GMC Collisions as Triggers of Star Formation. III. Density and Magnetically Regulated Star Formation
GMC Collisions as Triggers of Star Formation. III. Density and Magnetically Regulated Star Formation
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DOI：
10.3847/1538-4357/aa6ffa
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发表时间：
2017-02
期刊：
影响因子：
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通讯作者：
Benjamin Wu;J. Tan;D. Christie;F. Nakamura;S. Loo;D. Collins
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作者：
Benjamin Wu;J. Tan;D. Christie;F. Nakamura;S. Loo;D. Collins
我们研究巨分子云（GMC）碰撞及其触发星团形成的能力。通过实现恒星形成子网格模型，我们进一步发展了三维磁化、湍流、碰撞GMC模拟。研究了两种这样的模型：(1)“密度调节”，即在设定密度阈值之上的每次自由落体时间的固定效率；(2)“磁调节”，即在磁性超临界区域的每次自由落体时间的固定效率。还探讨了与这些模型相关的参数的变化。在非碰撞模拟中，恒星形成的总体水平对与有效密度阈值相关的模型参数选择很敏感。在GMC碰撞模拟中，最终的恒星形成速率和效率相对独立于这些参数。在非碰撞和碰撞情况下，我们比较了产生的星团的形态，恒星形成气体的性质，恒星形成速率（SFR）的时间演变，恒星的空间聚集，以及与出生气体相比产生的恒星运动学。我们发现，典型的碰撞，通过产生更大量的致密气体，触发更早和增强的恒星形成，导致10倍高的SFRs和效率。由GMC碰撞形成的星团表现出更大的空间亚结构和更大的运动扰动。
We study giant molecular cloud (GMC) collisions and their ability to trigger star cluster formation. We further develop our three-dimensional magnetized, turbulent, colliding GMC simulations by implementing star formation subgrid models. Two such models are explored: (1) “Density-Regulated,” i.e., fixed efficiency per free-fall time above a set density threshold and (2) “Magnetically Regulated,” i.e., fixed efficiency per free-fall time in regions that are magnetically supercritical. Variations of parameters associated with these models are also explored. In the non-colliding simulations, the overall level of star formation is sensitive to model parameter choices that relate to effective density thresholds. In the GMC collision simulations, the final star formation rates and efficiencies are relatively independent of these parameters. Between the non-colliding and colliding cases, we compare the morphologies of the resulting star clusters, properties of star-forming gas, time evolution of the star formation rate (SFR), spatial clustering of the stars, and resulting kinematics of the stars in comparison to the natal gas. We find that typical collisions, by creating larger amounts of dense gas, trigger earlier and enhanced star formation, resulting in 10 times higher SFRs and efficiencies. The star clusters formed from GMC collisions show greater spatial substructure and more disturbed kinematics.