Addressing the Hubble Tension: Insights from Reversible and Irreversible Thermodynamic Processes

TL;DR

This paper explores how reversible and irreversible thermodynamic processes in cosmology can influence the Hubble tension, proposing models with matter creation/annihilation and energy transfer that align with local measurements.

Contribution

It introduces thermodynamically motivated cosmological models with matter creation and energy exchange that can alleviate the Hubble tension while fitting observational data.

Findings

Matter annihilation models yield higher H0 values consistent with local measurements.

Models with matter creation or pure energy flow do not improve the Hubble tension.

Effective entropic dark energy evolves dynamically, mimicking radiation, matter, and approaching a cosmological constant.

Abstract

We investigate reversible and irreversible thermodynamic processes in cosmology and their impact on the Hubble tension. Gravitationally induced adiabatic matter creation/annihilation is treated as irreversible, while energy exchange between the cosmic bulk and horizon is modeled as reversible. Two scenarios are proposed: Model I features matter creation/annihilation across all species with energy transfer to effective entropic dark energy; Model II considers dark matter creation/annihilation with energy flow from baryonic matter and radiation. The creation rate is parameterized as $\Gamma(t)=\Gamma_0 H$, with energy transfer controlled by $\gamma$. We constrain both models using Pantheon$+$ supernovae, CMB distance priors, baryon acoustic oscillations, gamma-ray bursts, and cosmic chronometers, with and without SH$_0$ES. When SH$_0$ES is included, matter annihilation ($\Gamma_0<0$) is statistically preferred, yielding $H_0 = 71.75 \pm 0.79$ km s$^{-1}$ Mpc$^{-1}$ (Model I) and $H_0 = 71.06 \pm 0.81$ km s$^{-1}$ Mpc$^{-1}$ (Model II), corresponding to $1.2\sigma$ and $1.8\sigma$ consistency with the SH$_0$ES value $73.17 \pm 0.86$ km s$^{-1}$ Mpc$^{-1}$. Matter creation ($\Gamma_0>0$) or pure energy flow ($\Gamma=0$) do not improve the tension. Without SH$_0$ES, information criteria show no preference over $\Lambda$CDM. For the matter annihilation/creation with energy flow, the effective entropic dark energy evolves dynamically, mimicking radiation and matter before recombination and approaching a cosmological constant at late times. These results demonstrate that thermodynamically motivated interactions can alleviate the Hubble tension when calibrated with local measurements, while remaining consistent with cosmological data.