Thermodynamics of Chaplygin gas

TL;DR

This paper clarifies the thermodynamics of the Chaplygin gas by deriving thermal quantities and a new equation of state, supporting its role as a unified dark matter-energy model without phase transitions.

Contribution

It introduces an integrability condition and a new general equation of state for the Chaplygin gas, enhancing understanding of its thermodynamic behavior.

Findings

Derived thermal quantities as functions of volume and temperature

Established a new general equation of state for the Chaplygin gas

Confirmed the model's ability to unify dark matter and energy without phase transitions

Abstract

We clarify thermodynamics of the Chaplygin gas by introducing the integrability condition. All thermal quantities are derived as functions of either volume or temperature. Importantly, we find a new general equation of state, describing the Chaplygin gas completely. We confirm that the Chaplygin gas could show a unified picture of dark matter and energy which cools down through the universe expansion without any critical point (phase transition).