$\Lambda$ effect in the cosmological expansion of voids

TL;DR

This paper investigates how the cosmological constant $\Lambda$ influences the expansion dynamics of spherical voids in the universe, revealing significant effects on void growth and velocity flow, with implications for cosmic stability.

Contribution

It introduces a nonlinear perturbation model to analyze $\Lambda$'s impact on void evolution, highlighting the role of $\Lambda$ in void expansion and stability criteria.

Findings

$\Lambda$ amplifies void expansion rate at $z\,\sim 1.7$

Void velocity within depends solely on $\\Lambda$, as $\\vec{v}=\sqrt{\Lambda/3}\\vec{r}$

Spatially closed models lead to void sweeping out, indicating stability conditions.

Abstract

The dynamical effect of the cosmological constant $\Lambda$ on a single spherical void evolving in a the universe is investigated within a non linear perturbation of Newton-Friedmann models. The void expands with a huge initial burst which freezes asymptotically with time up to matching Hubble flow. For $\Omega_{\circ}\sim 0.3$, $\Lambda$-effect on the kinematics intervenes significantly by amplifying the expansion rate at redshift $z\sim 1.7$. As a result, the size increases with the background density and with $\Lambda$, what interprets by the gravitational attraction of borders from outside regions and the gravitational repulsion of borders. The velocity flow within the void region depends solely on $\Lambda$, it reads $\vec{v}=\sqrt{\Lambda/3}\vec{r}$. Hence, the empty regions are swept out for spatially closed Friedmann models what provides us with a stability criterion.