Anisotropic Cosmological Constant and the CMB Quadrupole Anomaly

TL;DR

This paper introduces an extended LCDM model with anisotropic vacuum pressure to address CMB quadrupole anomalies, providing exact solutions and bounds for anisotropy parameters, and connecting to elliptical universe proposals.

Contribution

It proposes a novel anisotropic extension of the LCDM model with exact solutions, linking anisotropic vacuum pressure to CMB anomalies and elliptical universe concepts.

Findings

Derived exact solutions for anisotropic cosmological scale factors.

Estimated bounds on the anisotropy deformation parameter.

Connected anisotropic vacuum pressure to CMB quadrupole anomaly.

Abstract

There are evidences that the cosmic microwave background (CMB) large-angle anomalies imply a departure from statistical isotropy and hence from the standard cosmological model. We propose a LCDM model extension whose dark energy component preserves its nondynamical character but wield anisotropic vacuum pressure. Exact solutions for the cosmological scale factors are presented, upper bounds for the deformation parameter are evaluated and its value is estimated considering the elliptical universe proposal to solve the quadrupole anomaly. This model can be constructed from a Bianchi I cosmology with cosmological constant from two different ways: i) a straightforward anisotropic modification of the vacuum pressure consistently with energy-momentum conservation; ii) a Poisson structure deformation between canonical momenta such that the dynamics remain invariant under scale factors rescalings.