Supernova remnants in the Magellanic Clouds. IV. X-ray emission from the largest supernova remnant in the Large Magellanic Cloud

R. M. Williams, Y. H. Chu, J. R. Dickel, R. A. Gruendl, R. Shelton, S. D. Points, R. C. Smith

Research output: Contribution to journalArticlepeer-review


We present the first X-ray detection of SNR 0450-70.9, the largest known supernova remnant (SNR) in the Large Magellanic Cloud. To study the physical conditions of this SNR, we have obtained XMM-Newton X-ray observations, optical images and high-dispersion spectra, and radio continuum maps. Optical images of SNR 0450-70.9 show a large, irregular elliptical shell with bright filaments along the eastern and western rims and within the shell interior. The interior filaments have higher [S II]/Hα ratios and form an apparent inner shell morphology. The X-ray emission region is smaller than the full extent of the optical shell, with the brightest X-ray emission found within the small interior shell and on the western rim of the large shell. The expansion velocity of the small shell is ·220 km s-1, while that of the large shell is ·120 km s-1. The radio image shows central brightening and a fairly flat radio spectral index over the SNR. However, no point X-ray or radio source corresponding to a pulsar is detected, and the X-ray emission is predominantly thermal. Therefore, these phenomena can be most reasonably explained in terms of the advanced age of the large SNR. Using hydrodynamic models combined with a nonequilibrium ionization model for thermal X-ray emission, we derived a lower limit on the SNR age of ·45,000 yr, well into the later stages of SNR evolution. Despite this, the temperature and density derived from spectral fits to the X-ray emission indicate that the renmant is still overpressured and thus that the development is largely driven by hot gas in the SNR interior.

Original languageEnglish (US)
Pages (from-to)948-955
Number of pages8
JournalAstrophysical Journal
Issue number2 I
StatePublished - Oct 1 2004

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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