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Transient chaos and resonant phase mixing in violent relaxation

Henry E. Kandrup·Ileana M. Vass·Ioannis V. Sideris
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Abstract

This paper explores how orbits in a galactic potential can be impacted by large amplitude time-dependences of the form that one might associate with galaxy or halo formation or strong encounters between pairs of galaxies. A period of time-dependence with a strong, possibly damped, oscillatory component can give rise to large amounts of transient chaos, and it is argued that chaotic phase mixing associated with this transient chaos could play a major role in accounting for the speed and efficiency of violent relaxation. Analysis of simple toy models involving time-dependent perturbations of an integrable Plummer potential indicates that this chaos results from a broad, possibly generic, resonance between the frequencies of the orbits and harmonics thereof and the frequencies of the time-dependent perturbation. Numerical computations of orbits in potentials exhibiting damped oscillations suggest that, within a period of 10 dynamical times t_D or so, one could achieve simultaneously both `near-complete' chaotic phase mixing and a nearly time-independent, integrable end state.

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Henry E. Kandrup, Ileana M. Vass, Ioannis V. Sideris. 2003-01-29. Transient chaos and resonant phase mixing in violent relaxation. https://doi.org/10.1046/j.1365-8711.2003.06466.x

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