Constraining the Anisotropy of the Universe from Supernovae and Gamma-ray Bursts

TL;DR

This study constrains the anisotropy of the universe using supernovae and gamma-ray burst data, finding a small but measurable anisotropic component aligned with a specific axis.

Contribution

It provides observational constraints on universe anisotropy by combining supernova and gamma-ray burst data, refining previous models with new dataset analysis.

Findings

Anisotropy magnitude D = -0.044 ± 0.018

Privileged axis at (l0, b0) = (306.1° ± 18.7°, -18.2° ± 11.2°)

Anisotropy is small, supporting isotropic models

Abstract

Recently, an anisotropic cosmological model was proposed. An arbitrary 1-form, which picks out a privileged axis in the universe, was added to the Friedmann-Robertson-Walker line element. The distance-redshift relation was modified such that it is direction dependent. In this paper, we use the Union2 dataset and 59 high-redshift gamma-ray bursts to give constraints on the anisotropy of the universe. The results show that the magnitude of anisotropy is about $D=-0.044\pm0.018$, and the privileged axis points towards the direction $(l_0,b_0)=(306.1^{\circ}\pm 18.7^{\circ},-18.2^{\circ}\pm 11.2^{\circ})$ in the galactic coordinate system. The anisotropy is small and the isotropic cosmological model is an excellent approximation.