arXiv2023
In this paper, we consider vacuum asymptotically anti-de Sitter spacetimes $( \mathscr{M}, g )$ with conformal boundary $( \mathscr{I}, \mathfrak{g} )$. We establish a correspondence, near $\mathscr{I}$, between such spacetimes and their conformal boundary data on $\mathscr{I}$. More specifically, given a domain $\mathscr{D} \subset \mathscr{I}$, we prove that the coefficients $\mathfrak{g}^{(0)} = \mathfrak{g}$ and $\mathfrak{g}^{(n)}$ (the undetermined term or stress energy tensor) in a Fefferman-Graham expansion of the metric $g$ from the boundary uniquely determine $g$ near $\mathscr{D}$, provided $\mathscr{D}$ satisfies a generalised null convexity condition (GNCC). The GNCC is a conformally invariant criterion on $\mathscr{D}$, first identified by Chatzikaleas and the second author, that ensures a foliation of pseudoconvex hypersurfaces in $\mathscr{M}$ near $\mathscr{D}$, and with the pseudoconvexity degenerating in the limit at $\mathscr{D}$. As a corollary of this result, we deduce that conformal symmetries of $( \mathfrak{g}^{(0)}, \mathfrak{g}^{(n)} )$ on domains $\mathscr{D} \subset \mathscr{I}$ satisfying the GNCC extend to spacetimes symmetries near $\mathscr{D}$. The proof, which does not require any analyticity assumptions, relies on three key ingredients: (1) a calculus of vertical tensor-fields developed for this setting; (2) a novel system of transport and wave equations for differences of metric and curvature quantities; and (3) recently established Carleman estimates for tensorial wave equations near the conformal boundary.