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

AST0206081MateoDwarf球状星系(DSph)可能是宇宙中最小的同时包含暗物质和发光物质的系统。如果能够收集到足够的运动学数据来约束模型，就可以详细研究dSphaxy中暗物质的含量和分布。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项新技术，将每个星系测量的恒星速度提高10-30倍。我们的目标不再是称重dSph，而是推导出质量分布，从而得出暗物质的分布。虽然到目前为止已经朝着这个目标迈出了很小的一步，英勇地收集了多达200颗恒星的样本，但只有在样本大得多的情况下，合理的模型才会相互区分。需要对dSph星系内的质量进行这样的映射，以批判性地将它们的暗物质晕与许多--有时是相互矛盾的--星系模型和宇宙中大规模结构形成的预测进行比较。这些研究人员将使用一台新的望远镜--智利拉斯坎帕纳斯天文台的麦哲伦6.5米望远镜--一台新的梯形光谱仪--麦哲伦-稻盛和夫-京瓷Echelle(Mike)光谱仪--以及一种新的256纤维系统，同时为这台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个运动学样本。***

AST 0206081MateoDwarf 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. ***