{
  "id": "1507.05656",
  "version": "v1",
  "published": "2015-07-20T21:07:54.000Z",
  "updated": "2015-07-20T21:07:54.000Z",
  "title": "Beyond the Halo: Redefining environment with unbound matter in N-body simulations",
  "authors": [
    "Genevieve M. Shattow",
    "Darren J. Croton"
  ],
  "comment": "14 pages, 9 Figures, Accepted MNRAS",
  "journal": "Monthly Notices of the Royal Astronomical Society 2015 452 (2): 1779-1791",
  "doi": "10.1093/mnras/stv1464",
  "categories": [
    "astro-ph.CO"
  ],
  "abstract": "Approximately half of the matter in the Universe is \"unbound\" at z = 0, according to N-body simulations such as the Millennium Run. Here, we use the milli-Millennium simulation to examine the distribution of unbound matter in relation to the dark matter halos which host galaxies. We measure the unbound matter within two types of windows, using a halo dependent radius and a fixed radius at several different scales. We also consider the timescales over which a halo can accrete the local unbound matter at z = 2 and z = 0. Finally, we compare the unbound matter to observable properties of galaxies, such as local galaxy count environment and stellar mass. We find that halos at z = 2 can accrete far more of the nearby unbound matter over a Hubble time than halos at z = 0 and that 78% of particles within 5 $R_{vir}$ of a halo at z = 2 will be accreted by z = 0, compared to 36% of particles within 5 $h^{-1}$ Mpc of the halo. We also find that galaxy count environment is closely related to the amount of nearby unbound matter when measured on the same scale.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-07-20T21:07:54.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "n-body simulations",
      "redefining environment",
      "nearby unbound matter",
      "local galaxy count environment",
      "local unbound matter"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1384084
    }
  }
}