Holographic dark energy in modified Barrow cosmology

TL;DR

This paper explores how modifying the entropy in holographic dark energy models using Barrow entropy affects cosmological equations and dynamics, including the universe's acceleration and phase transition.

Contribution

It introduces a modified holographic dark energy model based on Barrow entropy, analyzing its impact on cosmological evolution and dark sector interactions.

Findings

Barrow exponent influences the EoS parameter, allowing phantom crossing.

Modified entropy alters the deceleration parameter and universe phase transition timing.

Interaction between dark matter and dark energy is affected by the Barrow parameter.

Abstract

Thermodynamics-Gravity conjecture implies that there is a deep connection between the gravitational field equations and the first law of thermodynamics. Therefore, any modification to the entropy expression, directly modifies the field equations. By considering the modified Barrow entropy associated with the apparent horizon, the Friedmann equations get modified as well. In this paper, we reconsider the holographic dark energy (HDE) model when the entropy is in the form of Barrow entropy. This modification to the entropy not only changes the energy density of HDE, but also modifies the Friedmann equations. Therefore, one should take into account the modified HDE in the context of modified Friedmann equations. We study the Hubble horizon and the future event horizon as IR cutoffs, and investigate the cosmological consequences of this model. We also extend our study to the case where dark matter (DM) and dark energy (DE) interact with each other. We observe that Barrow exponent $\delta$ significantly affects the cosmological behavior of HDE, and in particular the equation of state (EoS) parameter can cross the phantom line $(w_{de}<-1)$. Also adding $\delta$ remarkably affects the deceleration parameter, and shifts the time of universe phase transition.