Measuring mass: Non-circular motions of gas in disk galaxies and radial velocities of stars in a globular cluster

Abstract

OF THE DISSERTATION Measuring Mass: Non-circular Motions of Gas in Disk Galaxies and Radial Velocities of Stars in a Globular Cluster by Ricardo Zanmar Sanchez Dissertation Director: J.A. Sellwood This thesis is concerned with the motions of gas in disk galaxies and with the motions of stars in a globular cluster to learn about their mass content. First we study non-circular streaming motions of HI gas in five representative disk galaxies with a bisymmetric model. We show that this physically motivated method can represent a wide range of bar-like distortions and that its model parameters can be related to useful physical parameters of galaxies like the amplitude of the forced non-circular speed, the bar angle, and halo ellipticity. We also model the non-circular gas flow in the strongly barred galaxy NGC 1365. The gravitational potential is based on new observations that include photometric imaging, Fabry-Perot emission line imaging spectroscopy and a detailed re-analysis of archival HI data from the VLA. We use our 2-dimensional velocity map to constrain the strength and positions of the shocks in hydrodynamical simulations and find that better agreement is found with a massive, but not fully maximal disk (M/L ' 2.0 ± 1.0) and a fast bar (corotation at 1.2Rbar). The analysis was complicated by the discovery of an asymmetric distribution of dust and kinematics in the bar region despite the remarkably bisymmetric