@article{Huber,
  author    = {Huber, Albert},
  title     = {The gravitational field of a massless particle on the horizon of a stationary black hole},
  series = {Classical and Quantum Gravity},
  journal   = {Classical and Quantum Gravity},
  abstract  = {In this work, the field of a gravitational shockwave generated by a massless point-like particle is calculated at the event horizon of a stationary Kerr-Newman black hole. Using the geometric framework of generalized Kerr-Schild deformations in combination with the spin-coefficient formalism of Newman and Penrose, it is shown that the field equations of the theory, at the event horizon of the black hole, can be reduced to a single linear ordinary differential equation for the so-called profile function of the geometry. This differential relation is solved exactly. Based on the results obtained, a physical interpretation is given for the found shockwave spacetime, and it is clarified how these results lead back to those of previous works on the subject, which deal with the much simpler cases of gravitational shockwaves in static black hole backgrounds.},
  subject      = {Gravitation},
  language  = {en}
}
@article{Huber,
  author    = {Huber, Albert},
  title     = {Hidden Killing fields, geometric symmetries and black hole mergers},
  series = {Annals of Physics},
  volume    = {434},
  journal   = {Annals of Physics},
  pages     = {17},
  abstract  = {In the present work, using the recently introduced framework of local geometric deformations, special types of vector fields - so-called hidden Killing vector fields - are constructed, which solve the Killing equation not globally, but only locally, i.e. in local subregions of spacetime. Taking advantage of the fact that the vector fields coincide locally with Killing fields and therefore allow the consideration of integral laws that convert into exact physical conservation laws on local scales, balance laws in dynamical systems without global Killing symmetries are derived that mimic as closely as possible the conservation laws for energy and angular momentum of highly symmetric models. The utility of said balance laws is demonstrated by a concrete geometric example, namely a toy model for the binary merger of two extremal Reissner-Nordstr{\"o}m black holes.},
  subject      = {Hidden Killing},
  language  = {en}
}