Noctua Suite of Simulations -- The Difficulty of Growing Massive Black Holes in Low-Mass Dwarf Galaxies
• Prospects for measuring neutrino mass with 21-cm forest
• Exploring the radio spectral energy distribution of the ultraluminous radio-quiet quasar SDSS J0100+2802 at redshift 6.3
• A complete search for redshift z>6.5 quasars in the VIKING survey
• Formation and Growth of the First Supermassive Black Holes in MOG
• Growth and Feedback from the First Black Holes
• Model-independent Reconstruction of UV Luminosity Function and Reionization Epoch
• Radio signals from early direct collapse black holes
• CFHQSIR: a Y-band extension of the CFHTLS-Wide survey
• The Diversity of Environments Around Luminous Quasars at Redshift $z\sim 6$
• 1 um Excess Sources in the UKIDSS - I. Three T Dwarfs in the SDSS Southern Equatorial Stripe
• Completeness III: identifying characteristic systematics and evolution in galaxy redshift surveys
• The Effect of Primordial Non-Gaussianities on the Seeds of Super-Massive Black Holes
• Direct Collapse to Precursors of Supermassive Black Hole Seeds:Radiation-feedback-generated Outflows
• Joint Lyα emitters - quasars reionization constraints
• VLBI observations of the high-redshift X-ray bright blazar SRGE J170245.3+130104
• Finding the Most Distant Quasars Using Bayesian Selection Methods
• Euclid: Discovery of 31 new quasars at $6.6<z<7.8$
• Merging Rates of the First Objects and the Formation of First Mini-Filaments in Models with Massive Neutrinos
• Lensing in the Darkness: A Bayesian Analysis of 22 Chandra Sources at $z\gtrsim 6$ Shows No Evidence of Lensing
• Black Hole merger rates in the first billion years in light of JWST data
• BASS XXX: Distribution Functions of DR2 Eddington-ratios, Black Hole Masses, and X-ray Luminosities
• Building a Radio AGN Sample from Cosmic Morning -- The Radio High-Redshift Quasar Catalog (RHzQCat): I. Catalog from SDSS Quasars and Radio Surveys at $z>3$
• Direct Collapse Pre-supermassive Black Hole Objects as Ly$\alpha$ Emitters
• Exploring Low Luminosity Quasar Diversity at z ~ 2.5 with the Gran Telescopio Canarias
• Radiative feedback on supermassive star formation: the massive end of the Population III initial mass function