Gamma-Ray Burst/Supernova Associations: Energy partition and the case of a magnetar central engine

TL;DR

This study analyzes multi-wavelength data of GRB/SN associations to understand energy partition and the potential role of magnetars as central engines, revealing correlations and energy distribution patterns.

Contribution

It provides a systematic analysis of 20 GRB/SN systems, confirming correlations and suggesting magnetars as plausible central engines for most but not all cases.

Findings

SN peak brightness and Ni mass are higher in GRB-associated SNe.

A significant correlation exists between GRB peak energy and SN brightness.

Most systems have total energy below the magnetar maximum energy, supporting magnetar central engine hypothesis.

Abstract

The favored progenitor model for Gamma-ray Bursts (GRBs) with Supernova (SN) association is the core collapse of massive stars. One possible outcome of such a collapse is a rapidly spinning, strongly magnetized neutron star ("magnetar"). We systematically analyze the multi-wavelength data of GRB/SN associations detected by several instruments before 2017 June. Twenty GRB/SN systems have been confirmed via direct spectroscopic evidence or a clear light curve bump, as well as some spectroscopic evidence resembling a GRB-SN. We derive/collect the basic physical parameters of the GRBs and the SNe, and look for correlations among these parameters. We find that the peak brightness, $\rm ^{56}Ni$ mass, and explosion energy of SNe associated with GRBs are statistically higher than other Type Ib/c SNe. A statistically significant relation between the peak energy of GRBs and the peak brightness of their associated SNe is confirmed. No significant correlations are found between the GRB energies (either isotropic or beaming-corrected) and the supernova energy. We investigate the energy partition within these systems and find that the beaming-corrected GRB energy of most systems is smaller than the SN energy, with less than 30\% of the total energy distributed in the relativistic jet. The total energy of the systems is typically smaller than the maximum available energy of a millisecond magnetar ($2\times 10^{52}$ erg), especially if aspherical SN explosions are considered. The data are consistent with-though not a proof of-the hypothesis that most, but not all, GRB/SN systems are powered by millisecond magnetars.