Asymptotic Expansion of the Gaussian Integral Operators on Riemannian submanifolds of ${\mathbb{R}}^n$

The Gaussian integral operator arises naturally as a local Euclidean approximation of the heat semigroup on a Riemannian manifold and plays a pivotal role in the analysis of graph Laplacians, particularly within the frameworks of manifold learning and spectral graph theory. In this paper, we study the asymptotic behavior of the Gaussian integral operator on a smooth Riemannian submanifold $M\subset {\mathbb{R}}^n$, focusing on its expansion as $\epsilon \to 0^{+}$. Under the assumption that the input function is real analytic near a fixed point $x\in M$, we derive a full asymptotic expansion of the operator and compute the first-order correction term explicitly in terms of the mean curvature vector and the scalar curvature of the submanifold. In particular, we apply our results to hypersurfaces in Euclidean space and investigate geometric conditions under which points exhibit \emph{equicurvature}.