Abstract:
We investigate a scenario where a dark energy quintessence field ϕ with positive kinetic energy is coupled with dark matter. With two different self-interaction potentials for the field and a particular choice of the coupling function, we show explicitly how the observable effective equation of state parameter weff for the dark energy field crosses the phantom barrier (weff = −1) while keeping the equation of state of the quintessence field
wϕ > −1. With appropriate choices of parameters, weff crosses the phantom divide around redshift z ∼ 0.5, transitioning from weff < −1 in the past to weff > −1 today. This explains DESI observations well. Our analysis reveals that the model remains consistent within the 2σ confidence intervals provided by DESI for several combinations of the scalar field parameters, highlighting its potential in explaining the dynamics of dark energy arising from a simple Yukawa-type long-range interaction in the dark sector. While the current findings offer a promising framework for interpreting DESI observations, future work, including a comprehensive Markov Chain Monte Carlo (MCMC) analysis, is necessary to constrain the parameter space further and strengthen the statistical significance of the results
