Confronting the Ellipsoidal Universe to the Planck 2018 Data

TL;DR

This paper compares Planck 2018 CMB data with an ellipsoidal universe model, focusing on quadrupole anisotropies to test for possible cosmic anisotropy and its parameters.

Contribution

It provides constraints on the eccentricity and axis orientation of an anisotropic universe model using Planck 2018 data, and suggests experimental polarization measurements could confirm or reject this model.

Findings

Quadrupole TE and EE correlations are consistent with the ellipsoidal universe model.

Constraints on the eccentricity at decoupling were obtained.

The model remains compatible with current large-scale polarization data.

Abstract

We compared the Planck 2018 data on the large-scale anisotropies in the cosmic microwave background to the results obtained in the slightly anisotropic ellipsoidal universe. We focused on the quadrupole temperature correlations to better constrain the eccentricity at decoupling and the direction of the symmetry axis. We found that the quadrupole TE and EE temperature correlations in the ellipsoidal universe are still in reasonable agreement with the Planck 2018 data. We suggested that an experimental estimate of the average large-scale polarisation by the Planck Collaboration could confirm or reject the anisotropic universe proposal.