Discovery of 16 New z ~ 5.5 Quasars : Filling in the Redshift Gap of Quasar Color Selection

Abstract

We present initial results from the first systematic survey of luminous $z\sim 5.5$ quasars. Quasars at $z\sim$ 5.5, the post-reionization epoch, are crucial tools to explore the evolution of intergalactic medium, quasar evolution and the early super-massive black hole growth. However, it has been very challenging to select quasars at redshifts 5.3 $\le z\le$ 5.7 using conventional color selections, due to their similar optical colors to late-type stars, especially M dwarfs, resulting in a glaring redshift gap in quasar redshift distributions. We develop a new selection technique for $z\sim$ 5.5 quasars based on optical, near-IR and mid-IR photometric data from Sloan Digital Sky Survey (SDSS), UKIRT InfraRed Deep Sky Surveys - Large Area Survey (ULAS), VISTA Hemisphere Survey (VHS) and Wide field Infrared Survey Explorer (WISE). From our pilot observations in SDSS-ULAS/VHS area, we have discovered 15 new quasars at 5.3 $\le z\le$ 5.7 and 6 new lower redshift quasars, with SDSS z band magnitude brighter than 20.5. Including other two $z\sim$ 5.5 quasars already published in our previous work, we now construct an uniform quasar sample at 5.3 $\le z\le$ 5.7 with 17 quasars in a $\sim$ 4800 square degree survey area. For further application in a larger survey area, we apply our selection pipeline to do a test selection by using the new wide field J band photometric data from a preliminary version of the UKIRT Hemisphere Survey (UHS). We successfully discover the first UHS selected $z\sim$ 5.5 quasar.

arXiv comment10 pages, 5 figures, accepted by AJ

References in corpus (39)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• Composite Quasar Spectra From the Sloan Digital Sky Survey
• Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample
• The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
• Preliminary Results from NEOWISE: An Enhancement to the Wide-field Infrared Survey Explorer for Solar System Science
• Observational constraints on Cosmic Reionization
• The Canada-France High-z Quasar Survey: nine new quasars and the luminosity function at redshift 6
• Model-independent evidence in favor of an end to reionization by z~6
• A Modified Magnitude System that Produces Well-Behaved Magnitudes, Colors, and Errors Even for Low Signal-to-Noise Ratio Measurements
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• The Pan-STARRS1 distant z>5.6 quasar survey: more than 100 quasars within the first Gyr of the universe
• Clustering of High Redshift ($z\ge 2.9$) Quasars from the Sloan Digital Sky Survey
• Eddington-limited accretion and the black hole mass function at redshift 6
• The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7
• The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low-Resolution Near-Infrared Spectra
• The Wide Field Spectrograph (WiFeS)
• The Sloan Digital Sky Survey quasar catalog: tenth data release
• The Wide Field Spectrograph (WiFeS): Performance and Data Reduction
• The z=5 Quasar Luminosity Function from SDSS Stripe 82
• A Survey of z~6 Quasars in the SDSS Deep Stripe: I. a Flux-Limited Sample at z_{AB}<21
• High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data
• PyWiFeS: A Rapid Data Reduction Pipeline for the Wide Field Spectrograph (WiFeS)
• Improved measurements of the intergalactic medium temperature around quasars: possible evidence for the initial stages of He-II reionisation at z~6
• Black-Hole Mass and Growth Rate at z~4.8: A Short Episode of Fast Growth Followed by Short Duty Cycle Activity
• The Subaru high-z quasar survey: discovery of faint z~6 quasars
• A survey of luminous high-redshift quasars with SDSS and WISE. I. target selection and optical spectroscopy
• Radio Properties of z>4 Optically-Selected Quasars
• Q0906+6930: The Highest-Redshift Blazar
• A survey of luminous high-redshift quasars with SDSS and WISE II. the bright end of the quasar luminosity function at z ~ 5
• The Discovery of Three New z>5 Quasars in the AGN and Galaxy Evolution Survey
• Quasar Probabilities and Redshifts from WISE mid-IR through GALEX UV Photometry
• Probabilistic selection of high-redshift quasars
• No excess of bright galaxies around the redshift 7.1 quasar ULAS J1120+0641
• ASERA: A Spectrum Eye Recognition Assistant for Quasar Spectra
• Discovery of a single faint AGN in a large sample of z>5 Lyman break galaxies
• The ALHAMBRA survey: Discovery of a faint QSO at z = 5.41

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• Building a Radio AGN Sample from Cosmic Morning -- The Radio High-Redshift Quasar Catalog (RHzQCat): I. Catalog from SDSS Quasars and Radio Surveys at $z>3$
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