{
  "id": "1903.07619",
  "version": "v1",
  "published": "2019-03-18T18:00:00.000Z",
  "updated": "2019-03-18T18:00:00.000Z",
  "title": "Correlation Between Mass Segregation and Structural Concentration in Relaxed Stellar Clusters",
  "authors": [
    "Ruggero de Vita",
    "Michele Trenti",
    "Morgan MacLeod"
  ],
  "comment": "9 pages, 3 figures, 2 tables; Accepted for publication in MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The level of mass segregation in the core of globular clusters has been previously proposed as a potential indicator of the dynamical constituents of the system, such as presence of a significant population of stellar-mass black holes (BHs), or even a central intermediate-mass black hole (IMBH). However, its measurement is limited to clusters with high-quality Hubble Space Telescope data. Thanks to a set of state-of-the-art direct N-body simulations with up to 200k particles inclusive of stellar evolution, primordial binaries, and varying BH/neutron stars, we highlight for the first time the existence of a clear and tight linear relation between the degree of mass segregation and the cluster structural concentration index. The latter is defined as the ratio of the radii containing 5% and 50% of the integrated light ($R_5/R_\\mathrm{50}$), making it robustly measurable without the need to individually resolve low-mass stars. Our simulations indicate that given $R_5/R_\\mathrm{50}$, the mass segregation $\\Delta m$ (defined as the difference in main sequence median mass between center and half-light radius) is expressed as $\\Delta m/M_\\odot = -1.166 R_5/R_\\mathrm{h} + 0.3246$, with a root-mean-square error of $0.0148$. In addition, we can explain its physical origin and the values of the fitted parameters through basic analytical modeling. Such correlation is remarkably robust against a variety of initial conditions (including presence of primordial binaries and IMBHs) and cluster ages, with a slight dependence in best-fit parameters on the prescriptions used to measure the quantities involved. Therefore, this study highlights the potential to develop a new observational tool to gain insight on the dynamical status of globular clusters and on its dark remnants.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-03-18T18:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "mass segregation",
      "relaxed stellar clusters",
      "correlation",
      "central intermediate-mass black hole",
      "main sequence median mass"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}