Galactic Dynamics and Local Dark Matter

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 pro...

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Bibliographic Details
Published in:arXiv.org 2009-02
Main Authors: Majewski, Steven R, Bullock, James, Burkert, Andreas, Gibson, Brad, Grebel, Eva, Gnedin, Oleg Y, Guhathakurta, Puragra, Helmi, Amina, Johnston, Kathryn V, Kroupa, Pavel, Metz, Manuel, Moore, Ben, Patterson, Richard J, Shaya, Edward, Strigari, Louis E, Roeland van der Marel
Format: Article
Language:English
Subjects:
Angular momentum
Anisotropy
Astrometry
Astronomical models
Cold dark matter
Dark matter
Exploration
Galactic evolution
Galaxies
Globular clusters
Local group (astronomy)
Milky Way Galaxy
Orbits
Space density
Stars & galaxies
Universe
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Summary: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.
ISSN:2331-8422