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E. Shaya (Univ. of Maryland), SIMDOG Team
The observational goal of the SIM key project "Dynamics of Galaxies" is to measure the proper motions, i.e. velocities in the plane of the sky, of ~30 nearby galaxies. In so doing, SIM will provide the final two components of these galaxies' position-momentum vectors. These seminal measurements of the deviation from pure Hubble flow will be of lasting importance in the modeling of the formation of the nearby groups and of the plane of the Local Supercluster. It will immediately reveal whether the Andromeda galaxy (or another Local Group galaxy) is headed directly for us. The measurement procedure is straightforward: simply measure the positions of the brightest stars in each galaxy over several years to better than 10 microArcsecond accuracy. Then, remove rotation effects and take averages to minimize the effect of internal motions. We will report on the latest advances of modeling the motions of galaxies in the local vicinity in an effort to learn the state of development of the groups and to determine the distribution of the dark matter on scales of 1-4 Mpc. In particular, we will report on comparison of N-body (forward calculations) and Numerical Action (backward calculations) and show that they agree well when a component of non-clumped material is added to the Numerical Action code.
The author(s) of this abstract have provided an email address for comments about the abstract: eshaya@umd.edu
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.