📝 SummarXiv

Abstract

Recent findings from the Dark Energy Spectroscopic Instrument (DESI), analyzed together with supernova observations and CMB measurements, provide statistically significant indications (at the 2-5$\sigma$ level) of a time-varying dark energy component alongwith a possible phantom-to-quintessence transition in the recent past. In this letter, we investigate the evolution of dark energy using a model-independent cosmographic approach and explore the possibility of phantom barrier crossing. By mapping the differential equation defining jerk parameter into an anharmonic oscillator, we derive an analytical expression for the dark energy equation of state (EoS), which, remarkably, depends on a single parameter. Using DESI-DR2 BAO data, supernova data, and a compressed Planck likelihood, we constrain the cosmological parameters and find deviations from a cosmological constant at late times. Unlike the CPL parametrization, our results show no phantom barrier crossing, highlighting the power of kinematic reconstructions in probing the nature of dark energy. Furthermore, using a dynamical system approach, we demonstrate that $w_{DE}=-1$ acts as a bifurcation point with degenerate stable fixed points and therefore prevents solutions from crossing this barrier from either side.