Exploring scalar field dynamics with Gaussian processes

TL;DR

This paper uses Gaussian processes to reconstruct scalar field properties and kinematic variables of the Universe's expansion from observational data, finding consistency with Lambda-CDM and insights into energy conditions.

Contribution

It introduces a non-parametric reconstruction method for scalar field dynamics and expansion variables using Gaussian processes applied to cosmological data.

Findings

Reconstructed scalar field variables align with Lambda-CDM model.

Null energy condition holds within the data range.

Strong energy condition is violated.

Abstract

The origin of the accelerated expansion of the Universe remains an unsolved mystery in Cosmology. In this work we consider a spatially flat Friedmann-Robertson-Walker (FRW) Universe with non-relativistic matter and a single scalar field contributing to the energy density of the Universe. Properties of this scalar field, like potential, kinetic energy, equation of state etc. are reconstructed from Supernovae and BAO data using Gaussian processes. We also reconstruct energy conditions and kinematic variables of expansion, such as the jerk and the slow roll parameter. We find that the reconstructed scalar field variables and the kinematic quantities are consistent with a flat Lambda-CDM Universe. Further we find that the null energy condition is satisfied for the redshift range of the Supernovae data considered in the paper but, the strong energy condition is violated.