Relativistic cosmological hydrodynamics

TL;DR

This paper derives general large-scale solutions for relativistic cosmological hydrodynamic perturbations, applicable across various curvature, cosmological constant, and evolving background conditions, highlighting a conserved gauge-invariant quantity.

Contribution

It provides the first comprehensive large-scale solutions for relativistic hydrodynamic perturbations in cosmology with general curvature and evolving background.

Findings

Identifies a conserved gauge-invariant quantity during large-scale evolution.

Derives solutions valid for any sign of spatial curvature and cosmological constant.

Connects perturbation variables to a perturbed potential in the comoving gauge.

Abstract

We investigate the relativistic cosmological hydrodynamic perturbations. We present the general large scale solutions of the perturbation variables valid for the general sign of three space curvature, the cosmological constant, and generally evolving background equation of state. The large scale evolution is characterized by a conserved gauge invariant quantity which is the same as a perturbed potential (or three-space curvature) in the comoving gauge.