Breaking the north-south symmetry: dyonic spinning black holes with synchronized gauged scalar hair

TL;DR

This paper constructs and analyzes new magnetically charged and dyonic Kerr-Newman black holes with scalar hair that breaks north-south symmetry, revealing unique observational features like skewed shadows and lensing.

Contribution

It introduces a family of asymmetric black holes with scalar hair induced by magnetic charge, extending the understanding of black hole solutions beyond symmetric configurations.

Findings

Existence of scalar clouds breaking north-south symmetry due to magnetic charge.

Construction of magnetically charged and dyonic black holes with scalar hair.

Imaging reveals skewed shadows and lensing effects distinct from symmetric black holes.

Abstract

We study stationary clouds of a gauged, complex scalar field on a magnetically (and possibly electrically as well) charged Kerr-Newman black hole (BH). The existence of a magnetic charge $Q_m$ promotes a north-south $\textit{asymmetry}$ of the scalar clouds. This breakdown of the clouds' $\mathbb{Z}_2$-symmetry carries through to the spacetime $\textit{geometry}$ for the non-linear continuation of the clouds: a family of magnetically charged (or dyonic) BHs with synchronized gauged scalar hair, which we construct. Their distinct phenomenology is illustrated by their imaging, exhibiting skewed shadows and lensing. Such hairy BHs could, in principle, result from the superradiant instability of magnetically charged Kerr-Newman BHs, unveiling a dynamical mechanism for creating north-south asymmetric BHs from standard $\mathbb{Z}_2$-symmetric electrovacuum BHs.