The search for high-redshift quasars

In 2015, an international team consisting of mainly Chinese astronomers announced the discovery of the most luminous quasar in the early Universe, powered by the most massive black hole known at the time. The discovery of this quasar, named SDSS J0100+2802, set a new record in the discovery of high redshift quasars with 2-meter telescopes, and sheds light just like a lighthouse to help us know more about the early Universe. Moreover, it presents substantial challenges to theories of the formation and growth of black holes in the early Universe. This article will discuss the following topics: (1) the historical discovery of quasars; (2) the nature of quasars and parameters to describe them; (3) the scientific motivation to study quasars; (4) the ways to select quasars, especially high redshift quasars; (5) how we discovered the quasar SDSS J0100+2802; (6) a perspective of future research on high redshift quasars. (authors)