Thermodynamic Constraints on the Dark Sector

TL;DR

This paper introduces a thermodynamically constrained, unified fluid model of the dark sector that includes interactions between dark energy and dark matter, tested against multiple cosmological observations.

Contribution

It generalizes dark sector models with time-varying equations of state and interactions, applying thermodynamic constraints and Bayesian analysis with observational data.

Findings

Thermodynamic constraints restrict dark sector interaction models.

The unified model fits observational data well.

The approach provides a thermodynamically consistent framework for dark sector studies.

Abstract

In this paper, we present a unified scheme based on the fluid description of the dark sector of the universe. The scheme captures models with interaction between dark energy and dark matter, being the core of generalization the time-varying equation-of-state parameter $\omega(a)$ and the time-dependent interactions through the interaction function $\epsilon(a)$, where $a$ is the scale factor. Furthermore, we propose thermodynamics constraints on this generalized class of models using the laws of thermodynamics which are combined with observational data. In order to test the observational viability of the unified model, we perform a Bayesian analysis using cosmic chronometers, type Ia supernovae, cosmic microwave background, and angular baryon acoustic oscillation measurements.