Quasars are one of the four major discoveries in radio astronomy in the 1960s. They are the brightest and the most energetical non-transient objects in the universe. These distant and bright quasars at the center of galaxies are important probes for studying black hole growth and galaxy evolution and exploring the very early universe. Since the discovery of the first quasar in 1963, the search for quasars has always been a frontier hotspot in astrophysical research, and significantly enhanced our understandings of the accretion process around supermassive black holes, the feedback mechanisms from the nuclei of galaxies and the history of cosmic reionization.
In recent years, with the development of various large-scale survey projects worldwide, an increasing number of quasars and candidates have been discovered. The identification and precise redshift measurement of quasars still need spectroscopic observations. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), the Chinese telescope that has produced the largest spectroscopic survey to date, is well suited for the quasar identification task.
The 12 yr LAMOST quasar survey since 2012 has independently discovered more than 40k quasars, making the LAMOST quasar survey currently the third-largest survey project in the world in terms of the number of quasars identified spectroscopically, second only to the Sloan Digital Sky Survey (SDSS) and the Dark Energy Spectroscopic Instrument (DESI) survey, as reported in a recent study published in the Astrophysical Journal Supplement Series by the LAMOST quasar survey team, which is led by Xue-Bing Wu, a professor at the Department of Astronomy, School of Physics, Peking University.
Figure 1: The sky distribution of quasars in LAMOST DR1-12 in equatorial coordinates.
In this paper, the team released a catalog including 11,346 quasars observed by LAMOST between September 2021 and June 2024. Among them, 8,427 were independently discovered by LAMOST, and 5,386 are new discoveries. In addition, they identified 807 Extreme Variability Quasars (EVQs) and 110 Broad Absorption Line (BAL) quasars, bringing the total number of BAL quasars discovered by LAMOST to 400. Together with four previous data releases, the team has identified 67,521 quasars, among them 40,293 are independent discoveries and 29,513 are new.
“Utilizing time-domain photometric data from the Zwicky Transient Facility (ZTF), we perform more accurate absolute flux calibrations for the LAMOST quasar spectra for the first time, which enable us to measure the properties of those quasars more precisely”, said the paper's first author, Dr. Bing Lyu, a postdoc and LAMOST Fellow at KIAA, Peking University.
According to Prof. Xue-Bing Wu, the LAMOST quasar survey not only increases the number of known quasars but also provides a rich spectroscopic dataset for studying quasar spectral variability and discovering rare quasars. Qian Yang et al. (2018) at Peking University discovered 21 new changing-look quasars using LAMOST, SDSS survey data and follow-up observations. Qian Dong et al. (2025) at Xiamen University discovered 40 new changing-look quasars using updated LAMOST and SDSS survey data. Zhi-Ying Huo et al. (2025) from NAOC used LAMOST to discover 1,300 new quasars behind the Galactic Plane (GPQs).
“As the LAMOST spectroscopic survey continues, LAMOST will discover more rare quasars in the future, making more contributions to scientific researches such as studying cosmic evolution and the physical nature of quasars, constructing the uniform reference frame for astrometry, and probing the chemistry and kinematics of intergalactic medium”, Xue-Bing Wu added.
Paper link: https://doi.org/10.3847/1538-4365/ae2b6e(Lyu, Wu, Jin et al., 2026, ApJS, 282, 72)
