Distinguishing between $w < -1$ Dark Energy Models

TL;DR

This paper reviews models of dark energy with equation of state parameter w less than -1, exploring their observational signatures and how to distinguish them without violating energy conditions.

Contribution

It provides a comparative analysis of w < -1 dark energy models and discusses observational strategies to differentiate their predictions.

Findings

Most data favor w < -1 at low redshifts

Models without null energy condition violation are viable

Observables can distinguish between different dark energy models

Abstract

Recent data and new data analysis methods show that most probably the parameter $w$ in the equation of state of the dark energy is smaller than -1 at low redshifts. We briefly review some of the models with such a property and without violating null energy condition. We investigate the difference between the observables and predictions of these models, and how they can be explored to single out or constrain the origin of dark energy and its properties.