Collaborative Research: A New Era of Mapping Dark Matter in Dwarf Spheroidal Galaxies

矮球状星系（dSph）可能是宇宙中包含暗物质和发光物质的最小系统。如果能收集到足够的运动数据来约束模型，就可以详细地研究dsph星系中的暗物质含量和分布。密歇根大学的马里奥·马特奥博士和亚利桑那大学的爱德华·奥尔谢夫斯基博士将使用三种新技术，将每个星系测量的恒星速度数量提高10-30倍。我们的目标不再是对深黑洞进行称重，而是推导出质量的分布，从而得出暗物质的分布。虽然到目前为止，我们已经朝着这个目标迈出了一小步，英勇地收集了多达200颗恒星的样本，但只有在更大的样本中，才能将合理的模型彼此区分开来。dSph星系内的这种质量映射需要与许多（有时是相互矛盾的）星系模型和宇宙中大规模结构形成模型的预测进行严格比较。这些研究人员将使用一种新的望远镜——智利拉斯坎帕纳斯天文台的麦哲伦6.5米望远镜——一种新的梯队光谱仪——麦哲伦-稻盛京华梯队光谱仪（MIKE）——和一种新的256光纤系统，同时为该光谱仪提供大量恒星。这种仪器组合将允许每个星系收集750-1500个运动样本。＊＊＊

AST 0205790OlszewskiDwarf spheroidal galaxies (dSph) are likely to be the smallest systems in the Universe which contain both dark matter and luminous matter. The dark matter content and distribution in dSphgalaxies can be studied in detail if one can collect enough kinematic data to constrain models. Dr. Mario Mateo, at the University of Michigan, and Dr. Edward Olszewski, at the University of Arizona, will use three new technologies to make a factor of 10-30 advance in the number of stellar velocities measured per galaxy. The goal is no longer to weigh the dSph's, but to derive the distribution of mass, thus the distribution of the dark matter. While small steps have been taken towards that goal to date, with heroically collected samples of up to 200 stars, it is only withsubstantially larger samples that reasonable models will be distinguished from each other. Suchmapping of the mass within dSph galaxies is required to critically compare their dark-matter haloswith the many - sometimes contradictory - predictions of models of galaxy and large-scale structure formation in the Universe. These researchers will use a new telescope - the Magellan 6.5-meter telescope of Las Campanas Observatory in Chile - a new echelle spectrograph - the Magellan-Inamori-Kyocera Echelle (MIKE) spectrograph - and a new 256-fiber system to feed this spectrograph a large number of stars simultaneously. This instrumental combination will allow the collection of 750-1500 kinematic samples per galaxy. ***