A Pilot Survey for KX QSOs in the UKIDSS Ultra Deep Survey Field

Abstract

We have undertaken a pilot survey for faint QSOs in the UKIDSS Ultra Deep Survey Field using the KX selection technique. These observations exploit the very deep near-infrared and optical imaging of this field from UKIRT and Subaru to select candidate QSOs based on their VJK colours and morphologies. We determined redshifts for 426 candidates using the AAOmega spectrograph on the AAT in service time. We identify 17 QSOs (M_B<= -23) in this pilot survey at z=1.57-3.29. We combine our sample with an X-ray selected sample of QSOs in the same field (a large fraction of which also comply with our KX selection) to constrain the surface density of QSOs with K<=20, deriving limits on the likely surface density of 85-150/deg^2. We use the good image quality available from our near-infrared imaging to detect a spatially extended component of the QSO light which probably represents the host galaxies. We also use our sample to investigate routes to improve the selection of KX QSOs at faint limits in the face of the significant contamination by compact, foreground galaxies. The brightest examples from our combined QSO sample will be used in conjunction with a large VLT VIMOS spectroscopic survey of high redshift galaxies in this region to study the structures inhabited by gas, galaxies and growing super-massive black holes at high redshifts in the UKIDSS UDS.

Accepted for publication in MNRAS

References in corpus (13)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• K-corrections and filter transformations in the ultraviolet, optical, and near infrared
• The Subaru/XMM-Newton Deep Survey (SXDS) - II. Optical Imaging and Photometric Catalogs
• Radio imaging of the Subaru/XMM-Newton Deep Field - I. The 100-microJy catalogue, optical identifications, and the nature of the faint radio source population
• The evolution of the near-IR galaxy Luminosity Function and colour bimodality up to z ~ 2 from the UKIDSS Ultra Deep Survey Early Data Release
• The 2dF-SDSS LRG and QSO (2SLAQ) Luminous Red Galaxy Survey
• The FIRST-2MASS Red Quasar Survey
• Luminous K-band Selected Quasars from UKIDSS
• Quasars in the COSMOS Field
• Number counts and clustering properties of bright Distant Red Galaxies in the UKIDSS Ultra Deep Survey Early Data Release
• The colour selection of distant galaxies in the UKIDSS Ultra-Deep Survey Early Data Release
• Near-infrared adaptive optics imaging of high redshift quasars
• Using a complete spectroscopic survey to find red quasars and test the KX method

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• The CALYMHA survey: Lya luminosity function and global escape fraction of Lya photons at z=2.23
• The Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) Quasar Survey: Quasar Properties from Data Release Six to Nine
• Multiwavelength characterization of faint Ultra Steep Spectrum radio sources : A search for high-redshift radio galaxies
• The Subaru-XMM-Newton Deep Survey (SXDS) VIII.: Multi-wavelength Identification, Optical/NIR Spectroscopic Properties, and Photometric Redshifts of X-ray Sources
• An ALMA survey of the SCUBA-2 Cosmology Legacy SurveyUKIDSS/UDS Field: Halo Masses for Submillimetre Galaxies
• The Obscured Fraction of Quasars at Cosmic Noon
• Imaging of diffuse HI absorption structure in the SSA22 proto-cluster region at z = 3.1
• More connected, more active: galaxy clusters and groups at z~1 and the connection between their quiescent galaxy fractions and large-scale environments
• On the nature of infrared-faint radio sources in the SXDF and VLA-VVDS fields
• Ultraviolet-to-far-infra-red self-consistent analysis of the stellar populations of massive starburst galaxies at intermediate redshifts
• The nature of sub-millimetre galaxies II: an ALMA comparison of SMG dust heating mechanisms