Accelerating Cosmologies with an Anisotropic Equation of State

TL;DR

This paper explores anisotropic dark energy models that make the universe's expansion direction-dependent, potentially explaining CMB anomalies and addressing the coincidence problem, with observational constraints and a vector field example.

Contribution

It introduces anisotropic dark energy models, demonstrates their cosmological viability, and connects them to observable effects and a vector field implementation.

Findings

Anisotropic models can explain CMB anomalies.

Such models are consistent with current observations.

A vector field action exemplifies the anisotropic dark energy.

Abstract

If the dark energy equation of state is anisotropic, the expansion rate of the universe becomes direction-dependent at late times. We show that such models are not only cosmologically viable but that they could explain some of the observed anomalies in the CMB, and shed some light into the coincidence problem. The possible anisotropy can then be constrained by studying its effects on the luminosity distance-redshift relation inferred from several observations. A vector field action for dark energy is also presented as an example of such possibility.