Title：Supermassive binary black holes in Active Galactic Nuclei:theoretical and observational perspectives

Speaker：Youjun Lu, Research Fellow
Unit：National Astronomical Observatories, Chinese Academy of Sciences
Time：2015.12.02（Wednesday） 15:00
Place：Physics Building 573, Haiyun Campus, Xiamen University
Abstract：The study of supermassive binary black holes (BBHs) is of greatimportance for various topics in physics and astrophysics, includingdetection of gravitational waves, formation and evolution of galaxies and supermassive black holes (SMBHs). Formation of BBHs in galacticcenters is an inevitable consequence of hierarchical mergers of galaxiesin the standard LambdaCDM cosmology. BBHs may be abundant in Active Galactic Nuclei (AGNs) and Quasars, which are believed to be triggered by major mergers of galaxies. However, direct observationalevidence for the existence of BBHs in AGNs and Quasars remains elusive. I will review the orbital evolution of BBHs and the characteristic observationalfeatures of BBHs at different evolutionary stages, and how these features canbe used to identify BBHs, including several methods that we proposed. I will also summarize previous and ongoing efforts in searching for BBHs and discusshow the current observations, specifically on the frequency of dual AGNs, can be used to constrain the evolution of BBHs and the triggering mechanismof nuclear activities.