Anisotropic Cosmological Constant and the CMB Quadrupole Anomaly
Abstract
Description
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.
8 pages, 2 columns, 1 figure. v2: figure improved, added comments on higher eccentricity powers and references. v3: typos corrected, version to appear in PRD
8 pages, 2 columns, 1 figure. v2: figure improved, added comments on higher eccentricity powers and references. v3: typos corrected, version to appear in PRD