Orateur
Description
The current tension between local late-universe measurements of the Hubble Constant (H0) and CMB + Lambda-CDM inferred values suggests growing evidence of new physics beyond the standard model. In this talk, I will review recent developments of the Cepheid and SNIa distance ladder, which has produced the most precise H0 local measurement. The talk will first focus on key improvements in geometric distance measurements in anchor galaxies, particularly from eclipsing binaries and Gaia parallaxes, which calibrate the Cepheid Period-Luminosity relation. The current status of the Cepheid metallicity dependence, which has long been debated, will also be presented. I will discuss new results from JWST observations that provide an independent check of HST-based Cepheid distances to a subset of SNIa host galaxies, effectively ruling out crowding as the source of the Hubble tension. Lastly, I will review progress from an ongoing HST program designed to cross-calibrate distances derived from Cepheids, the Tip of the Red Giant Branch (TRGB), and Carbon AGB stars (the JAGB method), aiming to better understand and constrain systematics affecting each technique.