Counts of Low-redshift SDSS Quasar Candidates

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

arXiv · astro-ph/0310566

Counts of Low-redshift SDSS Quasar Candidates

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

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Abstract

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.

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Z. Ivezic, R. H. Lupton, D. E. Johnston, G. T. Richards, P. B. Hall, D. Schlegel, X. Fan, J. A. Munn, B. Yanny, M. A. Strauss, G. R. Knapp, J. E. Gunn, D. P. Schneider. 2003-10-20. Counts of Low-redshift SDSS Quasar Candidates. https://arxiv.org/abs/astro-ph/0310566

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