Probing the $$H_0$$ tension with holographic dark energy in unimodular gravity: insights from DESI DR2

Abstract Motivated by the recent baryon acoustic oscillation measurements of DESI DR2 collaboration, this works presents an extended analysis of a cosmological model based on holographic dark energy within the framework of Unimodular Gravity. We probe the model with an extensive set of observations: cosmic chronometers, Pantheon Plus+SH0ES Type Ia supernovae, DESI DR2 BAO distances, quasar X-ray/UV fluxes (two independent calibrations), and Planck 2018 CMB data. The results are analyzed to assess the model’s ability to alleviate the Hubble tension and, in comparison with the standard $$\Lambda $$ Λ CDM framework, to determine which of the two scenarios is preferred according to Bayesian evidence. We conclude that the present implementation of holographic dark energy in Unimodular Gravity, while theoretically appealing, does not alleviate the Hubble tension and is not statistically preferred by Bayesian criteria when compared with the standard $$\Lambda $$ Λ CDM model. Nevertheless, in neither case does the preference become very strong or conclusive against it.