Observational signatures of near-extremal rotating black hole

by Dr Haopeng Yan (CHEP, PKU)

Wednesday 21 Oct 2020, 10:30 → 11:30 Asia/Shanghai

B105 (CHEP)

We are entering an exciting new era of imaging black holes with the help of the Event Horizon Telescope (EHT). While the observational signals may in general depend on a complex nearby environment of a black hole, it is possible to expect some universal and striking signals for the case of near-extremal rotating black holes. These particular signals may serve as a typical signature for identifying a near-extremal rotating (high-spin) black hole in the Universe. In this talk, I will introduce black hole shadow and images of a point-like orbiting emitter (referred to as a hot spot) near the Innermost Stable Circular Orbit (ISCO) of a high-spin black hole. A key feature of the optical appearance of an orbiting hot spot is that there are many images of it moving on a vertical portion of the black hole shadow and having a rich structure. I will first introduce the observational signature of a high spin Kerr black hole and discuss the influence of a surrounding plasma on it, then I will introduce observational signatures for high spin black holes in alternative gravity theories (MOG theory and string theory) that beyond general relativity. Tencent Meeting ID: 100 702 220