Thermodynamic analysis of universes with the initial and final de-Sitter eras

TL;DR

This paper explores the thermodynamics of cosmological models with initial and final de-Sitter phases, analyzing dark energy, thermal fluctuations, and particle production effects on horizon entropy and the first law of thermodynamics.

Contribution

It introduces a comprehensive thermodynamic analysis of cosmological models with variable dark energy and particle production, linking thermal fluctuations to cosmic interactions and horizon entropy.

Findings

Dark energy's state parameter must differ from -1 without fluid interaction.

Thermal fluctuations relate to mutual interactions and particle production rates.

Particle production influences horizon entropy and modifies the Bekenstein limit.

Abstract

Our aim is studying the thermodynamics of cosmological models including initial and final de-Sitter eras. For this propose, bearing Cai-Kim temperature in mind, we investigate the thermodynamic properties of a dark energy candidate with variable energy density, and show that the state parameter of this dark energy candidate should obey the $\omega_D\neq-1$ constraint, whiles there is no interaction between the fluids filled the universe, and the universe is not in the de-Sitter eras. Additionally, based on thermal fluctuation theory, we study the possibility of inducing fluctuations to the entropy of the dark energy candidate due to a mutual interaction between the cosmos sectors. Therefore, we find a relation between the thermal fluctuations and the mutual interaction between the cosmos sectors, whiles the dark energy candidate has a varying energy density. We point to models in which a gravitationally induced particle production process leads to change the expansion eras, whiles the corresponding pressure is considered as the cause of current acceleration phase. We study its thermodynamics, and show that such processes may also leave thermal fluctuations into the system. We also find an expression between the thermal fluctuations and the particle production rate. Finally, we use Hayward-Kodama temperature to get a relation for the horizon entropy in models including the gravitationally induced particle production process. Our study shows that the first law of thermodynamics is available on the apparent horizon whiles, the gravitationally induced particle production process, as the dark energy candidate, may add an additional term to the Bekenstein limit of the horizon.