Volume growth and asymptotic cones of manifolds with nonnegative Ricci curvature
Zhu Ye
TL;DR
This work investigates how volume growth on open manifolds with nonnegative Ricci curvature controls the dimension of asymptotic cones. By introducing the conic-at-infinity condition and employing a slope-lemma analysis of $f(R)=\ln\text{vol}(B_{e^R}(p))$ together with renormalized limit measures, it proves that there exists an asymptotic cone with upper box dimension bounded by the infimum volume-growth order $\text{IV}(M)$; in particular, $\text{dim}_{H}(Y)\le \text{IV}(M)$. When $\text{IV}(M)<2$ and the asymptotic cone is 1-dimensional, the paper obtains 1-dimensional blow-down limits and derives corollaries for Sormani-type linear growth results, including finite generation of the fundamental group in certain settings. It also constructs an explicit example of an open $n$-manifold with $\text{sec}_M\ge 0$ where volume growth oscillates between order $1$ and $n$ (so $\text{IV}(M)=1$, $\text{SV}(M)=n$), and provides a new proof of Sormani's sublinear diameter growth theorem, highlighting the sharp interplay between volume decay, cone-dimension, and large-scale geometry.
Abstract
Let $M$ be an open (i.e. complete and noncompact) manifold with nonnegative Ricci curvature. In this paper, we study whether the volume growth order of $M$ is always greater than or equal to the dimension of some (or every) asymptotic cone of $M$. Our first main result asserts that, under the conic at infinity condition, if the infimum of the volume growth order of $M$ equals $k$, then there exists an asymptotic cone of $M$ whose upper box dimension is at most $k$. In particular, this yields a complete affirmative answer to our problem in the setting of nonnegative sectional curvature. In the subsequent part of the paper, we extend or partially extend Sormani's results concerning $M$ with linear volume growth to more relaxed volume growth conditions. Our approach also allows us to present a new proof of Sormani's sublinear diameter growth theorem for open manifolds with $\mathrm{Ric}\geq 0$ and linear volume growth. Finally, we construct an example of an open $n$-manifold $M$ with $\mathrm{sec}_M\geq0$ whose volume growth order oscillates between 1 and $n$.
