Distant star clusters of the Milky Way in MOND

Haghi, H., Baumgardt, H. and Kroupa, P. (2011) Distant star clusters of the Milky Way in MOND. Astronomy and Astrophysics, 527 5: . doi:10.1051/0004-6361/201015573

Author Haghi, H.
Baumgardt, H.
Kroupa, P.
Title Distant star clusters of the Milky Way in MOND
Journal name Astronomy and Astrophysics   Check publisher's open access policy
ISSN 0004-6361
Publication date 2011-03-01
Sub-type Article (original research)
DOI 10.1051/0004-6361/201015573
Open Access Status DOI
Volume 527
Issue 5
Total pages 7
Place of publication Les Ulis, France
Publisher EDP Sciences
Collection year 2012
Language eng
Formatted abstract
We determine the mean velocity dispersion of six Galactic outer halo globular clusters, AM 1, Eridanus, Pal 3, Pal 4, Pal 15, and Arp 2 in the weak acceleration regime to test classical vs. modified Newtonian dynamics (MOND). Owing to the nonlinearity of MOND's Poisson equation, beyond tidal effects, the internal dynamics of clusters is affected by the external field in which they are immersed. For the studied clusters, particle accelerations are much lower than the critical acceleration a0 of MOND, but the motion of stars is neither dominated by internal accelerations (ai ae) nor external accelerations (ae ai). We use the N-body code N-MODY in our analysis, which is a particle-mesh-based code with a numerical MOND potential solver developed by Ciotti et al. (2006, ApJ, 640, 741) to derive the line-of-sight velocity dispersion by adding the external field effect. We show that Newtonian dynamics predicts a low-velocity dispersion for each cluster, while in modified Newtonian dynamics the velocity dispersion is much higher. We calculate the minimum number of measured stars necessary to distinguish between Newtonian gravity and MOND with the Kolmogorov-Smirnov test. We also show that for most clusters it is necessary to measure the velocities of between 30 to 80 stars to distinguish between both cases. Therefore the observational measurement of the line-of-sight velocity dispersion of these clusters will provide a test for MOND. © 2011 ESO.
Keyword Globular clusters: general
Methods: numerical
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online 21 January, 2011. Article #A33.

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2012 Collection
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Citation counts: TR Web of Science Citation Count  Cited 14 times in Thomson Reuters Web of Science Article | Citations
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Created: Tue, 22 Feb 2011, 15:38:04 EST by Dr Holger Baumgardt on behalf of Physics