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Title: First Clear Signature of an Extended Dark Matter Halo in the Draco Dwarf Spheroidal
Authors: Kleyna, J. T.
Wilkinson, M. I.
Evans, N. W.
Gilmore, G. F.
First Published: 7-Dec-2001
Publisher: American Astronomical Society, IOP Publishing
Citation: Astrophysical Journal Letters, 2001, 563 (2), pp.115-118
Abstract: We present the first clear evidence for an extended dark matter halo in the Draco dwarf spheroidal galaxy based on a sample of new radial velocities for 159 giant stars out to large projected radii. Using a two-parameter family of halo models spanning a range of density profiles and velocity anisotropies, we are able to rule out (at about the 2.5 σ confidence level) halos in which mass follows light. The data strongly favor models in which the dark matter is significantly more extended than the visible dwarf. However, halos with harmonic cores larger than the light distribution are also excluded. When combined with existing measurements of the proper motion of Draco, our data strongly suggest that Draco has not been tidally truncated within ~1 kpc. We also show that the rising velocity dispersion at large radii represents a serious problem for modified gravity (MOND).
DOI Link: 10.1086/338603
ISSN: 0004-6388
Type: Article
Rights: Archived with reference to SHERPA/RoMEO and publisher website. © 2001. The American Astronomical Society. All rights reserved.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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