论文标题
对星系恒星，冷和热气体和暗物质组件的自旋和形状对齐的合并影响
Merger Effects on the Spin and Shape Alignments of Galaxy Stellar, Cold and Hot Gas, and Dark Matter Components
论文作者
论文摘要
我们提供了一个数值证据，支持这种情况，即在星系在星系中没有最近的合并事件的情况下，在静止的演化期间产生了银河恒星旋转与局部潮汐张量的主要主要轴的特殊比对。分析了Illustristng项目的TNG300-1模拟中的合并树，我们找到了星系的最新合并时期，$ a（z_ {m}）$，并创建四个$ a（z_ {m}）$ - 被控制的样品可控制以共享相同的质量和密度分布。对于每个样品，我们分别确定星系恒星，冷和热气体以及暗物质成分的自旋和形状向量，并计算其对齐的平均强度与局部潮汐场的主要方向以及它们的相互对准趋势。发现最新合并事件发生在早期时代的星系的恒星（冷气）旋转轴与潮汐场的主要主要主要轴更强地对齐（弱反将）。还表明，尽管银河系DM旋转的质量依赖性过渡与合并事件的联系很少，但Galaxy四个成分的合并事件，旋转形状和形状剪切对准强度敏感地取决于$ a（z_ {m}）$。指出经历长期静止进化的星系的恒星成分具有明显的形状和非常强的自旋形状比对，因此我们建议可以通过使用恒星的星系形状而没有合并的签名来追溯局部潮汐场。
We present a numerical evidence supporting the scenario that the peculiar alignments of the galaxy stellar spins with the major principal axes of the local tidal tensors are produced during the quiescent evolution period when the galaxies experience no recent merger events. Analyzing the merger tree from the TNG300-1 simulation of the IllustrisTNG project, we find the latest merger epochs, $a(z_{m})$, of the galaxies, and create four $a(z_{m})$-selected samples that are controlled to share the identical mass and density distributions. For each sample, we determine the spin and shape vectors of the galaxy stellar, cold and hot gas, and dark matter components separately, and compute the average strengths of their alignments with the principal directions of the local tidal fields as well as their mutual alignment tendencies. It is found that the stellar (cold gas) spin axes of the galaxies whose latest merger events occur at earlier epochs are more strongly aligned (weakly anti-aligned) with the major principal axes of the tidal fields. It is also shown that although the mass-dependent transition of the galaxy DM spins have little connection with the merger events, the morphologies, spin-shape and shape-shear alignment strengths of the galaxy four components sensitively depend on $a(z_{m})$. Noting that the stellar components of the galaxies which undergo long quiescent evolution have distinctively oblate shapes and very strong spin-shape alignments, we suggest that the local tidal field might be traced by using the stellar shapes of galaxies without signatures of mergers as a proxy of their stellar spins.
