Observational and Thermodynamic aspects of one-dimensional Dark Energy EoS parametrization models

TL;DR

This paper evaluates two dark energy models using late-time cosmological data, showing that one model is favored over ΛCDM and demonstrating the utility of thermodynamic entropy as a probe of structure formation and cosmic acceleration.

Contribution

It introduces and constrains two Gong-Zhang dark energy parametrizations with observational data and employs configuration entropy as a novel thermodynamic diagnostic.

Findings

GZ-Type II model is favored over ΛCDM based on Bayesian evidence.

Both models fit late-time cosmological observations well.

Configuration entropy effectively traces dark energy effects on structure formation.

Abstract

We examine the observational viability and physical implications of the Gong-Zhang (GZ) dark--energy equation-of-state parametrizations using exclusively late-time cosmological probes. Two one-dimensional parametrization models, GZ-Type~I and GZ-Type~II, are constrained with Type~Ia supernovae (Union3, Pantheon+SH0ES, and DES-SN5YR), DESI baryon acoustic oscillations, and cosmic chronometer measurements of $H(z)$. Bayesian inference combined with information-criteria diagnostics shows that both parametrizations provide competitive alternatives to $\Lambda$CDM, while the GZ-Type~II model is consistently favored, exhibiting reduced parameter degeneracy and stronger Jeffreys-scale support. Beyond background expansion tests, we employ configuration entropy as a thermodynamically motivated probe of structure formation. We demonstrate that the entropy-production rate sensitively traces the impact of dynamical dark energy on late-time gravitational clustering while preserving standard early-time behavior. Our results establish the Gong-Zhang framework as a physically transparent and observationally consistent extension of $\Lambda$CDM, with configuration entropy providing a complementary diagnostic of late-time cosmic acceleration.