Robustness of slow contraction to cosmic initial conditions

TL;DR

This paper investigates the robustness of slow contraction in cosmology by conducting numerical relativity simulations with varied initial conditions, including non-perturbative regimes, and supports findings with analytical dynamical systems analysis.

Contribution

It provides a comprehensive numerical and analytical study of slow contraction's stability against a wide range of initial conditions, including large deviations from the attractor solution.

Findings

Slow contraction is robust to diverse initial conditions.

Numerical and analytical results are consistent.

Initial conditions outside perturbative regimes still lead to contraction.

Abstract

We present numerical relativity simulations of cosmological scenarios in which the universe is smoothed and flattened by undergoing a phase of slow contraction and test their sensitivity to a wide range of initial conditions. Our numerical scheme enables the variation of all freely specifiable physical quantities that characterize the initial spatial hypersurface, such as the initial shear and spatial curvature contributions as well as the initial field and velocity distributions of the scalar that drives the cosmological evolution. In particular, we include initial conditions that are far outside the perturbative regime of the well-known attractor scaling solution. We complement our numerical results by analytically performing a complete dynamical systems analysis and show that the two approaches yield consistent results.