{
  "id": "1902.08456",
  "version": "v1",
  "published": "2019-02-22T12:12:00.000Z",
  "updated": "2019-02-22T12:12:00.000Z",
  "title": "The Expansion of the Forward Shock of 1E 0102.2-7219 in X-rays",
  "authors": [
    "Long Xi",
    "Terrance J. Gaetz",
    "Paul P. Plucinsky",
    "John P. Hughes",
    "Daniel J. Patnaude"
  ],
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We measure the expansion of the forward shock of the Small Magellanic Cloud supernova remnant 1E\\,0102.2-7219 in X-rays using Chandra X-Ray Observatory on-axis Advanced CCD Imaging Spectromete(ACIS) observations from 1999-2016. We estimate an expansion rate of 0.025%\\pm0.006%yr^{-1} and a blast-wave velocity of 1.61\\pm0.37\\times10^3 km s^{-1}. Assuming partial electron-ion equilibration via Coulomb collisions and cooling due to adiabatic expansion, this velocity implies a postshock electron temperature of 0.84\\pm0.20 keV which is consistent with the estimate of 0.68\\pm0.05 keV based on the X-ray spectral analysis. We combine the expansion rate with the blast wave and reverse shock radii to generate a grid of one-dimensional models for a range of ejecta masses (2-6 \\msol) to constrain the explosion energy, age, circumstellar density, swept-up mass, and unshocked-ejecta mass. We find acceptable solutions for a constant density ambient medium and for an r^{-2} power-law profile (appropriate for a constant progenitor stellar wind). For the constant density case, we find an age of \\sim 1700 yr, explosion energies 0.87-2.61\\times10^{51} erg, ambient densities 0.85-2.54 amu cm^{-3}, swept-up masses 22-66 \\msol, and unshocked-ejecta masses 0.05-0.16 \\msol. For the power-law density profile, we find an age of \\sim 2600 yr, explosion energies 0.34-1.02\\times10^{51} erg, densities 0.22-0.66 amu cm^{-3} at the blast wave, swept-up masses 17-52 \\msol, and unshocked-ejecta masses 0.06-0.18 \\msol. Assuming the true explosion energy was 0.5-1.5\\times10^{51} erg, ejecta masses 2-3.5 \\msol are favored for the constant density case and 3-6 \\msol for the power-law case. The unshocked-ejecta mass estimates are comparable to Fe masses expected in core-collapse supernovae with progenitor mass 15.0-40.0 \\msol, offering a possible explanation for the lack of Fe emission observed in X-rays.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-02-22T12:12:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "forward shock",
      "explosion energy",
      "unshocked-ejecta mass",
      "observatory on-axis advanced ccd",
      "swept-up mass"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}