Jeans Instability in Classical and Modified Gravity

TL;DR

This paper compares gravitational instability across classical Jeans theory, General Relativity, and modified gravity, revealing faster perturbation growth with increased density and discovering a new high-frequency stable solution in modified gravity.

Contribution

It introduces a new high-frequency stable solution in modified gravity and analyzes the transition to Newtonian gauge with coordinate-dependent background metrics.

Findings

Faster growth of perturbations with increasing background density

Identification of a new high-frequency stable solution in modified gravity

Analysis of gauge transition in coordinate-dependent backgrounds

Abstract

Gravitational instability in classical Jeans theory, General Relativity, and modified gravity is considered. The background density increase leads to a faster growth of perturbations in comparison with the standard theory. The transition to the Newtonian gauge in the case of coordinate dependent background metric functions is studied. For modified gravity a new high frequency stable solution is found.