Einstein static universes are unstable in generic f(R) models

TL;DR

This paper investigates Einstein static universes within generic f(R) gravity models, demonstrating their existence but inherent instability under various perturbations, aligning with previous specific model findings.

Contribution

It provides a general analysis showing the instability of Einstein static solutions in broad f(R) models, extending prior specific case studies.

Findings

Existence of Einstein static solutions in many f(R) models

Universal instability of these solutions to perturbations

Methodology applicable to other f(R) gravity scenarios

Abstract

We study Einstein static universes in the context of generic f(R) models. It is shown that Einstein static solutions exist for a wide variety of modified gravity models sourced by a barotropic perfect fluid with equation of state w=p/rho, but these solutions are always unstable to either homogeneous or inhomogeneous perturbations. Our general results are in agreement with specific models investigated in that past. We also discuss how our techniques can be applied to other scenarios in f(R) gravity.