However, things are not so peaceful in all galaxies

 However, things are not so peaceful in all galaxies

When pairs of galaxies pull on each other via gravity, many stars may end up tugged too close to their galaxy's black hole. This ends badly for the stars: they are torn apart and devoured.

We are confident this must have happened in galaxies with black holes that weigh as much as a billion suns, because we can't imagine how else they could have grown so large. It may also have happened in the Milky Way in the past.

Black holes can also feed in a slower, more gentle way: by sucking in clouds of gas blown out by geriatric stars known as red giants.

Feeding time

In our new study, we looked closely at the feeding process among the 5,000 fastest-growing black holes in the universe