Reconstruction of dark energy density by non-parametric approaches

TL;DR

This paper reconstructs the dark energy density directly from observational data across cosmic history, revealing consistency with the standard model at lower redshifts but indicating negative values at higher redshifts.

Contribution

It introduces a non-parametric approach to directly reconstruct dark energy density from observational data, allowing analysis without assuming a specific equation of state.

Findings

Dark energy density aligns with ΛCDM up to redshift 1.5

Reconstruction indicates negative dark energy density at high redshifts

Method applied to latest SNIa, BAO, and cosmic chronometer data

Abstract

The evolution of dark energy density is a crucial quantity in understanding the nature of dark energy. Often, the quantity is described by the so-called equation of state, that is the ratio of dark energy pressure to its density. In this scenario, the dark energy density is always positive throughout cosmic history and a negative value is not allowed. Assuming a homogeneous and isotropic universe, we reconstruct the dark energy density directly from observational data and investigate its evolution through cosmic history. We consider the latest SNIa, BAO and cosmic chronometer data and reconstruct the dark energy density in both flat and non-flat universes up to redshift $z\sim 3$. The results are well in agreement with the $\Lambda$CDM up to redshift $z\sim 1.5$, whereas all data and methods, in our analysis, provide a negative dark energy density at high redshifts.