paper

Applying the Tremaine-Weinberg Method to Nearby Galaxies: Stellar Mass-Based Pattern Speeds, and Comparisons with ISM Kinematics

arXiv:2102.01091 · doi:10.3847/1538-3881/abe243

Abstract

We apply the Tremaine-Weinberg method to 19 nearby galaxies using stellar mass surface densities and velocities derived from the PHANGS-MUSE survey, to calculate (primarily bar) pattern speeds (). After quality checks, we find that around half (10) of these stellar mass-based measurements are reliable. For those galaxies, we find good agreement between our results and previously published pattern speeds, and use rotation curves to calculate major resonance locations (co-rotation radii and Lindblad resonances). We also compare these stellar-mass derived pattern speeds with H (from MUSE) and CO() emission from the PHANGS-ALMA survey. We find that in the case of these clumpy ISM tracers, this method erroneously gives a signal that is simply the angular frequency at a representative radius set by the distribution of these clumps (), and that this is significantly different to (20% in the case of H, and 50% in the case of CO). Thus, we conclude that it is inadvisable to use "pattern speeds" derived from ISM kinematics. Finally, we compare our derived pattern speeds and co-rotation radii, along with bar properties, to the global parameters of these galaxies. Consistent with previous studies, we find that galaxies with a later Hubble type have a larger ratio of co-rotation radius to bar length, more molecular-gas rich galaxies have higher , and more bulge-dominated galaxies have lower . Unlike earlier works, however, there are no clear trends between the bar strength and , nor between the total stellar mass surface density and the pattern speed.

arXiv comment22 pages, 13 figures, plus an additional 24 pages and 19 figures in appendices. Accepted for publication in AJ. Include DOI, as well as link to GitHub page containing .fits machine-readable version of Table 2

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