At the center of an ultra-compact dwarf galaxy, a very dense stellar system spanning tens of light-years, there is a vacuum cleaner at work. But instead of dust, it sucks in gas shed by dying stars. This gas does not fly off in all directions; instead, it spirals into a funnel, a rotating disk that gradually settles onto the black hole.

For a long time, it was unclear whether an intermediate-mass black hole (from 100 to 100,000 solar masses) could grow into a massive one from such gas. Astrophysicists built a model in which hundreds of aging stars eject material at speeds of 10–20 km/s. It turned out that the gas does not escape: the black hole's gravity captures it and twists it into a disk. Within 0.188 million years, 481.7 solar masses of gas accumulated within just 0.1 parsecs.

But the vacuum cleaner has an enemy: the birth of new stars. When gas in the disk compresses too densely, it ignites into young stars. These stars trap the gas and gravitationally disturb the disk, sometimes completely destroying it. Therefore, the black hole's growth is not infinite: part of the fuel is consumed in new stars.

The calculations showed that for 12 of the 17 observed ultra-compact dwarfs with massive black holes, the initial mass could have been in the intermediate range. This means that the vacuum cleaner can indeed turn a modest black hole into a giant.

The model gives observers a concrete clue: such systems should contain young stars with high velocities and elevated nitrogen abundances. If they are found, the mechanism will be confirmed. The vacuum cleaner at the center of a dwarf will become not a hypothesis but a working scheme.