2015MNRAS.452..747M -
Mon. Not. R. Astron. Soc., 452, 747-754 (2015/September-1)
The vertical effects of disc non-axisymmetries from perturbation theory: the case of the Galactic bar.
MONARI G., FAMAEY B. and SIEBERT A.
Abstract (from CDS):
Evidence for non-zero mean stellar velocities in the direction perpendicular to the Galactic plane has been accumulating from various recent large spectroscopic surveys. Previous analytical and numerical work has shown that a `breathing mode' of the Galactic disc, similar to what is observed in the solar vicinity, can be the natural consequence of a non-axisymmetric internal perturbation of the disc. Here we provide a general analytical framework, in the context of perturbation theory, allowing us to compute the vertical bulk motions generated by a single internal perturber (bar or spiral pattern). In the case of the Galactic bar, we show that these analytically predicted bulk motions are well in line with the outcome of a numerical simulation. The mean vertical motions induced by the Milky Way bar are small (mean velocity of less than 1 km/s) and cannot be responsible alone for the observed breathing mode, but they are existing. Our analytical treatment is valid close to the plane for all the non-axisymmetric perturbations of the disc that can be described by small-amplitude Fourier modes. Further work should study how the coupling of multiple internal perturbers and external perturbers is affecting the present analytical results.
Abstract Copyright:
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
Journal keyword(s):
Galaxy: evolution - Galaxy: kinematics and dynamics - solar neighbourhood - Galaxy: structure - galaxies: spiral
Simbad objects:
1
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