Using a complete spectroscopic survey to find red quasars and test the KX method

Abstract

We present an investigation of quasar colour-redshift parameter space in order to search for radio-quiet red quasars and to test the ability of a variant of the KX quasar selection method to detect quasars over a full range of colour without bias. This is achieved by combining IRIS2 imaging with the complete Fornax Cluster Spectroscopic Survey to probe parameter space unavailable to other surveys. We construct a new sample of 69 quasars with measured bJ - K colours. We show that the colour distribution of these quasars is significantly different from that of the Large Bright Quasar Survey's quasars at a 99.9% confidence level. We find 11 of our sample of 69 quasars have signifcantly red colours (bJ - K >= 3.5) and from this, we estimate the red quasar fraction of the K <= 18.4 quasar population to be 31%, and robustly constrain it to be at least 22%. We show that the KX method variant used here is more effective than the UVX selection method, and has less colour bias than optical colour-colour selection methods.

11 pages, 14 figures, accepted for publication in MNRAS

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Cited by in corpus (5)

• Extremely Red Quasars from SDSS, BOSS and WISE: Classification of Optical Spectra
• Luminous K-band Selected Quasars from UKIDSS
• A Pilot Survey for KX QSOs in the UKIDSS Ultra Deep Survey Field
• The Southern 2MASS AGN Survey: spectroscopic follow-up with 6dF
• Properties of Near-Infrared Selected AGN Candidates with 2MASS/ROSAT Catalogues