arXiv 2008.043202020-08astro-ph.GA

模拟矮星暴中年轻大质量星团的结构和旋转

Structure and rotation of young massive star clusters in a simulated dwarf starburst

Natalia Lahén, Thorsten Naab, Peter H. Johansson, Bruce Elmegreen, Chia-Yu Hu, Stefanie Walch

备注：: 21 pages, accepted for publication in ApJ
DOI：: 10.3847/1538-4357/abc001

摘要：

我们分析的三维形状和运动学的年轻星团人口形成的高分辨率GRIFFIN项目模拟的贫金属矮星系星爆。星团，遵循幂律质量分布，形成从冷ISM阶段与IMF采样与个别恒星下降到4个太阳质量在亚秒差距的空间分辨率。大质量恒星及其重要的反馈机制的详细建模。模拟的集群遵循一个令人惊讶的特定的角动量和质量之间的紧密关系与两个子群的迹象。大质量星系团（$M_\mathrm{cl}\gtrsim 3\times 10^4 M_{\odot})$）在低椭圆率（$ε\sim 0.2$）时具有最高的比角动量，并且在它们的形状和旋转之间显示出对齐。质量较低的星系团具有较低的比角动量和较大的散射，显示出更宽的伸长范围，并且通常不对齐，表明它们不是通过旋转形成的。质量最大的星系团$(M \gtrsim 10^5\,M_{\odot})$在$t \lesssim 10\,\rm Myr$时间尺度上从$ \lesssim 100\,\rm pc$尺度的局部星系环境中吸积气体和原星系团，继承了周围的角动量性质。它们的二维运动学图显示了形成时的有序旋转，直到$v \sim 8.5\,\rm km s^{-1}$，与观测到的年轻大质量星团和它们可能演化成的老球状星团一致。大规模集群的角动量参数$λ_R\lesssim 0.5$和高斯厄米系数$h_3$是反相关的速度，表明不对称的视线速度分布作为一个耗散的形成过程的签名。

英文摘要：

We analyze the three-dimensional shapes and kinematics of the young star cluster population forming in a high-resolution GRIFFIN project simulation of a metal-poor dwarf galaxy starburst. The star clusters, which follow a power-law mass distribution, form from the cold ISM phase with an IMF sampled with individual stars down to 4 solar masses at sub-parsec spatial resolution. Massive stars and their important feedback mechanisms are modelled in detail. The simulated clusters follow a surprisingly tight relation between the specific angular momentum and mass with indications of two sub-populations. Massive clusters ($M_\mathrm{cl}\gtrsim 3\times 10^4 M_{\odot})$ have the highest specific angular momenta at low ellipticities ($ε\sim 0.2$) and show alignment between their shapes and rotation. Lower mass clusters have lower specific angular momenta with larger scatter, show a broader range of elongations, and are typically misaligned indicating that they are not shaped by rotation. The most massive clusters $(M \gtrsim 10^5\,M_{\odot})$ accrete gas and proto-clusters from a $ \lesssim 100\,\rm pc$ scale local galactic environment on a $t \lesssim 10\,\rm Myr$ timescale, inheriting the ambient angular momentum properties. Their two-dimensional kinematic maps show ordered rotation at formation, up to $v \sim 8.5\,\rm km s^{-1}$, consistent with observed young massive clusters and old globular clusters, which they might evolve into. The massive clusters have angular momentum parameters $λ_R\lesssim 0.5$ and show Gauss-Hermite coefficients $h_3$ that are anti-correlated with the velocity, indicating asymmetric line-of-sight velocity distributions as a signature of a dissipative formation process.

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英文摘要：

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