How Holographic is the Dark Energy? A Spline Nodal reconstruction approach

Abstract: In this work, we explore the generalized holographic dark energy (HDE) scenario. We relate the HDE density to the future-horizon scale via a function $f(a)$, which we reconstruct via spline-based nodal interpolation. We perform a Bayesian analysis to assess model's consistency with current observations, including baryon acoustic oscillations (BAO) from the Dark Energy Spectroscopic Instrument (DESI) DR1, Type Ia supernovae (SNe Ia) from the Union3 and Pantheon+ compilations, and local measurements of the Hubble constant, $H_0$, from SH0ES. We show that under specific conditions, the model reduces to $\Lambda$CDM with one node. We find strong statistical evidence against the standard HDE model $\Delta \chi^2_{\rm HDE, \; 3\text{-Node}} \sim 20$, and in contrast, the reconstructed HDE model, with three nodes, provides a better fit to the data than the $\Lambda$CDM model, specifically, $\Delta \chi^2_{\Lambda \rm CDM, \; 3\text{-Node}} \sim 12$.