{
  "id": "2206.11904",
  "version": "v1",
  "published": "2022-06-23T18:00:00.000Z",
  "updated": "2022-06-23T18:00:00.000Z",
  "title": "A tentative $\\sim$1000 km s$^{-1}$ offset between the [CII] 158 $μ$m and Ly$α$ line emission in a star-forming galaxy at $z = 7.2$",
  "authors": [
    "R. Baier-Soto",
    "R. Herrera-Camus",
    "N. M. Förster Schreiber",
    "A. Contursi",
    "R. Genzel",
    "D. Lutz",
    "L. Tacconi"
  ],
  "comment": "Accepted for publication in Astronomy & Astrophysics Letters, 8 pages, 6 figures",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "GN-108036 is a star-forming galaxy at $z=7.21$, and one of the most distant known sources in the Northern hemisphere. Based on observations from the NOrthern Extended Millimeter Array (NOEMA), here we report the tentative detection of the [CII] line at $\\approx4\\sigma$ significance. The integrated [CII] line emission is spatially offset about $\\sim4$ kpc from the rest-frame ultraviolet (UV) emission. The total [CII] luminosity ($L_{\\rm [CII]}=2.7\\times10^8~L_{\\odot}$) is consistent with the relation between [CII] luminosity and star formation rate (SFR) observed in nearby and high-$z$ star forming galaxies. More interestingly, the [CII] line is blueshifted with respect to the Ly$\\alpha$ line by $980\\pm10$ km s$^{-1}$. If confirmed, this corresponds to the largest velocity offset reported to date between the Ly$\\alpha$ line and a non-resonant line at $z\\gtrsim6$. According to trends observed in other high redshift galaxies, the large Ly$\\alpha$ velocity offset in GN-108036 is consistent with its low Ly$\\alpha$ equivalent width and high UV absolute magnitude. Based on Ly$\\alpha$ radiative transfer models of expanding shells, the large Ly$\\alpha$ velocity offset in GN-108036 could be interpreted as the presence of a large column density of hydrogen gas, and/or an outflow with a velocity of $v_{\\rm out}\\sim\\Delta v_{\\rm Ly \\alpha}/2\\sim500$ km s$^{-1}$. We also report the 3$\\sigma$ detection of a potential galaxy companion located $\\sim30$ kpc east of GN-108036, at a similar systemic velocity, and with no counterpart rest-frame UV emission.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-06-23T18:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "line emission",
      "star-forming galaxy",
      "high uv absolute magnitude",
      "counterpart rest-frame uv emission",
      "similar systemic velocity"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}