Ringdown of a dynamical spacetime

Understand

The gravitational waves emitted (some time) after two black holes merge are well described by the theory of linear perturbations on a spacetime characterized by the mass and spin of the remnant.

• However, in the very early stages right after merger, both the mass and spin are changing.
• In this work we explore, in a set up based on Vaidya's spacetime, the dynamical consequences of a change of mass in the spacetime due to the accretion of null matter (for example, gravitational waves).
• We show that accretion imprints time-dependent frequencies and amplitude to a ringdown waveform, and we show how to model accurately this effect in certain regimes.