Spectral Analysis of the Stochastic Orbits in Triaxial Stellar Systems with Figure Rotation : Astrophysics and Relativity

概要

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A semi-stochastic orbit does not hold any exact integrals besides the Hamiltonian, but is confined in a definite region in the phase space and thus it gives approximately stationary contribution to the density model of triaxial elliptical galaxies. On the other hand, a fully stochastic orbit shows a time variation of the shape, which leads the unstationary contribution to the density. Hence, before the construction of the density model, we have to classify the orbits into semi-stochastic and fully stochastic orbits in a galactic potential. In order to extract the characteristics of the semi-stochastic orbits, we define the peak indicator which allows us to identify the most prominent peak, and carry out a successive subtraction of the prominent peaks until the total power of the residual becomes 10 % of the original one. The frequencies of the prominent peaks are plotted in the spectral diagram, which helps us to understand the evolution of the stochasticity of orbits. Compared with other characteristics of orbits, our method of the spectral analysis can yield enough information about orbital stochasticity. Since this method requires much less calculative time than calculating Lyapunov exponents, it is suitable for classification of the orbits in constructing the galactic models.
理論物理学刊行会の論文
1993-04-25