ORA Thesis: "On the dynamics of tidal streams in the Milky Way galaxy" - uuid:be113d1c-cff2-4cd5-a51f-40de15af2dce




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Reference: Andrew M Eyre, (2010). On the dynamics of tidal streams in the Milky Way galaxy. DPhil. University of Oxford.

Citable link to this page: http://ora.ox.ac.uk/objects/uuid:be113d1c-cff2-4cd5-a51f-40de15af2dce
Title: On the dynamics of tidal streams in the Milky Way galaxy

Abstract: We present a brief history of Galactic astrophysics, and explain the origin of halo substructure in the Milky Way Galaxy. We motivate our study of the dynamics of tidal streams in our Galaxy by highlighting the tight constraints that analysis of the trajectories of tidal streams can place on the form of the Galactic potential. We address the reconstruction of orbits from observations of tidal streams. We upgrade the geometrodynamical scheme reported by Binney (2008) and Jin & Lynden-Bell (2007), which reconstructs orbits from streams using radial-velocity measurements, to allow it to work with erroneous input data. The upgraded algorithm can correct for both statistical error on observations, and systematic error due to streams not delineating individual orbits, and given high-quality but realistic input data, it can diagnose the potential with considerable accuracy. We complement the work of Binney (2008) by deriving a new algorithm, which reconstructs orbits from streams using proper-motion data rather than radial-velocity data. We demonstrate that the new algorithm has a similar potency for diagnosing the Galactic potential. We explore the concept of Galactic parallax, which arises in connection with our proper-motion study. Galactic parallax allows trigonometric distance calculation to stars at 40 times the range of conventional parallax, although its applicability is limited to only those stars in tidal streams. We examine from first principles the mechanics of tidal stream formation and propagation. We find that the mechanics of tidal streams has a natural expression in terms of action-angle variables. We find that tidal streams in realistic galaxy potentials will generally not delineate orbits precisely, and that attempting to constrain the Galactic potential by assuming that they do can lead to large systematic error. We show that we can accurately predict the real-space trajectories of streams, even when they differ significantly from orbits.

Digital Origin:Born digital
Type of Award:DPhil
Level of Award:Doctoral
Awarding Institution: University of Oxford
Notes:174 pp., 148 figures.
About The Authors
institutionUniversity of Oxford
facultyMathematical,Physical & Life Sciences Division - Physics - Theoretical Physics
researchGroupGalaxy dynamics (Binney & Magorrian)
oxfordCollegeMerton College
Prof James Binney More by this contributor
Bibliographic Details
Issue Date: 2010
Copyright Date: 2010
Urn: uuid:be113d1c-cff2-4cd5-a51f-40de15af2dce
Item Description
Member of collection : ora:thesis
Alternate metadata formats
Copyright Holder: Andy Eyre
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