Speaker
Description
The stochastic gravitational-wave background (SGWB) provides a powerful probe of fundamental physics across a broad frequency range, accessible to ground-based interferometers such as the LIGO–Virgo Collaboration and pulsar timing arrays like NANOGrav. In this talk, I explore how SGWB observations can test extensions of the standard cosmological model involving dark vector fields.
After a brief overview of current multi-frequency gravitational-wave observations, I introduce a class of vector field models that modify gravitational-wave propagation, producing characteristic signatures in the SGWB such as frequency-dependent distortions and amplitude modulations.
Then, I focus on multi-Proca dark energy models, where distinctive imprints—including oscillatory features, scale-dependent suppression or enhancement, and possible chiral signatures—arise in the gravitational-wave spectrum. Finally, I discuss prospects for constraining these scenarios with pulsar timing array data, highlighting the potential of SGWB measurements to reveal new physics in the dark sector and shed light on the cosmological origin of SGWB.