# Newtonian Limits of Isolated Cosmological Systems on Long Time Scales

## TL;DR

This paper proves the existence of solutions to Einstein-Euler equations with a positive cosmological constant that approximate Newtonian gravity solutions on long time scales, extending understanding of relativistic and Newtonian cosmologies.

## Contribution

It establishes the existence of epsilon-dependent solutions to Einstein-Euler equations that converge to Newtonian solutions as epsilon approaches zero, for the first time in this context.

## Key findings

- Solutions exist globally to the future
- Solutions converge to Newtonian gravity solutions as epsilon approaches zero
- Solutions are inhomogeneous non-linear perturbations of FLRW fluid solutions

## Abstract

We establish the existence of $1$-parameter families of $\epsilon$-dependent solutions to the Einstein-Euler equations with a positive cosmological constant $\Lambda >0$ and a linear equation of state $p=\epsilon^2 K \rho$, $0<K\leq 1/3$, for the parameter values $0<\epsilon < \epsilon_0$. These solutions exist globally to the future, converge as $\epsilon \searrow 0$ to solutions of the cosmological Poison-Euler equations of Newtonian gravity, and are inhomogeneous non-linear perturbations of FLRW fluid solutions.