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B.C. Dunne, S.D. Points, Y.-H. Chu (UIUC)
Superbubbles are large (~100 pc across) shells in the interstellar medium (ISM) created by the combined action of stellar winds and supernova explosions of massive stars in an OB association. The hot (106 K) shock-heated gas interior to superbubbles emits X-ray radiation. X-ray observations of superbubbles can reveal a wealth of information on the structure and interior of superbubbles.
We present ROSAT PSPC observations of 12 superbubbles in the Large Magellanic Cloud (LMC). For this sample, diffuse X-ray emission is detected in each superbubble in excess of the predictions of the Weaver et al. model. This excess diffuse X-ray emission indicates the presence of interior supernova remnants (SNRs) shocking the inner walls of the superbubble shell. Furthermore, the diffuse X-ray emission can also be used to find ``breakout'' regions where the hot gas from the superbubble interior may be leaking out into the ISM. Unresolved peaks superposed on the diffuse X-ray emission may also indicate the presence of stellar X-ray sources interior to the superbubble.
We compare the superbubble volume, H\alpha luminosity, expansion velocity, and OB star count with the X-ray luminosity for our sample. We find that the X-ray luminosity is positively correlated with each of these parameters. The correlation is weakest for expansion velocity, moderate for volume and H\alpha luminosity, and strongest for OB star count.
The author(s) of this abstract have provided an email address for comments about the abstract: carolan@astro.uiuc.edu