The Extremely Luminous Quasar Survey (ELQS) in the Sloan Digital Sky Survey footprint. II. The North Galactic Cap Sample

Abstract

We present the North Galactic Cap sample of the Extremely Luminous Quasar Survey (ELQS-N), which targets quasars with $M_{1450}<-27$ at $2.8\le z<5$ in an area of $\sim 7600{\mathrm{deg}}^2$ of the Sloan Digital Sky Survey (SDSS) footprint with $90\text{°}<\mathrm{RA}<270\text{°}$. Based on a near-infrared/infrared \textit{JKW2} color cut, the ELQS selection efficiently uses random forest methods to classify quasars and to estimate photometric redshifts; this scheme overcomes some of the difficulties of pure optical quasar selection at $z\approx 3$. As a result, we retain a completeness of $>70\%$ over $z\sim 3.0-5.0$ at $m_i\lesssim 17.5$, limited toward fainter magnitudes by the depth of the Two Micron All Sky Survey (2MASS). The presented quasar catalog consists of a total of 270 objects, of which 39 are newly identified in this work with spectroscopy obtained at the Vatican Advanced Technology Telescope and the MMT $6.5\mathrm{m}$ telescope. In addition to the high completeness, which allowed us to discover new quasars in the already well-surveyed SDSS North Galactic Cap, the efficiency of our selection is relatively high at $\sim 79\%$. Using 120 objects of this quasar sample we are able to extend the previously measured optical quasar luminosity function (QLF) by one magnitude toward the bright end at $2.8\le z\le 4.5$. A first analysis of the QLF suggests a relatively steep bright-end slope of $\beta \approx -4$ for this sample. This result contrasts with previous results in the same redshift range, which find a much flatter slope around $\beta \sim -2.5$, but agrees with recent measurements of the bright-end slope at lower and higher redshifts. Our results constrain the bright-end slope at $z=2.8-4.5$ to $\beta <-2.94$ with a 99\% confidence.

arXiv comment23 pages, 13 figures, submitted to ApJ

References in corpus (73)

• Planck 2015 results. XIII. Cosmological parameters
• The Sloan Digital Sky Survey: Technical Summary
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Seventh Data Release of the Sloan Digital Sky Survey
• Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies
• The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission
• SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
• The Baryon Oscillation Spectroscopic Survey of SDSS-III
• Composite Quasar Spectra From the Sloan Digital Sky Survey
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• A luminous quasar at a redshift of z = 7.085
• An 800-million-solar-mass black hole in a significantly neutral Universe at redshift 7.5
• The Multi-Object, Fiber-Fed Spectrographs for SDSS and the Baryon Oscillation Spectroscopic Survey
• Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample
• The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
• The SDSS Quasar Survey: Quasar Luminosity Function from Data Release Three
• The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Overview and Early Data
• Spectral Classification and Redshift Measurement for the SDSS-III Baryon Oscillation Spectroscopic Survey
• The 2dF QSO Redshift Survey - XII. The spectroscopic catalogue and luminosity function
• The 2dF QSO Redshift Survey - I. The Optical QSO Luminosity Function
• An Empirical Ultraviolet Template for Iron Emission in Quasars as Derived from I Zw 1
• The Canada-France High-z Quasar Survey: nine new quasars and the luminosity function at redshift 6
• Optical and Radio Properties of Extragalactic Sources Observed by the FIRST and SDSS Surveys
• Second ROSAT all-sky survey (2RXS) source catalogue
• The Sloan Digital Sky Survey Quasar Catalog IV. Fifth Data Release
• The Sloan Digital Sky Survey Quasar Catalog: Fourteenth Data Release
• The Sloan Digital Sky Survey Quasar Catalog: twelfth data release
• Unification of Luminous Type 1 Quasars through CIV Emission
• A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Third Data Release
• High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data IV: Luminosity Function from the Fall Equatorial Stripe Sampl
• The SDSS Damped Lya Survey: Data Release 3
• The Pan-STARRS1 distant z>5.6 quasar survey: more than 100 quasars within the first Gyr of the universe
• Unusual Broad Absorption Line Quasars from the Sloan Digital Sky Survey
• Efficient Photometric Selection of Quasars from the Sloan Digital Sky Survey: II. ~1,000,000 Quasars from Data Release Six
• The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7
• The SDSS-III Baryon Oscillation Spectroscopic Survey: Quasar Target Selection for Data Release Nine
• The Frequency and Radio Properties of Broad Absorption Line Quasars
• Spectral Classification of Quasars in the Sloan Digital Sky Survey: Eigenspectra; Redshift and Luminosity Effects
• The 2dF-SDSS LRG and QSO Survey: the QSO luminosity function at 0.4<z<2.6
• The Radio-Loud Fraction of Quasars is a Strong Function of Redshift and Optical Luminosity
• Simulation of Stellar Objects in SDSS Color Space
• Fe II Emission in 14 Low-Redshift Quasars: I - Observations
• A strong redshift dependence of the broad absorption line quasar fraction
• The Distribution of Metallicity in the IGM at z~2.5: OVI and CIV Absorption in the Spectra of 7 QSOs
• The z=5 Quasar Luminosity Function from SDSS Stripe 82
• Think Outside the Color Box: Probabilistic Target Selection and the SDSS-XDQSO Quasar Targeting Catalog
• The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Quasar Target Selection
• A Near-Infrared Spectral Template for Quasars
• The SDSS-III Baryon Oscillation Spectroscopic Survey: The Quasar Luminosity Function from Data Release Nine
• A Survey of z~6 Quasars in the SDSS Deep Stripe: I. a Flux-Limited Sample at z_{AB}<21
• Finding counterparts for All-sky X-ray surveys with Nway: a Bayesian algorithm for cross-matching multiple catalogues
• The Half Million Quasars (HMQ) Catalogue
• Identification of 1.4 Million AGNs in the Mid-Infrared using WISE Data
• The Sloan Digital Sky Survey Quasar Lens Search. V. Final Catalog from the Seventh Data Release
• Dark energy and curvature from a future baryonic acoustic oscillation survey using the Lyman-alpha forest
• An X-shooter composite of bright 1 < z < 2 quasars from UV to infrared
• 2MASS Reveals a Large Intrinsic Fraction of BALQSOs
• An improved method of constructing binned luminosity functions
• Probing the Evolution of IR Properties of z~6 Quasars: Spitzer Observations
• Evolution of the Quasar Luminosity Function Over 3 < z < 5 in the COSMOS Survey Field
• The Demographics of Broad-Line Quasars in the Mass-Luminosity Plane. I. Testing FWHM-Based Virial Black Hole Masses
• SDSS quasars in the WISE preliminary data release and quasar candidate selection with optical/infrared colors
• Early and Extended Helium Reionization Over More Than 600 Million Years of Cosmic Time
• Luminous K-band Selected Quasars from UKIDSS
• A survey of luminous high-redshift quasars with SDSS and WISE II. the bright end of the quasar luminosity function at z ~ 5
• GALEX far-UV color selection of UV-bright high-redshift quasars
• NICMOS and VLA Observations of the Gravitatonally Lensed Ultraluminous BAL Quasar APM~08279+5255: Detection of a Third Image
• Bayesian High-Redshift Quasar Classification from Optical and Mid-IR Photometry
• Quasar candidate selection and photometric redshift estimation based on SDSS and UKIDSS data
• A search for signatures of quasar evolution: Comparison of the shapes of the rest-frame optical/UV continua of quasars at z>3 and z~0.1
• The Evolution and Luminosity Function of Quasars from Complete Optical Surveys
• The Extremely Luminous Quasar Survey (ELQS) in the SDSS footprint I.: Infrared Based Candidate Selection

Cited by in corpus (16)

• Exploring Reionization-Era Quasars III: Discovery of 16 Quasars at $6.4\lesssim z\lesssim 6.9$ with DESI Legacy Imaging Surveys and UKIRT Hemisphere Survey and Quasar Luminosity Function at $z\sim 6.7$
• 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
• Gravitationally lensed quasars in Gaia -- IV. 150 new lenses, quasar pairs, and projected quasars
• KiDS-SQuaD II: Machine learning selection of bright extragalactic objects to search for new gravitationally lensed quasars
• The Extremely Luminous Quasar Survey in the Sloan Digital Sky Survey footprint. III. The South Galactic Cap Sample and the Quasar Luminosity Function at Cosmic Noon
• The Pan-STARRS1 $\mathbf{z}>5.6$ Quasar Survey: III. The $\mathbf{z}\approx 6$ Quasar Luminosity Function
• On the AGN nature of two UV bright sources at z_spec~5.5 in the CANDELS fields: an update of the AGN space density at M1450~-22.5
• The Infrared Medium-deep Survey. VIII. Quasar Luminosity Function at $z\sim 5$
• A high space density of L* Active Galactic Nuclei at z~4 in the COSMOS field
• The Extremely Luminous Quasar Survey in the Pan-STARRS 1 Footprint (PS-ELQS)
• Ultra-luminous quasars at redshift $z>4.5$ from SkyMapper
• A Survey for High-redshift Gravitationally Lensed Quasars and Close Quasars Pairs. I. the Discoveries of an Intermediately-lensed Quasar and a Kpc-scale Quasar Pair at $z\sim 5$
• Mapping quasar light echoes in 3D with Lyα forest tomography
• Forecasting cosmic acceleration measurements using the Lyman-$\alpha$ forest
• Paving the Way for Euclid and JWST via Optimal Selection of High-z Quasars
• An Extremely Bright QSO at $z=2.89$