Are All Static Black Hole Solutions Spherically Symmetric?

TL;DR

This paper demonstrates that in certain theories with massive vector fields, static black hole solutions can lack spherical symmetry, challenging the common assumption that all such solutions are spherically symmetric.

Contribution

It provides explicit examples and general arguments showing static black holes can be non-spherically symmetric in theories with massive vector fields.

Findings

Counterexamples in electroweak theory show non-spherical static black holes.

Explicit solutions with no rotational symmetry are constructed.

Spherical symmetry is not a universal property of static black holes.

Abstract

The static black hole solutions to the Einstein-Maxwell equations are all spherically symmetric, as are many of the recently discovered black hole solutions in theories of gravity coupled to other forms of matter. However, counterexamples demonstrating that static black holes need not be spherically symmetric exist in theories, such as the standard electroweak model, with electrically charged massive vector fields. In such theories, a magnetically charged Reissner-Nordstrom solution with sufficiently small horizon radius is unstable against the development of a nonzero vector field outside the horizon. General arguments show that, for generic values of the magnetic charge, this field cannot be spherically symmetric. Explicit construction of the solution shows that it in fact has no rotational symmetry at all.