Hints Beyond $Λ$CDM from Barrow and Tsallis Holographic Dark Energy with GO cutoff

TL;DR

This work investigates Barrow and Tsallis holographic dark energy (HDE) with the Granda–Oliveros cutoff, deriving modified Friedmann equations from Barrow entropy via thermodynamic gravity and modeling the dark sector in both non-interacting and interacting scenarios. Through Bayesian MCMC analyses using PantheonPlus, Union3, Cosmic Chronometers, and DESI DR2 BAO data, the authors constrain the BHDE-GO parameters ($\Delta,\alpha,\beta,\gamma$) and compare to $\Lambda$CDM using AIC, finding that BHDE is generally compatible with current observations and can be mildly preferred in some dataset combinations, with a tendency toward mildly negative $\Delta$. The results highlight the physical relevance of generalized entropy frameworks in late-time cosmology and show that BHDE–GO can be a competitive alternative to $\Lambda$CDM, while also motivating extensions to perturbations and early-Universe probes. The analysis further notes that the BHDE and Tsallis HDE descriptions are equivalent up to a simple reparametrization, enabling direct translation between the two formalisms with $\Delta\to2(\varepsilon-1)$.

Abstract

Barrow and Tsallis Holographic Dark Energy (HDE) are two recent extensions of the standard HDE framework, obtained by introducing generalized entropy corrections through the Barrow and Tsallis formalisms. In this work, we examine the cosmological consequences of Barrow and Tsallis HDE implemented with the Granda-Oliveros (GO) infrared (IR) cutoff. After deriving the modified Friedmann equations within the thermodynamic-gravity conjecture, we study the background evolution in both non-interacting and interacting dark sector scenarios, emphasizing the role of the entropic parameter in shaping late-time dynamics. We then confront the model with state-of-the-art observations, including PantheonPlus and Union3 Type Ia supernovae, Cosmic Chronometers and DESI DR2 BAO measurements. Using Bayesian MCMC methods, we constrain the model parameters and compare the performance of BHDE with that of $Λ$CDM. Our results show that BHDE is compatible with current data and can exhibit a mild statistical preference over the concordance model for certain dataset combinations. Overall, the analysis underscores the relevance of generalized entropy frameworks in late-time cosmology and identifies Barrow-Tsallis holography with the GO cutoff as a competitive alternative to $Λ$CDM.

Figures (9)

• Figure 1: Confidence space for the posterior parameters for the non-interacting BHDE model.
• Figure 2: Confidence space for the best-fit parameters for the interacting BHDE model.
• Figure 3: Evolution of $\Omega_{de}$ against $z$ for BHDE in a flat cosmology for $\Omega_{m,0}=0.36$ and $\beta=0.56$. In the left panel $\delta=-0.04$, while in the right panel $\alpha=1.03$.
• Figure 4: Evolution of $w_{de}$ against $z$ for BHDE in a flat cosmology for $\Omega_{m,0}=0.36$ and $\beta=0.56$. In the left panel $\delta=-0.04$, while in the right panel $\alpha=1.03$.
• Figure 5: Evolution of the deceleration parameter $q$ against $z$ for BHDE in a flat cosmology for $\Omega_{m,0}=0.36$ and $\beta=0.56$. In the left panel $\delta=-0.04$, while in the right panel $\alpha=1.03$.