The quasi normal modes of growing dirty black holes

Understand

The ringdown of a perturbed black hole contains fundamental information about space-time in the form of Quasi Normal Modes (QNM).

• Modifications to general relativity, or extended profiles of other fields surrounding the black hole, so called "black hole hair", can perturb the QNM frequencies.
• Previous works have examined the QNM frequencies of spherically symmetric "dirty" black holes - that is black holes surrounded by arbitrary matter fields.
• Such analyses were restricted to static systems, making the assumption that the metric perturbation was independent of time.