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