Volume 588, April 2016
|Number of page(s)||14|
|Section||Galactic structure, stellar clusters and populations|
|Published online||22 March 2016|
Warp evidence in precessing galactic bar models
1 IEEC-UPC i Dept. de Matemàtiques, Universitat Politècnica de Catalunya, Diagonal 647 (ETSEIB), 08028 Barcelona, Spain
e-mail: email@example.com; firstname.lastname@example.org
2 Dept. d’Astronomia i Meteorologia, Institut de Ciències del Cosmos, Universitat de Barcelona, IEEC, Martí i Franquès 1, 08028 Barcelona, Spain
3 GTM – Grup de recerca en Tecnologies Mèdia, La Salle, Universitat Ramon Llull, Quatre Camins 2, 08022 Barcelona, Spain
Received: 3 September 2015
Accepted: 15 January 2016
Most galaxies have a warped shape when they are seen edge-on. The reason for this curious form is not completely known so far, so in this work we apply dynamical system tools to contribute to its explanation. Starting from a simple, but realistic model formed by a bar and a disc, we study the effect of a small misalignment between the angular momentum of the system and its angular velocity. To this end, a precession model was developed and considered, assuming that the bar behaves like a rigid body. After checking that the periodic orbits inside the bar continue to be the skeleton of the inner system even after inflicting a precession to the potential, we computed the invariant manifolds of the unstable periodic orbits departing from the equilibrium points at the ends of the bar to find evidence of their warped shapes. As is well known, the invariant manifolds associated with these periodic orbits drive the arms and rings of barred galaxies and constitute the skeleton of these building blocks. Looking at them from a side-on viewpoint, we find that these manifolds present warped shapes like those recognised in observations. Lastly, test particle simulations have been performed to determine how the stars are affected by the applied precession, this way confirming the theoretical results.
Key words: galaxies: kinematics and dynamics / galaxies: structure / galaxies: spiral
© ESO, 2016
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