Spectral Torical Band Inequalities and Generalizations of the Schoen-Yau Black Hole Existence Theorem

TL;DR

This paper extends scalar curvature inequalities to spectral bounds, providing new upper bounds for manifold widths and generalizing black hole existence theorems in higher dimensions using diverse mathematical techniques.

Contribution

It introduces spectral scalar curvature bounds into torical band inequalities, expanding classical results and applying multiple strategies across dimensions, including new rigidity statements.

Findings

Spectral bounds replace pointwise scalar curvature bounds.

Upper bounds for manifold widths are established using various methods.

Generalization of black hole existence theorems to higher dimensions.

Abstract

Generalized torical band inequalities give precise upper bounds for the width of compact manifolds with boundary in terms of positive pointwise lower bounds for scalar curvature, assuming certain topological conditions. We extend several incarnations of these results in which pointwise scalar curvature bounds are replaced with spectral scalar curvature bounds. More precisely, we prove upper bounds for the width in terms of the principal eigenvalue of the operator $-\Delta +cR$, where $R$ denotes scalar curvature and $c>0$ is a constant. Three separate strategies are employed to obtain distinct results holding in different dimensions and under varying hypotheses, namely we utilize spacetime harmonic functions, $\mu$-bubbles, and spinorial Callias operators. In dimension 3, where the strongest result is produced, we are also able to treat open and incomplete manifolds, and establish the appropriate rigidity statements. Additionally, a version of such spectral torus band inequalities is given where tori are replaced with cubes. Finally, as a corollary we generalize classical work of Schoen and Yau, on the existence of black holes due to concentration of matter, to higher dimensions and with alternate measurements of size.