THE DISKMASS SURVEY. VIII. ON THE RELATIONSHIP BETWEEN DISK STABILITY AND STAR FORMATION

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(-0.25)(+0.36) for the SVE and, at 1.5 diskscale lengths, a stability parameter of QRW = 2.0 +/- 0.9. We also find that the disk-averaged star-formation-rate surface density (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. 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,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. Sigma(e),*/Sigma(e),(g) alpha Sigma(1/2)(e,)(*.) e,*. 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.