Monte Carlo simulations of fast Newtonian and mildly relativistic shock breakout from a stellar wind

Hirotaka Ito*, Amir Levinson, Ehud Nakar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Strong explosion of a compact star surrounded by a thick stellar wind drives a fast (>0.1c) radiation mediated shock (RMS) that propagates in the wind, and ultimately breaks out gradually once photons start escaping from the shock transition layer. In exceptionally strong or aspherical explosions, the shock velocity may even be relativistic. The properties of the breakout signal depend on the dynamics and structure of the shock during the breakout phase. Here we present, for the first time, spectra and light curves of the breakout emission of fast Newtonian and mildly relativistic shocks, that were calculated using self-consistent Monte Carlo simulations of finite RMS with radiative losses. We find a strong dependence of the νFν peak on shock velocity, ranging from ∼1 keV for vs/c = 0.1 to ∼100 keV for vs/c = 0.5, with a shift to lower energies as losses increase. For all cases studied the spectrum below the peak exhibits a nearly flat component (Fν ∼ν0) that extends down to the break frequency below which absorption becomes important. This implies much bright optical/ultraviolet emission than hitherto expected. The computed light curves show a gradual rise over tens to hundreds of seconds for representative conditions. The application to SN 2008D/XRT 080109 and the detectability limits are also discussed. We predict a detection rate of about one per year with eROSITA.

Original languageEnglish
Pages (from-to)4961-4971
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - 1 Dec 2020


  • radiative transfer
  • shock waves
  • transients: supernovae


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