Simon Ross is a professor in the department of mathematical sciences at Durham University, and a member of the university’s Centre for Particle Theory.

Relating different charge densities gives black rings with non-trivial profiles with smooth horizons.

There is a rich space of solutions in five-dimensional supergravity, including smooth horizonless supertube solutions and black ring solutions. Supertubes can have arbitrary profiles, and varying charge densities along the profile, but previously-known black ring solutions required a constant charge density along the ring to have a smooth horizon.

Recently, we discovered a new kind of supersymmetric horizonless object which generalizes the supertube, which we dubbed the magnetube. They carry coordinated electric charge densities with respect to different Maxwell fields, organized in a way which allows them to preserve a magnetic-type supersymmetry. These are solutions in theories where five-dimensional supergravity is coupled to additional vector multiplets, which can be obtained by dimensional reduction from ten- or eleven-dimensional supergravity.

In our paper published in Classical and Quantum Gravity, we apply the same idea to black rings. We construct supersymmetric black ring solutions which carry varying electric charge densities with respect to several different Maxwell fields. These charge densities are functions of the coordinate along the ring, but they are coordinated so that some metric components remain independent of this coordinate. We show that this allows us to construct solutions involving varying charge densities where the horizon is nonetheless regular. This provides a new type of hair on black rings, which provides the largest known violation of black hole uniqueness.

Read the full article in Classical and Quantum Gravity:
Coiffured black rings
Iosif Bena, Simon F Ross and Nicholas P Warner
2014 Class. Quantum Grav. 31 165015

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