||The Origin of Excess X-Ray Emission in Two LMC Superbubbles
||438, The Dynamic Interstellar Medium: A Celebration of the Canadian Galactic Plane Survey
||Jaskot, A. E.; Strickland, D. K.; Oey, M. S.; Chu, Y.-H.
||Superbubbles significantly alter the structure and makeup of the
ISM by adding energy and heavy elements, shaping large-scale HI
shells, and generating the high-temperature component of the ISM,
the hot ionized medium. Understanding the origin of the hot, X-ray
emitting gas and superbubbles’ energy input complements studies of
neutral ISM phases and HI structures revealed by the CGPS and is
critical for ISM evolution and thermal phase balance in the ISM.
We present Chandra ACIS-S observations of two X-ray bright
LMC superbubbles, DEM L50 and DEM L152, in order to constrain the
energy generated through various mechanisms. About 20% of
DEM L50's luminosity comes from the bright southern rim,
supporting an origin in an off-center supernova remnant, while
the remainder of the emission likely comes from thermal conduction
from the shell walls. DEM L50 appears to have an unusually low
α/Fe ratio, which may reflect local ISM conditions. In
DEM L152, ∼ 80% of emission comes from the limb-brightened
central and western bubble regions, while knots in the blowout
region contribute less than 3% of the X-ray luminosity. Our
observations suggest that impulsive shock heating from supernova
activity rather than ablation of ISM inhomogeneities accounts
for the unexpected X-ray brightness of these superbubbles.