Milky Way和局域星系的天体测量揭示的暗物质性质
Properties of Dark Matter Revealed by Astrometric Measurements of the Milky Way and Local Galaxies
摘要：
事实上，暗物质（DM），到目前为止，只揭示了自己在星系和更大的尺度上，再次推到天体物理学的机会和责任，面对古老的奥秘“什么是物质的本质？“通过得出关于DM性质的基本数据--例如，粒子的质量，目前的平均温度，在星系和宇宙中其他结构中的分布，以及耗散坍缩的能力-我们将揭示宇宙中主要物质种类的性质，并显着扩展粒子物理学的标准模型。确定DM粒子的质量到一个数量级将有助于分类它（或它们）所属的粒子家族。除了质量，还有稳定性的问题。DM粒子可能是不稳定的，具有可测量的半衰期，或者它可能在从碰撞中吸收一定量的能量后变得不稳定。在这两种情况下，它都对目前的热暗物质成分有贡献。DM的一些关键参数可以在非常接近的宇宙中最准确地测量，因为DM在银河系外（MW）、本星系群中的其他星系以及整个本星系群中占主导地位。DM的存在和量可以通过研究这些实体内可观察到的精细细节的动态过程来量化。精确测量恒星、相干星流和星系边缘卫星恒星系统中恒星的三维速度，可以揭示“暗物质晕的形状、方向、密度规律和块状度”以及“星系的总质量是多少？"
英文摘要：
The fact that dark matter (DM), thus far, has revealed itself only on scales of galaxies and larger, again thrusts onto astrophysics the opportunity and the responsibility to confront the age old mystery "What is the nature of matter?" By deriving basic data on the nature of DM - e.g., mass of its particle(s), present mean temperature, distribution in galaxies and other structures in the universe, and capacity for dissipational collapse - we will be uncovering the properties of the dominant species of matter in the universe and significantly extending the standard models of particle physics. Determining the mass of the DM particle to an order of magnitude would help to sort out the particle family to which it (or they) belongs. Beyond mass, there are issues of stability. The DM particle may be unstable with a measurable half-life, or it may become unstable after absorbing a certain amount of energy from collisions. In both cases it would contribute to the present hot dark matter component. Some key parameters of DM can most accurately be measured in the very nearby universe because DM dominates the mass in the outer Milky Way (MW), in other galaxies in the Local Group, and in the Local Group in its entirety. The presence and amount of DM can be quantified by study of dynamical processes observable in fine detail within these entities. Precise measurements of 3-D velocities for stars, coherent star streams, and stars in satellite stellar systems out to the edge of the Galaxy can reveal "what is the shape, orientation, density law, and lumpiness of the dark matter halo" as well as "what is the total mass of the Galaxy?"
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