报告题目:Growth of Supermassive Black Holes in High-z Quasars
报告人：李立新
报告时间：7月3日 10：00
报告地点：理学楼报告厅
题目：Growth of Supermassive Black Holes in High-z Quasars
时间地点：7月3日 10：00 理学楼报告厅
报告人：李立新
讲座摘要：
Eddington accretion is very efficient in growing the mass of a black hole: in a fraction of the Eddington time its mass can grow to an arbitrary large value if the feedback effect is not taken into account. However, since super-Eddington accretion has a very low radiation efficiency, people have argued against it as a major process for the growth of the black holes in quasars since observations have constrained the average accretion efficiency of the black holes in quasars to be >~ 0.1. I show that the observational constraint does not need to be violated if the black holes in quasars have undergone a two-phase growing process: with a short super-Eddington accretion process they get their masses inflated by a very large factor until the feedback process becomes important, then with a prolonged sub-Eddington accretion process they have their masses increased by a factor >~2. The overall average efficiency of this two-phase process is then >~ 0.1, and the existence of black holes of 10^9 Msun by redshift 6 is easily explained.
报告人简介:
李立新，北京大学教授。1990年北京大学物理系本科毕业。1993年北京师范大学物理系硕士毕业，之后留校任教。2001年普林斯顿大学天体物理系博士毕业。之后在哈佛大学和马普天体物理研究所做博士后。2008年被北京大学引进在科维理天文与天体物理研究所任教。早年从事广义相对论和量子宇宙学的研究，后来研究领域扩展到天体物理领域。目前主要研究兴趣包括黑洞、吸积盘、伽玛射线暴、超新星、引力透镜、宇宙学等等。