Holographic Dark Energy with Cosmological Constant

TL;DR

This paper introduces a combined holographic dark energy and cosmological constant model, analyzes its theoretical behavior, and fits it to observational data, showing it fits current data comparably to standard models with degeneracy between components.

Contribution

The paper proposes the $ m extLambda$HDE model, integrating holographic dark energy with a cosmological constant, and analyzes its dynamics and observational constraints.

Findings

The $ m extLambda$HDE model fits observational data as well as standard models.

Parameters $d$ and $ m extOmega_{hde}$ define different universe fates.

Current data shows degeneracy between holographic dark energy and cosmological constant.

Abstract

Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the $\Lambda$HDE model. By studying the $\Lambda$HDE model theoretically, we find that the parameters $d$ and $\Omega_{hde}$ are divided into a few domains in which the fate of the universe is quite different. We investigate dynamical behaviors of this model, and especially the future evolution of the universe. We perform fitting analysis on the cosmological parameters in the $\Lambda$HDE model by using the recent observational data. We find the model yields $\chi^2_{\rm min}=426.27$ when constrained by $\rm Planck+SNLS3+BAO+HST$, comparable to the results of the HDE model (428.20) and the concordant $\Lambda$CDM model (431.35). At 68.3\% CL, we obtain $-0.07<\Omega_{\Lambda0}<0.68$ and correspondingly $0.04<\Omega_{hde0}<0.79$, implying at present there is considerable degeneracy between the holographic dark energy and cosmological constant components in the $\Lambda$HDE model.