Validity of Thermodynamical Laws in Dark Energy Filled Universe

TL;DR

This paper investigates the validity of thermodynamical laws in a dark energy dominated universe, finding they hold on the apparent horizon but may break down on the event horizon depending on the dark energy model and parameters.

Contribution

It analyzes the validity of thermodynamical laws in different dark energy models on various horizons, highlighting conditions for their validity or breakdown.

Findings

First and second laws valid on apparent horizon for all models.

Laws break down on the event horizon for models 1 and 2.

Second law may be valid on the event horizon for model 3 at late times.

Abstract

We have considered the flat FRW model of the universe which is filled with only dark energy. The general descriptions of first and second laws of thermodynamics are investigated on the apparent horizon and event horizon of the universe. We have assumed the equation of state of three different types of dark energy models. We have examined the validity of first and second laws of thermodynamics on apparent and event horizons for these dark energies. For these dark energy models, it has been found that on the apparent horizon, first and second laws are always valid. On the event horizon, the laws are break down for dark energy models 1 and 2. For model 3, first law cannot be satisfied on the event horizon, but second law may be satisfied at the late stage of the evolution of the universe and so the validity of second law on the event horizon depends on the values of the parameters only.