Light Curve and Spectral Models for the Hypernova SN 1998bw Associated with GRB 980425

By Takayoshi Nakamura, P. Mazzali, Ken'ichi Nomoto, K. Iwamoto. 2000

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A refined model for the unusual Type Ic supernova 1998bw, discovered as the optical counterpart to GRB 980425, 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 hydrodynamic 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 EK = 5 × 1052 ergs) and that 0.4 M☉ of 56Ni 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 (EK = 7 × 1051 ergs) 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 model with EK = 5 × 1052 ergs, so that γ-rays deposit more efficiently. An aspherical explosion can produce such a structure of the ejecta. We also study detailed nucleosynthesis calculations for hyperenergetic supernova explosions and compare the yields with those of normal supernovae.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/2d19eb6d4438100a1929f450307b99ac9edacfba

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Citations in the corpus

• The Observer's Guide to the Gamma-Ray Burst-Supernova Connection (2016, background): “As mentioned in the previous section, modelling of the late-time bolometric LC of SN 1998bw [9, 117, 214, 275] showed that some degree of asymmetry in the explosion is required to explain its decay behaviour (see as well Figure 10).”
• Dust in the Early Universe: Dust Formation in the Ejecta of Population III Supernovae (2003, background): “Also, the analysis of the light curve of SN 1998bw (Nakamura et al. 2001) led to the conclusion that the mass of 56Ni in the ejecta is 0.4M , which is larger than the typical value of 0.07M in the ejecta of ordinary CCSNe.”
• The Type Ic Hypernova SN 2003dh/GRB 030329 (2003, methodology): “32 M, models for SN 1998bw ( : Nakamura et al. 2001;0.4–0.7M, Iwamoto et al. 1998) and the mixing more extensive.”
• Supernova Nucleosynthesis in Population III 13-50 M☉ Stars and Abundance Patterns of Extremely Metal-poor Stars (2007, background): “The observed HNe have variations of the ejected Fe mass. Case A corresponds to typical HNe like SN 1998bw, which ejected M (56Ni) 0:4 M (Nakamura et al. 2001a), and case B corresponds to HNe like SN 1997ef, which ejected M (56Ni) 0:15 M ( Iwamoto et al. 2000; Mazzali et al. 2000).”
• A Two-Component Model for the Light Curves of Hypernovae (2003, methodology): “Nomoto et al. (2001) and Nakamura et al. (2001) then showed that, while the early light curve of SN 1998bw requires a high-energy model, the late-time light curve is well reproduced by a lower energy model with a smaller 56Ni mass, which is, however, too dim at early phases.”
• The death of massive stars – I. Observational constraints on the progenitors of Type II-P supernovae (2008, methodology): “More sophisticated radiative transfer modelling with Monte Carlo techniques (for example, Nakamura et al. 2001; Mazzali et al. 2007; Dessart et al. 2011) has been used to determine also the kinetic energy from the velocity information in the spectra.”
• The Unique Type Ib Supernova 2005bf at Nebular Phases: A Possible Birth Event of a Strongly Magnetized Neutron Star (2007, background): “For comparison, τγ ∼ 0.02−0.06 for SN 1998bw at t = 300d (Mej ∼ 10M⊙, E51 ∼ 20− 50: Maeda, Mazzali, & Nomoto 2006b; Nakamura et al. 2001a).”
• The Type Ic Hypernova SN 2002ap (2002, result): “In order to achieve a rapid rise of the light curve, and in particular to reproduce the earliest bolometric point on day 2, we had to mix56Ni out to high velocities, resulting in a local concentration of56Ni very close to the surface, as in the best-fit model for SN 1998bw (Nakamura et al. 2001).”
• Explosive Nucleosynthesis in Aspherical Hypernova Explosions and Late-Time Spectra of SN 1998bw (2000, methodology): “(2) Incomplete Si-burning and O-burning regions are more extended for larger explosion energies (Nakamura et al. 2001b).”
• Mass fall-back and accretion in the central engine of gamma-ray bursts (2008, unknown): “(47) For our canonical model, we estimate the total energy carried away by the wind to be 2 × 1052 erg, which is not dissimilar to the estimated explosion energy in hypernovae associated with GRBs (e.g. Nakamura et al. 2001; Mazzali et al. 2003).”
• Physical Properties of Wolf-Rayet Stars (2006, background): “Nevertheless, the light curves of broad-lined Type Ic supernovae – SN 1998bw, SN 2003dh and SN 2003lw – suggest ejected core masses of order 10M⊙ (Nakamura et al. 2001; Mazzali et al. 2003; Malesani et al. 2004).”
• The sub-energetic γ-ray burst GRB 031203 as a cosmic analogue to the nearby GRB 980425 (2004, background): “This discussion motivates the question: How are these two events related to cosmological GRBs? It has been suggested (see, for example, ref”