Inverse problems for heat equation and space-time fractional diffusion equation with one measurement

Abstract: Given a connected compact Riemannian manifold $(M,g)$ without boundary, $\dim M\ge 2$, we consider a space--time fractional diffusion equation with an interior source that is supported on an open subset $V$ of the manifold. The time-fractional part of the equation is given by the Caputo derivative of order $\alpha\in(0,1]$, and the space fractional part by $(-\Delta_g)^\beta$, where $\beta\in(0,1]$ and $\Delta_g$ is the Laplace--Beltrami operator on the manifold. The case $\alpha=\beta=1$, which corresponds to the standard heat equation on the manifold, is an important special case. We construct a specific source such that measuring the evolution of the corresponding solution on $V$ determines the manifold up to a Riemannian isometry.