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arXiv · 1310.4980

The Stability of Galaxy Disks

Kyle B. Westfall·David R. Andersen·Matthew A. Bershady·Thomas P. K. Martinsson·Robert A. Swaters·Marc A. W. Verheijen
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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.

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Kyle B. Westfall, David R. Andersen, Matthew A. Bershady, Thomas P. K. Martinsson, Robert A. Swaters, Marc A. W. Verheijen. 2013-10-18. The Stability of Galaxy Disks. https://arxiv.org/abs/1310.4980

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