Using Commensurabilities and Orbit Structure to Understand Barred Galaxy Evolution. (arXiv:1902.05081v1 [astro-ph.GA])

Using Commensurabilities and Orbit Structure to Understand Barred Galaxy Evolution. (arXiv:1902.05081v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Petersen_M/0/1/0/all/0/1">Michael S. Petersen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Weinberg_M/0/1/0/all/0/1">Martin D. Weinberg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Katz_N/0/1/0/all/0/1">Neal Katz</a>

We interpret simulations of secularly-evolving disc galaxies through orbit
morphology. Using a new geometric algorithm that rapidly isolates commensurate
(resonant) orbits, we identify phase-space regions occupied by different
orbital families. Compared to spectral methods, the geometric algorithm can
identify resonant orbits within a few dynamical periods, crucial for
understanding an evolving galaxy model. The flexible methodology accepts
arbitrary potentials, enabling detailed descriptions of the orbital structure.
We apply the machinery to four different potential models, including two barred
models, fully characterizing the orbital membership. We identify key
differences in orbital structures, including orbit families whose presence can
be used as an indicator of the bar evolutionary state and the shape of the dark
matter halo. We use the characterization of orbits to investigate the
shortcomings of analytic and self-consistent studies, comparing our findings to
the evolutionary epochs in self-consistent barred galaxy simulations. We
present a new observational metric that uses spatial and kinematic information
from integral field spectrometers that may reveal signatures of
commensurabilities and allow for a differentiation between halo models.

We interpret simulations of secularly-evolving disc galaxies through orbit
morphology. Using a new geometric algorithm that rapidly isolates commensurate
(resonant) orbits, we identify phase-space regions occupied by different
orbital families. Compared to spectral methods, the geometric algorithm can
identify resonant orbits within a few dynamical periods, crucial for
understanding an evolving galaxy model. The flexible methodology accepts
arbitrary potentials, enabling detailed descriptions of the orbital structure.
We apply the machinery to four different potential models, including two barred
models, fully characterizing the orbital membership. We identify key
differences in orbital structures, including orbit families whose presence can
be used as an indicator of the bar evolutionary state and the shape of the dark
matter halo. We use the characterization of orbits to investigate the
shortcomings of analytic and self-consistent studies, comparing our findings to
the evolutionary epochs in self-consistent barred galaxy simulations. We
present a new observational metric that uses spatial and kinematic information
from integral field spectrometers that may reveal signatures of
commensurabilities and allow for a differentiation between halo models.

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