Abstract

Oscillations are invoked to explain a range of astrophysical phenomena and discs are no exception. High frequency Quasi-Periodic Oscillations (QPOs) around compact objects are often modelled as oscillations of thick tori. However, the non-linear regime which is most relevant to observations, is still not well understood. Tilting modes in such rings, which break the symmetry about the mid-plane, may also match onto and extend our understanding of warped discs in the limit of thin tori.

To this end I have developed a novel ‘ring model’ which acts as a framework to investigate both slender tori and extended warps. Through a combination of semi-analytical methods I will talk about the discovery of highly non-linear resonant solutions, which couple extreme breathing modes to the tilt. These represent precessing warped structures in the previously untreated inviscid, Keplerian regime.