The Expansion of the Forward Shock of 1E 0102.2-7219 in X-Rays

Long Xi, Terrance J. Gaetz, Paul P. Plucinsky, John P. Hughes, Daniel J. Patnaude

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10 Scopus citations


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 Spectrometer observations from 1999 to 2016. We estimate an expansion rate of 0.025% ± 0.006% yr -1 and a blast wave velocity of (1.61 ± 0.37) × 10 3 km s -1 . Assuming partial electron-ion equilibration via Coulomb collisions and cooling due to adiabatic expansion, this velocity implies a post-shock electron temperature of 0.84 ± 0.20 keV, which is consistent with the estimate of 0.68 ± 0.05 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 M ) 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 ∼1700 yr, explosion energies (0.87-2.61) ×10 51 erg, ambient densities 0.85-2.54 amu cm -3 , swept-up masses , and unshocked-ejecta masses . For the power-law density profile, we find an age of ∼2600 yr, explosion energies (0.34-1.02) ×10 51 erg, densities at the blast wave, swept-up masses , and unshocked-ejecta masses . Assuming that the true explosion energy was (0.5-1.5) ×10 51 erg, ejecta masses are favored for the constant-density case and 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 M , offering a possible explanation for the lack of Fe emission observed in X-rays.

Original languageEnglish (US)
Article number14
JournalAstrophysical Journal
Issue number1
StatePublished - Mar 20 2019

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • ISM: supernova remnants
  • X-rays: ISM
  • X-rays: individual (1E 0102.2-7219)
  • shock waves


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