Interacting holographic Ricci dark energy as running vacuum

TL;DR

This paper proposes an interacting holographic Ricci dark energy model that enables a transition from deceleration to acceleration without a bare constant, aligns with cosmological data, and exhibits stable de Sitter phase and quintessence behavior.

Contribution

It introduces a novel interaction scenario in holographic Ricci dark energy that allows for cosmic transition and stability analysis without a bare constant in the vacuum density.

Findings

Model causes transition from deceleration to acceleration.

Interaction coupling is small, indicating slow decay of vacuum.

End de Sitter phase is stable and entropy is bounded.

Abstract

Earlier studies have shown that, in a two component model of the universe with dark matter and the running vacuum energy which is phenomenologically a combination of $H^2$ and $\dot{H},$ produces either eternal deceleration or acceleration in the absence of a bare constant in the density of the running vacuum. In this paper we have shown that, in the interaction scenario, where the interaction between matter and vacuum is introduced through a phenomenological term, the two component model is capable of causing a transition from a prior decelerated to a later accelerated epoch without a bare constant in the running vacuum density. On contrasting the model with the cosmological data, we have found that the interaction coupling constant, is small enough, for a slow decay of the running vacuum. The model is subjected to dynamical system analysis which revealed that the end de Sitter phase of the model is a stable one. We did an analysis on the thermal behavior of the system, which shows that the entropy is bounded at the end stage so that the system is behaving like an ordinary macroscopic system. Apart from these we have also performed the state finder diagnostic analysis which implies the quintessence nature of running vacuum and confirms that the model will approach the standard $\Lambda$CDM in the future.