{
  "id": "2203.03390",
  "version": "v1",
  "published": "2022-03-07T13:47:01.000Z",
  "updated": "2022-03-07T13:47:01.000Z",
  "title": "Multi-line assessment of narrow-line regions in $z \\sim$ 3 radio galaxies",
  "authors": [
    "Koki Terao",
    "Tohru Nagao",
    "Kyoko Onishi",
    "Kenta Matsuoka",
    "Masayuki Akiyama",
    "Yoshiki Matsuoka",
    "Takuji Yamashita"
  ],
  "comment": "17 pages, 10 figures, accepted for publication in the ApJ",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "In this paper, we utilize high-quality rest-UV spectra of three radio galaxies at $z \\sim$ 3 observed with VLT/FORS2 to measure the flux of several emission lines including relatively faint ones, such as NIV]$\\lambda$1486, OIII]$\\lambda$1663, and [NeIV]$\\lambda$2424. Additionally, we collect fluxes of faint rest-UV emission lines in 12 $z \\sim$ 3 radio galaxies from the literature. Previously, physical and chemical properties of narrow-line regions (NLRs) in high-$z$ active galactic nuclei (AGNs) have been investigated mostly by using only strong rest-UV emission-lines (e.g., NV$\\lambda$1240, CIV$\\lambda$1549, HeII$\\lambda$1640, and CIII]$\\lambda$1909). Such strong-line diagnostics are based on various assumptions due to the limitation in the number of available emission-line constraints. In this work, both physical and chemical properties of NLR clouds in each object are estimated by fitting detailed photoionization models to the measured emission-line fluxes. We confirm that the metallicity of NLRs in AGNs at $z \\sim$ 3 is solar or super-solar, without assuming the gas density and ionization parameter thanks to the constrains from the faint emission lines. This result suggests that high-$z$ radio galaxies are already chemically matured at $z \\sim$ 3.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-03-07T13:47:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "radio galaxies",
      "narrow-line regions",
      "multi-line assessment",
      "faint rest-uv emission lines",
      "ionization parameter thanks"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}