Black holes and naked singularities in the infinite momentum frame

The problem of the construction of shock waves by the method of boosting the metricsof black holes and bare singularities is considered. It is noted that when boosting, singularterms may arise that prevent the generation of shock waves, in particular, in the absenceof quasi-Cartesian coordinates. When boosting the Fisher metric of a black hole with ascalar charge and a singular horizon, it is found that the scalar field disappears as a resultof boosting, unlike the case of black holes with electric and magnetic charges. It is noted17 that boosted metrics are solutions of the linearized Einstein equations, while the originalmetrics are exact nonlinear solutions of these equations. When boosting, the event horizondisappears, so boosting of naked singularities leads to the same result as boosting blackholes. This is also confirmed by the example of gamma-metrics (Zipoy-Vourhees solution).Finally, it is shown that when a linearized metric is boosted with the Newman-Unti-Tamburino parameter (NUT) along the Misner string, a shock wave with a non-diagonalstructure of the gyraton is obtained.