Thermodynamical properties of interacting holographic dark energy model with apparent horizon

TL;DR

This paper explores the thermodynamical behavior of a universe with interacting holographic dark energy, focusing on the apparent horizon as the IR cutoff, and examines the validity of thermodynamic laws in this context.

Contribution

It demonstrates the role of the apparent horizon as IR cutoff in a curved universe with interacting dark energy and analyzes thermodynamic laws in this setting.

Findings

Apparent horizon is a natural IR cutoff in curved universe models.

The effective equation of state of dark energy remains constant with interaction.

Modified first law of thermodynamics can revert to the classic form under certain conditions.

Abstract

We have investigated the thermodynamical properties of the universe with dark energy. It is demonstrated that in a universe with spacial curvature the natural choice for IR cutoff could be the apparent horizon radius. We shown that any interaction of pressureless dark matter with holographic dark energy, whose infrared cutoff is set by the apparent horizon radius, implying a constant effective equation of state of dark component in a universe. In addition we found that for the static observer in space, the comoving distance has a faster expansion than the apparent horizon radius with any spatial curvature. We also verify that in some conditions the modified first law of thermodynamics could return to the classic form at apparent horizon for a universe filled with dark energy and dark matter. Besides, the generalized second law of thermodynamics is discussed in a region enclosed by the apparent horizon.