Astronomers believe they have solved a long-standing puzzle over why supermassive black holes at the centre of galaxies never run out of "fuel" despite blasting away the very gas they need to grow. An international team led by Julie Hlavacek-Larrondo of the University of Montreal used the James Webb Space Telescope to observe the galaxy NGC 4696, confirming that gas heated and expelled by black hole jets eventually cools, condenses into thread-like filaments, and falls back towards the black hole in a self-sustaining recycling cycle.

Using around eight hours of observation with JWST's NIRSpec instrument, the team achieved a resolution fine enough to distinguish structures just 30 light-years across in the galaxy, located roughly 145 million light-years from Earth. They found that a previously observed S-shaped spiral around the black hole is in fact a rotating gas disc some 800 light-years wide, with gas moving at several hundred kilometres per second, and that filaments of cooled gas flow directly into this disc before ultimately feeding the black hole. Computer simulations further suggested that stretched magnetic fields act like ropes, stripping angular momentum from the infalling gas to help it spiral inward, offering the first direct visualisation of this complete feeding pathway.