Holographic dark energy in Barrow cosmology with Granda-Oliveros IR cutoff

TL;DR

This paper investigates how modified Barrow entropy influences holographic dark energy models with Granda-Oliveros IR cutoff, revealing effects on cosmic acceleration, stability, and distinctions from the standard Lambda-CDM model.

Contribution

It introduces a novel analysis of holographic dark energy within Barrow cosmology, incorporating quantum fluctuation-inspired entropy modifications and their impact on cosmic evolution.

Findings

Barrow parameter $oldsymbol{\delta}$ affects transition to acceleration

Equation of state crosses the phantom divide recently

Interaction and $oldsymbol{\delta}$ induce past instability

Abstract

Applying the modified Barrow entropy, inspired by the quantum fluctuation effects, to the cosmological background, and using thermodynamics-gravity conjuncture, the Friedmann equations get modified as well. In this paper, we explore the holographic dark energy with Granda-Oliveros (GO) IR cutoff, in the context of the modified Barrow cosmology. First, we assume two dark components of the universe evolves independently and obtain the cosmological parameters and explore the cosmic evolution. Second, we consider an interaction term between dark energy (DE) and dark matter (DM). We observe that the Barrow parameter $\delta$ crucially affects the cosmic dynamics, causes the transition from the decelerating phase to the accelerating phase occurs later. We find out that the equation of state parameter is in the quintessence region in the past and crosses the phantom divide at the present time. Finally, we examine the squared speed of sound analysis for this model. According to the squared sound speed diagrams, the results indicate that the presence of interaction between DM and DE as well as increasing in the value of $\delta$ leads to the manifestation of signs of instability in the past $(v_s^2<0)$. Furthermore, by examining the statefinder, we find that presence of $\delta$ also makes a distinction between holographic dark energy in Barrow cosmology with GO-IR cutoff and the $\Lambda$CDM model. In fact, increasing $\delta$ causes the statefinder diagram move away from the point of $\left\lbrace r,s\right\rbrace= \left\lbrace 1,0\right\rbrace$ at $z=0$.