H. Balasin et H. Nachbagauer, THE ULTRARELATIVISTIC KERR GEOMETRY AND ITS ENERGY-MOMENTUM TENSOR, Classical and quantum gravity, 12(3), 1995, pp. 707-713
The ultrarelativistic limit of the Schwarzschild and Kerr geometries,
together with their respective energy-momentum tensors, is derived. Ou
r approach is based on tenser distributions making use of the underlyi
ng Kerr-Schild structure, which remains stable under the ultrarelativi
stic boost.