| Title | Efficient Photometric Selection of Quasars from the Sloan Digital Sky Survey: 100,000 z < 3 Quasars from Data Release One |
| Authors | Richards, Gordon T.; Nichol, Robert C.; Gray, Alexander G.; Brunner, Robert J.; Lupton, Robert H.; Vanden Berk, Daniel E.; Chong, Shang Shan; Weinstein, Michael A.; Schneider, Donald P.; Anderson, Scott F.; Munn, Jeffrey A.; Harris, Hugh C.; Strauss, Michael A.; Fan, Xiaohui; Gunn, James E.; IveziÄ, Željko; York, Donald G.; Brinkmann, J.; Moore, Andrew W. |
| Bibcode | 2004ApJS..155..257R Search ADS ↗ |
| Abstract | We present a catalog of 100,563 unresolved, UV-excess (UVX) quasar candidates to g=21 from 2099 deg2 of the Sloan Digital Sky Survey (SDSS) Data Release One (DR1) imaging data. Existing spectra of 22,737 sources reveals that 22,191 (97.6%) are quasars; accounting for the magnitude dependence of this efficiency, we estimate that 95,502 (95.0%) of the objects in the catalog are quasars. Such a high efficiency is unprecedented in broadband surveys of quasars. This ``proof-of-concept'' sample is designed to be maximally efficient, but still has 94.7% completeness to unresolved, g<~19.5, UVX quasars from the DR1 quasar catalog. This efficient and complete selection is the result of our application of a probability density type analysis to training sets that describe the four-dimensional color distribution of stars and spectroscopically confirmed quasars in the SDSS. Specifically, we use a nonparametric Bayesian classification, based on kernel density estimation, to parameterize the color distribution of astronomical sources-allowing for fast and robust classification. We further supplement the catalog by providing photometric redshifts and matches to FIRST/VLA, ROSAT, and USNO-B sources. Future work needed to extend this selection algorithm to larger redshifts, fainter magnitudes, and resolved sources is discussed. Finally, we examine some science applications of the catalog, particularly a tentative quasar number counts distribution covering the largest range in magnitude (14.2 |
| Objects | 100563 Objects Search NED ↙ |
