A Quasigroup Approach for Conservation Laws in Asymptotically Flat Spacetimes

Abstract: In the framework of the quasigroup approach to conservation laws in general relativity, we show how the infinite-parametric Newman-Unti group of asymptotic symmetries can be reduced to the Poincare quasigroup. We compute Noether's charges associated with any element of the Poincare quasialgebra. The integral conserved quantities of energy momentum and angular momentum, being linear on generators of the Poincare quasigroup, are identically equal to zero in Minkowski spacetime. We present a definition of the angular momentum free of the supertranslation ambiguity. We provide an appropriate notion of intrinsic angular momentum and a description of the mass reference frame's center at future null infinity. Finally, in the center of mass reference frame, the momentum and angular momentum are defined by the Komar expression.