Francesco Iacovelli "Forecasting the population properties of merging black holes"

Wednesday 24 Sept 2025, 12:30 → 14:00 Europe/Rome

The direct detection of gravitational waves in 2015, thanks to the LIGO and Virgo interferometers, opened a new window on our Universe. The discoveries during the first four observing runs already had an extraordinary impact on astrophysics, cosmology, and fundamental physics, and the fourth run is ongoing.

The gravitational-wave community is now looking at the next long-prepared step: `third-generation' detectors. Thanks to an increase of more than one order of magnitude in sensitivity and a larger bandwidth, Einstein Telescope (ET) and Cosmic Explorer (CE) will have an outstanding potential, capable of triggering fundamental discoveries.

These instruments will observe up to millions of merging binary black holes. With such a vast dataset, stacking events into population analyses will arguably be more important than analyzing single sources. I will present the first application of population-level Fisher-matrix forecasts tailored to third-generation gravitational-wave interferometers, based on the formalism first derived by Gair et al. [Mon. Not. R. Astron. Soc. 519, 2736 (2023)] and explore how ET and CE will constrain the distributions of black-hole masses, spins, and redshift. 

Third-generation detectors will be transformative, improving constraints on the population hyperparameters by several orders of magnitude compared to current data. At the same time, I will highlight how a single third-generation observatory and a network of detectors will deliver qualitatively similar performances. Obtaining precise measurements of some population features (e.g., peaks in the mass spectrum) will require only a few months of observations while others (e.g., the fraction of binaries with aligned spins) will instead require years if not decades.