Galactic winds are powerful streams of gas that are blown out of galaxies, carrying away material at high speeds. These winds are driven primarily by two major energy sources: supernova explosions from massive stars and activity from supermassive black holes at the centers of galaxies, known as active galactic nuclei (AGN). Both processes inject enormous amounts of energy into a galaxy’s interstellar medium, heating the gas and accelerating it to escape velocities that allow it to stream into intergalactic space.
Supernova-driven galactic winds are most common in galaxies that are rapidly forming stars. Massive young stars explode as supernovae, releasing shock waves that can combine to form large-scale outflows of gas. These winds remove cold gas—the raw material for star formation—from galaxies, reducing their ability to form new stars in the future. This process plays a key role in regulating star formation and preventing galaxies from growing too quickly.
AGN-driven winds are even more powerful. When a supermassive black hole accretes large amounts of matter, it releases intense radiation and high-energy jets that can drive gas out at speeds of thousands of kilometers per second. These winds can heat or expel gas over vast regions of a galaxy, shutting down star formation completely. This helps explain why many massive galaxies in the universe appear “quenched” or inactive, containing mainly old stars.
Galactic winds also enrich the space between galaxies by carrying heavy elements like carbon, oxygen, and iron—produced in stars—into the intergalactic medium. This chemical enrichment affects future galaxy formation and the evolution of the universe on large scales. Overall, galactic winds are a crucial feedback mechanism that shapes galaxies by controlling their gas content, star formation, and long-term evolution.