Future evolution in a backreaction model and the analogous scalar field cosmology

TL;DR

This paper explores the future evolution of the universe within a backreaction framework, showing potential for the global acceleration to cease at a finite time, modeled via an emergent scalar field constrained by observational data.

Contribution

It introduces a two-domain backreaction model that predicts finite-time cessation of acceleration and maps it to a scalar field cosmology constrained by current observations.

Findings

Global acceleration can vanish at finite future time.

The model's scalar field potential is fixed and free from phenomenological parameters.

Observational data constrains the model parameters effectively.

Abstract

We investigate the future evolution of the universe using the Buchert framework for averaged backreaction in the context of a two-domain partition of the universe. We show that this approach allows for the possibility of the global acceleration vanishing at a finite future time, provided that none of the subdomains accelerate individually. The model at large scales is analogously described in terms of a homogeneous scalar field emerging with a potential that is fixed and free from phenomenological parametrization. The dynamics of this scalar field is explored in the analogous FLRW cosmology. We use observational data from Type Ia Supernovae, Baryon Acoustic Oscillations, and Cosmic Microwave Background to constrain the parameters of the model for a viable cosmology, providing the corresponding likelihood contours.