Abstract:
The growth of cosmic structures is investigated through the analyses of f(z) and σ8(z) cosmic
observables data, using non-parametric Gaussian Process reconstructions combined with
MCMC statistical analyses. The standard flat-LCDM model, General Relativity–based
extensions, and F(R) modified gravity scenarios are systematically compared in terms of
statistical performance, physical consistency, and the level of tension in the S8 parameter
relative to the Planck -2018 benchmark. Our results show that, while LCDM remains consistent
with current data, it exhibits deviations at high redshifts. Among physically viable alternatives,
the Hu–Sawicki (n = 1) model emerges as the most robust scenario, providing good
agreement with observational data and compatibility with local gravity tests, while the
Starobinsky (n = 2) model appears as a competitive alternative by moderately alleviating
the S8 tension.
