Scientists solve mystery of 'Brightest explosion of all time'

First detected accidentally by US military satellites in the late 1960s, cosmic explosions known as gamma ray bursts (GRBs) have come to be understood as the brightest explosions in the universe. Typically, they are the result of the cataclysmic birth of a black hole in a distant galaxy.

One way this can happen is through the collapse of a single, massive star. Astronomers such as myself working in the field are well aware of the massive energy scales involved in GRBs. We know they can release as much energy in gamma rays as the Sun does throughout its lifetime.

But every once in a while, an event is observed that still gives us pause. In October 2022, gamma-ray detectors on the orbital satellites Fermi and the Neil Gehrels Swift Observatory noted a burst known as GRB 221009A (the date of detection). This quickly turned out to be a record-setter. It was dubbed the Brightest Of All Time, or the “Boat”, as convenient shorthand among astronomers studying and observing the event. Not only did the Boat start out bright, it refused to fade away like other bursts. We still do not fully know why the burst was so exceptionally bright, but our new study, published in Science Advances, provides an answer for its stubborn persistence.