Description
Despite being well studied in N-body simulations, many challenges remain for understanding the role of chaos in the orbital evolution of isolated disc galaxies. Common methods used to identify chaos in simulations (e.g., surface of section, frequency drift, Lyapunov exponents) require long-duration sampling (on the order of a Hubble time) and/or static potentials. This poses a challenge in addressing the importance of chaos in galaxy evolution, as galaxies inherently have evolving, dynamic potentials (e.g., rotating and slowing bars). Furthermore, it is unclear whether and under what circumstances orbits have transient episodes of chaos or remain chaotic after passing through overlapping resonant regions. Expanding our toolbox in this regime will allow significant progress when addressing questions of galaxy evolution, such as how and in what cases the formation of a boxy-peanut-X (BPX) bulge feature depends on resonant sweeping or the firehose instability. We have developed PECCARY (Permutation Entropy and statistiCal Complexity Analysis for astRophYsics), a novel method for identifying chaotic, regular, and stochastic behavior in timeseries on dynamical timescales in time-dependent potentials. In this talk, I will discuss how combining PECCARY with basis function expansions (BFEs) of galaxy potentials can be used to probe the correlation between changes in the underlying potential, resonant passages, and episodes of chaos in stellar orbits. The synergy between PECCARY and BFEs represents a powerful new approach for better understanding the role of chaos in galaxy evolution.
