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The least-action method, cold dark matter, and omegaPeebles has suggested an interesting technique, called the least-action method, to trace positions of galaxies back in time. This method applied on the Local Group galaxies seems to indicate that we live in an omega approximately = 0.1 universe. We have studied a cold dark matter (CDM) N-body simulation with omega = 0.2 and H = 50 km/s/Mpc and compared trajectories traced back by the least-action method with the ones given by the center of mass of the CDM halos. We show that the agreement between these sets of trajectories is at best qualitative. We also show that the line-of-sight peculiar velocities of halos are underestimated. This discrepancy is due to orphans, i.e., CDM particles which do not end up in halos. We vary the value of omega in the least-action method until the line-of-sight velocities agree with the CDM ones. The best value for this omega underestimates one of the CDM simulations by a factor of 4-5.
Document ID
19950052214
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Dunn, A. M.
(University of Cambridge Cambridge, United Kingdom)
Laflamme, R.
(Los Alamos National Laboratory, Los Alamos, NM United States)
Date Acquired
August 16, 2013
Publication Date
April 10, 1995
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 443
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A83813
Distribution Limits
Public
Copyright
Other

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