Cosmology with the matter component decaying faster than radiation

TL;DR

This paper investigates how a rapidly decaying matter component affects the universe's expansion, using a hydrodynamic approach based on Hamiltonian formalism, revealing its influence depends on its energy contribution.

Contribution

It introduces a hydrodynamic framework derived from Hamiltonian formalism to analyze the effects of a fast decaying matter component on cosmic expansion.

Findings

Decaying matter influences universe expansion depending on its energy sign.

Hydrodynamic equations for cosmic expansion are derived from Hamiltonian formalism.

Illustrative figures demonstrate the impact of the decaying component.

Abstract

The impact of a fast decaying component of mass-energy, that decreases faster than radiation with the increase of the scale factor, on the evolution of the universe is studied using a hydrodynamic approach. Proceeding from the Hamiltonian formalism, the hydrodynamic-like equations for the velocity and acceleration of the expansion of the universe as a function of conformal time are obtained. The influence of a fast decaying component on the dynamics of the expansion of the universe is determined by the sign of its contribution to the total energy density of the system. The effects of this component are illustrated by figures.