Determination of Stable Branches of Relative Equilibria of the N-Vortex Problem on the Sphere

Abstract

We consider the N-vortex problem on the sphere assuming that all vorticities have equal strength. We investigate relative equilibria (RE) consisting of n latitudinal rings which are uniformly rotating about the vertical axis with angular velocity \(\omega \). Each such ring contains m vortices placed at the vertices of a concentric regular polygon and we allow the presence of additional vortices at the poles. We develop a framework to prove existence and orbital stability of branches of RE of this type parametrised by \(\omega \). Such framework is implemented to rigorously determine and prove stability of segments of branches using computer-assisted proofs. This approach circumvents the analytical complexities that arise when the number of rings \(n\ge 2\) and allows us to give several new rigorous results. We exemplify our method providing new contributions consisting of the determination of enclosures and proofs of stability of several equilibria and RE for \(5\le N\le 12\).