Generalized tracker quintessence models for dark energy

TL;DR

This paper investigates generalized tracker quintessence models for dark energy, establishing conditions for tracker behavior and acceleration, analyzing perturbations, and comparing models with observations to address fine-tuning issues.

Contribution

It introduces a general parametrization of potentials for tracker quintessence, analyzes conditions for tracker behavior and acceleration, and includes perturbation effects in a comprehensive framework.

Findings

Conditions for early-time tracker behavior identified

Models can produce late-time acceleration with near -1 equation of state

Perturbations influence cosmological observables and model viability

Abstract

We study the dynamical properties of tracker quintessence models using a general parametrization of their corresponding potentials, and show that there is a general condition for the appearance of a tracker behavior at early times. Likewise, we determine the conditions under which the quintessence tracker models can also provide an accelerating expansion of the universe with an equation of state closer to $-1$. Apart from the analysis of the background dynamics, we also include linear density perturbations of the quintessence field in a consistent manner and using the same parametrization of the potential, with which we show the influence they have on some cosmological observables. The generalized tracker models are compared to observations, and we discuss their appropriateness to ameliorate the fine-tuning of initial conditions and their consistency with the accelerated expansion of the Universe at late times.