An analytic approach to quasinormal modes for coupled linear systems

Understand

Quasinormal modes describe the ringdown of compact objects deformed by small perturbations.

• In generic theories of gravity that extend General Relativity, the linearized dynamics of these perturbations is described by a system of coupled linear differential equations of second order.
• We first show, under general assumptions, that such a system can be brought to a Schr\"odinger-like form.
• We then devise an analytic approximation scheme to compute the spectrum of quasinormal modes.