Gravitational wave tests of cosmology, gravity and astrophysics

27.03.2026 11:50 – 12:50

Gravitational-wave dark sirens provide a clean measurement of the luminosity distance to their sources, as this information is directly encoded in their waveform. However, their relatively poor angular resolution makes identifying the host galaxy challenging, limiting the ability to obtain spectroscopic redshifts needed to construct a Hubble diagram and constrain cosmological models. Furthermore, the standard line-of-sight method is very sensitive to incompleteness in galaxy catalogues, which is an important limitation. I will introduce a novel technique called Peak Sirens, based on three-dimensional cross-correlations between galaxies and gravitational-waves. Using this method, I will present the first measurement of the Hubble constant and new constraints on the gravitational-wave bias. This approach naturally incorporates large-scale structure information into dark siren analyses. In the second part of the talk, I will present a model-independent test of the graviton mass using multi-messenger lensing time-delays as well as a dark siren test of gravity, based on dispersion induced friction. Applying this method to selected events from the third observing run of LIGO–Virgo–KAGRA, I will show as an example, that we obtain competitive constraints on the graviton mass.

Lieu

Bâtiment: Ecole de Physique

EP234

entrée libre