论文标题
小天狼星项目。 I.星形簇和星系形成的星星模拟的星形形成模型
SIRIUS project. I. Star formation models for star-by-star simulations of star clusters and galaxy formation
论文作者
论文摘要
大多数恒星在星系中形成为星形簇，然后分散到银河系中。即将到来的Exascale超级计算设施将通过解决单个恒星（星星模拟）来实现星系及其形成的模拟。这将大大提高我们对星系中星系，星团形成和星系组装历史的恒星形成的理解。在以前的星系模拟中，使用了简单的恒星种群近似。但是，通过这种近似值很难改善质量分辨率。因此，必须建立用于形成可以用于星系模拟的单个恒星的模型。在一系列Sirius（模拟单个恒星）项目的第一篇论文中，我们演示了一个随机恒星模拟的随机恒星形成模型。假定的恒星初始质量函数（IMF）随机分配给新形成的恒星。我们引入了最大的搜索半径，以组装周围气体颗粒的质量以形成星形颗粒。在这项研究中，我们对来自湍流分子云和超生物矮星系的恒星簇形成进行了一系列N体/平滑粒子流体动力学模拟，作为测试案例。如果采用大于从恒星形成的阈值估计的最大搜索半径大于估计的值，则可以正确采样IMF。在小云中，由于恒星数量少，大恒星的形成是高度随机的。我们确认恒星形成效率和阈值密度不会强烈影响结果。我们发现我们的模型可以自然地重现最大的恒星与恒星簇的总恒星质量之间的关系。在此，我们证明我们的模型可以应用于从星形簇到星系的模拟，以进行各种分辨率。
Most stars are formed as star clusters in galaxies, which then disperse into galactic disks. Upcoming exascale supercomputational facilities will enable performing simulations of galaxies and their formation by resolving individual stars (star-by-star simulations). This will substantially advance our understanding of star formation in galaxies, star cluster formation, and assembly histories of galaxies. In previous galaxy simulations, a simple stellar population approximation was used. It is, however, difficult to improve the mass resolution with this approximation. Therefore, a model for forming individual stars that can be used in simulations of galaxies must be established. In this first paper of a series of the SIRIUS (SImulations Resolving IndividUal Stars) project, we demonstrate a stochastic star formation model for star-by-star simulations. An assumed stellar initial mass function (IMF) is randomly assigned to newly formed stars. We introduce a maximum search radius to assemble the mass from surrounding gas particles to form star particles. In this study, we perform a series of N-body/smoothed particle hydrodynamics simulations of star cluster formations from turbulent molecular clouds and ultra-faint dwarf galaxies as test cases. The IMF can be correctly sampled if a maximum search radius that is larger than the value estimated from the threshold density for star formation is adopted. In small clouds, the formation of massive stars is highly stochastic because of the small number of stars. We confirm that the star formation efficiency and threshold density do not strongly affect the results. We find that our model can naturally reproduce the relationship between the most massive stars and the total stellar mass of star clusters. Herein, we demonstrate that our models can be applied to simulations varying from star clusters to galaxies for a wide range of resolutions.
