Beginning inflation in conformally curved spacetimes

TL;DR

This paper uses numerical relativity to study how cosmic inflation begins from highly inhomogeneous and curved initial conditions, demonstrating that inflation can still successfully homogenize and flatten the universe.

Contribution

It shows that large initial inhomogeneities and curvature do not prevent the onset of inflation in conformally curved spacetimes, confirming the robustness of inflationary homogenization.

Findings

Inflation initiates successfully even with large tensor and vector fluctuations.

The universe homogenizes and flattens within a few tens of e-folds during inflation.

Inflation leads to a Friedmann-Lemaître-Robertson-Walker universe after initial inhomogeneities.

Abstract

We investigate the initiation of cosmic inflation, in full numerical relativity, from pre-inflationary scenarios with large tensor and vector fluctuations in the metric. These settings are characterized by having large values in the Weyl curvature tensor. In the matter sector, we consider a single scalar field with inhomogeneous field velocities, corresponding to a kination period. In the context of large-field inflation, it is shown that the onset of inflation continues to be robust to this type of initial conditions, and that during inflation the Universe successfully homogenizes and flattens any type of curvature, leading to a Friedmann-Lema\^itre-Robertson-Walker Universe after just a few tens of efolds of accelerating expansion.