March 30, 2021 to April 1, 2021
Institut Henri Poincaré
Europe/Paris timezone

Spinning black holes fall in Love

Mar 30, 2021, 9:30 AM


Dr Alexandre Le Tiec (Observatoire de Paris)


The open question of whether a black hole can become tidally deformed by an external gravitational field has profound implications for fundamental physics, astrophysics and gravitational-wave astronomy. Love tensors characterize the tidal deformability of compact objects such as astrophysical (Kerr) black holes under an external static tidal field. We prove that all Love tensors vanish identically for a Kerr black hole in the nonspinning limit or for an axisymmetric tidal perturbation. In contrast to this result, we show that Love tensors are generically nonzero for a spinning black hole. Specifically, to linear order in the Kerr black hole spin and the weak perturbing tidal field, we compute in closed form the Love tensors that couple the mass-type and current-type quadrupole moments to the electric-type and magnetic-type quadrupolar tidal fields. For a dimensionless spin ~ 0.1, the nonvanishing quadrupolar Love tensors are ~ 0.002, thus showing that black holes are particularly "rigid" compact objects.

Primary authors

Dr Alexandre Le Tiec (Observatoire de Paris) Dr Marc Casals (Centro Brasileiro de Pesquisas Fisicas) Dr Edgardo Franzin (Scuola Internazionale Superiore di Studi Avanzati)

Presentation materials