More on Emergent Dark Energy from Unparticles

Abstract

In a recent paper [1] we suggested the possibility that the present acceleration of the Universe is due to thermodynamical behavior of unparticles. The model is free of scalar fields, modified gravity, coincidence problem, initial conditions problem and possesses interesting distinct predictions regarding the equation of state of Dark Energy, the growth rate and the number of relativistic degrees of freedom at BBN and CMB decoupling. We further suggested that the model can remove some of the Hubble tension. A recent paper mostly considering a different range of parameter space criticized the idea, claiming the model is unstable and does not fit the data [2]. We demonstrate that these claims are due to incorrect use of approximations and initial conditions and that the model stands tall. We further suggest a consistency condition of the model in terms of observables. We then fit publicly available supernovae data to derive the expected Hubble parameter and constrain the parameters of the model.