Memory effect from the scattering of Taub-NUT black holes

Abstract: Taub-NUT black holes are somewhat exotic solutions to the vacuum Einstein equations, which have received limited attention in gravitational phenomenology. We use the soft behaviour of scattering amplitudes to compute the memory effect of the waveform resulting from the scattering of Kerr-Taub-NUT black holes. Due to the non-linear nature of gravity, NUT charges introduce intriguing features in the soft dynamics, which have no counterpart in the closely related setting of monopole charges in electromagnetism. In addition to this potentially realistic problem, we also comment on the purely academic problem in complexified gravity of the scattering of self-dual Taub-NUT black holes, which have been discussed recently in the context of celestial holography.