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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