Sharp Strichartz estimates on non-trapping asymptotically conic manifolds
Andrew Hassell, Terence Tao, Jared Wunsch
TL;DR
The paper proves local-in-time Strichartz estimates for Schrödinger evolution on non-trapping asymptotically conic manifolds, extending Euclidean-like dispersion to non-Euclidean geometries. It develops a robust framework of local Schrödinger integral operators (LSIOs) and a scattering calculus, introducing the X-space with half-angular smoothing to manage angular derivatives without derivative loss. A parametrix construction based on cones and balls, together with a positive-commutator argument, yields local smoothing and dispersive bounds; the Christ-Kiselev lemma then delivers the full non-endpoint Strichartz range for q>2. The analysis handles short-range and long-range metrics, including a detailed treatment of the phase Φ, geodesic structure, and conormal function algebras, culminating in a compositional LSIO calculus and dispersive estimates that feed into the Strichartz bounds and applications to semilinear Schrödinger equations. The results connect with prior work on asymptotically Euclidean and flat geometries, and suggest pathways to endpoint results and global-in-time theory.
Abstract
We obtain the Strichartz inequalities $$ \| u \|_{L^q_t L^r_x([0,1] \times M)} \leq C \| u(0) \|_{L^2(M)}$$ for any smooth $n$-dimensional Riemannian manifold $M$ which is asymptotically conic at infinity (with either short-range or long-range metric perturbation) and non-trapping, where $u$ is a solution to the Schrödinger equation $iu_t + {1/2} Δ_M u = 0$, and $2 < q, r \leq \infty$ are admissible Strichartz exponents ($\frac{2}{q} + \frac{n}{r} = \frac{n}{2}$). This corresponds with the estimates available for Euclidean space (except for the endpoint $(q,r) = (2, \frac{2n}{n-2})$ when $n > 2$). These estimates imply existence theorems for semi-linear Schrödinger equations on $M$, by adapting arguments from Cazenave and Weissler \cite{cwI} and Kato \cite{kato}. This result improves on our previous result in \cite{HTW}, which was an $L^4_{t,x}$ Strichartz estimate in three dimensions. It is closely related to the results of Staffilani-Tataru, Burq, Tataru, and Robbiano-Zuily, who consider the case of asymptotically flat manifolds.
