Gravitational Memory from AdS States in the Flat-Space Limit

Abstract

We study linearized gravitational reconstruction in global AdS$_4$ with dynamical scalar matter, building on vacuum Einstein perturbations with fixed boundary metric and nontrivial normalizable data. External scalar sources prepare an excited state and modify the holographic Ward identities, while subsequent evolution can proceed without boundary driving. Separating the bulk matter-sourced response from vacuum perturbations, we derive an electric quadrupole master equation with the matter-dependent corrections required by the Einstein constraints. We also verify that a cylindrical boundary integral reproduces the Regge--Wheeler master field mode by mode, without identifying it with the full global Fefferman--Graham reconstruction. For weakly interacting scalars that become massless in the flat-space limit, we extract the Bondi shear and news from retarded gravitational evolution. The resulting supertranslation memory agrees numerically with the outgoing energy redistribution and the quadrupole moment of the boundary work. In the ordered flat-space limit, later boundary controls leave the first event's waveform unchanged, despite cancelling residual gravitational modes at finite AdS radius.