{
  "id": "1002.1220",
  "version": "v1",
  "published": "2010-02-05T16:37:53.000Z",
  "updated": "2010-02-05T16:37:53.000Z",
  "title": "Mass Segregation in the Galactic Centre",
  "authors": [
    "Clovis Hopman",
    "Ann-Marie Madigan"
  ],
  "comment": "Proceedings article to be published in \"The Galactic Center: A Window on the Nuclear Environment of Disk Galaxies\", ed. Mark Morris, Daniel Q. Wang and Feng Yuan",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Two-body energy exchange between stars orbiting massive black holes (MBHs) leads to the formation of a power-law density distribution n(r)~r^(-a) that diverges towards the MBH. For a single mass population, a=7/4 and the flow of stars is much less than N(<r)/t_r (enclosed number of stars per relaxation time). This \"zero-flow\" solution is maintained for a multi-mass system for moderate mass ratios or systems where there are many heavy stars, and slopes of 3/2<a<2 are reached, with steeper slopes for the more massive stars. If the heavy stars are rare and massive however, the zero-flow limit breaks down and much steeper distributions are obtained. We discuss the physics driving mass-segregation with the use of Fokker-Planck calculations, and show that steady state is reached in 0.2-0.3 t_r. Since the relaxation time in the Galactic centre (GC) is t_r ~2-3 * 10^(10) yr, a cusp should form in less than a Hubble time. The absence of a visible cusp of old stars in the GC poses a challenge to these models, suggesting that processes other than two-body relaxation have played a role. We discuss astrophysical processes within the GC that depend crucially on the details of the stellar cusp.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2010-02-05T16:37:53.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "galactic centre",
      "mass segregation",
      "heavy stars",
      "relaxation time",
      "power-law density distribution"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 845122,
      "adsabs": "2011ASPC..439..180H"
    }
  }
}