More on Emergent Dark Energy from Unparticles

TL;DR

This paper defends a model where unparticles drive the universe's acceleration, showing it remains viable under certain conditions and fitting supernova data to constrain its parameters.

Contribution

It clarifies the viability of an unparticle-based dark energy model and refutes claims of inconsistency, providing observational constraints.

Findings

Model remains consistent in specific parameter regions.

Supernova data constrains model parameters.

Provides a new consistency condition based on observables.

Abstract

In a recent paper \cite{Artymowski:2020zwy} 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, a Cosmological Constant (CC), the 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. In this work, we relate to a recent paper \cite{Abchouyeh:2021wey}, which discusses a similar setup of unparticles with and without a CC as an external source of late-time acceleration. The authors have shown how such a model is inconsistent with the data. We show that these claims are viable only in a particular part of the parameter space and that model \cite{Artymowski:2020zwy} stands tall. We further suggest a consistency condition in terms of observables. We then fit publicly available supernovae data to derive the expected Hubble parameter and constrain the parameters of the model.