A supermassive black hole started feasting on surrounding matter resulting in one of the most dramatic "switching on" events ever seen.
Transients are astronomical events or objects that change in brightness over short periods of time, and the one powered by this greedy black hole — J221951 — is one of the brightest transients ever recorded. The position of the black hole corresponds with the center of a previously observed galaxy, just where a supermassive black hole would be expected to sit. However, astronomers still aren't sure exactly what is causing the transient event witnessed in J221951 .
