Multi-Dimensional Simulations of Radiative Transfer in Aspherical Core-Collapse Supernovae

TL;DR

This paper introduces a multi-dimensional Monte Carlo radiative transfer code to analyze optical signals from aspherical supernovae, enabling verification of supernova shape and explosion properties through observations.

Contribution

The authors developed SAMURAI, a novel multi-dimensional radiative transfer code that models optical light curves and spectra of aspherical supernovae at various phases.

Findings

Optical observations of SN 1998bw are consistent with an aspherical explosion viewed from the polar direction.

The code successfully reproduces early and late phase spectra and light curves.

Properties of off-axis hypernovae are briefly discussed.

Abstract

We study optical radiation of aspherical supernovae (SNe) and present an approach to verify the asphericity of SNe with optical observations of extragalactic SNe. For this purpose, we have developed a multi-dimensional Monte-Carlo radiative transfer code, SAMURAI (SupernovA MUlti-dimensional RAdIative transfer code). The code can compute the optical light curve and spectra both at early phases (<~ 40 days after the explosion) and late phases (~ 1 year after the explosion), based on hydrodynamic and nucleosynthetic models. We show that all the optical observations of SN 1998bw (associated with GRB 980425) are consistent with polar-viewed radiation of the aspherical explosion model with kinetic energy 20 x 10^{51} ergs. Properties of off-axis hypernovae are also discussed briefly.