A SURVEY of LUMINOUS HIGH-REDSHIFT QUASARS with SDSS and WISE. I. TARGET SELECTION and OPTICAL SPECTROSCOPY

Feige Wang, Xue Bing Wu, Xiaohui Fan, Jinyi Yang, Weimin Yi, Fuyan Bian, Ian D. McGreer, Qian Yang, Yanli Ai, Xiaoyi Dong, Wenwen Zuo, Linhua Jiang, Richard Green, Shu Wang, Zheng Cai, Ran Wang, Minghao Yue

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

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 ≲ M1450 ≲ -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 <z <5.4. Among 72 newly identified quasars, 12 of them are at 5.2 <z <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 M1450 <-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 SDSSWISE selection.

Original languageEnglish (US)
Article number24
JournalAstrophysical Journal
Volume819
Issue number1
DOIs
StatePublished - Mar 1 2016

Keywords

  • galaxies: active
  • galaxies: high-redshift
  • quasars: emission lines
  • quasars: general

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

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    Wang, F., Wu, X. B., Fan, X., Yang, J., Yi, W., Bian, F., McGreer, I. D., Yang, Q., Ai, Y., Dong, X., Zuo, W., Jiang, L., Green, R., Wang, S., Cai, Z., Wang, R., & Yue, M. (2016). A SURVEY of LUMINOUS HIGH-REDSHIFT QUASARS with SDSS and WISE. I. TARGET SELECTION and OPTICAL SPECTROSCOPY. Astrophysical Journal, 819(1), [24]. https://doi.org/10.3847/0004-637X/819/1/24