http://arxiv.org/abs/1311.3450
Self-consistent N-body simulations are an efficient tool to study galactic dynamics. However, it can be challenging to use them for the detailed study of individual trajectories (or ensembles of trajectories). Such orbital studies are important to shed light on global phase space properties, which are the underlying cause of observed structures. The potentials needed to describe self-consistent models are in this case time-dependent. For this reason, we aim to investigate the different dynamical properties (such as regular and chaotic motion) of a non-autonomous galactic system, whose time-dependent potential adequately mimics certain realistic trends arising from N-body barred galaxy simulations. We construct a fully time-dependent analytical model, which manages to capture and reproduce several features of an N-body simulation. We model the gravitational potentials of three components (disc, bar and dark matter halo), whose time-dependent parameters are derived from an N-body simulation. We start by studying the dynamical stability of its reduced time-independent 2-degrees of freedom model by charting the different islands of stability associated with certain orbital morphologies and detecting the chaotic and regular regions. We then turn our interest to the full 3-degrees of freedom time-dependent case, where we show a few representative trajectories which experience different typical dynamical behaviours, i.e., an interplay between regular and chaotic motion for different epochs. Finally, we focus on the study of the underlying global dynamical transitions of the time-dependent system in terms of estimating the relative total fraction of (un)stable motion of an ensemble of initial conditions taken from the simulation and evolved with the time-dependent potential. We find that, for such an ensemble, the fraction of regular motion increases with time.
Fri, 15 Nov 13
15/56
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