Speaker
Description
The morphology of a galactic bar is a feature of the particular resonant orbits of which it is comprised. We can constrain the properties of the bar by measuring the extent of these resonant orbits via frequency analysis. This involves computing the fundamental frequencies of orbits in rotating, N-body-derived potential models, classifying the stars as members of bar supporting orbits, and finding the extent of the apo-center distribution, which defines the dynamical length of the bar. Recent work has demonstrated that an updated classification criterion can be used to isolate the so-called "Warm" inner Lindblad resonance (ILR) orbits. These orbits have been shown to contain the looped x1 orbits, which dominate the "shoulder regions" of the bar and largely contribute to the radial extent. In this talk, I will demonstrate the need for this updated classification method for the frequency analysis technique and show that we are able to make more robust measurements of the dynamical length of a galactic bar. I will then discuss the results of applying our updated method to the Milky Way using 6D phase-space data from more than 240,000 stars. Our data set includes over 43,000 more stars than in previous work, with many reaching to the far side of the bar. From our modeling, we find that multiple dynamical lengths and pattern speeds are consistent with the data to within 5 percent.
