Ideal gas with a varying (negative absolute) temperature: An alternative to dark energy?

TL;DR

This paper explores whether the universe's evolution can be modeled using an ideal gas with a varying negative absolute temperature, offering an alternative explanation to dark energy without exotic matter or modified gravity.

Contribution

It proposes a novel cosmological model based on an ideal gas with a negative absolute temperature to explain cosmic acceleration as an effective quintessence.

Findings

NAT can mimic dark energy effects in cosmology

The model provides an alternative to exotic dark energy

The approach avoids the need for modified gravity theories

Abstract

The present work is an attempt to investigate whether the evolutionary history of the Universe from the offset of inflation can be described by assuming the cosmic fluid to be an ideal gas with a specific gas constant but a varying negative absolute temperature (NAT). The motivation of this work is to search for an alternative to the "exotic" and "supernatural" dark energy (DE). In fact, the NAT works as an "effective quintessence" and there is need to deal neither with exotic matter like DE nor with modified gravity theories. For the sake of completeness, we release some clarifications on NATs in Section 3 of the paper.