Exceptional Points and Resonance in Black Hole Ringdown

Rodrigo Panosso Macedo (NBI, Copenhagen)

Jan 13. 2026, 15:00 — 15:30

We study black-hole ringdown in the presence of exceptional points (EPs) using a hyperboloidal framework that extends the standard quasinormal-mode (QNM) description. Near EPs, we find the near-coalescence of both QNM eigenvalues and eigenfunctions, giving rise to genuine resonant behavior that is not captured by conventional QNM analyses. Using a phenomenological environmental black-hole model evolved on hyperboloidal slices, we show that these spectral features lead to enhanced mode contributions and characteristic departures from simple exponentially damped oscillations in the time domain. We further identify the EP frequency, given by the averaged value of the interacting modes, as the physically relevant observable in the near-EP regime.

Further Information
Venue:
ESI Boltzmann Lecture Hall
Recordings:
Recording
Associated Event:
Hyperboloidal Foliations and their Application (Workshop)
Organizer(s):
Roland Donninger (U of Vienna)
David Hilditch (IST Lisboa)
Maciej Maliborski (TU Wien)
Rodrigo Panosso Macedo (NBI, Copenhagen)
Alex Vañó Viñuales (U de Les Illes Balears)
Anil Colpan Zenginoglu (U of Maryland)