Stability of the Einstein static universe in IR modified Ho\v{r}ava gravity

TL;DR

This paper investigates the stability of the Einstein static universe within an IR-modified Horava gravity framework, revealing a broad parameter space where stable solutions can exist, thus contributing to understanding early universe models.

Contribution

It introduces an analysis of Einstein static universe stability in IR-modified Horava gravity, highlighting new stable solution regions due to the theory's modifications.

Findings

Existence of large stable solution regions in parameter space.

Stability depends on the equation of state parameter w.

Stability regions are influenced by Horava gravity parameters.

Abstract

Recently, Horava proposed a power counting renormalizable theory for (3+1)-dimensional quantum gravity, which reduces to Einstein gravity with a non-vanishing cosmological constant in IR, but possesses improved UV behaviors. In this work, we analyze the stability of the Einstein static universe by considering linear homogeneous perturbations in the context of an IR modification of Horava gravity, which implies a `soft' breaking of the `detailed balance' condition. The stability regions of the Einstein static universe are parameterized by the linear equation of state parameter w=p/\rho and the parameters appearing in the Horava theory, and it is shown that a large class of stable solutions exists in the respective parameter space.