Nucleosynthesis of 56Ni in wind-driven supernova explosions and constraints on the central engine of gamma-ray bursts

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. © 2009 RAS.