SPACE seminar: Marco de Cesare - "Gravitational wave propagation in bigravity in the late universe"

Tuesday 9 Dec 2025, 12:00 → 13:00 Europe/Rome

Aula 4 (San Marcellino)

Speaker: Dr. Marco de Cesare (Scuola Superiore Meridionale)

Abstract: In this talk, I will present a detailed analysis of gravitational-wave propagation in ghost-free bimetric gravity in a late-time de Sitter epoch. In this regime, the dynamical equations for the massless and massive graviton modes can be decoupled and solved exactly. The system admits different dynamical regimes, depending on the propagation properties of the massive graviton, and whether the massless and massive components of the signal can be temporally resolved or not. The gravitational-wave luminosity distance is computed analytically in each regime as a function of redshift. This allows for the derivation of a new observational bound for the ghost-free bimetric theory using the multi-messenger event GW170817. Further, we show that the massless and massive components of the signal retain their coherence also in the regime where they can be temporally resolved, even when couplings to incoherent matter degrees of freedom are included. Talk based on arxiv:2507.11526 , in collaboration with D. Brizuela and A. Soler Oficial.

Zoom link: click here