2008AJ....136..954G -
Astron. J., 136, 954-962 (2008/September-0)
An exploratory search for z ≳ 6 quasars in the UKIDSS early data release.
GLIKMAN E., EIGENBROD A., DJORGOVSKI S.G., MEYLAN G., THOMPSON D., MAHABAL A. and COURBIN F.
Abstract (from CDS):
We conducted an exploratory search for quasars at z ∼ 6-8, using the Early Data Release (EDR) from the United Kingdom Infrared Deep Sky Survey (UKIDSS) cross-matched to panoramic optical imagery. High-redshift quasar candidates are chosen using multi-color selection in i, z, Y, J, H, and K bands. After removal of apparent instrumental artifacts, our candidate list consisted of 34 objects. We further refined this list with deeper imaging in the optical for ten of our candidates. Twenty-five candidates were followed up spectroscopically in the near-infrared and in the optical. We confirmed 25 of our spectra as very low-mass main-sequence stars or brown dwarfs, which were indeed expected as the main contaminants of this exploratory search. The lack of quasar detection is not surprising: the estimated probability of finding a single z > 6 quasar down to the limit of UKIDSS in 27.3 deg2 of the EDR is <5%. We find that the most important limiting factor in this work is the depth of the available optical data. Experience gained in this pilot project can help refine high-redshift quasar selection criteria for subsequent UKIDSS data releases.
Abstract Copyright:
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Journal keyword(s):
cosmology: observations - quasars: general - stars: low-mass, brown dwarfs - surveys
Nomenclature:
Table 1: [GED2008] JHHMMSS.ss+DDMMSS.ss N=34.
Simbad objects:
40
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