Cosmological implications of tracker scalar fields: Testing the evidence for dynamical dark energy with recent data

TL;DR

This study tests non-phantom tracker scalar field models as dynamical dark energy using recent cosmological data, finding no evidence to favor these models over the standard Lambda-CDM model.

Contribution

It provides a comprehensive analysis of specific tracker scalar field models with recent data, concluding that they do not outperform Lambda-CDM in explaining observations.

Findings

No significant deviation from Lambda-CDM in data fits

Mild suppression in matter power spectrum compared to Lambda-CDM

Data do not support dynamical dark energy in non-phantom models

Abstract

We investigate non phantom tracker scalar field models as dynamical dark energy scenario. These models can alleviate the cosmic coincidence problem and transition to a cosmological constant-like behaviour at late times. Focusing on the inverse axionlike and inverse steep exponential potentials, we study their background evolution and perturbations, finding a mild suppression in the matter power spectrum compared to $\Lambda$CDM but no distinguishing features in the bispectrum. Using combined datasets of ${\rm CMB}+{\rm BAO\; (DESI~DR1\; \&\; DR2)}+{\rm Pantheon~Plus}+{\rm Hubble\; parameter}+{\rm RSD}$, we perform a statistical comparison based on the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). Our results indicate that, within the framework of non-phantom tracker models, the data show no evidence for dynamical dark energy. The $\Lambda$CDM model continues to provide a better fit to current observations in the non phantom regime. We emphasise, however, that our analysis does not rule out the possibility of phantom-crossing dark energy models, which have been found in other studies to provide a better fit to some datasets.