On Oct. 9, 2022, astronomers recorded an extraordinary flash of high-energy light. This gamma-ray burst (GRB 221009A), nicknamed the “BOAT” (Brightest Of All Time), was the brightest and most energetic cosmic explosion ever witnessed. It came from a galaxy about 2 billion light-years away, and its blast of gamma rays briefly overwhelmed detectors on orbiting satellites. Scientists say such a powerful GRB is extremely rare – roughly a once-in-10,000-year event – and its record-setting nature offers a rare chance to study the death of a star and the physics of these extreme blasts.

Decoding the ‘BOAT’

According to the paper, GRB 221009A was first detected by NASA’s Fermi and Swift spacecraft. Its initial, powerful gamma-ray flash blinded detectors around the world. Its extreme nature marked it out immediately from other GRBs. Though astronomers originally detected the BOAT as an immensely bright flash of high-energy gamma rays, this flash was followed by a fading afterglow across many wavelengths of light, thus allowing non-gamma-ray-based telescopes to study it.

One of the biggest challenges was that the related supernova, SN 2022xiw, was hidden by the brilliance of the GRB and only visible much later. This behaviour highlights how the burst’s huge energy can disguise temporarily the underlying death of the star, making total observation challenging.

Insights on GRBs

Gamma-ray bursts such as this result from the collapse of a star’s core into a black hole. The newly born black hole powers twin beams of particles at nearly the speed of light, breaking through the star and creating the seen gamma rays. GRB 221009A data fit this model but surprise us. Astronomers employed the James Webb Space Telescope to locate the supernova burst but could not detect a hint of heavy elements such as gold or platinum in the debris. Meanwhile, NASA’s Fermi satellite observed an odd gamma-ray line, which is potentially the first unmistakable detection of electrons colliding with positrons (their antimatter counterparts) and annihilating in a GRB jet. These clues are helping researchers refine models of GRBs, stellar collapse, and how heavy elements are forged.