Analysis of harmonic functions under lower bounds of $N$-weighted Ricci curvature with $\varepsilon$-range

Abstract

The behavior of harmonic functions on Riemannian manifolds under lower bounds of the Ricci curvature has been studied from both analytic and geometric viewpoints. For example, some Liouville type theorems are obtained under lower bounds of the Ricci curvature. Recently, those results are generalized under lower bounds of the $N$-weighted Ricci curvature $\mbox{Ric}_\psi^N$ with $N \in [n,\infty]$. In this paper, we present a Liouville type theorem for harmonic functions of sublinear growth and a gradient estimate of harmonic functions on weighted Riemannian manifolds under weaker lower bounds of $\mbox{Ric}_\psi^N$ with $N < 0$. We also prove an $L^p$-Liouville theorem under lower bounds of $\mbox{Ric}_\psi^N$ with $N \in [n,\infty]$ in a way different from that of [Wu, 2014]. Our results are obtained as a consequence of an argument under lower bounds of $\mbox{Ric}_\psi^N$ with $\varepsilon$-range, which is a unification of constant and variable curvature bounds. Among various methods considered for the analysis of harmonic functions, this paper focuses on methods using the Moser's iteration procedure.