On the vacuum Einstein equations along curves with a discrete local rotational and reflection symmetry

TL;DR

This paper investigates the limitations of symmetry-based dimensional reduction in S3 black-hole lattices, revealing a tensorial term that prevents simplified evolution equations and necessitates full 3+1 Einstein equation integration.

Contribution

It analytically identifies and numerically verifies a tensorial term that invalidates previous symmetry-based reduction methods in black-hole lattice evolutions.

Findings

The tensorial term causes deviations from simplified models.

Numerical verification confirms the term's significance in an 8-black-hole lattice.

Symmetry-based reductions are insufficient without accounting for this tensorial contribution.

Abstract

We discuss the possibility of a dimensional reduction of the Einstein equations in S3 black-hole lattices. It was reported in previous literature that the evolution of spaces containing curves of local, discrete rotational and reflection Symmetry (LDRRS) can be carried out via a system of ODEs along these curves. However, 3+1 Numerical Relativity computations demonstrate that this is not the case, and we show analytically that this is due to the presence of a tensorial quantity which is not suppressed by the symmetry. We calculate the term analytically, and verify numerically for an 8-black-hole lattice that it fully accounts for the anomalous results, and thus quantify its magnitude in this specific case. The presence of this term prevents the exact evolution of these spaces via previously-reported methods which do not involve a full 3+1 integration of Einstein's equation.