Online seminar: Alexandre Le Tiec
Our online seminar #3 will take place on April 27 at 5:00 PM (CET), featuring a talk by Alexandre Le Tiec (Observatoire de Paris) titled “Tidal deformations of black holes”.
Title:
Tidal deformations of black holes
About the speaker:
Alexandre Le Tiec is an astrophysicist at the Paris Observatory whose research focuses on general relativity, black holes, and gravitational waves. He was awarded the Bronze Medal of the French National Centre for Scientific Research (CNRS) in 2019 in recognition of his scientific contributions. He has recently initiated an interdisciplinary line of inquiry aimed at tracing the deeper origins of the Anthropocene.
Abstract:
Tidal interactions provide a powerful probe of the structure of self-gravitating bodies. In Newtonian gravity, this response is encoded in tidal Love numbers, which relate induced multipole moments and surface deformations to an external field. In general relativity, however, black holes present a striking case: nonrotating solutions exhibit vanishing tidal Love numbers, suggesting an absence of conservative tidal response. This raises a natural question: how, and in what sense, can a black hole be tidally deformed? In this seminar, we revisit this question for spinning (Kerr) black holes. We will introduce two complementary notions of tidal response: one based on asymptotic multipole moments (field Love numbers), and another rooted in the geometry of the horizon itself (surficial Love numbers). After a brief pedagogical overview of the Newtonian framework, we will present recent developments in the definition and computation of these quantities for rotating black holes, emphasizing the role of horizon geometry and its multipolar structure.