DESI z >~ 5 Quasar Survey. I. A First Sample of 400 New Quasars at z ~ 4.7-6.6

Abstract

We report the first results of a high-redshift ($z$ >~ 5) quasar survey using the Dark Energy Spectroscopic Instrument (DESI). As a DESI secondary target program, this survey is designed to carry out a systematic search and investigation of quasars at $z$ >~ 5, up to redshift 6.8. The target selection is based on the DESI Legacy Imaging Surveys (the Legacy Surveys) DR9 photometry, combined with the Pan-STARRS1 data and $J$-band photometry from public surveys. A first quasar sample has been constructed from the DESI Survey Validation 3 (SV3) and first-year observations until May 2022. This sample includes more than 400 new quasars at redshift 4.7 <= $z$ < 6.6, down to 21.5 magnitude in the $z$ band, discovered from 35% of the entire target sample. Remarkably, there are 220 new quasars identified at $z$ >= 5, more than one third of existing quasars previously published at this redshift. The observations so far result in an average success rate of 23% at $z$ > 4.7. The current spectral dataset has already allowed analysis of interesting individual objects (e.g., quasars with damped Ly$\alpha$ absorbers and broad absorption line features), and statistical analysis will follow the survey's completion. A set of science projects will be carried out leveraging this program, including quasar luminosity function, quasar clustering, intergalactic medium, quasar spectral properties, intervening absorbers, and properties of early supermassive black holes. Additionally, a sample of 38 new quasars at $z$ ~ 3.8-5.7 discovered from a pilot survey in the DESI SV1 is also published in this paper.

28 pages, 9 figures, and 2 tables; Published in ApJS

References in corpus (39)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• A luminous quasar at a redshift of z = 7.085
• Observational constraints on Cosmic Reionization
• Initial Performance of the NEOWISE Reactivation Mission
• An ultra-luminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30
• The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release
• The LOFAR Two-metre Sky Survey -- V. Second data release
• Overview of the Instrumentation for the Dark Energy Spectroscopic Instrument
• The Sloan Digital Sky Survey Quasar Catalog: twelfth data release
• The Pan-STARRS1 distant z>5.6 quasar survey: more than 100 quasars within the first Gyr of the universe
• Pōniuā'ena: A Luminous $z=7.5$ Quasar Hosting a 1.5 Billion Solar Mass Black Hole
• The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7
• Metallicity Evolution of Damped Lyman-alpha Systems out to z~5
• Physical properties of 15 quasars at $z\gtrsim 6.5$
• Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample
• DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation
• The Spectroscopic Data Processing Pipeline for the Dark Energy Spectroscopic Instrument
• Target Selection and Validation of DESI Luminous Red Galaxies
• Target Selection and Validation of DESI Quasars
• The Robotic Multi-Object Focal Plane System of the Dark Energy Spectroscopic Instrument (DESI)
• Target Selection and Validation of DESI Emission Line Galaxies
• The identification of z-dropouts in Pan-STARRS1: three quasars at 6.5<z<6.7
• The UKIRT Hemisphere Survey: Definition and J-band Data Release
• Overview of the DESI Milky Way Survey
• The Target-selection Pipeline for the Dark Energy Spectroscopic Instrument
• Measurements of the z ~ 6 Intergalactic Medium Optical Depth and Transmission Spikes Using a New z > 6.3 Quasar Sample
• The X-shooter/ALMA Sample of Quasars in the Epoch of Reionization. II. Black Hole Masses, Eddington Ratios, and the Formation of the First Quasars
• Three new VHS-DES Quasars at 6.7 < z < 6.9 and Emission Line Properties at z > 6.5
• Deep Full-sky Coadds from Three Years of WISE and NEOWISE Observations
• The DESI Survey Validation: Results from Visual Inspection of the Quasar Survey Spectra
• A Search for L/T Transition Dwarfs With Pan-STARRS1 and WISE. II. L/T Transition Atmospheres and Young Discoveries
• Preliminary Target Selection for the DESI Luminous Red Galaxy (LRG) Sample
• Preliminary Target Selection for the DESI Bright Galaxy Survey (BGS)
• Revealing the Accretion Physics of Supermassive Black Holes at Redshift z~7 with Chandra and Infrared Observations
• Preliminary Target Selection for the DESI Quasar (QSO) Sample
• Preliminary Target Selection for the DESI Milky Way Survey (MWS)
• Preliminary Target Selection for the DESI Emission Line Galaxy (ELG) Sample
• Discovery of 24 radio-bright quasars at $4.9\le z\le 6.6$ using low-frequency radio observations
• ASERA: A Spectrum Eye Recognition Assistant for Quasar Spectra

Cited by in corpus (21)

• The Early Data Release of the Dark Energy Spectroscopic Instrument
• "Little red dots" cannot reside in the same dark matter halos as comparably luminous unobscured quasars
• GA-NIFS and EIGER: A merging quasar host at z=7 with an overmassive black hole
• The missing FeII bump in faint JWST AGN: possible evidence for metal-poor broad-line regions at early cosmic times
• PICZL: Image-based Photometric Redshifts for AGN
• Discovery and characterization of 25 new quasars at 4.6 < z < 6.9 from wide-field multi-band surveys
• The host galaxies of radio-loud quasars at z>5 with ALMA
• Prospects for Observing High-redshift Radio-loud Quasars in the SKA Era: Paving the Way for 21-cm Forest Observations
• Galaxy Formation and Symbiotic Evolution with the Inter-Galactic Medium in the Age of ELT-ANDES
• Model-Independent Probe of Cosmic Distance Duality Relation
• High-$z$ radio Quasars in RACS I: Selection, identification, and multi-wavelength properties
• Euclid: The potential of slitless infrared spectroscopy: A z=5.4 quasar and new ultracool dwarfs
• JWST's PEARLS: A z=6 quasar in a train-wreck galaxy merger system
• VLBI observations of the high-redshift X-ray bright blazar SRGE J170245.3+130104
• The clustering of C IV and Si IV at the end of reionisation: A perspective from the E-XQR-30 survey
• Dynamical evolution timescales for the supermassive black hole system in the galaxy NGC 7727 (Arp 222)
• AllBRICQS: The Discovery of Luminous Quasars in the Northern Hemisphere
• Direct Collapse Pre-supermassive Black Hole Objects as Ly$\alpha$ Emitters
• 4MOST ChANGES: Catalog of high-redshift quasar candidates (4.5 < $z$ < 7) selected with SED fitting
• Estimating the completeness of the QUBRICS Survey with 3501 QSO redshifts from Gaia DR3 spectra
• Building a Radio AGN Sample from Cosmic Morning -- The Radio High-Redshift Quasar Catalog (RHzQCat): I. Catalog from SDSS Quasars and Radio Surveys at $z>3$