Planting seeds for gravitational wave generators around active galactic nuclei: Analog of planetary systems around massive black holes

主讲人 (Speaker): Douglas N. C. Lin （林潮）

主讲人单位 (Speaker's Institute): University of California, Santa Cruz and Tsinghua University

邀请人 (Invited by): 冯珑珑

时间 (Time): 星期一, 2016/11/14 - 10:30 to 11:30

地点 (Location): 珠海校区行政楼八层天琴引力中心大会议室

摘要 (Abstract):

Advanced LIGO event GW150914 has been attributed to the coalescence of two black holes with masses more than double that of most known stellar black holes. Formation of such stellar black holes directly through supernova explosions requires massive, metal-deficient progenitors. This requirement and their nearly equal masses may not be compatible with its occurrence in the local Universe.  I consider an alternative possibility which may lead to the robust production of binary black holes with masses up to a hundred solar masses in the proximity of active galactic nuclei (AGN's). I will describe some relevant mechanisms which are analogous to the astrophysics of planet formation. I will discuss the implications of this scenario in the context of structure
and evolution of AGN disks including the cause of their super solar metallicity, duty cycle of their active phase, and the rapid growth of their central massive black holes.

主讲人简介 (Speaker's CV):

Douglas N. C. Lin (born May 7, 1949) is Professor of Astronomy and Astrophysics at the University of California, Santa Cruz. He was born in New York and grew up in Beijing. He earned his BSc from McGill University, his PhD from the Institute of Astronomy, Cambridge University, and performed postdoctoral research at both Harvard and Cambridge. In 1979 he took an Assistant Professorship at UCSC, and has remained there since. He is also the founding director of the Kavli Institute for Astronomy and Astrophysics at Peking University. "Douglas Lin's principal research interests are in the origin of the solar system, star formation, astrophysical fluid dynamics, dynamics of stellar clusters, structure of galaxies, active galactic nuclei, and galaxy formation," according to his UCSC faculty home page. He is one of the scientists who collaborates closely with observational colleagues Burton Jones and Arnold Klemola in working towards accurate estimates of the properties of the Large Magellanic Cloud. Lin observes that, over recent years, astronomers have newly expanded horizons within which to research. They have progressed from having only planets within a single solar system, our own, to study, to the point where now they are currently in the midst of "a revolution in the search for extra solar planets. In little over a decade, over 200 extra solar planets have been discovered." This growth of potential study subjects has led Lin to look toward observing the formation of planetary systems from their creation through to more mature systems, since scientists can now observe "dozens of mature systems and dozens more in birth throes." His research goal, from the study of this rich new data, is to eventually construct "a unified theory which can explain the statistical properties of planetary systems." As a mark of respect to his long history of contribution within astronomy, the Monash University recently held a Symposium titled Evolution of Plantary and Stellar Systems (nicknamed Linfest) in his honour.[7] He also sits on the selection committee for the Astronomy award, given under the auspices of the Shaw Prize.