Flash in space: An artist’s view of a gamma-ray burst. Credit: DESY, Science Communication Lab Using the H.E.S.S. observatory, researchers at GRB 190829A observe unusual features that challenge models. Researchers from the H.E.S.S. Collaboration succeeded to derive the intrinsic spectrum of the very-high-energy gamma-ray afterglow emission of a relatively nearby gamma-ray burst. Surprisingly, the gamma-ray spectrum resembles that of the much lower-energy X-rays, while the fading emission from both bands was observed to march in parallel over three nights. These remarkable findings challenge the current emission scenarios. Gamma-ray bursts (GRBs) are bright X-ray and gamma-ray flashes observed in the sky, emitted by distant extragalactic sources. They are associated with the creation or merging of neutron stars or black holes; processes that result in an explosive outburst of material moving incredibly close to the speed of light. The initial flashes, which last a few seconds, are...