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Observational and theoretical evidence have identified two different origin for the gamma-ray bursts (GRBs): the death of very massive stars or the merger of compact objects. The evidence for massive star explosions is indicated by the observed association with type Ic broad line supernovae, while the association with kilonovae indicates a merger origin. GRBs are also classified as long and short events and long GRBs (LGRBs) are often observed in association with collapsar GRBs. This happens so frequently that the classification as long or short GRBs is commonly interpreted as synonym of a massive star or merger origin. In this context the peculiar short GRB 200826A at redshift z=0. 7486, with a rest-frame duration of 0. 5 s, goes against this common interpretation. The relatively low redshift motivated multi-wavelength follow-up campaign to search for a possible associated supernova (SN), and thus understand the origin of this burst. To this aim we obtained a combination of deep near-infrared (NIR) and optical imaging. Our analysis reveals an optical and NIR bump in the light curve whose luminosity and evolution are in agreement with several with those of several LGRB-SNe. We conclude that GRB 200826A is a typical collapsar event in the low tail of the duration distribution of LGRBs. These findings support theoretical predictions that events produced by massive star explosions can be as short as 0. 5 s in the host frame and further confirm that duration alone is not an efficient discriminator for the progenitor class of a GRB.
Rossi et al. (Mon,) studied this question.