At the heart of nearly every large galaxy lurks a supermassive black hole. As it devours gas, it blasts powerful outflows back into space, like a dragon that can't swallow all its prey and breathes fire. These 'winds' accelerate to thousands of kilometers per second and can sweep away the gas reservoirs from which stars are born.
The James Webb Space Telescope peered into two merging galaxies — F11119+3257 and F05189-2524. Both shine brightly in the infrared due to intense star formation and active galactic nuclei. Its medium-resolution spectrograph detected neon emission lines blueshifted to 4000 km/s — about 10 times faster than a bullet. In F05189-2524, the outflow expands in two cones stretching about 2 kiloparsecs (6,500 light-years) from the center.
Molecular hydrogen, the fuel for star formation, has nearly vanished in the central region (within 1 kiloparsec of the nucleus). The winds appear to blow it away, preventing new stars from igniting. Yet the outflows themselves don't drag along much molecular gas; they act more like a broom sweeping dust than a bulldozer. The energy of these winds is enough to explain why galaxies eventually 'fall asleep' and stop building stars. In this way, the central black hole governs the life of its entire stellar island.
The gas outflow speed in these galaxies is 13 times the speed of sound in air on Earth.
In Dan Simmons' novel 'Hyperion', black holes and their radiation influence the fates of entire planets — much like these winds shape galaxies.