Axion boson stars with wormhole topology

We investigate a novel gravitational configuration formed by a massless real phantom field and an axion scalar field, minimally coupled to gravity. This system describes an Ellis-type wormhole situated at the center of an axion star. By normalizing the mass of the axion field to unity, the physical properties of the model are determined by three independent parameters: the potential’s decay constant, the frequency of the axion field, and the wormhole’s throat parameter. We assess the traversability of this wormhole by examining the curvature scalars and energy conditions of the static solution. Our analysis of the wormhole’s embedding diagrams indicates that, although the wormhole typically exhibits a single-throat geometry, a double-throat configuration featuring an equatorial plane may arise under specific conditions. Finally, an analysis of the null-geodesics reveals the existence of at least one unstable light ring at the wormhole throat.

💡 Research Summary

The paper presents a novel gravitating configuration that combines a mass‑less real phantom scalar field with an axion‑like complex scalar field, both minimally coupled to Einstein gravity. The phantom field, characterized by a negative kinetic term, supplies the exotic matter required to sustain a traversable wormhole of the Ellis type, while the axion field—described by the QCD‑motivated potential V(ψ)=2μ²fₐ²