Extend the Killing initial data characterization beyond analytic asymptotic data
Establish the converse Killing initial data theorem for smooth, non-analytic asymptotic data in higher dimensions: namely, prove that a conformal Killing vector field satisfying the Killing initial data equation extends uniquely to a bulk Killing vector for the associated positive-cosmological-constant vacuum spacetime.
References
The Theorem is expected to hold beyond the analytic class of data, although up to the author's knowledge, no formal proof has yet been established.
— Asymptotics of Killing horizons: A Characterization in de Sitter Spacetime
(2609.37427 - Peón-Nieto, 29 Sep 2026) in Remark immediately following Theorem KIDanal, Section 2.3 (Killing initial data)