How Accurately Can the Inclination Angle, Position Angle, and Location of the Dynamic Center be Measured from the Neutral Hydrogen Disk in the Central Regions of Dwarf Galaxies?
Abstract
Rotation curves measured using Hi emission are a powerful tool for probing the mass distribution of galaxies. We investigate the accuracy with which rotation curves can be determined using the tilted-ring model. We have examined the effect of varying the dynamic center on measured rotation velocities within the inner regions of galaxies where the disagreement between theory and observation is the greatest. We examine a sample of dwarf galaxies (and one spiral galaxy) from the THINGS high-resolution survey (Walter et al. 2008). We find that the measured rotation curve is quite sensitive to the location of the dynamic center. This center is difficult to determine for dwarf galaxies. We also find that errors in rotation velocities determined with the tilted-ring method have been underestimated in previous studies.