
Outflows of gas driven by stars and black holes that regulate galaxy evolution.Galactic winds are large-scale outflows of gas and dust driven by intense star formation or the activity of a supermassive black hole at a galaxy's center. These winds can travel at hundreds to thousands of kilometers per second, carrying material far beyond the galactic disk. They play a crucial role in regulating star formation by removing the gas needed to form new stars, and they enrich the intergalactic medium with heavy elements forged in stars.
The concept was developed in the 1960s and 1970s, with early theoretical work by astronomers like Lyman Spitzer and William Mathews. Observations of starburst galaxies in the 1990s provided direct evidence for these outflows.
The wind is powered by the combined energy of supernova explosions and stellar winds from hot, massive stars, or by the accretion disk around a supermassive black hole. This energy heats the surrounding gas to millions of degrees, causing it to expand and accelerate outward. The hot gas can also sweep up cooler clouds of gas and dust, dragging them along. The wind's speed and structure depend on the balance between the energy input and the gravitational pull of the galaxy.
Galactic winds are key to understanding galaxy evolution, including why massive galaxies stop forming stars and how heavy elements spread through the universe. They are also studied as potential sources of cosmic rays.
The wind from the Milky Way's central black hole, Sagittarius A*, is so powerful that it carves out a 'chimney' of hot gas extending thousands of light-years above and below the galactic plane.

















