Dynamics of thick, open spirals in Perlas potentials. (arXiv:1812.04068v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Chaves_Velasquez_L/0/1/0/all/0/1">L. Chaves-Velasquez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Patsis_P/0/1/0/all/0/1">P. A. Patsis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Puerari_I/0/1/0/all/0/1">I. Puerari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moreno_E/0/1/0/all/0/1">E. Moreno</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pichardo_B/0/1/0/all/0/1">B. Pichardo</a>
The PERLAS potential has been successfully used in many studies related with
the dynamics of the spiral arms textit{on} the equatorial plane of normal
(non-barred) spiral galaxies. In the present work we extend these studies by
investigating the three-dimensional dynamics of the spiral arms in the same
type of potential. We consider a typical open, logarithmic, spiral pattern of
pitch angle 25$^{circ}$ and we examine the stellar orbits that can support it
as the ratio of the masses of the spiral over the disk component
($M_{s}/M_{d}$) varies. We indicate the families of `three-dimensional’
periodic orbits that act as the backbone of the spiral structure and we discuss
their stability in the models we present. We study further the quasi-periodic
and non-periodic orbits in general that follow spiral-supporting orbits as the
$M_{s}/M_{d}$ ratio increases. We find that a bisymmetric spiral with
25$^{circ}$ pitch angle is better supported by orbits in models with
$0.03lessapprox M_{s}/M_{d} lessapprox 0.07$. In these cases a strong spiral
pattern is supported between the radial 2:1 and 4:1 resonances, while local
enhancements of the imposed spirals are encountered in some models between 4:1
and corotation. A characteristic bar-like structure is observed in all models
at radii smaller than the radius of the 2:1 resonance.
The PERLAS potential has been successfully used in many studies related with
the dynamics of the spiral arms textit{on} the equatorial plane of normal
(non-barred) spiral galaxies. In the present work we extend these studies by
investigating the three-dimensional dynamics of the spiral arms in the same
type of potential. We consider a typical open, logarithmic, spiral pattern of
pitch angle 25$^{circ}$ and we examine the stellar orbits that can support it
as the ratio of the masses of the spiral over the disk component
($M_{s}/M_{d}$) varies. We indicate the families of `three-dimensional’
periodic orbits that act as the backbone of the spiral structure and we discuss
their stability in the models we present. We study further the quasi-periodic
and non-periodic orbits in general that follow spiral-supporting orbits as the
$M_{s}/M_{d}$ ratio increases. We find that a bisymmetric spiral with
25$^{circ}$ pitch angle is better supported by orbits in models with
$0.03lessapprox M_{s}/M_{d} lessapprox 0.07$. In these cases a strong spiral
pattern is supported between the radial 2:1 and 4:1 resonances, while local
enhancements of the imposed spirals are encountered in some models between 4:1
and corotation. A characteristic bar-like structure is observed in all models
at radii smaller than the radius of the 2:1 resonance.
http://arxiv.org/icons/sfx.gif
