Colloquium on May. 19, 2025

Bumpy universe model suggested by DESI BAO observation as a possible solution for the Hubble tension

Speaker: Toshi Futamase (Kyoto Sangyo University)

Venue: SWIFAR Building 2111

Time: 16:00 PM, Monday, May. 19, 2025

Abstract:

The Hubble parameter at redshifts of around 0.5 obtained from the Baryon Acaustic Oscillation (BAO) observation by DESI (Dark Energy Spectroscopic Instrument) is inconsistent with the standard cosmological model obtained from CMB. Some consider this to be an evidence of the time evolution of dark energy. On the other hand, infrared observations suggest the existence of a 300 Mpc-scale void in our vicinity. By spatially averaging Einstein equations over a domain, we can construct an effective FRW universe with domain dependent cosmological parameters. By interpreting the results of DESI from this perspective, it is possible to construct an inhomogeneous cosmological model without introducing time dependent dark energy. It is also shown that this model naturally explains the Hubble tension, which has been a hot topic in cosmology in recent years.