General Boosted Black Holes: A First Approximation
Abstract
In this paper we obtain an approximate solution of Einstein field equations which describes a general boosted Kerr-Newman black hole relative to a Lorentz frame at future null infinity. The boosted black hole is obtained from a general twisting metric whose boost emerges from the BMS group. Employing a standard procedure we build the electromagnetic energy-momentum tensor with the Kerr boosted metric together with its timelike Killing vector as the electromagnetic potential. We demonstrate that our solution satisfies Einstein field equations up to a fourth-order expansion in , indicating that the spacetime closely resembles a Kerr-Newman black hole whose boost points in a arbitrary direction. Spacetime structures of the general black hole -- namely the event horizon and ergosphere -- are examined in Bondi-Sachs coordinates. For a proper timelike observer we show that the electric field generated by the boosted black hole exhibits a purely radial behavior, whereas the magnetic field develops a complex structure characterized by two pronounced lobes oriented opposite to the boost direction.
Cite
@article{arxiv.2508.09988,
title = {General Boosted Black Holes: A First Approximation},
author = {Rodrigo Maier},
journal= {arXiv preprint arXiv:2508.09988},
year = {2026}
}