Dark energy, matter creation and curvature

TL;DR

This paper explores an alternative cosmological model involving gravitational particle creation and spatial curvature, which can explain accelerated expansion without dark energy, potentially alleviating the cosmic coincidence problem.

Contribution

It provides a detailed analysis of a particle creation model with spatial curvature, showing its ability to address the cosmic coincidence problem and proposing improvements over previous models.

Findings

Model fits supernova data as well as ΛCDM

Alleviates the cosmic coincidence problem

Identifies limitations of some particle creation models

Abstract

The most studied way to explain the current accelerated expansion of the universe is to assume the existence of dark energy; a new component that fill the universe, does not clumps, currently dominates the evolution, and has a negative pressure. In this work I study an alternative model proposed by Lima et al. \cite{lima96}, which does not need an exotic equation of state, but assumes instead the existence of gravitational particle creation. Because this model fits the supernova observations as well as the $\Lambda$CDM model, I perform in this work a thorough study of this model considering an explicit spatial curvature. I found that in this scenario we can alleviate the cosmic coincidence problem, basically showing that these two components, dark matter and dark energy, are of the same nature, but they act at different scales. I also shown the inadequacy of some particle creation models, and also I study a previously propose new model that overcome these difficulties.