Discovery of six high-redshift quasars with the Lijiang 2.4 m telescope and the Multiple Mirror Telescope |
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| Authors: | Xue-Bing Wu Wen-Wen Zuo Qian Yang Wei-Min Yi Chen-Wei Yang Wen-Juan Liu Peng Jiang Xin-Wen Shu and Hong-Yan Zhou |
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| Institution: | 3,4 1 Department of Astronomy, Peking University, Beijing 100871, China; 2 National Astronomical Observatories / Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming 650011, China 3 Key Laboratory for Research in Galaxies and Cosmology, The University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China 4 Polar Research Institute of China, Shanghai 200136, China |
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| Abstract: | Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from spectroscopy with the Yunnan Faint Object Spectrograph and Camera (YFOSC) at the Lijiang 2.4 m telescope in February, 2012. These quasars are in the list of z > 3.6 quasar candidates selected by using our proposed J K/i Y criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as z > 3.6 quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that z > 4 quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained. |
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| Keywords: | quasars: general — quasars: emission lines — galaxies: active — galax- ies: high-redshift |
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