{
  "id": "2104.07231",
  "version": "v1",
  "published": "2021-04-15T04:24:44.000Z",
  "updated": "2021-04-15T04:24:44.000Z",
  "title": "Studying Infall in Infrared Dark Clouds with Multiple HCO+ Transitions",
  "authors": [
    "Jinjin Xie",
    "Jingwen Wu",
    "Gary A. Fuller",
    "Nicolas Peretto",
    "Zhiyuan Ren",
    "Longfei Chen",
    "Yaoting Yan",
    "Guodong Li",
    "Yan Duan",
    "Jifeng Xia",
    "Yongxiong Wang",
    "Di Li"
  ],
  "comment": "22 pages, 14 figures, accepted by RAA",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "We investigate the infall properties in a sample of 11 infrared dark clouds (IRDCs) showing blue-asymmetry signatures in HCO$^{+}$ J=1--0 line profiles. We used JCMT to conduct mapping observations in HCO$^{+}$ J=4--3 as well as single-pointing observations in HCO$^{+}$ J =3--2, towards 23 clumps in these IRDCs. We applied the HILL model to fit these observations and derived infall velocities in the range of 0.5-2.7 km s$^{-1}$, with a median value of 1.0 km s$^{-1}$, and obtained mass accretion rates of 0.5-14$\\times$10$^{-3}$ Msun yr$^{-1}$. These values are comparable to those found in massive star forming clumps in later evolutionary stages. These IRDC clumps are more likely to form star clusters. HCO$^{+}$ J =3--2 and HCO$^{+}$ J =1--0 were shown to trace infall signatures well in these IRDCs with comparable inferred properties. HCO$^{+}$ J=4--3, on the other hand, exhibits infall signatures only in a few very massive clumps, due to smaller opacties. No obvious correlation for these clumps was found between infall velocity and the NH3/CCS ratio.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-04-15T04:24:44.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "infrared dark clouds",
      "studying infall",
      "transitions",
      "infall velocity",
      "form star clusters"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 22,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}