Nucleosynthesis of 56Ni in wind-driven Supernova Explosions and Constraints on the Central Engine of Gamma-Ray Bursts

TL;DR

This paper models wind-driven supernova explosions to understand their properties and how they relate to gamma-ray burst central engines, providing analytical formulations and constraints based on observed supernovae like SN 1998bw.

Contribution

It introduces analytical models for wind/jet-driven supernovae and links explosion characteristics to central engine parameters, explaining observed supernova diversity.

Findings

SN 1998bw likely produced 56Ni in the stellar mantle, not the wind.

Explosion properties depend on energy and mass injection rates.

Constraints on GRB central engines derived from supernova observations.

Abstract

Theoretically expected natures of a supernova 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 (Edot_iso) and the mass injection rate (Mdot_iso). To explain observations of SN 1998bw associated with Gamma-Ray Burst (GRB) 980425, the following conditions are required: Edot_iso Mdot_iso > ~ 10^{51} erg M_sun s^{-2} and Edot_iso > ~ 2 x 10^{52} erg s^{-1} (if the wind Lorentz factor Gamma_w ~ 1) or Edot_iso > ~ 7 x 10^{52} erg s^{-1} (if Gamma_w >> 1). In SN 1998bw, 56Ni (~ 0.4M_sun) is probably produced in the shocked stellar mantle, not in the wind. The expected natures of SNe, e.g., ejected 56Ni masses and ejecta masses, vary depending on Edot_iso and Mdot_iso. The sequence of the SN properties from high Edot_iso and Mdot_iso to low Edot_iso and Mdot_iso is the following: SN 1998bw-like -- intermediate case -- low mass ejecta (< ~ 1M_sun$) where 56Ni is from the wind -- whole collapse. This diversity may explain the diversity of supernovae associated with GRBs. Our result can be used to constrain natures of the wind/jet, which is linked to the central engine of GRBs, by studying properties of the associated supernovae.