论文标题
子弹矮人碰撞中的无暗星系
A trail of dark matter-free galaxies from a bullet dwarf collision
论文作者
论文摘要
NGC1052组中的Ultra-diffuse Galaxies DF2和DF4具有多种异常特性：它们均具有较大的尺寸，丰富的过多的球形和大球状簇，并且速度分散体很少或没有暗物质。有人提出，这些星系是在高速遇到的富含气星系的高速相遇中形成的，这些事件类似于造成子弹群但尺度较小的碰撞的碰撞。气体与碰撞中的暗物质分离，随后的恒星形成导致一个或多个无暗星系的形成。在这里，我们表明，DF2和DF4的当今视线距离和径向速度与大约八十亿年前的单个子弹折碰撞后的联合形成一致。此外，我们发现DF2和DF4是7-11个大型低亮度对象的明显线性子结构的一部分。我们建议所有这些都起源于同一事件，形成了一条无暗的星系痕迹，该星系长超过2 MPC，距离视线距离为7 +-2度。我们还暂时确定了这两个祖先星系的高度深色物质遗物，这些残留物预期在步道的前沿。
The ultra-diffuse galaxies DF2 and DF4 in the NGC1052 group share several unusual properties: they both have large sizes, rich populations of overluminous and large globular clusters, and very low velocity dispersions indicating little or no dark matter. It has been suggested that these galaxies were formed in the aftermath of high velocity encounters of gas rich galaxies, events that resemble the collision that created the bullet cluster but on much smaller scales. The gas separates from the dark matter in the collision and subsequent star formation leads to the formation of one or more dark matter-free galaxies. Here we show that the present-day line-of-sight distances and radial velocities of DF2 and DF4 are consistent with their joint formation in the aftermath of a single bullet-dwarf collision, around eight billion years ago. Moreover, we find that DF2 and DF4 are part of an apparent linear substructure of 7-11 large, low-luminosity objects. We propose that these all originated in the same event, forming a trail of dark matter-free galaxies that is more than 2 Mpc long and angled 7 +- 2 degrees from the line of sight. We also tentatively identify the highly dark matter-dominated remnants of the two progenitor galaxies that are expected at the leading edges of the trail.
