Dynamics and Energy Loss in Superbubbles

Abstract

Interstellar bubbles appear to be smaller in observations than expected from calculations. Instabilities at the shell boundaries create three-dimensional ef- fects, and are probably responsible for part of this discrepancy. We investigate instabilities and dynamics in superbubbles by 3D hydrodynamics simulations with time-resolved energy input from massive stars, including the supernova explosions. We find that the superbubble shells are accelerated by supernova explosions, coincident with substantial brightening in soft X-ray emission. In between the explosions, the superbubbles lose energy efficiently, approaching the momentum-conserving snowplow limit. This and enhanced radiative losses due to instabilities reduce the expansion compared to the corresponding radiative bubbles in pressure-driven snowplow models with constant energy input. We note generally good agreement with observations of superbubbles and some open issues. In particular, there are hints that the shell velocities in the X-ray-bright phases is underpredicted.

16 pages, 5 figures, accepted by ApJ letters

References in corpus (5)

• The History and Future of the Local and Loop I Bubbles
• Feedback by massive stars and the emergence of superbubbles II. X-ray properties
• Multi-dimensional models of circumstellar shells around evolved massive stars
• A Cosmic Ray Resolution to the Superbubble Energy-Crisis
• Model of the expansion of H II region RCW 82

Cited by in corpus (2)

• 26Al kinematics: superbubbles following the spiral arms? Constraints from the statistics of star clusters and HI supershells
• The non-thermal superbubble in IC 10: the generation of cosmic ray electrons caught in the act