Thurston geometries and parameter constraints from SNIa data

TL;DR

This paper investigates whether extending the standard cosmological model with Thurston geometries can reveal anisotropies in the universe, using supernova data to constrain these models and find potential deviations from isotropy.

Contribution

It introduces Thurston geometries as anisotropic extensions of the standard model and uses supernova data to constrain their parameters, exploring large-scale isotropy violation.

Findings

Mild evidence of large-scale isotropy violation

Constraints on shear, eccentricity, and curvature parameters

Potential preferred axis in the universe

Abstract

Following the numerous evidence for large-scale cosmic isotropy violation with the advent of the `precision cosmology' era, we explore the possible advantages of extending the flat $\Lambda$CDM model to more general models in order to constrain anisotropies in the universe, otherwise absent in the standard model based on FLRW spacetime. Such extensions are offered by the topologically unique Thurston geometries, which are homogeneous but anisotropic spacetime models. In this work, we attempt to distinguish Thurston geometries from one another by introducing anisotropies via different scale factors in different directions, thereby introducing additional model parameters such as shear, eccentricity, curvature, and a preferred axis. We used the latest compilation of Pantheon+ \& SH0ES Type Ia supernova data for deriving model constraints, and found mild evidence of large-scale isotropy violation.