PIRSA:26090041

Video URL

https://pirsa.org/26090041

Spectral instabilities in the time domain

May, T. (2026). Spectral instabilities in the time domain. Perimeter Institute for Theoretical Physics. https://pirsa.org/26090041

May, Taillte. Spectral instabilities in the time domain. Perimeter Institute for Theoretical Physics, Sep. 24, 2026, https://pirsa.org/26090041 

          @misc{ scivideos_PIRSA:26090041,
            doi = {10.48660/26090041},
            url = {https://pirsa.org/26090041},
            author = {May, Taillte},
            keywords = {Strong Gravity},
            language = {en},
            title = {Spectral instabilities in the time domain},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2026},
            month = {sep},
            note = {PIRSA:26090041 see, \url{https://scivideos.org/pirsa/26090041}}
          }

Taillte May Perimeter Institute

Talk numberPIRSA:26090041
DOI10.48660/26090041
Source RepositoryPIRSA
Collection
Talk Type Scientific Series
Subject

Abstract

Quasinormal-mode frequencies are characteristic frequencies of a black hole spacetime, and can be detected using gravitational waves. The measurement of these frequencies is used to test the nature of astrophysical black holes. However, the quasinormal-mode spectrum is unstable. The spectral instability of black holes refers to the large change in quasinormal-mode frequencies produced by small perturbations to the gravitational potential. Historically, this phenomenon has been studied primarily in the frequency domain. Here we investigate its effect on the time domain waveform using a simple model. We show that there is a time delay before any shift in the frequencies, related to the echo time between the perturbation and the primary potential. In a perturbative limit, the change in the frequencies after a single echo matches the usual frequency-domain perturbed frequencies. Outside of that limit, the change in the signal at intermediate times cannot be described by a constant shift in frequency.