SnIa Constraints on the event-horizon Thermodynamical model of Dark Energy

Abstract

We apply the thermodynamical model of the cosmological event horizon of the spatially flat FLRW metrics to the study of the recent accelerated expansion phase and to the coincidence problem. This model, called "ehT model" hereafter, led to a dark energy (DE) density $\Lambda $ varying as $r^{-2},$ where $r$ is the proper radius of the event horizon. Recently, another model motivated by the holographic principle gave an independent justification of the same relation between $\Lambda $ and $r$. We probe the theoretical results of the ehT model with respect to the SnIa observations and we compare it to the model deduced from the holographic principle, which we call "LHG model" in the following.Our results are in excellent agreement with the observations for $H\_{0}=64kms^{-1}Mpc^{-1}$, and $\Omega \_{\Lambda }^{0}=0.63\_{-0.01}^{+0.1}$, which leads to $q\_{0}=-0.445$ and $z\_{T}\simeq 0.965$.