• Citer

Gravitational wave signatures of dark matter environments

par Machet, Ludovico
Président du jury Lopez Honorez, Laura
Promoteur Compère, Geoffrey ;Hertog, Thomas
Publication Non publié, 2026-01-13

Thèse de doctorat

• Accès en ligne
• Détails
• Contenu
• Statistiques

Résumé :

Gravitational wave observations opened an exciting new window to study the gravitational Universe. Direct detections of black holes and neutron stars are revealing the dynamics of compact objects and are likely to improve our understanding of gravity in the strong-field regime. To properly interpret these signals, the potential influence of matter surrounding their source has to be evaluated. This work explores how matter effects modify the properties of gravitational wave sources, focusing on an environment composed by dark matter. First, we model a Schwarzschild black hole immersed in a dark matter spike, deriving a fully relativistic matter density profile. We compute the system’s quasi-normal oscillation frequencies, and its response to a tidal perturbation. The relativistic dark matter profile leads to distinct scaling laws for the quasi-normal modes frequency shifts compared to non-relativistic models, while the Love numbers provide a potential signature of the dark matter presence. We then introduce a different model for the dark matter component, a scalar field resulting from nonlinear sigma models, motivated by string theory compactification. We first study boson stars solutions to these models, self-gravitating condensates of massive bosonic fields. We show that these theories allow for spherically symmetric solutions, that have properties dependent on the sigma mode curvature. Next, we study the dynamics of such scalar fields on black hole spacetimes, simulating their accretion onto isolated black holes and their impact on binary black hole mergers. Using numerical relativity, we show that the curvature of the sigma model dictates whether the scalar field behaves as an attractive or repulsive self-interaction, altering the accretion physics and the gravitational wave emission. By incorporating nonlinear field theories, relativistic dark matter profiles, and advanced numerical techniques, we contribute to the effort of detecting subtle imprints of exotic physics in gravitational wave signals, as well as improving high-precision tests of general relativity with future gravitational waves detectors.