{
  "id": "2106.09737",
  "version": "v1",
  "published": "2021-06-17T18:00:04.000Z",
  "updated": "2021-06-17T18:00:04.000Z",
  "title": "Luminous Late-time Radio Emission from Supernovae Detected by the Karl G. Jansky Very Large Array Sky Survey (VLASS)",
  "authors": [
    "M. C. Stroh",
    "G. Terreran",
    "D. L. Coppejans",
    "J. S. Bright",
    "R. Margutti",
    "M. F. Bietenholz",
    "F. De Colle",
    "L. DeMarchi",
    "R. Barniol Duran",
    "D. Milisavljevic",
    "K. Murase",
    "K. Paterson",
    "W. L. Williams"
  ],
  "comment": "17 pages, 4 figures, 1 table",
  "categories": [
    "astro-ph.HE",
    "astro-ph.SR"
  ],
  "abstract": "We present a population of 20 radio-luminous supernovae (SNe) with emission reaching $L_{\\nu}{\\sim}10^{26}-10^{29}\\rm{erg s^{-1} Hz^{-1}}$ in the first epoch of the Very Large Array Sky Survey (VLASS) at $2-4$ GHz. Our sample includes one long Gamma-Ray Burst, SN 2017iuk/GRB171205A, and 19 core-collapse SNe detected at $\\approx (1-60)$ years after explosion. No thermonuclear explosion shows evidence for bright radio emission, and hydrogen-poor progenitors dominate the sub-sample of core-collapse events with spectroscopic classification at the time of explosion (73%). We interpret these findings into the context of the expected radio emission from the forward shock interaction with the circumstellar medium (CSM). We conclude that these observations require a departure from the single wind-like density profile (i.e., $\\rho_{\\rm{CSM}}\\propto r^{-2}$) that is expected around massive stars and/or a departure from a spherical Newtonian shock. Viable alternatives include the shock interaction with a detached, dense shell of CSM formed by a large effective progenitor mass-loss rate $\\dot M \\sim (10^{-4}-10^{-1})$ M$_{\\odot}$ yr$^{-1}$ (for an assumed wind velocity of $1000\\,\\rm{km\\,s^{-1}}$); emission from an off-axis relativistic jet entering our line of sight; or the emergence of emission from a newly-born pulsar-wind nebula. The relativistic SN\\,2012ap that is detected 5.7 and 8.5 years after explosion with $L_{\\nu}{\\sim}10^{28}$ erg s$^{-1}$ Hz$^{-1}$ might constitute the first detections of an off-axis jet+cocoon system in a massive star. Future multi-wavelength observations will distinguish among these scenarios. Our VLASS source catalogs, which were used to perform the VLASS cross matching, are publicly available at https://doi.org/10.5281/zenodo.4895112.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-06-17T18:00:04.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "large array sky survey",
      "luminous late-time radio emission",
      "effective progenitor mass-loss rate",
      "supernovae",
      "shock interaction"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}