Counts of Low-redshift SDSS Quasar Candidates

Ivezic, Z.; Lupton, R. H.; Johnston, D. E.; Richards, G. T.; Hall, P. B.; Schlegel, D.; Fan, X.; Munn, J. A.; Yanny, B.; Strauss, M. A.; Knapp, G. R.; Gunn, J. E.; Schneider, D. P.

Counts of Low-redshift SDSS Quasar Candidates

Authors

Description

We analyze the counts of low-redshift quasar candidates selected using nine-epoch SDSS imaging data. The co-added catalogs are more than 1 mag deeper than single-epoch SDSS data, and allow the selection of low-redshift quasar candidates using UV-excess and also variability techniques. The counts of selected candidates are robustly determined down to g=21.5. This is about 2 magnitudes deeper than the position of a change in the slope of the counts reported by Boyle et al. (1990, 2000) for a sample selected by UV-excess, and questioned by Hawkins & Veron (1995), who utilized a variability-selected sample. Using SDSS data, we confirm a change in the slope of the counts for both UV-excess and variability selected samples, providing strong support for the Boyle et al. results.
to be published in the Proceedings of "AGN Physics with the SDSS"