Induced cosmological anisotropy by a gauge-gravity interaction

TL;DR

This paper introduces a supergravity-inspired model where gauge-gravity interactions induce small anisotropies in the early universe, which decay over time, aligning with FLRW cosmology and potentially explaining cosmological tensions.

Contribution

It presents a novel gauge-gravity interaction model that generates and studies cosmological anisotropies as perturbations on FLRW geometry, with implications for understanding early universe anisotropies.

Findings

Anisotropies are generated by gauge-gravity interactions.

Anisotropies decay and vanish at late times, leading to FLRW.

The model aligns with standard cosmology and may address cosmological tensions.

Abstract

We present a simple model which generates cosmological anisotropies on top of standard FLRW geometry. This is in some sense reminiscent of the mean field approximation, where the mean field cosmological model under consideration would be the standard FLRW, and the anisotropy is a small perturbative correction on top of it. Using a supergravity-inspired model, we confirm that the stable fixed point of our model corresponds to standard FLRW cosmology. We use a Bianchi VII$_0$-type model supplemented with a scalar and $U(1)$ gauge fields, and we show that the anisotropies of the geometry are generated by the non-trivial interaction between the gravity sector and the $U(1)$ gauge sector. Studying the attractor flow, we show that the anisotropies are present at early times (high redshift) and decay asymptotically to an FLRW attractor fixed point. With such a mechanism, observations of non-isotropy are not contradictory to FLRW geometry or indeed the $\Lambda$CDM model. Such models could in principle shed some insights on the present cosmological tensions.