Probing the anisotropic expansion history of the universe with cosmic microwave background

TL;DR

This paper introduces a method to detect anisotropic expansion in the universe's history by analyzing shape distortions in CMBR fluctuations, constraining such anisotropy to less than 35%.

Contribution

It presents a novel shape analysis technique to identify anisotropic expansion stages from inflation to last scattering using CMBR data.

Findings

No significant anisotropic expansion detected beyond 35%.

Shape distortions in CMBR can reveal early universe anisotropies.

Method provides new constraints on universe's expansion history.

Abstract

We propose a simple technique to detect any anisotropic expansion stage in the history of the universe starting from the inflationary stage to the surface of last scattering from the CMBR data. We use the property that any anisotropic expansion in the universe would deform the shapes of the primordial density perturbations and this deformation can be detected in a shape analysis of superhorizon fluctuations in CMBR. Using this analysis we obtain the constraint on any previous anisotropic expansion of the universe to be less than about 35%.