Cosmic dissonance: new physics or systematics behind a short sound horizon?

Speaker

Nikki Arendse
DARK, University of Copenhagen (Denmark)

Abstract

Persistent tension between low-redshift observations and the Cosmic Microwave Background radiation (CMB) suggests residual systematics or new physics beyond the standard Λ-CDM model. In this talk, I will show results obtained from local observations of supernovae and baryon acoustic oscillations combined with low-redshift distance calibrators, that provide constraints on the Hubble constant and the sound horizon in a cosmologically independent way. When these values are compared to constraints from the CMB, a tension up to 5 σ arises. Several modifications of Λ-CDM have been put forward to reconcile the tension, but how well do these models actually perform? I will talk about the current status of tensions between the CMB-based and local (based on gravitational time delays and classical distance ladder) distance calibrations. I will also critically review most popular extensions of Λ-CDM proposed to reconcile these measurements.

Date and Time

May 27 2021
4pm KST (= 7am UTC)

Recording

Link to the recording on Youtube