Astronomers spot dying radio galaxies revealing what happens when black holes shut down

When a supermassive black hole ceases its feeding, the cosmos does not announce the moment — it simply grows quieter, over millions of years. Astronomers have now identified 12 remnant radio galaxies in the XMM–LSS field, structures whose vast plasma lobes are slowly dimming in the long aftermath of their engines switching off. The discovery, made using three of the world's most powerful radio telescope arrays, reveals that these fading phases last between 8 and 42 million years — younger and briefer than previously known — suggesting that an entire chapter of galactic life has been hiding in