期刊
ASTRONOMICAL JOURNAL
卷 138, 期 6, 页码 1925-1937出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-6256/138/6/1925
关键词
quasars: general
资金
- Alfred P. Sloan Foundation
- Participating Institutions
- National Science Foundation
- U.S. Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho, the Max Planck Society
- Higher Education Funding Council for England
We have conducted a pilot survey for z > 3.5 quasars by combining the FIRST radio survey with the Sloan Digital Sky Survey (SDSS). While SDSS already targets FIRST sources for spectroscopy as quasar candidates, our survey includes fainter quasars and greatly improves the discovery rate by using strict astrometric criteria for matching the radio and optical positions. Our method allows for selection of high-redshift quasars with less color bias than with optical selection, as using radio selection essentially eliminates stellar contamination. We report the results of spectroscopy for 45 candidates, including 29 quasars in the range 0.37 < z < 5.2, with 7 having redshifts z > 3.5. We compare quasars selected using radio and optical criteria, and find that radio-selected quasars have a much higher fraction of moderately reddened objects. We derive a radio-loud quasar luminosity function at 3.5 < z < 4.0, and find that it is in good agreement with expectations from prior SDSS results.
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