It confused me too. At first I thought it meant that a collection of matter became dense enough to form an event horizon and become a black hole. Instead, fro

It confused me too. At first I thought it meant that a collection of matter became dense enough to form an event horizon and become a black hole. Instead, from https://www.livescience.com/space/black-holes/gargantuan-black-hole-switches-on-becoming-one-of-the-brightest-objects-ever-seen https://www.livescience.com/space/black-holes/gargantuan-bla... > If J221951 is indeed a supermassive black hole, its sudden burst of brightness has two possible explanations, according to the researchers. First, the black hole could have pulled an orbiting star into its clutches, stretching and tearing the star to shreds in a messy process called a tidal disruption event or "spaghettification." The second, more mysterious possibility is that the black hole could have shifted states from dormant to actively feeding, as it suddenly began gorging on the fast-moving disk of gas that surrounds it.