Speeding up the Universe with a generalised axion-like potential

TL;DR

This paper introduces a new scalar field model with a generalized axion-like potential that naturally explains the Universe's late-time acceleration without fine-tuning, addressing the coincidence problem effectively.

Contribution

The paper proposes a novel quintessence model with a generalized axion-like potential that facilitates late-time acceleration and alleviates the coincidence problem without initial condition fine-tuning.

Findings

The model achieves late-time acceleration via an effective cosmological constant.

It naturally addresses the coincidence problem through a tracking regime.

The scalar field density parameter rapidly increases in the late universe.

Abstract

Understanding the late-time acceleration of the Universe is one of the major challenges in cosmology today. In this paper, we present a new scalar field model corresponding to a generalised axion-like potential. In fact, this model can be framed as a quintessence model based on physically motivated considerations. This potential is capable of alleviating the coincidence problem through a tracking regime. We will as well prove that this potential allows for a late-time acceleration period induced by an effective cosmological constant, which is reached without fine-tuning the initial conditions of the scalar field. In our model, the generalised axion field fuels the late-time acceleration of the Universe rather than fuelling an early dark energy era. Additionally, we will show how the late-time transition to dark energy dominance could be favoured in this model, since the density parameter of the scalar field will rapidly grow in the late phase of the tracking regime.