The Stability of Galaxy Disks
Abstract
We calculate the stellar surface mass density (Sigma_*) and two-component (gas+stars) disk stability (Q_RW) for 25 late-type galaxies from the DiskMass Survey. These calculations are based on fits of a dynamical model to our ionized-gas and stellar kinematic data performed using a Markov Chain Monte Carlo sampling of the Bayesian posterior. Marginalizing over all galaxies, we find a median value of Q_RW=2.0+/-0.9 at 1.5 scale lengths. We also find that Q_RW is anti-correlated with the star-formation rate surface density (Sigma_SFR), which can be predicted using a closed set of empirical scaling relations. Finally, we find that the star-formation efficiency (Sigma_SFR/Sigma_g) is correlated with Sigma_* and weakly anti-correlated with Q_RW. The former is consistent with an equilibrium prediction of Sigma_SFR/Sigma_g propto Sigma_*^{1/2}. Despite its order-of-magnitude range, we find no correlation of Sigma_SFR/Sigma_g/Sigma_*^{1/2} with any other physical quantity derived by our study.
Keywords
Cite
@article{arxiv.1310.4980,
title = {The Stability of Galaxy Disks},
author = {Kyle B. Westfall and David R. Andersen and Matthew A. Bershady and Thomas P. K. Martinsson and Robert A. Swaters and Marc A. W. Verheijen},
journal= {arXiv preprint arXiv:1310.4980},
year = {2013}
}
Comments
4 pages, 2 figures; To appear in Structure and Dynamics of Disk Galaxies, eds. M. S. Seigar and P. Treuthardt