Cosmic acceleration without dark energy: Background tests and thermodynamic analysis

TL;DR

This paper proposes a cosmological model driven by gravitationally induced particle creation, which explains cosmic acceleration without dark energy, and shows it aligns well with observational data and thermodynamic principles.

Contribution

It introduces a novel model linking early and late de Sitter phases through particle creation, reducing reliance on dark energy and providing thermodynamic consistency.

Findings

Model reproduces observed cosmic acceleration.

Approaches thermodynamic equilibrium in the long run.

Fits well with recent observational data.

Abstract

A new cosmic scenario with gravitationally induced particle creation is proposed. In this model the Universe evolves from an early to a late time de Sitter era, with the recent accelerating phase driven only by the negative creation pressure associated with the cold dark matter component. The model can be interpreted as an attempt to reduce the so-called cosmic sector (dark matter plus dark energy) and relate the two cosmic accelerating phases (early and late time de Sitter expansions). A detailed thermodynamic analysis including possible quantum corrections is also carried out. For a very wide range of the free parameters, it is found that the model presents the expected behavior of an ordinary macroscopic system in the sense that it approaches thermodynamic equilibrium in the long run (i.e., as it nears the second de Sitter phase). Moreover, an upper bound is found for the Gibbons-Hawking temperature of the primordial de Sitter phase. Finally, when confronted with the recent observational data, the current `quasi'-de Sitter era, as predicted by the model, is seen to pass very comfortably the cosmic background tests.