Cheng-Kui Li

In October 2022, the space-based detector GECAM-C caught the most powerful gamma-ray burst ever seen, GRB 221009A — an explosion that briefly became the brightest source of gamma rays in the sky. But the most interesting part came after: the instrument detected a series of additional flares, and one of them was record-breaking.

The Einstein Probe space telescope detected a celestial storm: after a short (0.4-second) gamma-ray burst — a cosmic lightning bolt — came a long roll of X-ray thunder. It lasted nearly 10 minutes. This is the first direct proof that such explosions leave a lingering X-ray afterglow.

An avalanche in a sandpile starts with a single grain. No one knows exactly where it will slip or how big the slide will be. But if you keep pouring sand, the pile itself reaches a state where avalanches of all sizes, from tiny trickles to massive collapses, follow the same law.