Orateur
Description
One of the most striking open problems in modern cosmology is the Hubble tension: the persistent disagreement between measurements of the present-day expansion rate of the Universe obtained from local observations and the lower values inferred from cosmic microwave background data within the standard ΛCDM framework. This mismatch has motivated extensive scrutiny of both late-time measurements and early-Universe assumptions.
Furthermore, this discrepancy may point to gaps in our understanding of the physics around the epoch of recombination, where the sound horizon at decoupling plays a central role. Because the value of the sound horizon depends on the microphysics of the early Universe, it is crucial to derive both H0 and the sound horizon without relying on model-dependent assumptions. In this talk, I will present recent work demonstrating how the combination of baryon acoustic oscillations with CMB lensing and galaxy weak lensing and clustering enables sound-horizon–agnostic determinations of the Hubble constant, and I will discuss how allowing for massive neutrinos impacts the inferred value of H0.