DESI results: hint towards coupled dark matter and dark energy

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 w eff for the dark energy field crosses the phantom barrier ( w eff = -1) while keeping the equation of state of the quintessence field w ϕ > -1. With appropriate choices of parameters, w eff crosses the phantom divide around redshift z ∼ 0.5, transitioning from w eff < -1 in the past to w eff > -1 today. This explains DESI observations well. Our analysis reveals that the model remains consistent within the 2 σ 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.