Evolution of clustered supernovae

Abstract

We study the merging and evolution of isolated supernovae (SNe) remnants in a stellar cluster into a collective superbubble, with the help of 3-D hydrodynamic simulations. We particularly focus on the transition stage when the isolated SNe remnants gradually combine to form a superbubble. We find that when the SN rate is high (${\nu }_{\mathrm{sn}}\sim 10^{-9}$ pc${}^{-3}$ yr${}^{-1}$), the merging phase lasts for $\sim 10^4$ yr, for $n=1–10$ cm${}^{-3}$, and the merging phase lasts for a longer time ($\sim 0.1$ Myr or more) for lower SN rates (${\nu }_{\mathrm{sn}}\le 10^{-10}$ pc${}^{-3}$ yr${}^{-1}$). During this transition phase, the growing superbubble is filled with dense and cool fragments of shells and most of the energy is radiated away during this merging process. After passing through the intermediate phase, the superbubble eventually settles on to a new power-law wind asymptote that is smaller than estimated in a continuous wind model. This results in a significant (more than {\it several times}) underestimation of the mechanical luminosity needed to feed the bubble. We determine the X-ray and H$\alpha$ surface brightnesses as functions of time for such merging SNe in a stellar cluster and find that clusters with high SN rate shine predominantly in soft X-rays and H$\alpha$. In particular, a low value of the volume averaged H$\alpha$ to H$\beta$ ratio and its large spread can be a good indicator of the transition phase of merging SNe.

15 pages, 15 figures, accepted to MNRAS

References in corpus (5)

• How multiple supernovae overlap to form superbubbles
• Complexes of triggered star formation in supergiant shell of Holmberg II
• Numerical comparison of Riemann solvers for astrophysical hydrodynamics
• On physical and numerical instabilities arising in simulations of non-stationary radiatively cooling shocks
• 3D Spectroscopy of Blue Compact Galaxies. Diagnostic Diagrams

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• Numerical studies on the link between radioisotopic signatures on Earth and the formation of the Local Bubble. II. Advanced modeling of interstellar 26Al, 53Mn, 60Fe, and 244Pu influxes as traces of past supernovae in the solar neighborhood
• Lack of thermal energy in superbubbles: hint of cosmic rays?
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• On the relationship between metallicity distributions of globular clusters and of circumgalactic gas
• Velocity Dispersion and H$\alpha$ emission of Ionized Gas in Star-forming Regions
• Impact of the external radiation field on the structure and evolution of supernova remnants
• Tracking Dusty Cloud Crushed by a Hot Flow
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• Interstellar Medium in Extremely High Star-Formation Regions: A Prospect of Observations on the Millimetron Space Observatory
• Indicatives of Early Stages of Star Formation in the Universe