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A.C. Peel, E.J. Shaya, S.D. Phelps (U. of Maryland), R.B. Tully (Institute for Astronomy, U. of Hawaii), P.J.E. Peebles (Joseph Henry Labs., Princeton University)
The Numerical Action Method (NAM) seeks to recreate past orbits of large galaxies and galaxy groups by application of the least action principle. Recent improvements to NAM include: addition of a smooth, constant density background; time-dependent masses for haloes following linear perturbation theory; and solving for present distances and redshifts simultaneously to optimize fitting observations. We show that this improved NAM reconstructs reasonable orbits which agree with a large-scale numerical N-body code and with far less multiplicity than earlier efforts. We present results on the flow of galaxies, groups and clusters within 3000 km/s based on very recent HST TRGB-distance measurements. We can therefore expect to place theoretical constraints on observations of transverse velocities by future astrometric missions such as SIM and GAIA, as well as existing measurements of the proper motion of M33 by VLBI. This work is funded in part by the Space Interferometry Mission (SIM) through NASA/JPL Contract FCPO.1254270.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.