Cosmology and fundamental physics from compact binary coalescences detected by the LIGO, Virgo and KAGRA collaboration

by Simone Mastrogiovanni (Istituto Nazionale di Fisica Nucleare)

Monday 17 Nov 2025, 15:00 → 16:30 Europe/Rome

Aula Conversi (Dip. di Fisica - Edificio G. Marconi)

The Universe expansion is one of the most puzzling open problems in modern cosmology. For over 20 years, measurements of the Universe expansion rate from close-by and far sources are in tension hinting for the presence of new physics at cosmological scales. Our struggle to corroborate the presence of new physics is due to the difficulty of observing cosmological sources for which the distance is known without the need of a cosmological ladder. However, a new player entered the cosmological match in 2015: Gravitational Waves (GWs) from compact binary coalescences (CBCs). CBCs are Standard Sirens, they are the only known cosmological source for which it is possible to directly measure the luminosity distance from their GW emission. Unfortunately, the GW do not provide the other ingredient to measure the Universe expansion: the redshift. Starting from the first multi-messenger observation of a binary neutron star merger in 2017, I will discuss how GWs are rapidly becoming a new avenue to study the cosmic expansion and what are their population properties. I will show how astrophysical assumptions on the black hole's formation and correlations with electromagnetic surveys for galaxies and neutral hydrogen abundances can provide a measure of the cosmic expansion as well as tests of fundamental physics on cosmic scales. Finally, I will discuss the most recent results for the LIGO, Virgo, KAGRA observations.

Google slides

seminar_mastrogiovanni_INFN.pdf