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The Dark Matter Halo of M54

Carlberg, Raymond G. and Grillmair, Carl J. (2022) The Dark Matter Halo of M54. Astrophysical Journal, 935 (1). Art. No. 14. ISSN 0004-637X. doi:10.3847/1538-4357/ac7d54.

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M54 is a prototype for a globular cluster embedded in a dark matter halo. Gaia Early Data Release 3 photometry and proper motions separate the old, metal-poor stars from the more metal-rich and younger dwarf galaxy stars. The metal-poor stars dominate the inner 50 pc, with a velocity dispersion profile that declines to a minimum around 30 pc then rises back to nearly the central velocity dispersion, as expected for a globular cluster at the center of a cold dark matter (CDM) cosmology dark matter halo. The Jeans equation mass analysis of the three separate stellar populations gives consistent masses that rise approximately linearly with radius to 1 kpc. These data are compatible with an infalling CDM dark matter halo reduced to ≃3 × 10⁸ M_⊙ at the 50 kpc apocenter 2.3 Gyr ago, with a central globular cluster surrounded by the remnant of a dwarf galaxy. Tides gradually remove material beyond 1 kpc but have little effect on the stars and dark matter within 300 pc of the center. M54 appears to be a “transitional” system between globular clusters with and without local dark halos whose evolution within the galaxy depends on the time of accretion and orbital pericenter.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Carlberg, Raymond G.0000-0002-7667-0081
Grillmair, Carl J.0000-0003-4072-169X
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2022 March 2; revised 2022 June 28; accepted 2022 June 28; published 2022 August 9. 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 Galaxy; Dark matter
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Globular star clusters (656); Milky Way Galaxy (1054); Dark matter (353)
Record Number:CaltechAUTHORS:20220810-402887000
Persistent URL:
Official Citation:Raymond G. Carlberg and Carl J. Grillmair 2022 ApJ 935 14
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116225
Deposited By: George Porter
Deposited On:12 Aug 2022 02:07
Last Modified:12 Aug 2022 02:07

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