Relativistic models of structure formation with stable end-state configuration

TL;DR

This paper develops an analytical relativistic model for stable astrophysical structures, using generalized LTB spacetime with tangential pressure, and demonstrates how these models evolve through collapse and oscillations.

Contribution

It extends the LTB model to include tangential pressure from angular momentum and provides a reconstruction method for stable structure formation.

Findings

Models exhibit dust-like behavior during collapse

Final states are static with oscillations around equilibrium

Approximate solutions simplify the reconstruction process

Abstract

The aim of this paper is to provide an analytical model for the formation of stable structures (cosmological or astrophysical), where stability is obtained through the tangential pressure countering the effect of gravity. We utilize the generalization of the Lemaitre-Tolman-Bondi (LTB) spacetime to matter with tangential pressure generated by the angular momentum of fluid particles. Extending the Krasi\'nski-Hellaby (KH) LTB reconstruction method, we show how set of three functions defined on two arbitrary hypersurfaces can fully determine the spacetime geometry. We further restrict our attention to the bounded case and develop the weak-field and the small-angular-momentum approximations. We show how these can be applied to the exact solution on the initial hypersurface, together with the oscillatory solution on the final hypersurface, to considerably simplify the reconstruction scheme. The so obtained models exhibit explicit dust-like behaviour in the early and middle stages of the collapse, and reach the final state as oscillations around the static solution.