{
  "id": "2203.01365",
  "version": "v1",
  "published": "2022-03-02T19:19:35.000Z",
  "updated": "2022-03-02T19:19:35.000Z",
  "title": "The Dark Matter Halo of M54",
  "authors": [
    "Raymond G. Carlberg",
    "Carl J. Grillmair"
  ],
  "comment": "AAS submitted",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "M54 is a prototype of a globular cluster embedded in a dark matter halo. Gaia EDR3 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 dark matter halo. The Jeans analysis of the three separate stellar populations give consistent masses that rise approximately linearly with radius to 1 kpc, implying a small core or cuspy halo. These data are compatible with an infalling CDM dark matter halo reduced to 3x10^8 M_sun 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 sensitively on the time of accretion and orbital pericenter.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-03-02T19:19:35.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "globular cluster",
      "velocity dispersion",
      "infalling cdm dark matter halo",
      "metal poor stars dominate",
      "younger dwarf galaxy stars"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}