How radiation affects superbubbles: Through momentum injection in early phase and photo-heating thereafter

Abstract

Energetic winds and radiation from massive star clusters push the surrounding gas and blow superbubbles in the interstellar medium (ISM). Using 1-D hydrodynamic simulations, we study the role of radiation in the dynamics of superbubbles driven by a young star cluster of mass $10^6$ M${}_{\odot }$. We have considered a realistic time evolution of the mechanical power as well as radiation power of the star cluster, and detailed heating and cooling processes. We find that the ratio of the radiation pressure on the shell (shocked ISM) to the thermal pressure ($\sim 10^7$ K) of the shocked wind region is almost independent of the ambient density, and it is greater than unity before $\lesssim 1$ Myr. We explore the parameter space of density and dust opacity of the ambient medium, and find that the size of the hot gas ($\sim$ 10${}^7$ K) cavity is insensitive to the dust opacity (${\sigma }_d\approx (0.1-1.5)\times 10^{-21}$ cm${}^2$), but the structure of the photoionized ($\sim 10^4$ K) gas depends on it. Most of the radiative losses occur at $\sim 10^4$ K, with sub-dominant losses at $\lesssim 10^3$ K and $\sim 10^6-10^8$ K. The superbubbles can retain as high as $\sim 10\%$ of its input energy, for an ambient density of $10^{3}m{}_{\mathrm{H}}\mathrm{c}{\mathrm{m}}^{-3}$. We discuss the role of ionization parameter and recombination-averaged density in understanding the dominant feedback mechanism. Finally, we compare our results with the observations of 30 Doradus.

19 pages, 20 figures, 1 table; Accepted for publication in MNRAS; Added references and appendix; Comments welcome

References in corpus (5)

• PLUTO: a Numerical Code for Computational Astrophysics
• The Dynamics of Radiation Pressure-Dominated HII Regions
• Inefficient star formation through turbulence, magnetic fields and feedback
• A Detailed Study of Feedback from a Massive Star
• On the impact of radiation pressure on the dynamics and inner structure of dusty wind-driven shells

Cited by in corpus (7)

• The molecular cloud lifecycle
• Gas expulsion vs gas retention: what process dominates in young massive clusters?
• Catastrophic Cooling in Superwinds: Line Emission and Non-equilibrium Ionization
• The Global Star-Formation Law by Supernova Feedback
• Lack of thermal energy in superbubbles: hint of cosmic rays?
• Momentum and energy injection by a supernova remnant into an inhomogeneous medium
• An Alternative Explanation of the Varying Boron to Carbon in Galactic Cosmic rays