The recent discovery of diffuse dwarf galaxies that are deficient in dark matter appears to challenge the current paradigm of structure formation in our Universe. We describe the numerical experiments to determine if the so-called dark matter deficient galaxies (DMDGs) could be produced when two gas-rich, dwarf-sized galaxies collide with a high relative velocity of $\sim 300\,{\rm kms^{-1}}$. Using idealized high-resolution simulations with both mesh-based and particle-based gravito-hydrodynamics codes, we find that DMDGs can form as high-velocity galaxy collisions separate dark matter from the warm disk gas which subsequently is compressed by shock and tidal interaction to form stars. Then using a large simulated universe IllustrisTNG, we discover a number of high-velocity galaxy collision events in which DMDGs are expected to form. However, we did not find evidence that these types of collisions actually produced DMDGs in the TNG100-1 run. We argue that the resolution of the numerical experiment is critical to realize the "collision-induced" DMDG formation scenario. Our results demonstrate one of many routes in which galaxies could form with unconventional dark matter fractions.

中文翻译：

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高分辨率数值模拟中高速星系碰撞产生的暗物质缺陷星系

最近发现的缺乏暗物质的弥散矮星系似乎挑战了我们宇宙中结构形成的当前范式。我们描述了数值实验，以确定当两个富含气体的矮星系以 $\sim 300\,{\rm kms^ 的高相对速度碰撞时是否可以产生所谓的暗物质缺陷星系 (DMDGs) {-1}}$。使用基于网格和基于粒子的引力流体动力学代码的理想化高分辨率模拟，我们发现 DMDG 可以在高速星系碰撞将暗物质与温暖的盘状气体分离时形成，后者随后被冲击和潮汐相互作用压缩为形成星星。然后使用大型模拟宇宙 IllustrisTNG，我们发现了许多预计会形成 DMDG 的高速星系碰撞事件。然而，我们没有发现证据表明这些类型的碰撞实际上在 TNG100-1 运行中产生了 DMDG。我们认为数值实验的分辨率对于实现“碰撞诱导”DMDG 形成场景至关重要。我们的结果证明了星系可以用非常规暗物质部分形成的众多途径之一。