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arXiv 1709.03604astro-ph.GA
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富气星系中的棒猝灭

Bar quenching in gas-rich galaxies

S. Khoperskov, M. Haywood, P. Di Matteo, M. D. Lehnert, F. Combes

摘要:

星系巡天研究表明,在大质量盘状星系中,恒星形成率的快速和持续下降,即“淬火”,通常与棒的存在有关。光学和近红外观测表明,近60%的盘星系都有棒斑,因此了解盘星系中棒斑与恒星形成的关系具有重要意义。最近的观测结果表明,银河系在大约9-10 Gyr前淬火,在运动学上热的,老的,金属贫乏的厚盘和运动学上冷的,年轻的,更富含金属的薄盘之间停止生长的过渡。尽管可能是巧合,但淬火事件也可能与酒吧的形成有关。为了定量研究富气星系中棒形成与恒星形成的关系,我们模拟了富气盘状孤立星系。我们的模拟包括处方恒星形成,恒星反馈,并为调节多相星际介质。我们发现恒星棒的作用有效地抑制了恒星的形成,在不到1 Gyr的时间内使恒星形成率降低了10倍。分析和自洽的星系模拟酒吧表明,恒星酒吧的行动增加了气体的随机运动的酒吧内的共同旋转半径。事实上,我们发现在酒吧形成阶段结束时的气体速度分散增加到20-35公里/秒。恒星形成效率迅速下降,在我们所有的模型中,酒吧熄灭了星系中的恒星形成。恒星形成效率是低得多的模拟酒吧相比,unbarred星系和更快的酒吧形成意味着更快的淬火。

英文摘要:

Galaxy surveys have suggested that rapid and sustained decrease in the star-formation rate, "quenching", in massive disk galaxies is frequently related to the presence of a bar. Optical and near-IR observations reveal that nearly 60% of disk galaxies in the local universe are barred, thus it is important to understand the relationship between bars and star formation in disk galaxies. Recent observational results imply that the Milky Way quenched about 9-10 Gyr ago, at the transition between the cessation of the growth of the kinematically hot, old, metal-poor thick disk and the kinematically colder, younger, and more metal-rich thin disk. Although perhaps coincidental, the quenching episode could also be related to the formation of the bar. To explore the relation between bar formation and star formation in gas rich galaxies quantitatively, we simulated gas-rich disk isolated galaxies. Our simulations include prescriptions for star formation, stellar feedback, and for regulating the multi-phase interstellar medium. We find that the action of stellar bar efficiently quenches star formation, reducing the star-formation rate by a factor of 10 in less than 1 Gyr. Analytical and self-consistent galaxy simulations with bars suggest that the action of the stellar bar increases the gas random motions within the co-rotation radius of the bar. Indeed, we detect an increase in the gas velocity dispersion up to 20-35 km/s at the end of the bar formation phase. The star-formation efficiency decreases rapidly, and in all of our models, the bar quenches the star formation in the galaxy. The star-formation efficiency is much lower in simulated barred compared to unbarred galaxies and more rapid bar formation implies more rapid quenching.

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