Why the brightest gamma-ray burst ever looks bluer than expected

Nguyen M. Khang, Gavin P. Lamb, Helena-M. S. Grabham, Conor M. B. Omand, Hamid Hamidani, Andrew J. Levan, Nial R. Tanvir, Valerio D'Elia, Luca Izzo

GRB 221009A, the brightest gamma-ray burst on record, was obscured by dust that made its true color hard to pin down. New infrared and optical spectra from JWST and the Very Large Telescope show the burst is bluer than typical, with extreme dust absorption. The data suggest particles are accelerated more efficiently than physics predicts, and the jet's core is narrow and unusually energetic.