Test of the cosmic evolution using Gaussian processes

TL;DR

This paper uses Gaussian processes to reconstruct cosmic acceleration history from diverse data, finding no evidence for slowing down within 95% confidence, and highlighting the limitations of traditional parametrizations.

Contribution

It introduces a model-independent Gaussian process approach to analyze cosmic acceleration, avoiding biases of specific dark energy parametrizations.

Findings

No slowing down of cosmic acceleration within 95% C.L.

Traditional parametrizations can create a false impression of slowing down.

Gaussian processes effectively model the cosmic expansion history.

Abstract

Much focus was on the possible slowing down of cosmic acceleration under the dark energy parametrization. In the present paper, we investigate this subject using the Gaussian processes (GP), without resorting to a particular template of dark energy. The reconstruction is carried out by abundant data including luminosity distance from Union2, Union2.1 compilation and gamma-ray burst, and dynamical Hubble parameter. It suggests that slowing down of cosmic acceleration cannot be presented within 95\% C.L., in considering the influence of spatial curvature and Hubble constant. In order to reveal the reason of tension between our reconstruction and previous parametrization constraint for Union2 data, we compare them and find that slowing down of acceleration in some parametrization is only a "mirage". Although these parameterizations fits well with the observational data, their tension can be revealed by high order derivative of distance $D$. Instead, GP method is able to faithfully model the cosmic expansion history.