Luminous K-band Selected Quasars from UKIDSS
Natasha Maddox (1, 2), Paul C. Hewett (1), S. J. Warren (3), S. M., Croom (4) ((1) Institute of Astronomy, Cambridge, (2) Astrophysikalisches, Institut Potsdam, (3) Imperial College London, (4) University of Sydney)

TL;DR
This paper presents a large, K-band selected quasar sample from UKIDSS, revealing a significant population of quasars missed by optical surveys due to dust reddening and host galaxy light, with implications for quasar demographics.
Contribution
It introduces a novel K-band selection method that uncovers quasars overlooked by optical surveys, including dust-reddened and host-dominated objects, expanding the known quasar population.
Findings
KX-selection identifies quasars missed by SDSS due to optical colour criteria.
Nearly half of the quasars with K<17.0 at z<3 are too faint in i-band for SDSS targeting.
Less than 10% of quasars are missed due to dust reddening, with an obscured fraction likely below 20%.
Abstract
The largest K-band flux-limited sample of luminous quasars to date has been constructed from the UKIDSS Large Area Survey Early Data Release, covering an effective area of 12.8 deg^2. Exploiting the K-band excess of all quasars with respect to foreground stars, including quasars experiencing dust reddening and objects with non-standard SEDs, a list of targets suitable for spectroscopic follow-up observations with the AAOmega multi-object spectrograph is constructed, resulting in more than 200 confirmed AGN. KX-selection successfully identifies as quasar candidates objects that are excluded from the SDSS quasar selection algorithm due to their colours being consistent with the stellar locus in optical colour space (with the space density of the excluded objects agreeing well with results from existing completeness analyses). Nearly half of the KX-selected quasars with K<17.0 at z<3 are…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
