Foliation of null cones by surfaces of constant spacetime mean curvature near MOTS

Marginally outer trapped surfaces (MOTS) in spacetimes are well‐known to indicate the existence of black holes. Using flow techniques, we prove that a neighbourhood of a stable MOTS in a null cone may be foliated by hypersurfaces of constant spacetime mean curvature. We also provide methods to construct prescribed spacetime mean curvature surfaces within null cones.