{
  "id": "2301.07023",
  "version": "v1",
  "published": "2023-01-17T17:14:14.000Z",
  "updated": "2023-01-17T17:14:14.000Z",
  "title": "Dynamical signature of a stellar bulge in a quasar host galaxy at $z\\simeq 6$",
  "authors": [
    "Roberta Tripodi",
    "Federico Lelli",
    "Chiara Feruglio",
    "Fabrizio Fiore",
    "Fabio Fontanot",
    "Manuela Bischetti",
    "Roberto Maiolino"
  ],
  "comment": "8 pages, 4 figures, 3 tables. Accepted by A&A",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present a dynamical analysis of a quasar-host galaxy at $z\\simeq 6$ (SDSS J2310+1855) using a high-resolution ALMA observation of the [CII] emission line. The observed rotation curve is fitted with mass models that consider the gravitational contribution of a thick gas disc, a thick star-forming stellar disc, and a central mass concentration, likely due to a combination of a spheroidal component (i.e. a stellar bulge) and a supermassive black hole (SMBH). The SMBH mass of $5\\times 10^9\\ \\rm M_{\\odot}$, previously measured using the CIV and MgII emission lines, is not sufficient to explain the high velocities in the central regions. Our dynamical model suggests the presence of a stellar bulge with a mass of $\\rm M_{bulge}\\sim 10^{10}\\ \\rm M_{\\odot}$ in this object, when the Universe was less than 1 Gyr old. To end up on the local $M_{\\rm SMBH}-M_{\\rm bulge}$ relation, the bulge mass should increase by a factor of $\\sim$40 from $z=6$ to 0, while the SMBH mass should grow at most by a factor of 4, pointing to asynchronous galaxy-BH co-evolution. Imaging with JWST will allow us to validate this scenario.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-01-17T17:14:14.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "quasar host galaxy",
      "stellar bulge",
      "dynamical signature",
      "smbh mass",
      "mgii emission lines"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}