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

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 $\hat{I}›$CDM but no distinguishing features in the bispectrum. Using combined datasets of $\mathrm{CMB}+\mathrm{BAO}(\mathrm{DESI}DR1\&DR2)+\mathrm{Pantheon}\mathrm{Plus}+\mathrm{Hubble}\mathrm{parameter}+\mathrm{RSD}$, 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 $\hat{I}›$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.

16 pages, 1 table, 8 figures, Accepted in PRD