Optical Emission from Aspherical Core-Collapse Supernovae

Optical emission from supernovae (SNe) reflects physical properties of SNe, such as mass and kinetic energy of the ejecta and the ejected 56Ni mass, which are closely related to the central remnants, explosion scenarios and progenitor stars of SNe. Modelling of the optical emission has been done mostly under the assumption of spherical symmetry. In this paper, we present multidimensional modelling of optical emission using a multi‐dimensional Monte‐Carlo radiative transfer code, SAMURAI (SupernovA MUlti‐dimensional RAdIative transfer code). We show that all the optical observations of SN 1998 bw/GRB 980425, including the light curve and optical spectra at early and late phases, are consistent with polar‐viewed radiation of the aspherical explosion model. The kinetic energy, which has been estimated to be 30–50×1051 ergs by spherical models, can be reduced to 20×1051 ergs. Such reduction of the kinetic energy is less effective for off‐axis or less aspherical cases. As an observational test of SN asphericit...