Parametric and nonparametric methods hint dark energy evolution

Abstract

We openly study dark energy through the viewpoints of parametric and nonparametric analyses of late-time cosmological data. We consider three Hubble parameter priors reflecting the Hubble tension and make use of two phenomenological functions, namely, a normalized dark energy density and a compactified dark energy equation of state. We predict the shape of both functions and present new constraints on the dark energy equation of state. The results hint at dark energy evolution regardless of the choice of the method and of the priors. Given that dark energy evolution is arrived at by drastically different approaches, it emphasizes the result that the cosmological data prefers a nontrivial evolution.

A model-independent test of speed of light variability with cosmological observations

“…We reconstruct the D A (z) and H(z) data points using a non-parametric approach based on the Gaussian Processes method with the GaPP package [87] -see also [88]. Similar approaches have been extensively explored in the literature for the sake of obtaining cosmological constraints without making a priori assumptions on the material content of the Universe [89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107][108]. Therefore, such a method provide robust evidence for the reconstructed quantities of interest, making GP suitable for tests like the one we pursue here.…”

Reconstruction in the Horndeski theory within the scope of the Bianchi I cosmology

“…For the BI model, there is an additional contribution to the dynamics of H(t), X(t) from the nonzero anisotropic charges. R. C. Bernardo et al [17,18] significantly develop the ideas of reconstruction in connection with observational data. Authors [17] reconstruct the parameters H(t) from cosmic chronometers, supernovae, and baryon acoustic oscillations compiled data sets via the Gaussian process method and use it to draw out HG that are fully anchored on expansion history data.…”

“…Authors [17] reconstruct the parameters H(t) from cosmic chronometers, supernovae, and baryon acoustic oscillations compiled data sets via the Gaussian process method and use it to draw out HG that are fully anchored on expansion history data. In the work [18], dark energy is studied through the viewpoints of parametric and nonparametric analyses of late-time cosmological data.…”