Holographic Dark Energy Characterized by the Total Comoving Horizon and Insights to Cosmological Constant and Coincidence Problem

TL;DR

This paper proposes a holographic dark energy model based on the total comoving horizon, which naturally explains the universe's acceleration, addresses the cosmological constant and coincidence problems, and fits observational data comparably to the standard Lambda-CDM model.

Contribution

It introduces the $ m exteta$HDE model characterized by the total comoving horizon and demonstrates its consistency with cosmological observations, offering insights into longstanding cosmological problems.

Findings

$ m exteta$HDE fits observational data well.

The model's best-fit parameters are $ m extOmega_{m0}=0.270$ and $ m extOmega_{de0}=0.730$.

The $ m exteta$HDE model has a $ m extchi^2_{min}$ comparable to $ m extchi^2$ of $ m extLambda$CDM.

Abstract

The observed acceleration of the present universe is shown to be well explained by the holographic dark energy characterized by the total comoving horizon of the universe ($\eta$HDE). It is of interest to notice that the very large primordial part of the comoving horizon generated by the inflation of early universe makes the $\eta$HDE behave like a cosmological constant. As a consequence, both the fine-tuning problem and the coincidence problem can reasonably be understood with the inflationary universe and holographical principle. We present a systematic analysis and obtain a consistent cosmological constraint on the $\eta$HDE model based on the recent cosmological observations. It is found that the $\eta$HDE model gives the best-fit result $\Omega_{m0}=0.270$ ($\Omega_{de0}=0.730$) and the minimal $\chi^2_{min}=542.915$ which is compatible with $\chi^2_{\Lambda {\rm CDM}}=542.919$ for the $\Lambda$CDM model.