Speaker
David Pereniguez
Description
At high frequencies, black hole dynamics can be described by Penrose-limit plane waves adapted to the photon ring. I will show that, in this limit, gravitational electric–magnetic duality is restored on shell, leading to QNM isospectrality in GR as well as a specific class of EFT extensions. I will then explain how this high-frequency perspective can be used to construct exact nonlinear QNM solutions. If time allows, I will briefly discuss a second, unrelated regime in which ringdown nonlinearities are also exactly tractable: the large-D limit of GR.