PIRSA ID: 21020052
Series: Strong Gravity
Event Type: Seminar
Scientific Area(s): Strong Gravity
End date: 2021-02-25
Speaker(s): Paul Chesler Massachusetts Institute of Technology (MIT) - Department of Physics
Light rays can orbit the photon shell of a black hole many times before escaping to infinity. This means that a distant observer can see a successive series of "echo" images, each separated in time by the photon shell orbital period, and each dimmer than the previous. I will present a study of light echos using coherent autocorrelation functions sourced by fluctuating matter in accretion flows. I will demonstrate that coherent autocorrelation functions are peaked at integer multiples of the photon shell orbital period. Furthermore, I will argue that the power in echos from supermassive black holes is too small to be observed on Earth.
Zoom Link: https://pitp.zoom.us/j/92751681169?pwd=V0hQeUMwaWtTQjQ3UzdxekJiT0lmQT09