This Picture of the Week shows a stunning spiral galaxy known as NGC 4945. This little corner of space, near the constellation of Centaurus and over 12 million light-years away, may seem peaceful at first — but NGC 4945 is locked in a violent struggle.

At the very centre of nearly every galaxy is a supermassive black hole. Some, like the one at the centre of our own Milky Way, aren’t particularly hungry. But NGC 4945’s supermassive black hole is ravenous, consuming huge amounts of matter — and the MUSE instrument at ESO’s Very Large Telescope (VLT) has caught it playing with its food. This messy eater, contrary to a black hole’s typical all-consuming reputation, is blowing out powerful winds of material. This cone-shaped wind is shown in red in the inset, overlaid on a wider image captured with the MPG/ESO telescope at La Silla. In fact, this wind is moving so fast that it will end up escaping the galaxy altogether, lost to the void of intergalactic space.

This is part of a new study that measured how winds move in several nearby galaxies. The MUSE observations show that these incredibly fast winds demonstrate a strange behaviour: they actually speed up far away from the central black hole, accelerating even more on their journey to the galactic outskirts.

This process ejects potential star-forming material from a galaxy, suggesting that black holes control the fates of their host galaxies by dampening the stellar birth rate. It also shows that the more powerful black holes impede their own growth by removing the gas and dust they feed on, driving the whole system closer towards a sort of galactic equilibrium. Now, with these new results, we are one step closer to understanding the acceleration mechanism of the winds responsible for shaping the evolution of galaxies, and the history of the universe.