# Optical Emission from Aspherical Supernovae and the Hypernova SN 1998bw

Source: [Optical Emission from Aspherical Supernovae and the Hypernova SN 1998bw](<https://www.sota2.com/research/paper/68fa28a12c2a3760193c9219>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T12:25:33.175Z

Authors: K. Maeda, P.A. Mazzali, & K. Nomoto

Published: 2005-11-14T12:40:41.000Z

## Abstract

A fully 3D Monte Carlo scheme is applied to compute optical bolometric light curves for aspherical (jet-like) supernova explosion models. Density and abundance distributions are taken from hydrodynamic explosion models, with the energy varied as a parameter to explore the dependence. Our models show initially a very large degree ($\\sim 4$ depending on model parameters) of boosting luminosity toward the polar ($z$) direction relative to the equatorial ($r$) plane, which decreases as the time of peak is approached. After the peak, the factor of the luminosity boost remains almost constant ($\\sim 1.2$) until the supernova enters the nebular phase. This behavior is due mostly to the aspherical $^{56}$Ni distribution in the earlier phase and to the disk-like inner low-velocity structure in the later phase. Also the aspherical models yield an earlier peak date than the spherical models, especially if viewed from near the z-axis. Aspherical models with ejecta mass $\\sim 10\\Msun$ are examined, and one with the kinetic energy of the expansion $\\sim 2 \\pm 0.5 \\times 10^{52}$ ergs and a mass of $^{56}$Ni $\\sim 0.4\\Msun$ yields a light curve in agreement with the observed light curve of SN 1998bw (the prototypical hyper-energetic supernova). The aspherical model is also at least qualitatively consistent with evolution of photospheric velocities, showing large velocities near the z-axis, and with a late-phase nebular spectrum. The viewing angle is close to the z-axis, strengthening the case for the association of SN 1998bw with the gamma ray burst GRB980425.

## Recorded benchmark results

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/astro-ph/0511389>)

[PDF](<https://arxiv.org/pdf/astro-ph/0511389.pdf>)