The Inhomogeneous Wave Equation with $L^p$ Data

We prove existence and uniqueness of $L^2$ solutions to the inhomogeneous wave equation on ${\mathbb{R}}^{n-1}\times \mathbb{R}$ under the assumption that the inhomogeneous data lies in $L^p({\mathbb{R}}^n)$ for $p=2n\mathrm{/}(n+4)$. We also require the Fourier transform of the inhomogeneous data to vanish on an infinite cone where the solution could become singular. Subsequently, we show sharpness of the exponent $p$. This extends work of Michael Goldberg, in which similar Fourier-analytic techniques were used to study the inhomogeneous Helmholtz equation.