Unveiling the origin of black-hole binaries with gravitational waves

After ten years of gravitational-wave observations with the LIGO–Virgo–KAGRA interferometers, over 200 signals from merging black hole binaries have been detected, bringing us closer to understanding how these systems form. Addressing this question observationally involves searching for gravitational-wave signals in noisy data, estimating their source parameters (masses, spins, etc.), and comparing the observed distribution with predictions from different formation models. In this seminar I will present recent advancements on these three fronts.

I will introduce the principles of gravitational-wave detection, and illustrate them with sensitivity improvements achieved by modeling additional harmonics beyond the dominant quadrupole. Next, I will describe physical heuristics that disentangle the structure of posterior distributions, enabling efficient and robust parameter estimation, with applications to simulation-based inference. Finally, I will show how individual observations are combined while accounting for selection effects, measurement uncertainty, and statistical significance, and I will highlight recent observational results in the context of the leading formation channels of compact binary mergers.