Scientists have obtained the best view so far of the most powerful type of cosmic explosion, which happened this time in our cosmological “backyard.” Using the High Energy Stereoscopic System (H.E.S.S.), the research team recorded the most energetic radiation and longest gamma-ray afterglow of a gamma-ray burst (GRB) ever observed. The results challenged the established theory of GRBs. “Gamma-ray bursts are bright X-ray and gamma-ray flashes observed in the sky, emitted by distant extragalactic sources,” said DESY scientist Sylvia Zhu, one of the authors of the paper, in a statement. “They are the biggest explosions in the universe and associated with the collapse of a rapidly rotating massive star to a black hole,” she added. “A fraction of the liberated gravitational energy feeds the production of an ultrarelativistic blast wave. Their emission is divided into two distinct phases: an initial chaotic prompt phase lasting tens of seconds, followed by a …