Nucleosynthesis of 56Ni in wind-driven supernova explosions and constraints on the central engine of gamma-ray bursts |
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| Authors: | Keiichi Maeda Nozomu Tominaga |
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| Institution: | Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, Kashiwano-ha 5-1-5, Kashiwa-shi, Chiba 277-8568, Japan;Division of Optical and Infrared Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan |
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| Abstract: | Theoretically expected natures of a supernova (SN) driven by a wind/jet are discussed. Approximate analytical formulations are derived to clarify basic physical processes involved in the wind/jet-driven explosions, and it is shown that the explosion properties are characterized by the energy injection rate  and the mass injection rate  . To explain observations of Supernova 1998bw associated with gamma-ray burst (GRB) 980425, the following conditions are required:  and  (if the wind Lorentz factor Γw∼ 1 ) or  (if Γw≫ 1 ). In Supernova 1998bw, 56Ni (∼0.4 M⊙) is probably produced in the shocked stellar mantle, not in the wind. The expected natures of SNe, e.g. ejected 56Ni mass and ejecta mass, vary depending on  and  . The sequence of the SN properties from high  and  to low  and  is as follows: Supernova 1998bw-like – intermediate case – low mass ejecta (≲1 M⊙) where 56Ni is from the wind – whole collapse. This diversity may explain the diversity of SNe associated with GRBs. Our result can be used to constrain natures of the wind/jet, which are linked to the central engine of GRBs, by studying properties of the associated SNe. |
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| Keywords: | nuclear reactions nucleosynthesis abundances supernovae: general supernovae: individual: SN 1998bw gamma-ray: bursts |
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