报告人：Pedro V. P. Cunha博士

题目:The light ring instability

时间：2022年10月17日（周一）下午3:00

ZoomID：815 1928 4631

联系人：魏少文（Shao-Wen Wei）

报告摘要:

The ringdown and shadow of the astrophysically significant Kerr Black Hole (BH) are both intimately connected to a special set of bound null orbits known as Light Rings (LRs). Similarly, ultracompact objects with LRs but without an horizon could mimic BHs in some of their strong gravity phenomenology. However, are such ultracompact objects dynamically viable? Stationary and axisymmetric ultracompact objects that can form from smooth, quasi-Minkowski initial data must have at least one stable LR, which has been argued to trigger a spacetime instability. Until recently its development and fate had been unknown. We confirm that the LRs indeed triggered an instability in fully non-linear numerical evolutions of ultracompact bosonic stars free of any other known instabilities. The results shows that the LR instability can be effective in destroying horizonless ultracompact objects that could be plausible BH imitators.

报告人简介：

Pedro V. P. Cunha is a postdoctoral Junior researcherinthe University of Aveiro, Portugal. He obtained his Ph.D. in 2019 from the University of Lisbon. He used to be a postdoctoral fellow at Max Planck Institute for Gravitational Physics. His research interests include the strong gravitational effect of black holes, such as lensing, shadow, and hairy black holes. He has published more than 20 papers including 4 in PRL.