{
  "id": "2406.19439",
  "version": "v1",
  "published": "2024-06-27T18:00:00.000Z",
  "updated": "2024-06-27T18:00:00.000Z",
  "title": "Gas conditions of a star-formation selected sample in the first billion years",
  "authors": [
    "Tom J. L. C. Bakx",
    "Hiddo S. B. Algera",
    "Bram Venemans",
    "Laura Sommovigo",
    "Seiji Fujimoto",
    "Stefano Carniani",
    "Masato Hagimoto",
    "Takuya Hashimoto",
    "Akio K. Inoue",
    "Dragan Salak",
    "Stephen Serjeant",
    "Livia Vallini",
    "Stephen Eales",
    "Andrea Ferrara",
    "Yoshinobu Fudamoto",
    "Chihiro Imamura",
    "Shigeki Inoue",
    "Kirsten K. Knudsen",
    "Hiroshi Matsuo",
    "Yuma Sugahara",
    "Yoichi Tamura",
    "Akio Taniguchi",
    "Satoshi Yamanaka"
  ],
  "comment": "20 pages; 13 figures; accepted for publication in MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present Atacama Large Millimetre/submillimetre Array (ALMA) observations of the [O$_{\\rm III}$] 88 $\\mu$m emission of a sample of thirteen galaxies at $z$ = 6 to 7.6 selected as [C$_{\\rm II}$]-emitting companion sources of quasars. To disentangle the origins of the luminous Oxygen line in the $z$ > 6 Universe, we looked at emission-line galaxies that are selected through an excellent star-formation tracer [C$_{\\rm II}$] with star-formation rates between 9 and 162 M$_{\\odot}$/yr. Direct observations reveal [O$_{\\rm III}$] emission in just a single galaxy (L$_{\\rm [O_{\\rm III}]}$/L$_{\\rm [C_{\\rm II}]}$ = 2.3), and a stacked image shows no [O$_{\\rm III}$] detection, providing deep upper limits on the L$_{\\rm [O_{\\rm III}]}$/L$_{\\rm [C_{\\rm II}]}$ ratios in the $z > 6$ Universe (L$_{\\rm [O_{\\rm III}]}$/L$_{\\rm [C_{\\rm II}]}$ < 1.2 at 3${\\sigma}$). While the fidelity of this sample is high, no obvious optical/near-infrared counterpart is seen in the JWST imaging available for four galaxies. Additionally accounting for low-redshift CO emitters, line stacking shows that our sample-wide result remains robust: The enhanced L$_{\\rm [O_{\\rm III}]}$/L$_{\\rm [C_{\\rm II}]}$ reported in the first billion years of the Universe is likely due to the selection towards bright, blue Lyman-break galaxies with high surface star-formation rates or young stellar populations. The deep upper limit on the rest-frame 90 $\\mu$m continuum emission (< 141 $\\mu$Jy at 3${\\sigma}$), implies a low average dust temperature (T$_{\\rm dust}$ < 30K) and high dust mass (M$_{\\rm dust}$ ~ 10$^8$ M$_{\\odot}$). As more normal galaxies are explored in the early Universe, synergy between JWST and ALMA is fundamental to further investigate the ISM properties of the a broad range of samples of high-$z$ galaxies.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-06-27T18:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "star-formation selected sample",
      "first billion",
      "gas conditions",
      "deep upper limit",
      "high surface star-formation rates"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 20,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}