Zwaartekrachtgolfsignaturen van donkere-materieomgevingen

Next-generation gravitational wave detectors will require higher accuracy waveform models to faithfully recover the parameters of the detected signals' sources. In this thesis, motivated by this consideration and by the opportunities to uncover new physics in these high-precision measurements, we investigate the impacts of a dark matter distribution on potential gravitational waves sources for this class of detectors. We focus on two kinds of candidates: a fluid-like cold dark matter and a minimally coupled scalar field sector derived from a nonlinear sigma model. This work discussed how these matter distributions could imprint signatures on a gravitational wave source. First, we model a Schwarzschild black hole immersed in a dark matter spike, deriving a fully relativistic density profile for the fluid-like dark matter through adiabatic contraction of an initial Hernquist profile. Via black hole perturbation theory on this spacetime, we compute the system's quasi-normal modes (QNMs), and its response to a tidal perturbation via the tidal Love numbers (TLNs). We observe that the QNMs receive corrections with respect to their values in a vacuum Schwarzschild spacetime, and that the TLNs are non-vanishing. We find that the relativistic dark matter profile leads to distinct scaling laws for the quasi-normal modes frequency shifts compared to non-relativistic models, and that the shifts are suppressed for massive and diluted halos. The Love numbers, while small, provide a new channel for energy loss during the inspiral phase, which could alter a binary black hole dynamics over several orbits. In the second part of the thesis, we introduce a scalar field resulting from nonlinear sigma models, motivated by string theory compactification arguments. We identify spherically symmetric boson stars solutions to these models, self-gravitating condensates of massive bosonic fields. The curvature of the sigma models is shown to affect significantly the properties of such solutions. The hyperbolic model yields light and diluted boson stars, while the spherical theory allows for solutions with mass and compactness of the order of those of neutron stars. Finally, 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 simulations with the GRChombo code, 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. The hyperbolic field behaves with an attractive self-interaction, while the spherical one shows a repulsive dynamics. This emerges clearly in the accretion process when the scalar field mass is low with respect to the black hole scale. In the binary black hole case, the scalar field forms a circumbinary cloud that induces a dephasing in the GW waveform, with the direction and magnitude of the dephasing depending on the model's curvature. We observe indications that these models suppress bosenova phenomena, i.e. a rapid instability which results in the ejection of the boson cloud from the binary system. The results of this work contribute to ongoing efforts to characterise the main contributions from an environment that will have to be included in the waveform generation pipelines for future gravitational waves observatories. We argue that this line of research will be key to unlock the maximal amount of information from future observations, allowing for precise tests of general relativity and for the detection of new fundamental physics in the gravity sector.