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Distribution functions for resonantly trapped orbits in our Galaxy

Published online by Cambridge University Press:  02 August 2018

G. Monari
Affiliation:
The Oskar Klein Centre for Cosmoparticle Physics, Dept. of Physics, Stockholm University AlbaNova, 10691 Stockholm, Sweden email: giacomo.monari@fysik.su.se
B. Famaey
Affiliation:
Université de Strasbourg, CNRS UMR 7550, Observatoire astronomique de Strasbourg 11 rue de l’Université, 67000 Strasbourg, France
J.-B. Fouvry
Affiliation:
Institute for Advanced Study Einstein Drive, Princeton, NJ 08540, USA
J. Binney
Affiliation:
Rudolf Peierls Centre for Theoretical Physics Keble Road, Oxford OX1 3NP, UK
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Abstract

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We show how to capture the behaviour of the phase-space distribution function (DF) of a Galactic disc stellar population at a resonance. This is done by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. We then assign to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits only depends on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of distribution functions in action space.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2018 

References

Binney, J. & Tremaine, S. 2008, Galactic Dynamics: Second Edition. Princeton University PressGoogle Scholar
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Monari, G., Famaey, B., Siebert, A., 2016, MNRAS, 457, 2569Google Scholar
Monari, G., Famaey, B., Fouvry, J.-B., & Binney, J. 2017, arXiv:1707.05306Google Scholar