A Newtonian approach to the cosmological dark fluids

TL;DR

This paper presents a unified Newtonian framework for modeling the dark sector in cosmology as a single, barotropic dark fluid with zero sound speed, bridging Newtonian and relativistic descriptions.

Contribution

It introduces a novel unified dark fluid model with simple assumptions, combining Newtonian and relativistic approaches to dark sector cosmology.

Findings

Unified dark fluid model with zero sound speed

Bridging Newtonian and relativistic descriptions

Simplified assumptions for dark sector modeling

Abstract

We review the hydrodynamics of the dark sector components in Cosmology. For this purpose we use the approach of Newtonian gravitational instability, and thereafter we add corrections to arrive to a full relativistic description. In Cosmology and Astrophysics, it is usual to decompose the dark sector into two species, dark matter and dark energy. We will use instead a unified approach by describing a single unified dark fluid with very simple assumptions, namely the dark fluid is barotropic and its sound speed vanishes.