The Spacelike-Characteristic Cauchy Problem of General Relativity in Low Regularity

Abstract

In this paper we study the spacelike-characteristic Cauchy problem for the Einstein vacuum equations. Given initial data on a maximal spacelike hypersurface $$\Sigma \simeq \overline{B_1} \subset {{\mathbb {R}}}^3$$ and the outgoing null hypersurface $${{\mathcal {H}}}$$ emanating from $${\partial }\Sigma $$ , we prove a priori estimates for the resulting future development in terms of low-regularity bounds on the initial data at the level of curvature in $$L^2$$ . The proof uses the bounded $$L^2$$ curvature theorem [22], the extension procedure for the constraint equations [12], Cheeger-Gromov theory in low regularity [13], the canonical foliation on null hypersurfaces in low regularity [15] and global elliptic estimates for spacelike maximal hypersurfaces.