Density, purity P and completeness C of variability-based selections of quasar candidates.
|Selection||Target||All quasars||z > 2.15||2.15 < z < 3.0||z > 3.0|
|Extreme var. only||3.4||2.9||86||1.7||49||6||1.4||41||7||0.3||8||5|
Notes. Densities are in deg-2 over an area of 220 deg-2. Purity is the ratio of the density of the quasars in a given sample to the target density. Completeness includes all identified high-redshift quasars, whether from their color, variability, radio emission, etc. Column “Target” is for all candidates, “All quasars” refers to confirmed quasars independently of their redshift. Line “Extreme var.” includes both the extreme variability sample and the main sample targets that fulfilled the requirement yNN > 0.95. Line “Extreme var. only” refers to objects rejected from the main sample due to their colors.
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