Stationary double black hole without naked ring singularity

TL;DR

This paper introduces a new exact solution describing two co-rotating black holes with specific electromagnetic properties, which is free of ring singularities and asymptotically Kerr, advancing the understanding of ultra-compact objects beyond the Kerr paradigm.

Contribution

It presents a novel, simple double black hole solution with no ring singularities, featuring specific electromagnetic moments and a mild string-like singularity, expanding the class of physically realistic black hole models.

Findings

Solution is asymptotically Kerr with zero net charge.

Contains two co-rotating black holes with opposite magnetic and NUT charges.

Free of ring curvature singularities, only mild string-like singularity on the axis.

Abstract

Recently double black hole vacuum and electrovacuum metrics attracted attention as exact solutions suitable for visualization of ultra-compact objects beyond the Kerr paradigm. However, many of the proposed systems are plagued with ring curvature singularities. Here we present a new simple solution of this type which is asymptotically Kerr, has zero electric and magnetic charges, but is endowed with magnetic dipole moment and electric quadrupole moment. It is manifestly free of ring singularities, and contains only a mild string-like singularity on the axis corresponding to a distributional energy-momentum tensor.Its main constituents are two extreme co-rotating black holes carrying equal electric andopposite magnetic and NUT charges.