HEP Colloquia 2025

by Andrea Cozzumbo (Istituto Nazionale di Fisica Nucleare)

Wednesday 21 May 2025, 14:30 → 15:00 Europe/Rome

Sala Consiliare (Department of Physics)

Multi-messenger cosmology: probing the cosmic acceleration with gravitational waves and gamma-ray bursts

Why is the expansion of the Universe speeding up? This question has remained central in cosmology since the discovery of cosmic acceleration, and it grows more pressing in light of recent results from the DESI collaboration. To unravel this mystery, increasingly precise and diverse probes of the Universe's expansion history are essential.

Gravitational wave (GW) and multi-messenger (MM) astronomy offer new avenues to study Dark Energy (DE) and test deviations from General Relativity (GR), using the distance-redshift and distance duality relations, respectively. Since both analyses rely on the same observables, MM astronomy is a powerful tool to explore the nature of DE and gravity.
To this end, we employ a catalog of 38 gamma-ray bursts (GRBs), supposedly originating from binary neutron star (BNS) mergers detected by Fermi and Swift high energy satellites, to generate a mock dataset of MM event. Using a prior-informed Fisher matrix, we forecast the sensitivity of the Einstein Telescope (ET) to constrain cosmological and modified gravity (MG) parameters.
We assess the performance of standard DE and MG parametrizations with a more flexible, model-independent method based on Gaussian Processes (GP).
We examine synergies among next-generation GW interferometers and cosmological probes such as Cosmic Microwave Background (CMB), Type IA Supernovae (SnIA) and Baryon Acoustic Oscillation (BAO) and we show that fewer than 40 GRB-GW events can provide unprecedented accuracy in constraining DE phenomenology as well as potential departures from GR.