Modified cosmology through generalized mass-to-horizon entropy: observational constraints from DESI DR2 BAO data

Abstract

A generalized mass-to-horizon entropy has recently been proposed as an extension of the Bekenstein-Hawking area law, derived from a modified mass-horizon relation constructed to ensure consistency with the Clausius equation. Within the gravity-thermodynamics conjecture, this entropy formulation yields modified Friedmann equations, which recover the standard CDM cosmology in the appropriate limit of the model’s two free parameters. In the present study, we constrain this framework using observations from Type Ia supernovae (SNIa), cosmic chronometers (CC) and baryon acoustic oscillations (BAO), including the Second Data Release of the Dark Energy Spectroscopic Instrument (DESI DR2) survey, together with the Supernovae for the Equation of State (SH0ES) distance–ladder prior, across four combinations of data sets. Although the extended entropic scenario yields a slightly better, or statistically comparable, fit to the data, model selection via the Akaike Information Criterion (AIC) mildly favors the cosmological constant as the dark energy candidate. Moreover, the CDM limit lies within of our constraints, indicating no significant deviation from standard cosmology with current data.

GGL would like to thank Prof. Gamze for her warm inspiration. The research of GGL is supported by the Ayuda Postdoctoral of the Univer- sity of Lleida (project code: X25027). GGL gratefully acknowledges the contribution of the LISA Cosmology Working Group (CosWG), as well as support from the COST Actions CA21136 - Addressing observational ten- sions in cosmology with systematics and fundamental physics (CosmoVerse) - CA23130, Bridging high and low energies in search of quantum gravity (BridgeQG) and CA21106 - COSMIC WISPers in the Dark Universe: The- ory, astrophysics and experiments (CosmicWISPers). AP was Financially supported by FONDECYT 1240514 ETAPA 2025.