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arXiv 1606.07091astro-ph.GA
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相互作用星系中星团的形成和演化

The formation and evolution of star clusters in interacting galaxies

Moupiya Maji, Qirong Zhu, Yuexing Li, Jane Charlton, Lars Hernquist, Alexander Knebe

摘要:

球状星团的观测表明,它们具有普遍的对数正态质量函数,其特征峰位于$\sim 2\times 10^{5}\, {\rm{M_{\odot}}}$,但这种峰值分布的起源存在很大争议。在这里,我们调查的形成和演化的星团在相互作用的星系使用高分辨率的流体动力学模拟进行了两个不同的代码,以减轻数值伪影。我们发现,在$\sim 10^{5.5} - 10^{7.5}\, {\rm{M_{\odot}}}$范围内的大质量星团优先形成于星系相互作用产生的高冲击区。新生的星团形成云具有$P/k \sim 10^8 - 10^{12}\, \rm{K}\,\rm{cm^{-3}}$范围内的高气压,比星际介质的典型压力高$\sim 10^4 - 10^8$倍,但与最近在银河系中观测到的前超级星团云一致。此外,这些大质量星团具有准对数正态的初始质量函数,峰值在$\sim 10^{6}\, {\rm{M_{\odot}}}$附近。由于破坏性过程,星系团的数量随着时间的推移而减少,但在星系碰撞过程中,质量函数的形状和峰值并没有显着变化。我们的研究结果表明,富含气体的星系合并可能为大质量星团(如球状星团)的形成提供了有利的环境,对数正态质量函数和独特的峰值可能来源于诞生云的极端高压条件,并可能在动力学演化中幸存下来。

英文摘要:

Observations of globular clusters show that they have universal lognormal mass functions with a characteristic peak at $\sim 2\times 10^{5}\, {\rm{M_{\odot}}}$, but the origin of this peaked distribution is highly debated. Here we investigate the formation and evolution of star clusters in interacting galaxies using high-resolution hydrodynamical simulations performed with two different codes in order to mitigate numerical artifacts. We find that massive star clusters in the range of $\sim 10^{5.5} - 10^{7.5}\, {\rm{M_{\odot}}}$ form preferentially in the highly-shocked regions produced by galaxy interactions. The nascent cluster-forming clouds have high gas pressures in the range of $P/k \sim 10^8 - 10^{12}\, \rm{K}\,\rm{cm^{-3}}$, which is $\sim 10^4 - 10^8$ times higher than the typical pressure of the interstellar medium but consistent with recent observations of a pre-super star cluster cloud in the Antennae Galaxies. Furthermore, these massive star clusters have quasi-lognormal initial mass functions with a peak around $\sim 10^{6}\, {\rm{M_{\odot}}}$. The number of clusters declines with time due to destructive processes, but the shape and the peak of the mass functions do not change significantly during the course of galaxy collisions. Our results suggest that gas-rich galaxy mergers may provide a favorable environment for the formation of massive star clusters such as globular clusters, and that the lognormal mass functions and the unique peak may originate from the extreme high-pressure conditions of the birth clouds and may survive the dynamical evolution.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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