Selecting Quasars by their Intrinsic Variability - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




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Abstract: We present a new and simple technique for selecting extensive, complete andpure quasar samples, based on their intrinsic variability. We parametrize thesingle-band variability by a power-law model for the light-curve structurefunction, with amplitude A and power-law index gamma. We show that quasars canbe efficiently separated from other non-variable and variable sources by thelocation of the individual sources in the A-gamma plane. We use ~60 epochs ofimaging data, taken over ~5 years, from the SDSS stripe 82 S82 survey, whereextensive spectroscopy provides a reference sample of quasars, to demonstratethe power of variability as a quasar classifier in multi-epoch surveys. ForUV-excess selected objects, variability performs just as well as the standardSDSS color selection, identifying quasars with a completeness of 90% and apurity of 95%. In the redshift range 2.5







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