Coupled-Channel Spectral Theory for a Non-Separable Rotating Geometry: Normal Modes and Two-Boundary Response in the Rotating AdS-Teo Wormhole

Abstract

We investigate scalar perturbations of a rotating asymptotically anti-de Sitter (AdS)Teo traversable wormhole with a controlled nonseparable angular deformation. The geometry retains a regular wormhole throat and the required AdS asymptotics, while explicit quadrupolar deformation generates angular-channel coupling in the intermediate region. A sufficient condition is derived for an ergoregion free parameter regime in which the spectral analysis is performed. Projecting the geometry derived Klein Gordon equation onto spherical harmonics yields a matrix valued Sturm Liouville system and an associated quadratic operator pencil. Throat regularity together with normalizable AdS boundary conditions leads to a determinant quantization condition for the discrete normal mode spectrum. Two, four, and six channel calculations demonstrate systematic numerical convergence of the retained low lying normal mode frequencies under enlargement of the angular basis. The complete finite generalized eigenspectrum is also examined without imposing a near reality selection criterion, and no growing scalar mode is found within the ergoregion free parameter range and numerical resolutions studied. The six channel rotation continuation exhibits a finite interior level repulsion feature accompanied by collective redistribution of the multichannel eigenvectors. The same coupled spectral framework formally defines a matrix valued two boundary response whose poles are selected by the normal-mode matching condition, the response plots presented here illustrate this structure using the reduced two channel effective model rather than a numerical reconstruction of the full six channel response.