Parametrizing the Hubble function instead of dark energy: Many possibilities

TL;DR

This paper introduces a flexible parametrization of the Hubble function that encompasses various cosmological models without directly parametrizing dark energy, and tests it against recent observational data.

Contribution

It proposes a novel, versatile parametrization of the Hubble function that can include multiple cosmological scenarios, tested against current astronomical observations.

Findings

Mild deviation from ΛCDM with combined datasets

Model is thermodynamically consistent

Performs well in model comparison tests

Abstract

In the present article, we propose a very simple parametrization of the Hubble function without parametrizing the dark components of the Universe. One of the novelties of the parametrization is that it may include a wide variety of the cosmological models, such as dark energy (both noninteracting and interacting fluids), modified gravity, cosmological matter creation and other known scenarios. The model is constrained with the latest astronomical probes from Hubble parameter measurements, three distinct versions of Type Ia Supernovae (Pantheon+, DESY5, Union3) and baryon acoustic oscillations from Sloan Digital Sky Survey and Dark Energy Spectroscopic Instrument data releases 1 and 2. Our results suggest a mild deviation from the standard $\Lambda$CDM cosmological model for most of the combined datasets. We also find that our model is thermodynamically consistent and performs well in the model comparison tests.