Orateur
Description
The cosmic distance ladder is a combination of overlapping
astronomical methods used to measure distances in the universe,
starting from nearby objects and extending to the farthest visible
distances. In its modern and most precise implementation it combines
parallaxes, two standard candles (Cepheids and Type Ia supernovae),
and BAO standard rulers.
This measurement is at the center of two widely discussed tensions in
the cosmological model: the now one-decade old Hubble tension whose
significance exceeds 5 sigmas, and the recently-noticed ~3σ deviation
from ΛCDM expectations in the distance-redshift relation.
The measurement of the luminosity ratio between low- and high-redshift
supernovae constitutes the middle—and arguably weakest—rung of this
ladder. In this contribution we review potential weaknesses in this
measurement and present the LEMAITRE project, an ongoing effort to
strengthen this rung by delivering a new, independent sample of Type Ia
supernovae to the Hubble diagram and a fully rewritten, end-to-end
analysis pipeline.
