Dynamics and Energy Loss in Superbubbles

TL;DR

This study uses 3D hydrodynamics simulations to analyze the dynamics and energy loss mechanisms in superbubbles, revealing how supernovae influence shell acceleration and energy dissipation, aligning with observations but also highlighting some discrepancies.

Contribution

It introduces detailed 3D simulations with time-resolved energy input to better understand superbubble evolution and energy loss processes.

Findings

Supernova explosions accelerate superbubble shells and cause bright X-ray emission.

Between explosions, superbubbles lose energy efficiently, nearing the momentum-conserving limit.

Radiative losses and instabilities reduce expansion compared to pressure-driven models.

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.