Symmetries in the gravitational physics of black holes

by Valerio De Luca (Johns Hopkins University)

Thursday 4 Jun 2026, 16:00 → 17:30 Europe/Rome

Aula Conversi (Dipartimento di Fisica-Ed. Marconi)

The dynamics of coalescing black hole binaries are deeply governed by underlying symmetry principles across all phases of their evolution. We explore how symmetry arguments illuminate three key observables: tidal Love numbers, quasi-normal modes, and gravitational memory. During the inspiral, tidal Love numbers describe the conservative response of compact objects to external tidal fields. We revisit their vanishing for black holes in General Relativity from a symmetry-based perspective, examining the fragility of this property when the symmetry structure is broken. In the ringdown, quasi-normal modes encode the characteristic oscillations of perturbed black holes. We discuss isospectrality between different parity sectors and trace its origin to spacetime symmetries. Finally, gravitational memory describes the permanent offset in the gravitational wave strain arising from the nonlinear nature of gravity. We explore its relation to Bondi-Metzner-Sachs symmetries at future null infinity in synchronous coordinates and discuss the associated soft theorems for scattering amplitudes and in-in correlation functions.