A Peculiarly Short-duration Gamma-Ray Burst from Massive Star Core Collapse

TL;DR

This paper analyzes GRB 200826A, a short-duration gamma-ray burst with properties indicating a massive star core collapse origin, challenging the traditional duration-based classification of GRBs.

Contribution

It provides evidence for a short GRB originating from stellar core collapse, highlighting limitations of duration-based classification and suggesting the need for multi-wavelength criteria.

Findings

GRB 200826A has a 1-second duration with properties similar to long GRBs.

Its spectral and energetic characteristics differ from typical short GRBs.

The burst's features support a core-collapse origin despite its short duration.

Abstract

Gamma-ray bursts (GRBs) have been phenomenologically classified into long and short populations based on the observed bimodal distribution of duration. Multi-wavelength and multi-messenger observations in recent years have revealed that in general long GRBs originate from massive star core collapse events, whereas short GRBs originate from binary neutron star mergers. It has been known that the duration criterion is sometimes unreliable, and multi-wavelength criteria are needed to identify the physical origin of a particular GRB. Some apparently long GRBs have been suggested to have a neutron star merger origin, whereas some apparently short GRBs have been attributed to genuinely long GRBs whose short, bright emission is slightly above the detector's sensitivity threshold. Here we report the comprehensive analysis of the multi-wavelength data of a bright short GRB 200826A. Characterized by a sharp pulse, this burst shows a duration of 1 second and no evidence of an underlying longer-duration event. Its other observational properties such as its spectral behaviors, total energy, and host galaxy offset, are, however, inconsistent with those of other short GRBs believed to originate from binary neutron star mergers. Rather, these properties resemble those of long GRBs. This burst confirms the existence of short duration GRBs with stellar core-collapse origin, and presents some challenges to the existing models.