{
  "id": "2001.10547",
  "version": "v1",
  "published": "2020-01-28T19:00:02.000Z",
  "updated": "2020-01-28T19:00:02.000Z",
  "title": "Outflows and extended [CII] halos in high redshift galaxies",
  "authors": [
    "Elia Pizzati",
    "Andrea Ferrara",
    "Andrea Pallottini",
    "Simona Gallerani",
    "Livia Vallini",
    "Davide Decataldo",
    "Seiji Fujimoto"
  ],
  "comment": "13 pages, 7 figures; submitted to MNRAS",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "Recent stacked ALMA observations have revealed that normal, star-forming galaxies at $z\\approx 6$ are surrounded by extended ($\\approx 10\\,\\mathrm{kpc}$) [CII] emitting halos which are not predicted by the most advanced, zoom-in simulations. We present a model in which these halos are the result of supernova-driven cooling outflows. Our model contains two free parameters, the outflow mass loading factor, $\\eta$, and the parent galaxy dark matter halo circular velocity, $v_c$. The outflow model successfully matches the observed [CII] surface brightness profile if $\\eta = 3.20 \\pm 0.10$ and $v_c = 170 \\pm 10{\\,\\rm km\\,s^{-1}}$, corresponding to a dynamical mass of $\\approx 10^{11}\\, \\mathrm{M}_\\odot$. The predicted outflow rate and velocity range are $128 \\pm 5 \\,\\mathrm{M}_\\odot {\\rm yr}^{-1}$ and $300-500 {\\,\\rm km\\,s^{-1}}$, respectively. We conclude that: (a) extended halos can be produced by cooling outflows; (b) the large $\\eta$ value is marginally consistent with starburst-driven outflows, but it might indicate additional energy input from AGN; (c) the presence of [CII] halos requires an ionizing photon escape fraction from galaxies $f_{\\rm esc} \\ll 1$. The model can be readily applied also to individual high-$z$ galaxies, as those observed, e.g., by the ALMA ALPINE survey now becoming available.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-01-28T19:00:02.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "high redshift galaxies",
      "galaxy dark matter halo circular",
      "parent galaxy dark matter halo",
      "dark matter halo circular velocity"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 13,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}