The Pattern Speeds of 38 Barred Galaxies

Abstract

We estimate the pattern speeds of 38 barred galaxies by simulation modeling. We construct the gravitational potentials of the galaxies from near-IR photometry by assuming that the mass-to-light ratio (M/L) is constant in the H band and a single pattern speed dominates in the stellar disk. We use the response of gaseous and stellar particle disks to a rigidly rotating potential to determine the pattern speed. If our assumptions are correct, then the pattern speed depends on the morphological type: the average value of the ratio of the corotation resonance radius to the bar radius, R, increases from about 1.1 in type SB0/a to 1.4 in SBb and 1.7 in SBc. Within the error estimates, all the bars in galaxies of type SBab or earlier are fast rotators, having R ≤ 1.4, whereas late-type galaxies include both fast and slow rotators. © 2005. The American Astronomical Society. All rights reserved.