Observational Study Of Peculiar High-redshift Quasars

Observational study of high-redshift quasars provides one of the most powerful probes to explore the early Universe, including the epoch of reionization,the evolution of galaxies and black holes, the formation and distribution of intergalactic medium(IGM) and so on. The thesis is involved in this scienti?c frontier relying upon the Lijiang 2.4 meter telescope(a?liated to Yunnan Observatories, Chinese Academy of Sciences), and dedicated on the investigations and explorations with some peculiar high-redshift quasars observed by the Lijiang 2.4meter telescope.The ?rst chapter introduces the history of AGN, and the detailed illustrations are focused on the quasar, including the current status and the latest progress, the open questions and corresponding challenges. The observational platform is introduced in Chapter 2, especially the improved and creative methods applied to observations, are introduced in order. In Chapter 3, the ?rst peculiar radio-loud quasar is introduced, in terms of the progress made so far.Due to the special properties of a newly discovered radio-loud quasar at z = 5.18,such as a SMBH hosted in the center and it is a potentially super-Eddington candidate, this quasar was quickly followed up by other research groups using multiwavelength facilities. In combination of these observational results, the ongoing study of ultra-luminous radio-loud quasars seems particularly valuable. An ultraluminous quasar at z = 6.3 is then introduced in Chapter 4. So far, this is the?rst time discovering a quasar of redshift larger than 6 with 2-meter telescopes all over the world. It poses a great challenge for the current growth theory of SMBH(Eddington-limited accretion) since it was only 0.9 billion years after the Big Bang. In addition, this quasars can be widely used to explore the formation of galaxies and stars, the distribution of IGM, complex absorption systems and the epoch of reionization, which are partly ongoing within our works. In Chapter5, we bring up another peculiar type of AGN, the broad absorption line quasar(BALQSO), as a retrospect of SMBH and a new start referring to AGN feedbacksin the early Universe. In chapter 6, a new perspective is introduced to tentatively explore the possible ”Grand Uni?cation” of AGN variabilities. We reviewed the AGN classi?cation based on the uni?ed model, especially for the dichotomy of radio-loud and radio-quiet quasars. Through introducing the eigenvector analytical method, some discussions are made to further explore the inherently physical drivers and external phenomena, including the covert process of incredible energy radiation among quasars and the possible connection between relativistic jets and sub-relativistic out?ows characterized by RLQs and BALQSOs.At the end, we give a summary of the main results presented in this thesis and an outline on the future study of peculiar high-redshift quasars.