Observational constraints on Luciano-Saridakis entropic cosmology

Abstract

A recently proposed generalized entropy by Luciano and Saridakis extends the standard Boltzmann-Gibbs and Bekenstein-Hawking framework through a microscopically motivated construction involving two independent entropic exponents. When applied within the gravity-thermodynamics correspondence, this entropy leads to a modified cosmological dynamics that can be interpreted as an effective dark energy sector of entropic origin, while recovering $Λ$CDM in appropriate limits. In this work, we perform the first observational confrontation of the resulting entropic cosmology at the background level. Focusing on the case $α_δ=0$, we constrain the model using Cosmic Chronometers, Pantheon$^+$ Type Ia supernovae calibrated with SH0ES, BAO measurements from DESI DR2 and compressed Planck 2018 CMB information. We find that the model yields a statistically robust fit to the combined data sets and can simultaneously satisfy Pantheon$^+$, SH0ES and CMB shift-parameter constraints, unlike $Λ$CDM. Although the entropic parameters remain close to their standard values, the $Λ$CDM limit is excluded at the $2σ$ level within the restricted parameter space considered. These results indicate that the Luciano-Saridakis entropic cosmology offers a viable extension of the standard model with the potential to alleviate the Hubble tension at the background level.

Figures (5)

• Figure 1: Percentage difference of the sound horizon calculated in the LSEC model with respect to $\Lambda$CDM: Upper panel: Sound horizon at recombination, Lower panel: Sound horizon at the drag epoch. The values of $h$, $\omega_m$, $\omega_b$, $\tilde{\alpha}_\epsilon$ and $\epsilon$ are fixed to their mean values reported in Table \ref{['tab:results']}.
• Figure 2: Percentage difference of the comoving distance calculated in the LSEC model with respect to $\Lambda$CDM. The values of $h$, $\omega_m$, $\omega_b$, $\tilde{\alpha}_\epsilon$ and $\epsilon$ are fixed to their mean values reported in Table \ref{['tab:results']}.
• Figure 3: Results for the statistical analyses considering CMB (Planck 18 - Shift parameters), CC, SnIa + SH0ES (PPS), BAO (DESI DR2) datasets separately. Contour plots and 1-dimensional for the LSEC model with $\alpha_\delta=0$. The contours represent 68% and 95% confidence levels.
• Figure 4: Results for the statistical analyses considering CMB (Planck 18 - Shift parameters), CC, SnIa + SH0ES (PPS), BAO (DESI DR2) datasets separately. Contour plots and 1-dimensional posteriors for $\rm \Lambda CDM$. The contours represent 68% and 95% confidence levels.
• Figure 5: Posterior distributions for the parameters of the LSEC model with $\alpha_\delta=0$ using CMB+CC+BAO+SnIa datasets. The contours represent 68% and 95% confidence levels.