We propose to use gravitational wakes as a direct observational probe of the collisional nature of the dark matter. We calculate analytically the structure of a wake generated by the motion of a galaxy in the core of an X-ray cluster for dark matter in the highly collisional and collisionless limits. Although the difference between these limits is most likely too subtle to be detected with weak lensing observations, we show that the two cases can be distinguished through detailed X-ray observations. We also discuss the sizes of subhalos in these limits. Preliminary X-ray data on the motion of NGC 1404 through the Fornax group disfavors fluidlike dark matter but does not exclude scenarios in which the dark matter is weakly collisional.
展开▼
机译：我们建议使用重力尾流作为暗物质碰撞性质的直接观测探针。我们分析性地计算了在高度碰撞和无碰撞极限下，暗物质在暗物质的X射线簇核心中由星系运动产生的尾波的结构。尽管这些限制之间的差异很可能太微妙，以至于用弱透镜观察都无法检测到，但我们表明可以通过详细的X射线观察来区分这两种情况。我们还讨论了在这些限制范围内亚晕的大小。 NGC 1404通过Fornax组运动的初步X射线数据不利于类流体暗物质，但不排除暗物质弱碰撞的情况。
展开▼
