原子核钟、硅基-硫基光电子技术、数据标准、量子态虚度 | 本周物理讲座

摘要：

Nuclear and globular star clusters (NSC and GC) are  spectacular self-gravitating stellar systems in our Galaxy and across  the Universe - in many respects. They populate disks and spheroids of  galaxies as well as almost every galactic center. In massive elliptical  galaxies NSCs harbor supermassive black holes, which might influence the  evolution of their host galaxies as a whole. The evolution of star  clusters is not only governed by the aging of their stellar populations  and simple Newtonian dynamics. For increasing particle number, unique  gravitational effects of collisional many-body systems begin to dominate  the early cluster evolution. Direct N-body simulations are the most  computationally expensive but also the most astrophysically advanced  method to simulated GC and NSC evolution, using massively parallel  supercomputers with GPU acceleration. Algorithmic and astrophysical  improvements of Nbody6++GPU in recent years are shown and selected  current results. For example we find that intermediate mass black holes  form in initially dense clusters, through mergers of massive stars,  binary induced interactions with black holes, and several generations of  relativistic black hole coalescences. GC models of the DRAGON and  DRAGON-II simulations provide reasonable predictions e.g. on rates of  coalescences observable with current gravitational wave instruments.  While NSCs are of interest as sources of gravitational waves as well  they also are sources of tidal disruption events, of which quite a  number has been observed now in different electromagnetic wavelengths.  Preliminary results for NSC will be shown, together with a novel and  detailed treatment of tidal disruption events (depending on stellar  parameters), tidal disruption of binaries, direct capture of low-mass  stars by the central supermassive black hole, and tidal capture through  classical tidal dissipation or relativistic dynamics (in case of compact  objects).

报告人简介：

Rainer Spurzem has completed his Ph.D. at the University of Göttingen (Germany) in 1988 with a thesis on stellar systems around supermassive black holes. During the 90s he worked as a researcher and teaching assistant at the University of Kiel (Germany), bringing GRAPE special purpose computers for astrophysical N-body simulations to Europe. After postdocs and visiting fellowships in the UK, Japan and the US he moved to the University of Heidelberg, Germany in 1996, where he obtained an extracurricular professorship in 2003. In 2011 he received with his team the PRACE award of European Supercomputing Centers for their joint Chinese-European supercomputing project, and in 2015 an Alexander-von-Humboldt Polish Honorary Research Fellowship. Since 2009 he is leading the Silk Road Project as a visiting professor of Chinese Academy of Sciences in Beijing, and he is adjunct faculty member of KIAA since then. Since 2013 he is a special state foreign expert appointed by the government of China. His fields of interest are nuclear and globular star clusters, black holes and gravitational waves and high-performance supercomputing.