星系薄盘的脆弱性-- I.构建定制的N体星系模型
The fragility of thin discs in galaxies -- I. Building tailored N-body galaxy models
摘要：
薄的恒星盘在银河系和核，sub-kpc尺度被认为是脆弱的结构，将很容易在主要的合并中被破坏。反过来，这使得它们的恒星星族的年龄测定成为星系组装历史的有用诊断。我们的目标是仔细探索这种恒星盘的脆弱性，在中等和低质量的遭遇，使用高分辨率的N体模拟的星系模型与实际观察到的星系的结构和运动学特性。作为第一个但具有挑战性的一步，我们创建了一个动力学模型FCC 170，一个几乎在天炉座星系团的边缘星系，具有多个星系组成部分，包括星系尺度和核恒星盘（NSD），使用详细的运动学数据从多单元光谱探测器和一种新的方法，用于构建基于分布函数的自洽星系模型。然后，我们创建N体实现这个模型，并证明它仍然处于平衡状态，并保持其属性超过许多陀螺仪，当进化与足够高的粒子数。然而，NSD更倾向于数值加热，即使在我们最高分辨率的运行中，它的厚度也会在10 Gyr内逐渐增加22%。尽管如此，这些N体模型可以在合并模拟中作为真实星系的真实表示。
英文摘要：
Thin stellar discs on both galactic and nuclear, sub-kpc scales are believed to be fragile structures that would be easily destroyed in major mergers. In turn, this makes the age-dating of their stellar populations a useful diagnostics for the assembly history of galaxies. We aim at carefully exploring the fragility of such stellar discs in intermediate- and low- mass encounters, using high-resolution N-body simulations of galaxy models with structural and kinematic properties tailored to actually observed galaxies. As a first but challenging step, we create a dynamical model of FCC 170, a nearly edge-on galaxy in the Fornax cluster with multiple galactic components and including both a galactic scale and nuclear stellar disc (NSD), using detailed kinematic data from the Multi Unit Spectroscopic Explorer and a novel method for constructing distribution function-based self-consistent galaxy models. We then create N-body realisations of this model and demonstrate that it remains in equilibrium and preserves its properties over many Gyr, when evolved with a sufficiently high particle number. However, the NSD is more prone to numerical heating, which gradually increases its thickness by up to 22 per cent in 10 Gyr even in our highest-resolution runs. Nevertheless, these N-body models can serve as realistic representations of actual galaxies in merger simulations.
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