Light Curves from Supernova Shock Breakout through an Extended Wind

TL;DR

This paper improves the modeling of supernova light curves by using Monte Carlo simulations to account for deviations from diffusion approximation in extended winds, revealing significant differences from previous models.

Contribution

It introduces a Monte Carlo approach to accurately simulate photon transfer in supernovae with extended winds, surpassing the limitations of diffusion approximation.

Findings

Monte Carlo simulations show significant deviations from diffusion approximation in extended winds.

Flux-limited diffusion approximation often produces qualitatively incorrect results.

Extended winds require more careful treatment of radiation transfer for accurate light curve modeling.

Abstract

Recent observations suggest that some supernovae may be the result of an explosion into an optically thick circumstellar material, the product of pre-explosion mass-loss (wind) by the progenitor star. This scenario has been studied previously both analytically and numerically. However, many previous studies base their analysis on the diffusion approximation for radiation transfer, which is inappropriate in the optically thin outer layers of the wind. Here we study the deviations from diffusion, and calculate light curves more accurately using a Monte Carlo approach to photon transfer. We distinguish between "compact" winds, for which the diffusion approximation is appropriate, and "extended" winds, which require a more delicate treatment of the radiation. We show that this effect is more significant than that of the light travel time difference to a distant observer, which has a secondary influence on the light curves of extended-wind systems. We also comment on the applicability of the widely used flux-limited diffusion approximation in this context: we find that it generally does not reproduce the Monte Carlo results. The flux-limited diffusion approximation leads to results which are not only quantitatively, but also qualitatively wrong, in the extended-wind regime.