{
  "id": "0903.4683",
  "version": "v1",
  "published": "2009-03-26T20:13:40.000Z",
  "updated": "2009-03-26T20:13:40.000Z",
  "title": "Dissolution is the solution: on the reduced mass-to-light ratios of Galactic globular clusters",
  "authors": [
    "J. M. Diederik Kruijssen",
    "Steffen Mieske"
  ],
  "comment": "17 pages, 10 figures, 6 tables; paper accepted for publication in A&A",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The observed dynamical mass-to-light (M/L) ratios of globular clusters (GCs) are systematically lower than those expected from `canonical' simple stellar population models, which do not account for the preferential loss of low-mass stars due to energy equipartition. It was recently shown that low-mass star depletion can qualitatively explain the M/L discrepancy. To verify whether it is indeed the driving mechanism, we derive dissolution timescales and use these to predict the M/L_V ratios of the 24 Galactic GCs for which orbital parameters and dynamical M/L_V are known. We also predict the slopes of their low-mass stellar mass functions (MFs). We use the SPACE cluster models, which include dynamical dissolution, low-mass star depletion, stellar evolution, stellar remnants and various metallicities. The predicted M/L_V are in 1 sigma agreement with the observations for 12 out of 24 GCs. The discrepancy for the other GCs probably arises because our predictions give global M/L ratios, while the observations represent extrapolated central values that are different from global ones in case of mass segregation and a long dissolution timescale. GCs in our sample which likely have dissimilar global and central M/L ratios can be excluded by imposing limits on the dissolution timescale and King parameter. For the remaining GCs, the observed and predicted average M/L_V are 78^+9_-11% and 78+/-2% of the canonically expected values, while for the entire sample the values are 74^+6_-7% and 85+/-1%. The predicted correlation between the slope of the low-mass stellar MF and M/L_V is qualitatively consistent with observed MF slopes. It is concluded that the variation of M/L ratio due to dissolution and low-mass star depletion is a plausible explanation for the discrepancy between the observed and canonically expected M/L ratios of GCs. (Abridged)",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-03-26T20:13:40.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "galactic globular clusters",
      "reduced mass-to-light ratios",
      "low-mass star depletion",
      "m/l ratio",
      "represent extrapolated central values"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1051/0004-6361/200811453",
      "journal": "Astronomy and Astrophysics",
      "year": 2009,
      "month": "Jun",
      "volume": 500,
      "number": 2,
      "pages": 785
    },
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 816407,
      "adsabs": "2009A&A...500..785K"
    }
  }
}