Parameter estimation in an anisotropic expanding spacetime

TL;DR

This paper examines how small anisotropic disturbances in an expanding universe influence the precision of cosmological parameter estimation, revealing directional sensitivities and coupling-dependent effects on Fisher information spectra.

Contribution

It introduces a method to incorporate anisotropy as a gravitational disturbance and analyzes its impact on Fisher information for key cosmological parameters.

Findings

Anisotropy causes oscillations in Fisher information spectrum.

Parameter estimation sensitivity depends on momentum direction.

Differences observed between minimal and conformal couplings at low momentum.

Abstract

In this work, we investigate how the anisotropy affects the cosmological parameters estimation. Here the anisotropy is incorporated as a small gravitational disturbance. We calculate the Fisher information for both cosmological parameters $\epsilon$ (expansion volume) and $\rho$ (expansion rate), and we show that the anisotropy introduces oscillations in the Fisher information spectrum. This implies that the estimation of the cosmological parameters is sensible to the direction of the momentum $k$ of particles. In addition, we observe that for small values of the momentum $k$ there is a substantial difference between the Fisher information spectrum for the minimum and conformal couplings.