Light Curve and Spectral Models for the Hypernova SN 1998bw associated with GRB980425

Takayoshi Nakamura; Paolo A. Mazzali; Ken'ichi Nomoto; Koichi Iwamoto

doi:10.1086/319784

paper

Light Curve and Spectral Models for the Hypernova SN 1998bw associated with GRB980425

arXiv:astro-ph/0007010 · doi:10.1086/319784

Abstract

A refined model for the unusual Type Ic supernova 1998bw, discovered as the optical counterpart of GRB980425, is presented, and synthetic light curves and spectra are compared with the observations. The first 30 days of the light curve and the broad line features of the spectra can be reproduced with the hydrodynamical model of the explosion of a 14 $M_{⊙}$ C+O star, the core of a star with initial mass 40 $M_{⊙}$ , assuming that the explosion was very energetic (kinetic energy $E_{K} = 5 \times 1 0^{52}$ erg) and that 0.4 $M_{⊙}$ of $^{56}$ Ni were synthesized. At late times, however, the observed light curve tail declines more slowly than this energetic model, and is in better agreement with a less energetic ( $E_{K} = 7 \times 1 0^{51}$ erg) one. This shift to a less energetic model may imply that the inner part of the ejecta has higher density and lower velocities than the spherically symmetric model with $E_{K} = 5 \times 1 0^{52}$ erg, so that $γ$ -rays deposit more efficiently. We suggest that an aspherical explosion can produce such a structure of the ejecta. We also study detailed nucleosynthesis calculations for hyper-energetic supernova explosions and compare the yields with those of normal supernovae.

Accepted for publication in ApJ (12 November 2000)

Light Curve and Spectral Models for the Hypernova SN 1998bw associated with GRB980425

Abstract

References in corpus (11)

Cited by in corpus (135)