Inverse source problems for a multidimensional time-fractional wave equation with integral overdetermination conditions (2503.17404v1)

Abstract: In this paper, we consider two linear inverse problems for the time-fractional wave equation, assuming that its right-hand side takes the separable form $f(t)h(x)$, where $t \geq 0$ and $x \in \Omega \subset R^N $. The objective is to determine the unknown function $f(t)$ (Inverse Problem 1) and $h(x)$ (Inverse Problem 2), given that the other function is known. For Inverse Problem 1, we impose an overdetermination condition in the form of a spatial integral over the domain $\Omega $, involving the solution of the corresponding direct problem an initial-boundary value problem with standard Cauchy conditions and homogeneous Dirichlet boundary conditions. The integral is weighted by the known spatial factor h(x) from the right-hand side of the equation. This choice of an additional condition enables the explicit construction of a solution to the inverse problem and allows us to prove its unique solvability within the class of regular solutions. To study the direct problem, the regular solution approach is used. For Inverse Problem 2, we introduce a novel integral-type additional condition, referred to as the time-averaged velocity, incorporating an appropriate weight function. The time-dependent factor of the right-hand side of the equation serves as this weight function. Depending on its choice, the additional condition reduces to specifying either the final-time offset or the time-averaged offset. Under this formulation, we establish a new uniqueness result.