A survey of luminous high-redshift quasars with SDSS and WISE. I. Target selection and optical spectroscopy
- Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China)
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
- Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China)
- Research School of Astronomy and Astrophysics, Australian National University, Weston Creek, ACT 2611 (Australia)
- School of Physics and Astronomy, Sun Yat-Sen University, Guangzhou 510275 (China)
- Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China)
- Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
High-redshift quasars are important tracers of structure and evolution in the early universe. However, they are very rare and difficult to find when using color selection because of contamination from late-type dwarfs. High-redshift quasar surveys based on only optical colors suffer from incompleteness and low identification efficiency, especially at z≳4.5. We have developed a new method to select 4.7≲z≲5.4 quasars with both high efficiency and completeness by combining optical and mid-IR Wide-field Infrared Survey Explorer (WISE) photometric data, and are conducting a luminous z∼5 quasar survey in the whole Sloan Digital Sky Survey (SDSS) footprint. We have spectroscopically observed 99 out of 110 candidates with z-band magnitudes brighter than 19.5, and 64 (64.6%) of them are quasars with redshifts of 4.4≲z≲5.5 and absolute magnitudes of −29≲M{sub 1450}≲−26.4. In addition, we also observed 14 fainter candidates selected with the same criteria and identified 8 (57.1%) of them as quasars with 4.7<5.4. Among 72 newly identified quasars, 12 of them are at 5.2<5.7, which leads to an increase of ∼36% of the number of known quasars at this redshift range. More importantly, our identifications doubled the number of quasars with M{sub 1450}<−27.5 at z>4.5, which will set strong constraints on the bright end of the quasar luminosity function. We also expand our method to select quasars at z ≳ 5.7. In this paper we report the discovery of four new luminous z ≳ 5.7 quasars based on SDSS–WISE selection.
- OSTI ID:
- 22886985
- Journal Information:
- Astrophysical Journal, Vol. 819, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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