Dark energy, inflation and the cosmic coincidence problem

TL;DR

This paper proposes that holographic dark energy, combined with early universe inflation, can explain the small current dark energy density and address the cosmic coincidence problem, supported by numerical analysis matching observations.

Contribution

It introduces a model linking holographic dark energy with inflation to solve the cosmic coincidence problem, providing approximate formulas and numerical validation.

Findings

Holographic dark energy can account for small current dark energy density.

Inflation with about 65 e-folds may resolve the cosmic coincidence problem.

Numerical results align well with observational data.

Abstract

We show that holographic dark energy could explain why the current dark energy density is so small, if there was an inflation with a sufficient expansion in the early universe. It is also suggested that an inflation with the number of e-folds $N\simeq 65$ may solve the cosmic coincidence problem in this context. Assuming the inflation and the power-law acceleration phase today we obtain approximate formulas for the event horizon size of the universe and dark energy density as functions of time. A simple numerical study exploiting the formula well reproduces the observed evolution of dark energy. This nontrivial match between the theory and the observational data supports both inflation and holographic dark energy models.