A comprehensive data-driven odyssey to explore the equation of state of dark energy

Understand

For the first time, we reconstruct the dark energy equation of the state parameter $w$ from the combination of background and perturbation observations, specifically combining the Hubble parameter data from cosmic chronometer observations and the logarithmic growth rate data from the growth rate observations.

• We do this analysis using posterior Gaussian process regression without considering any specific cosmological model or parametrization.
• However there are three main assumptions: (I) a flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) metric is considered for the cosmological background, (II) there is no interaction between dark energy and matter sectors, and (III) for the growth of inhomogeneity, sub-Hubble approximation and linear perturbations are considered.
• This study is unique in the sense that the reconstruction of $w$ is independent of any derived parameters such as the present values of the matter-energy density parameter and Hubble parameter.