A Ricci-type flow on globally null manifolds and its gradient estimates

Abstract

Locally, a screen integrable globally null manifold $M$ splits through a Riemannian leaf $M^{\prime }$ of its screen distribution and a null curve $\mathcal{C}$ tangent to its radical distribution. The leaf $M^{\prime }$ carries a lot of geometric information about $M$ and, in fact, forms a basis for the study of expanding and non-expanding horizons in black hole theory. In the present paper, we introduce a degenerate Ricci-type flow in $M^{\prime }$ via the intrinsic Ricci tensor of $M$. Several new gradient estimates regarding the flow are proved.

26 pages