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arXiv 0902.2759astro-ph.COastro-ph.GA
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银河系动力学与局域暗物质

Galactic Dynamics and Local Dark Matter

Steven R. Majewski, James Bullock, Andreas Burkert, Brad Gibson, Eva Grebel, Oleg Y. Gnedin, Puragra Guhathakurta, Amina Helmi, Kathryn V. Johnston, Pavel Kroup… 展开作者

Steven R. Majewski, James Bullock, Andreas Burkert, Brad Gibson, Eva Grebel, Oleg Y. Gnedin, Puragra Guhathakurta, Amina Helmi, Kathryn V. Johnston, Pavel Kroupa, Manuel Metz, Ben Moore, Richard J. Patterson, Edward Shaya, Louis E. Strigari, Roeland van der Marel

摘要:

宇宙结构形成的一致性λ冷暗物质(Lambda-CDM)模型虽然在描述大尺度结构观测方面非常成功,但在星系尺度上的观测仍然面临挑战。幸运的是,CDM模型和他们提出的各种替代方案作出了丰富多样的可测试的预测,使本星系组和我们自己的银河系的关键实验室探索暗物质(DM)在这个制度。然而,当地DM的一些最权威的测试需要微弱源的微弧秒天体测量,这是SIM Lite的独特利基的天体测量制度。本章探讨了SIM Lite在探索星系尺度上的星系动力学和DM方面可以做出的重要而独特的贡献,这些贡献具有宇宙学后果。潜在SIM Lite探索的关键领域包括:(1)测量银河系和其他附近星系的暗晕的形状、方向、密度规律和块状度,(2)确定银河系卫星的轨道,这些卫星可能是银河系分层形成的晚期坠落的代表,(3)确定恒星和球状星团在星系晕外围的角动量分布和轨道各向异性,动力学性质为银河系早期的等级形成提供了线索,(4)通过对附近dSph星系核心的相空间密度施加强约束来测量DM的物理性质,(5)通过确定本星系群各组成星系的轨道和质量,重建本星系群的动力学历史。

英文摘要:

The concordance Lambda Cold Dark Matter (Lambda-CDM) model for the formation of structure in the Universe, while remarkably successful at describing observations of structure on large scales, continues to be challenged by observations on galactic scales. Fortunately, CDM models and their various proposed alternatives make a rich variety of testable predictions that make the Local Group and our own Milky Way Galaxy key laboratories for exploring dark matter (DM) in this regime. However, some of the most definitive tests of local DM require microarcsecond astrometry of faint sources, an astrometric regime that is a unique niche of SIM Lite. This chapter explores the important and distinct contributions that can be made by SIM Lite in the exploration of galaxy dynamics and DM on galaxy scales and that have cosmological consequences. Key areas of potential SIM Lite exploration include (1) measuring the shape, orientation, density law, and lumpiness of the dark halo of the Milky Way and other nearby galaxies, (2) determining the orbits of Galactic satellites, which may be representatives of late infall from the hierarchical formation of the Milky Way, (3) ascertaining the distribution of angular momentum and orbital anisotropy of stars and globular clusters to the outer reaches of the Galactic halo, dynamical properties that hold clues to the early hierarchical formation of the Galaxy, (4) measuring the physical nature of DM by placing strong constraints on the phase space density in the cores of nearby dSph galaxies, and (5) reconstructing the dynamical history of the Local Group through the determination of orbits and masses of its constituent galaxies.

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