Cavity effect in the quasinormal mode spectrum of topological stars

Understand

We study scalar perturbations of topological solitons, smooth horizonless solutions in five-dimensional Einstein-Maxwell theory that correspond to coherent states of gravity via the dynamics of extra compact dimensions.

• First, we compute scalar quasinormal modes for topological stars that have a single unstable photon sphere, and we show that the spectrum is very similar to that of a black hole with the same photon sphere.
• Next, we study topological stars that have both a stable inner photon sphere and an unstable one.
• The first few quasinormal modes are localized around the inner photon sphere.