在1.25 pc分辨率模拟中高速星系碰撞中同时形成暗物质缺乏星系及其成员星团
Dark Matter Deficient Galaxies And Their Member Star Clusters Form Simultaneously During High-velocity Galaxy Collisions In 1.25 pc Resolution Simulations
摘要：
缺乏暗物质的弥漫矮星系--如NGC 1052-DF 2和NGC 1052-DF 4--是如何形成的仍然是一个谜。与它们的发光成员球状星团（GC）一起，所谓的暗物质缺乏星系（DMDG）对观测者和理论家都提出了挑战。在这里，我们报告了一套星系碰撞模拟使用自适应网格细化代码ENZO与1.25 pc的分辨率，这表明，高速星系碰撞诱导形成DMDG和他们的星团（SC）的同时。数值分辨率明显优于我们以前的研究（Shin等人，2020），我们解析了所产生的DMDG的动力学结构及其SC的详细形成历史，这些SC可能是DMDG成员GC的祖先。特别是，我们表明，一个星系碰撞与高相对速度的$\sim 300\;{\rm km\;s}^{-1}$，调用严重的冲击压缩，产生多个大规模的SC（$\gtrsim 10^{6}\;{\rm M}_{\odot}$）碰撞后150万年内。在我们的~ 8亿年基准运行结束时，得到的$M_{\star} \simeq 3.5\times 10^{8}\;{M}_{\odot}$的DMDG拥有10个发光（$M_{\rm V} \lesssim -8.5\;{\rm mag}$），引力束缚的SC，具有视线速度色散$11.2\;{\rm km\;s}^{-1}$。我们的研究表明，DMDG及其发光成员SC可以在高速星系碰撞中同时形成，同时符合NGC 1052-DF 2和NGC 1052-DF 4的关键观测特性。
英文摘要：
How diffuse dwarf galaxies that are deficient in dark matter -- such as NGC1052-DF2 and NGC1052-DF4 -- formed remains a mystery. Along with their luminous member globular clusters (GCs), the so-called dark matter deficient galaxies (DMDGs) have challenged observers and theorists alike. Here we report a suite of galaxy collision simulations using the adaptive mesh refinement code ENZO with 1.25 pc resolution, which demonstrates that high-velocity galaxy collisions induce the formation of DMDGs and their star clusters (SCs) simultaneously. With a numerical resolution significantly better than our previous study (Shin et al. 2020), we resolve the dynamical structure of the produced DMDGs and the detailed formation history of their SCs which are possible progenitors of the DMDG's member GCs. In particular, we show that a galaxy collision with a high relative velocity of $\sim 300\;{\rm km\;s}^{-1}$, invoking severe shock compression, spawns multiple massive SCs ($\gtrsim 10^{6}\;{\rm M}_{\odot}$) within 150 Myr after the collision. At the end of our ~ 800 Myr fiducial run, the resulting DMDG of $M_{\star} \simeq 3.5\times 10^{8}\;{M}_{\odot}$ hosts 10 luminous ($M_{\rm V} \lesssim -8.5\;{\rm mag}$), gravitational bound SCs with a line-of-sight velocity dispersion $11.2\;{\rm km\;s}^{-1}$. Our study suggests that DMDGs and their luminous member SCs could form simultaneously in high-velocity galaxy collisions while being in line with the key observed properties of NGC1052-DF2 and NGC1052-DF4.
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