Measurements of H₀ and reconstruction of the dark energy properties from a model-independent joint analysis

Gaussian processes (GP) provide an elegant and model-independent method for extracting cosmological information from the observational data. In this work, we employ GP to perform a joint analysis by using the geometrical cosmological probes such as Supernova Type Ia (SN), Cosmic chronometers (CC), Baryon Acoustic Oscillations (BAO), and the H0LiCOW lenses sample to constrain the Hubble constant H₀ H 0 , and reconstruct some properties of dark energy (DE), viz., the equation of state parameter w , the sound speed of DE perturbations c²ₛ c s 2 , and the ratio of DE density evolution X = ρ de/ρ de,0 X = ρ de / ρ de , 0 . From the joint analysis SN+CC+BAO+H0LiCOW, we find that H₀ H 0 is constrained at 1.1% precision with H₀ = 73.78 ± 0.84\ km\ s⁻¹\,Mpc⁻¹ H 0 = 73.78 ± 0.84 km s - 1 Mpc - 1 , which is in agreement with SH0ES and H0LiCOW estimates, but in ~ 6.2 σ ∼ 6.2 σ tension with the current CMB measurements of H₀ H 0 . With regard to the DE parameters, we find c²ₛ < 0 c s 2 < 0 at ~ 2 σ ∼ 2 σ at high z , and the possibility of X to become negative for $$z > 1.5$$ z > 1.5 . We compare our results with the ones obtained in the literature, and discuss the consequences of our main results on the DE theoretical framework.