A Solution for the Hubble Tension: Late Phantom Energy

Abstract

Although cosmology is entering the precision era, there is a quantity for which its measurements are not converging to an exact value, but rather the opposite: the Hubble Constant (H0). Because its incompatible values stem from observations of the early and late Universe, respectively, in this work we propose a phantom equation of state (ω < -1, ω constant) for dark energy, which could change the Universe evolution in such a way that the two values would be compatible. We will calculate a value of ! that could solve this tension, making the Universe dynamics start to deviate from the ΛCDM standard model at z ~ 1. Furthermore, we will study the problems that arise from this exotic dark energy and review alternative theories that also address the Hubble tension. We will solve numerically the Friedman equations to find the Universe scale factor evolution over time, for both phantom and Λ dark energy types.