Adiabatic expansion of polytropic universe with varying cosmological constant: Models tested with observational data

TL;DR

This paper investigates polytropic universe models with a varying cosmological constant using supernova data, finding some models fit observations better than the standard Lambda-CDM model.

Contribution

The paper introduces new equations for polytropic universe models with a varying cosmological constant and tests their fit against supernova data, showing improved descriptions over standard models.

Findings

One model with a varying {} fits supernova data better than CD.

Polytropic matter significantly influences the universe's expansion.

Models with varying  better explain observational data.

Abstract

We use two large collections of observational data of supernovae type Ia (SNe Ia) to investigate the polytropic Universe including the situation with a varying cosmological constant; details of our new derivations are presented. We examine the fitness of our new models of a polytropic Universe with two sets of SNe Ia data to test if these are better descriptions than the current standard model of cosmology. Beginning with the established relationships for polytropic matter we derive new equations describing the influence of polytropic matter on the expanding Universe including the situation with a varying cosmological constant. When the models derived here are tested with large sets of supernovae type I a data we find a significant influence of polytropic matter on the state of our expanding Universe. We find that one of our models with a varying {\Lambda} describes the SNe Ia data significantly better than the, {\Lambda}CDM, standard model.