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 fransfer code, SAMURAI (SupemovA MUlti-dimensional RAdlative fransfer code). We show that all the optical observations of SN 1998bw/GRB 980425, including the light curve and optical specfra 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 × 10 ⁵¹ ergs by spherical models, can be reduced to 20 × 10 ⁵¹ ergs. Such reduction of the kinetic energy is less effective for offaxis or less aspherical cases. As an observational test of SN asphericity, we also show our recent specfropolarimetric observations of Type Ic SN 2007gr with Subaru telescope. The data clearly indicate the difference in the distribution of the newly synthesized elements and the elements in the pre-explosion star