Stellar Rejuvenation in Galactic Center and AGNs: Analog of Planet Formation in Gravitational Wave Sources----中国科学院紫金山天文台

Seminar Title	Stellar Rejuvenation in Galactic Center and AGNs: Analog of Planet Formation in Gravitational Wave Sources

Speaker:	Prof. D. N. C. Lin

Affiliation:	(University of California, Santa Cruz)

When	Wednesday afternoon, July 3, 15:00 p.m.

Where:	Room 302 No.3 building , Xianlin campus (PMO, CAS)
	Welcome to Attend

	( PMO Academic Committee & Academic Circulating committee)

Abstract: The prevalence of massive black holes and nuclear stellar clusters implies some stars may be trapped in accretion disks around active galactic nuclei. We determine the star trapping rate and we show that the trapped stars rapidly accrete gas which leads to a top heavy initial mass function similar to that found in Galactic Center. These massive stars undergo supernova explosion, pollute the accretion disks around high-redshift quasars to produce super solar metallicity. They also produce single stellar-mass black hole remnants which gain mass through accretion and capture companions. Binary seed black holes lose angular momentum to the surrounding gas to tighten their separation. They generate intense gravitational wave when they coalesce. We provide analysis on the distribution of their masses, mass ratio, spin rate, binary orbit-spin obliquity and red-shift-dependent occurrence rate as observable predictions. I will describe some relevant mechanisms which are analogous to the astrophysics of planet formation and the implications of this scenario in the context of 1) coeval population and kinematic properties of disk and S stars around the Galactic center, 2) super solar metallicity, 3) duty cycle of AGN active phase, and 4) the rapid growth of their central massive black holes.

Awards and recognition: Catherine Wolfe Bruce Gold Medal from Astronomical Society of the Pacific (2015); Carnegie Professorship from St Andrew University (2015); Brouwer Award from American Astronomical Society (2014); Peter Wall International Distinguished Professor from University of British Columbia (2014); Lecar Lecturer from Center for Astrophysics, Harvard University (2014)

D. N. C. Lin is a professor of astronomy and astrophysics. He was the Founding Director of Kavli Institute for Astronomy & Astrophysics at Peking University, the chair of Astronomy Department at. He is the first to propose models of protoplanets’ type II migration, comprehensive core accretion model of planet formation, population synthesis model on the statistical property of exoplanets, tidal inflation of hot Jupiter, accretion disk models for the formation, structure, stability and evolution of protostellar disks, star capture, growth, supernova explosion, and pollution in accretion disks around massive black holes.