Titol: Black Hole Environments and Dark Matter through Gravitational Waves

Lloc: Seminari del DAA. Edifici Investigació Jeroni Muñoz, planta quarta, a Burjassot.

Dia: Dimarts, 14 de juliol de 2026. Hora: 12:00.

Resum:

Gravitational wave (GW) observations allow us to reconstruct the orbital dynamics of compact binaries with remarkable precision. When such systems evolve in dense environments—such as active galactic nucleus discs, nuclear star clusters, or dark matter structures—interactions with their surroundings can leave characteristic imprints on the GW phase evolution. When accurately modelled, these effects provide a new way to probe the astrophysical environments of compact binaries, with implications ranging from accretion physics to the nature of dark matter. If neglected, however, they can bias source-parameter inference and potentially contaminate precision tests of general relativity and applications of GWs to cosmology. In this talk, I will discuss both the scientific opportunities enabled by incorporating environmental effects into waveform models and the risks associated with neglecting them. I will briefly review recent progress in the field, spanning semi-ana!
 lytic general-relativistic calculations and high-resolution numerical simulations. I will then focus on the distinctive potential of GW astronomy to probe dark matter, outlining how current and future observations can test different aspects of dark matter microphysics. Finally, I will present results from the first dedicated search for signatures of light scalar fields in the orbital dynamics of black hole binaries using LIGO–Virgo–KAGRA data. I will highlight the intriguing case of GW190728, whose signal exhibits features compatible with those predicted in the presence of a light scalar field with a mass of order 10^{-12} eV. Although this result does not constitute evidence for new physics, it provides a valuable case study of how GW observations can begin to test dark-sector scenarios in regimes that are difficult to access with conventional searches.