Stellar dynamics in the outer galactic disk under the influence of a central bar [Elektronische Ressource] / presented by Gerhard Mühlbauer

Dissertationsubmitted to theCombined Faculties for the Natural Sciences and for Mathematicsof the Ruperto-Carola University of Heidelberg, Germanyfor the degree ofDoctor of Natural Sciencespresented byDiplom-Physicist Gerhard Muhlbauer¨born in Furth im WaldOral examination: 29th October 2003Stellar Dynamics in the Outer Galactic Diskunder the Influence of a Central BarReferees: Prof. Dr. Hans-Walter RixProf. Dr. Roland WielenAbstractIn this work, we investigate the possible influence of a central bar in a disk galaxy on the velocitydistribution in the outer stellar disk, which is thought to arise mostly via resonant phenomena. Forthis, we numerically integrate orbits of a large number of sample points in a 2D model potentialconsisting of a rotating bar component in an axisymmetric background. Central to our analysis is theconstruction of the first and second moments of the velocity distribution in their spatial variability.From these, other important quantities like Oort constants, dispersion axis ratio and vertex deviationcan be deduced. For the latter, we predict non-vanishing values for a large number of kinematicalconfigurations. Regarding the axis ratio, we are able to obtain values smaller than , in agreementwith observations in the solar neighbourhood which are hitherto unexplained by theory.