Cosmological Foundations revisited with Pantheon+Confirmed

by Antonia Seifert (Perimeter Institute)

Tuesday Jan 28, 2025, 11:00 a.m. → 12:30 p.m. America/Toronto

PI/4-405 - Bob Room (Perimeter Institute for Theoretical Physics)

The standard model of cosmology is built upon the assumptions of homogeneity and isotropy. Invoking backreaction of inhomogeneities leads to an alternative model, the timescape cosmology. It is homogeneous and isotropic on a statistical level but departs from average Friedmann-Lemaître-Robertson-Walker evolution and replaces dark energy by kinetic gravitational energy and its gradients.

 

In this talk, I will give an overview of the timescape cosmology and present a statistical analysis of the Pantheon+ Type Ia Supernovae spectroscopic comparing the timescape and spatially flat ΛCDM cosmological models. This analysis is based on the Tripp equation for supernova standardisation alone, thereby avoiding any potential correlation in the stretch and colour distributions and finds very strong evidence (ln B > 5) in favour of timescape over ΛCDM when considering the entire Pantheon+ sample.