Collapse driven by a scalar field without final singularity

TL;DR

This paper investigates a scalar field-driven gravitational collapse in a symmetric, isotropic universe that avoids singularity, analyzing back-reaction effects and resulting energy density fluctuations with a flat spectral index.

Contribution

It introduces a model of collapse driven by a scalar field with a variable timescale that prevents singularity formation, and studies the associated back-reaction and fluctuation spectra.

Findings

Back-reaction effects are calculated during collapse.

Energy density fluctuations have a spectral index of n_s=0.

Fluctuation amplitude increases with collapse strength.

Abstract

We explore a collapsing cosmology driven by a scalar field which is minimally coupled to gravity in a spatially at and spherically symmetric, isotropic and homogeneous space-time, with a variable timescale that avoids the final singularity. The equation of state that describes the collapse is $\omega=1$. We calculate the back-reaction of the space-time during the collapse and the energy density fluctuations related to this back-reaction has a spectral index $n_s = 0$, favouring short-wavelengths modes to be detected. The interesting is that the amplitude of these fluctuations increase with time when the collapse is sufficiently strong.