The Hubble-Lemaître Law: What Have We Learned from HST and JWST?

by Prof. Wendy Freedman (University of Chicago)

Friday 17 May 2024, 11:00 → 13:00 Europe/Brussels

Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve)

The question of whether there is new physics beyond our current standard model, Lambda Cold Dark Matter (LCDM), is a crucial unresolved issue in cosmology today. Recent measurements of the Hubble constant (Ho) using Cepheids and Type Ia supernovae (SNe) appear to differ significantly (5-sigma) from values inferred from the cosmic microwave background (CMB) fluctuations. This discrepancy, if real, could indicate new physics beyond the standard model. In this talk, I will review the Hubble Space Telescope results on measuring Ho and present new results from a James Webb Space Telescope. It utilizes three independent methods for measuring the distances to (the same) nearby galaxies that provide a calibration for SNe: Cepheid variables, Tip of the Red Giant Branch (TRGB) stars and J-Region Asymptotic Giant Branch (JAGB) stars. The Near-Infrared Camera on JWST has four times the resolution and ten times the sensitivity of HST in the near infrared, and is critical for ascertaining whether new physics is required beyond the standard model of cosmology.