{
  "id": "1611.00002",
  "version": "v1",
  "published": "2016-10-31T20:00:00.000Z",
  "updated": "2016-10-31T20:00:00.000Z",
  "title": "ALMA observations of the dense and shocked gas in the nuclear region of NGC 4038 (Antennae galaxies)",
  "authors": [
    "Junko Ueda",
    "Yoshimasa Watanabe",
    "Daisuke Iono",
    "David J. Wilner",
    "Giovanni G. Fazio",
    "Satoshi Ohashi",
    "Ryohei Kawabe",
    "Toshiki Saito",
    "Shinya Komugi"
  ],
  "comment": "10 pages, 5 figures, 1 table. Accepted for publication in PASJ",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present 1\" (<100 pc) resolution maps of millimeter emission from five molecules-CN, HCN, HCO+, CH3OH, and HNCO-obtained towards NGC 4038, which is the northern galaxy of the mid-stage merger, Antennae galaxies, with the Atacama Large Millimeter/submillimeter Array. Three molecules (CN, CH3OH, and HNCO) were detected for the first time in the nuclear region of NGC 4038. High-resolution mapping reveals a systematic difference in distributions of different molecular species and continuum emission. Active star forming regions identified by the 3 mm and 850 um continuum emission are offset from the gas-rich region associated with the HCN (1-0) and CO (3-2) peaks. The CN (1-0)/HCN (1-0) line ratios are enhanced (CN/HCN = 0.8-1.2) in the star forming regions, suggesting that the regions are photon dominated. The large molecular gas mass (10^8 Msun) within a 0.6\" (~60 pc) radius of the CO (3-2) peak and a high dense gas fraction (>20 %) suggested by the HCN (1-0)/CO (3-2) line ratio may signify a future burst of intense star formation there. The shocked gas traced in the CH3OH and HNCO emission indicates sub-kpc scale molecular shocks. We suggest that the molecular shocks may be driven by collisions between inflowing gas and the central massive molecular complex.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-10-31T20:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "shocked gas",
      "nuclear region",
      "antennae galaxies",
      "alma observations",
      "sub-kpc scale molecular shocks"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}