Speaker
Description
Short Gamma-ray burst (sGRBa) are linked to the merger of compact objects. However the GRB 200826A is peculiar because by definition it was a SGRB, with a rest-frame duration of ∼ 0.5 s, but this event was energetic and soft, which is consistent with long GRBs (LGRBs) associated with the end states of very massive stars. The relatively low redshift (z=0.75) motivated a multi-wavelength follow-up campaign to understand the origin of this burst. To this aim we obtained a combination of deep near-infrared (NIR) imaging in adaptive optics, coupled with optical imaging and spectroscopy. Our analysis reveals an optical and NIR bump in the light curve whose luminosity and evolution is in agreement with several LGRB-SNe. It is not compatible with both theoretical models of kilonovae (KNe) and with AT2017gfo, the KNa associated with the gravitational wave signal GW 170817. Analysis of the prompt GRB shows that this event follows the Amati relation found for LGRBs. The host galaxy is a low-mass star-forming galaxy, typical for LGRBs, but with one of the highest specific star-formation rates. We conclude that GRB 200826A is a typical collapsar event in the low tail of the duration distribution of LGRBs.
ADS link: https://ui.adsabs.harvard.edu/abs/2021arXiv210503829R/abstract
