The Geometrodynamical Origin of Equilibrium Gravitational Configurations

TL;DR

This paper links the stability of gravitational systems' trajectories to their equilibrium configurations, showing that marginal stability correlates with observed galaxy-like structures and cosmological halos.

Contribution

It introduces a geometric approach connecting trajectory stability and equilibrium states, demonstrating that marginally stable configurations resemble observed astrophysical structures.

Findings

Null scalar curvature corresponds to relaxed equilibria with marginal stability.

Simulations confirm the link between trajectory stability and equilibrium configurations.

Configurations resemble observed elliptical galaxies and cosmological halos.

Abstract

The origin of equilibrium gravitational configurations is sought in terms of the stability of their trajectories, as described by the curvature of their Lagrangian configuration manifold. We focus on the case of spherical systems, which are integrable in the collisionless (mean field) limit despite the apparent persistence of local instability of trajectories even as $N \rightarrow \infty$. It is shown that when the singularity in the potential is removed, a null scalar curvature is associated with an effective, averaged, equation of state describing dynamically relaxed equilibria with marginally stable trajectories. The associated configurations are quite similar to those of observed elliptical galaxies and simulated cosmological halos. This is the case because a system starting far from equilibrium finally settles in a state which is integrable when unperturbed, but where it can most efficiently wash out perturbations. We explicitly test this interpretation by means of direct simulations.