Distance-Redshift Relations in an Anisotropic Cosmological Model

TL;DR

This study investigates an anisotropic cosmological model based on a Bianchi type-III metric, analyzing supernova and CMB data to determine the potential observability of anisotropy in the universe.

Contribution

It introduces a specific anisotropic model and assesses its compatibility with current observational data, highlighting the possibility of detecting anisotropy with future measurements.

Findings

Small anisotropy is consistent with current data.

More precise high-redshift supernova measurements could reveal anisotropy.

Anisotropy could be observed at distances above redshift 2.

Abstract

In this paper we study an anisotropic model generated from a particular Bianchi type-III metric, which is a generalization of G\"odel's metric and an exact solution of Einstein's field equations. We analyse type Ia supernova data, namely the SDSS sample calibrated with the MLCS2k2 fitter, and we verify in which ranges of distances and redshifts the anisotropy could be observed. We also consider, in a joint analysis, the position of the first peak in the CMB anisotropy spectrum, as well as current observational constraints on the Hubble constant. We conclude that a small anisotropy is permitted by the data, and that more accurate measurements of supernova distances above z = 2 might indicate the existence of such anisotropy in the universe.