A Statistical Study of the Gamma-Ray Burst and Supernova Association

TL;DR

This study compares long gamma-ray bursts with and without supernova associations, revealing that those without supernovae may originate from different progenitors and have distinct event rates aligned with star formation.

Contribution

It provides a comparative analysis of LGRBs with and without supernovae, highlighting potential differences in their progenitors and event rates.

Findings

LGRBs without SN association have event rates matching star formation.

SN-associated LGRBs show different event rate patterns.

Some long bursts may originate from binary mergers, not core-collapse SNe.

Abstract

The association between long gamma-ray bursts (LGRBs) and core-collapse supernovae (SNe) has been well established since the discovery of SN 1998bw, which was linked to the low-luminosity LGRB 980425. However, long-term monitoring of several well-localized, low-redshift LGRBs has yielded compelling evidence for the absence of accompanying SNe. Notably, two long bursts, GRB 211211A and GRB 230307A, show signatures consistent with kilonova emission from compact binary mergers, indicating that at least some long events may originate from progenitors other than core-collapse SNe. In this study, we conduct a comparative analysis of two samples of LGRBs, i.e., LGRBs with and without SN associations, to investigate the differences that may reveal intrinsic distinctions in their progenitors. A detailed examination of their prompt emission properties, host galaxy environments, and event rates is performed. While the two samples exhibit considerable overlap in most observed properties, a significant discrepancy in their event rate is revealed. LGRBs without SN association have an event rate that aligns well with the star formation rate, whereas that of SN-associated LGRBs differs significantly. It indicates that LGRBs without an SN association may constitute a distinct subclass with intrinsically different progenitors.