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Quasars, as the most luminous active galactic nuclei, are crucial for studying supermassive black holes, galaxy evolution and cosmology. In last two decades, we carried out three major spectroscopic quasar surveys in China. The LAMOST quasar survey identified 67,521 quasars, and 29,513 of them are new discoveries. The bright high-redshift survey found over 100 quasars at z > 5, offering a key database for studying the evolution after the cosmic reionization. The discovery of a quasar with 12-billion-solar-mass black hole at z = 6.3, later confirmed by JWST, challenging the theory of black hole growth in the early Universe. We also carried out a survey of quasars behind the Galactic Plane, a rarely explored region due to severe Galactic extinction. We selected more than 160,000 quasar candidates and identified about 1,500 quasars behind the Galactic Plane. We measured the emission-line properties and black hole masses of all these quasars. In the future, we will continue the quasar survey with the Chinese Space Station Telescope (CSST), expected to be launched in 2027, and look forward to further collaborations with Australian astronomers. |
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