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Date and Time of the Query: 2019-08-22 T18:37:43 PDT
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For refcode 2014ApJ...785...43W:
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Copyright by American Astronomical Society. Reproduced by permission
2014ApJ...785...43W The DiskMass Survey. VIII. On the Relationship between Disk Stability and Star Formation Westfall, Kyle B.; Andersen, David R.; Bershady, Matthew A.; Martinsson, Thomas P. K.; Swaters, Robert A.; Verheijen, Marc A. W. Abstract. We study the relationship between the stability level of late-type galaxy disks and their star-formation activity using integral-field gaseous and stellar kinematic data. Specifically, we compare the two-component (gas+stars) stability parameter from Romeo & Wiegert (Q_RW_), incorporating stellar kinematic data for the first time, and the star-formation rate estimated from 21 cm continuum emission. We determine the stability level of each disk probabilistically using a Bayesian analysis of our data and a simple dynamical model. Our method incorporates the shape of the stellar velocity ellipsoid (SVE) and yields robust SVE measurements for over 90% of our sample. Averaging over this subsample, we find a meridional shape of {sigma}_z/{sigma}_R = 0.51^{+0.36}_{-0.25}_ for the SVE and, at 1.5 disk scale lengths, a stability parameter of Q_RW_ = 2.0 +/- 0.9. We also find that the disk-averaged star-formation-rate surface density (\dot{{SIGMA}}_{e,*}_) is correlated with the disk-averaged gas and stellar mass surface densities (Sigma_ e, g_ and Sigma_ e, *_) and anti-correlated with Q_RW_. We show that an anti-correlation between \dot{{SIGMA}}_{e,*}_ and Q_RW_ can be predicted using empirical scaling relations, such that this outcome is consistent with well-established statistical properties of star-forming galaxies. Interestingly, \dot{{SIGMA}}_{e,*}_ is not correlated with the gas-only or star-only Toomre parameters, demonstrating the merit of calculating a multi-component stability parameter when comparing to star-formation activity. Finally, our results are consistent with the Ostriker et al. model of self-regulated star-formation, which predicts \dot{{SIGMA}}_{e,*}_/{SIGMA}_{e,g}_ is proportional to {SIGMA}_{e,*}_^{1/2}. Based on this and other theoretical expectations, we discuss the possibility of a physical link between disk stability level and star-formation rate in light of our empirical results. Key words: galaxies: evolution, galaxies: kinematics and dynamics, galaxies: spiral, galaxies: star formation
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