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Testing for Dark Matter in the Outskirts of Globular Clusters

Carlberg, Raymond G. and Grillmair, Carl J. (2021) Testing for Dark Matter in the Outskirts of Globular Clusters. Astrophysical Journal, 922 (2). Art. No. 104. ISSN 0004-637X. doi:10.3847/1538-4357/ac289f.

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The proper motions of stars in the outskirts of globular clusters are used to estimate cluster velocity dispersion profiles as far as possible within their tidal radii. We use individual color–magnitude diagrams to select high-probability cluster stars for 25 metal-poor globular clusters within 20 kpc of the Sun, 19 of which have substantial numbers of stars at large radii. Of the 19, 11 clusters have a falling velocity dispersion in the 3–6 half-mass radii range, 6 are flat, and 2 plausibly have a rising velocity dispersion. The profiles are all in the range expected from simulated clusters that started at high redshift in a zoom-in cosmological simulation. The 11 clusters with falling velocity dispersion profiles are consistent with no dark matter above the Galactic background. The six clusters with approximately flat velocity dispersion profiles could have local dark matter, but are ambiguous. The two clusters with rising velocity dispersion profiles are consistent with a remnant local dark matter halo, but need membership confirmation and detailed orbital modeling to further test these preliminary results.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Carlberg, Raymond G.0000-0002-7667-0081
Grillmair, Carl J.0000-0003-4072-169X
Additional Information:© 2021. The American Astronomical Society. Received 2021 June 1; revised 2021 September 7; accepted 2021 September 19; published 2021 November 24. This research was supported by NSERC of Canada.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:Globular star clusters; Milky Way dark matter halo
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Globular star clusters (656); Milky Way dark matter halo (1049)
Record Number:CaltechAUTHORS:20211203-204702838
Persistent URL:
Official Citation:Raymond G. Carlberg and Carl J. Grillmair 2021 ApJ 922 104
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112214
Deposited By: George Porter
Deposited On:03 Dec 2021 22:49
Last Modified:03 Dec 2021 22:49

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