A note on Ricci flow from small curvature concentration and a Morrey-type condition

TL;DR

This paper extends previous Ricci flow results by replacing bounded curvature assumptions with a Morrey-type condition on the metric's gradient, allowing for unbounded curvature on non-compact manifolds.

Contribution

It generalizes existing Ricci flow existence results by using a Morrey-type condition instead of bounded curvature, enabling analysis of metrics with potentially unbounded curvature.

Findings

Long-time Ricci flow solutions exist under the new conditions.

Curvature decay estimates imply the manifold is diffeomorphic to al^n.

The approach accommodates metrics equivalent to bounded curvature metrics with unbounded curvature.

Abstract

In \cite{ChauMartens} the authors proved the long-time existence of Ricci flow starting from complete bounded curvature Riemannian manifolds with scale-invariant integral curvature bounded by a dimensional constant times the inverse of the Sobolev constant. We generalize this result by replacing the bounded curvature assumption with the assumption that $g$ is only equivalent to a complete bounded curvature metric $h$ while satisfying a Morrey-type condition on the gradient of $g$ relative to $h$: a local integral condition on the covariant derivative $\nabla_h g$. The Morrey-type condition was first considered in \cite{LeeLiu} in the context of Ricci flow on non-compact manifolds, and in particular allows the possibility for $g$ to have unbounded curvature on $M$. As in \cite{ChauMartens}, our long-time solution enjoys curvature decay estimates implying in particular that $M$ is diffeomorphic to $\mathbb{R}^n$.