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arXiv 1402.1499astro-ph.GAastro-ph.CO
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DiskMass调查。VIII。星盘稳定性与恒星形成的关系

The DiskMass Survey. VIII. On the Relationship Between Disk Stability and Star Formation

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

摘要:

利用积分场气体和恒星运动学数据研究了晚型星系盘的稳定性水平与恒星形成活动之间的关系。具体来说,我们比较了罗密欧和Wiegert(Q_RW)的两个组件(气体+恒星)的稳定性参数,纳入恒星运动学数据的第一次,和恒星形成率估计从21厘米连续辐射。我们确定的稳定性水平,每个磁盘的概率使用贝叶斯分析我们的数据和一个简单的动力学模型。我们的方法采用了恒星速度椭球(SVE)的形状,并产生强大的SVE测量超过90%的样本。对该子样本进行平均,我们发现SVE的σ_z/σ_R = 0.51^{+0.36}_{-0.25}的三角形形状,并且在1.5圆盘尺度长度下,稳定性参数Q_RW = 2.0 +/-0.9。我们还发现,盘平均恒星形成率面密度(Sigma-dot_e,*)与盘平均气体和恒星质量面密度(Sigma_e,g和Sigma_e,*)相关,与QRW反相关。我们发现,Sigma-dot_e,* 和Q_RW之间的反相关可以使用经验标度关系来预测,使得这一结果与恒星形成星系的公认统计特性是一致的。有趣的是,Sigma-dot_e,* 与仅气体或仅恒星的Toomre参数不相关,这表明当与恒星形成活动相比时计算多组分稳定性参数的优点。最后,我们的结果与Ostriker等人的自我调节恒星形成模型一致,该模型预测了Sigma-dot_e,*/Sigma_e,g/sqrt(Sigma_e,*)。基于这一点和其他理论预期,我们讨论了磁盘稳定性水平和恒星形成率之间的物理联系,根据我们的经验结果的可能性。

英文摘要:

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 21cm 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 (Sigma-dot_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-dot_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-dot_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-dot_e,*/Sigma_e,g/sqrt(Sigma_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.

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