{
  "id": "2310.07257",
  "version": "v1",
  "published": "2023-10-11T07:33:56.000Z",
  "updated": "2023-10-11T07:33:56.000Z",
  "title": "A survey of SiO $J=$ 1 -- 0 emission toward massive star-forming regions",
  "authors": [
    "W. -J. Kim",
    "J. S. Urquhart",
    "V. S. Veena",
    "G. A. Fuller",
    "P. Schilke",
    "K-T Kim"
  ],
  "comment": "23 pages, 16 figures, accepted for A&A for publication",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "The application of silicon monoxide (SiO) as a shock tracer arises from its propensity to occur in the gas phase as a result of shock-induced phenomena, including outflow activity and interactions between molecular clouds and expanding HII regions or supernova remnants. We searched for indications of shocks toward 366 massive star-forming regions by observing the ground rotational transition of SiO ($v=0$, $J=1-0$) at 43 GHz with the Korean VLBI Network (KVN) 21 m telescopes to extend our understanding on the origins of SiO in star-forming regions. We detected SiO emission toward 104 regions that consist of 57 IRDCs, 21 HMPOs, and 26 UCHIIs. The determined median SiO column density, $N$(SiO), and abundance, $X$(SiO), relative to $N$(H$_2$) are $8.12\\times10^{12}$ cm$^{-2}$ and $1.28\\times10^{-10}$, respectively. These values are similar to those obtained toward other star-forming regions and also consistent with predicted values from shock models with low-velocity shocks ($\\lesssim$10 - 15 km s$^{-1}$). While the $X$(SiO) does not exhibit any strong correlation with the evolutionary stages of their host clumps, $L_{\\rm SiO}$ is highly correlated with dust clump mass, and $L_{\\rm SiO}/L_{\\rm bol}$ also has a strong negative correlation with $T_{\\rm dust}$. This shows that colder and younger clumps have high $L_{\\rm SiO}/L_{\\rm bol}$ suggestive of an evolutionary trend. This trend is not due to excess emission at higher velocities, such as SiO wing features, as the colder sources with high $L_{\\rm SiO}/L_{\\rm bol}$ ratios lack wing features. Comparing SiO emission with H$_2$O and Class I CH$_3$OH masers, we find a significant correlation between $L_{\\rm SiO}$/$L_{\\rm bol}$ and $L_{\\rm CH_3OH}/L_{\\rm bol}$ ratios, whereas no similar correlation is seen for the H$_2$O maser emission. This suggests a similar origin for the SiO and Class I CH$_3$OH emission in these sources.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-10-11T07:33:56.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "massive star-forming regions",
      "correlation",
      "sio emission",
      "determined median sio column density",
      "ratios lack wing features"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 23,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}