Black holes in Sol minore

TL;DR

This paper explores five-dimensional gauged supergravity black holes with Sol and nil geometry horizons, analyzing their equations of motion, thermodynamics, nonexistence of certain solutions, and the attractor mechanism for extremal cases.

Contribution

It provides explicit solutions for Sol horizon black holes, proves a no-go theorem for supersymmetric solutions, and studies the attractor mechanism in non-BPS extremal black holes with anisotropic horizons.

Findings

Explicit Sol horizon black hole solutions derived.

No supersymmetric solutions with Sol-invariant horizons exist.

Attractor geometries exist for magnetic but not electric extremal black holes.

Abstract

We consider black holes in five-dimensional $N=2$ $\text{U}(1)$-gauged supergravity coupled to vector multiplets, with horizons that are homogeneous but not isotropic. We write down the equations of motion for electric and magnetic ans\"atze, and solve them explicitely for the case of pure gauged supergravity with magnetic $\text{U}(1)$ field strength and Sol horizon. The thermodynamics of the resulting solution, which exhibits anisotropic scaling, is discussed. If the horizon is compactified, the geometry approaches asymptotically a torus bundle over AdS$_3$. Furthermore, we prove a no-go theorem that states the nonexistence of supersymmetric, static, Sol-invariant, electrically or magnetically charged solutions with spatial cross-sections modelled on solve\-geometry. Finally, we study the attractor mechanism for extremal static non-BPS black holes with nil- or solvegeometry horizons. It turns out that there are no such attractors for purely electric field strengths, while in the magnetic case there are attractor geometries, where the values of the scalar fields on the horizon are computed by extremization of an effective potential $V_{\text{eff}}$, which contains the charges as well as the scalar potential of the gauged supergravity theory. The entropy density of the extremal black hole is then given by the value of $V_{\text{eff}}$ in the extremum.