Ultra-luminous high-redshift quasars from SkyMapper -- II. New quasars and the bright end of the luminosity function

Abstract

We search for ultra-luminous Quasi-Stellar Objects (QSOs) at high redshift using photometry from the SkyMapper Southern Survey Data Release 3 (DR3), in combination with 2MASS, VHS DR6, VIKING DR5, AllWISE, and CatWISE2020, as well as parallaxes and proper motions from Gaia DR2 and eDR3. We report 142 newly discovered Southern QSOs at $3.8<z<5.5$, of which 126 have $M_{145}<-27$ ABmag and are found in a search area of 14,486 deg${}^2$. This Southern sample, utilising the Gaia astrometry to offset wider photometric colour criteria, achieves unprecedented completeness for an ultra-luminous QSO search at high redshift. In combination with already known QSOs, we construct a sample that is $>80$ per cent complete for $M_{145}<-27.33$ ABmag at $z=4.7$ and for $M_{145}<-27.73$ ABmag at $z=5.4$. We derive the bright end of the QSO luminosity function at restframe 145 nm for $z=4.7-5.4$ and measure its slope to be $\beta =-3.60\pm 0.37$ and $\beta =-3.38\pm 0.32$ for two different estimates of the faint-end QSO density adopted from the literature. We also present the first $z\sim 5$ QSO luminosity function at restframe 300 nm.

25 pages. Resubmitted to MNRAS after significant revisions. 23 new QSOs added; overhaul of methodology; important changes to results

References in corpus (22)

• An Observational Determination of the Bolometric Quasar Luminosity Function
• Updated Nearby Galaxy Catalog
• The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release
• The WFCAM Science Archive
• The Optical to Mid-Infrared Extinction Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS, 2MASS and WISE Surveys
• The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7
• The CatWISE2020 Catalog
• SkyMapper Southern Survey: Second Data Release (DR2)
• The Wide Field Spectrograph (WiFeS): Performance and Data Reduction
• The VISTA Science Archive
• The Half Million Quasars (HMQ) Catalogue
• A downturn in intergalactic CIV as redshift 6 is approached
• A survey of luminous high-redshift quasars with SDSS and WISE II. the bright end of the quasar luminosity function at z ~ 5
• Second Data Release of the All-sky NOIRLab Source Catalog
• 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 space density of ultra-luminous QSOs at the end of reionization epoch by the QUBRICS Survey and the AGN contribution to the hydrogen ionizing background
• Random Forests as a viable method to select and discover high redshift quasars
• The Extremely Luminous Quasar Survey in the Pan-STARRS 1 Footprint (PS-ELQS)
• Ultra-luminous quasars at redshift $z>4.5$ from SkyMapper
• The Luminosity Function of bright QSOs at z~4 and implications for the cosmic ionizing background
• The Probabilistic Random Forest applied to the selection of quasar candidates in the QUBRICS Survey
• A Thirty-Four Billion Solar Mass Black Hole in SMSS J2157-3602, the Most Luminous Known Quasar