Numerical Study of Inhomogeneous Pre-Big-Bang Inflationary Cosmology

TL;DR

This paper numerically investigates inhomogeneous pre-big-bang inflation in spherical symmetry, revealing that initial inhomogeneities can suppress inflation and are not smoothed out during the process, unlike standard inflation.

Contribution

It provides the first detailed numerical analysis of inhomogeneous pre-big-bang inflation, highlighting differences from conventional inflation regarding inhomogeneity damping.

Findings

Large initial inhomogeneity suppresses inflation onset.

Inhomogeneities are not homogenized during pre-big-bang inflation.

Irregularities ('hairs') persist, contrasting with standard inflation behavior.

Abstract

We study numerically the inhomogeneous pre-big-bang inflation in a spherically symmetric space-time. We find that a large initial inhomogeneity suppresses the onset of the pre-big-bang inflation. We also find that even if the pre-big-bang inflationary stage is realized, the initial inhomogeneities are not homogenized. Namely, during the pre-big-bang inflation ``hairs''(irregularities) do not fall, in sharp contrast to the usual (potential energy dominated) inflation where initial inhomogeneity and anisotropy are damped and thus the resulting universe is less sensitive to initial conditions.