Astronomers using ALMA studied a cataclysmic stellar explosion known as a gamma-ray burst, or GRB, and found its enduring “afterglow.” The rebound, or reverse shock, triggered by the GRB’s powerful jets slamming into surrounding debris, lasted thousands of times longer than expected. These observations provide fresh insights into the physics of GRBs, one of the universe’s most energetic explosions.

Credit: NRAO/AUI/NSF; S. Dagnello