Anisotropic universe with anisotropic dark energy

TL;DR

This study explores anisotropic dark energy within an axisymmetric universe, constraining its properties using supernova data, and finds evidence favoring anisotropic models over standard cosmology.

Contribution

It introduces a novel analysis of anisotropic dark energy in a Bianchi-I universe using recent supernova data, identifying a preferred axis of anisotropy and comparing different cosmological models.

Findings

Mean anisotropic dark energy equation of state: $ar{w} = -0.86^{+0.15}_{-0.11}$

Detected anisotropic axis at galactic coordinates $(272^{\circ}, 21^{\circ})$

Data favor anisotropic dark energy model over standard $ m f extLambda$CDM

Abstract

We investigate the anisotropic parameterization of the dark energy equation of state within the framework of an axisymmetric (planar) Bianchi-I universe. Using the latest Pantheon+ Type Ia Supernova dataset, augmented by SH0ES Cepheid distance calibrators, we constrain both the equation of state for anisotropic dark energy and other standard cosmological parameters. Additionally, we examine the presence of an underlying anisotropic axis. Our analysis yields a mean anisotropic dark energy equation of state of $\bar{w} = -0.86^{+0.15}_{-0.11}$ and a difference in the equation of states in and perpendicular to the plane of the axisymmetric Bianchi-I spacetime of $\delta_w = -0.129^{+0.090}_{-0.064}$. We also identify an axis of anisotropy at approximately $(272^{\circ}, 21^{\circ})$ in galactic coordinates. Through a comparative study of different cosmological models, we find that the data favor a Bianchi-I universe with anisotropic dark energy, where the equation of state deviates from ``-1'' along the axis of anisotropy (the $w_b$CDM model), over both other anisotropic models considered and the standard flat $\Lambda$CDM or $w$CDM models.