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Title: The kinematical center and mass profile of the local group

Abandoning the assumption that light traces mass, I seek the location of the center of the Local Group of galaxies based solely on kinematic data and the plausible assumption of infall. The available set of positions and radial velocities is shown to be a misleading indicator of Local Group motions, giving a direction to the center offset from the true one; statistical techniques of moderate sophistication do not catch the offset. Corrected calculations show the center to lie in the direction of M31 within the uncertainty of the method, within a few degrees. The distance to the center is not well determined, lying about 0.5 Mpc from the Milky Way. The pattern of observed (galactocentric) radial velocities excludes both dynamically important 'orphan halos' and any extended dark matter halo for the Group as a whole, and shows the Group to have formed from a much more extended volume than it presently occupies. Kinematics alone indicates that the mass of the Group is concentrated effectively in M31 and the Milky Way.
Authors:
 [1]
  1. University of Birmingham, Edgbaston Road, Birmingham B15 2TT (United Kingdom)
Publication Date:
OSTI Identifier:
22364997
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 793; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DISTANCE; GALAXY CLUSTERS; MASS; MECHANICS; MILKY WAY; NONLUMINOUS MATTER; RADIAL VELOCITY; VISIBLE RADIATION