Inertial waves near corotation in three-dimensional hydrodynamical discs |
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| Authors: | Henrik N Latter Steven A Balbus |
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| Institution: | Laboratoire de Radioastronomie, École Normale Supérieure, 24 rue Lhomond, Paris 75005, France |
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| Abstract: | This paper concerns the interaction between non-axisymmetric inertial waves and their corotation resonances in a hydrodynamical disc. Inertial waves are of interest because they can localize in resonant cavities circumscribed by Lindblad radii and, as a consequence, can exhibit discrete oscillation frequencies that may be observed. It is often hypothesized that these trapped eigenmodes are affiliated with the poorly understood quasi-periodic oscillation phenomenon. We demonstrate that a large class of non-axisymmetric three-dimensional (3D) inertial waves cannot manifest as trapped normal modes. This class includes any inertial wave whose resonant cavity contains a corotation singularity. Instead, these 'singular' modes constitute a continuous spectrum and, as an ensemble, are convected with the flow, giving rise to shearing waves. Finally, we present a simple demonstration of how the corotation singularity stabilizes 3D perturbations in a slender torus. |
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| Keywords: | accretion accretion discs hydrodynamics instabilities waves |
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