Astronomers have uncovered striking new evidence that galactic winds, long suspected of shutting down star formation in massive galaxies, were already blowing fiercely just a billion years after the Big Bang.<\/p>\n
Using resolved observations of both cold and ionized gas, researchers have identified a powerful supernova-driven outflow<\/a> in a galaxy at redshift 5.3, when the Universe was only 1.1 billion years old. This marks the first time that scientists have directly observed winds blowing fiercely enough to quench star formation in such an early, massive system.<\/p>\n This outflow, probably driven by projected merger activity, is expelling gas at a two-to-one ratio relative to its generation. If continued, it could realistically blow all of the galaxy\u2019s cool gas out within 100 million years = essentially dusting the cupboard where food is stored for new stars.<\/p>\n \u201cOur results suggest that powerful merger-driven outflows may be a key mechanism to produce abundant massive quiescent galaxies in the early Universe<\/a> when a large fraction of massive galaxies is interacting<\/a>,\u201d the team reports.<\/p>\n The most energetic outflows ever witnessed in the universe<\/a><\/p>\n The mass and energetics of this common, distant outflow have much in common with starburst-driven superwinds seen in more nearby galaxies. That kind of consistency points to something surprising: the efficiency of stellar feedback, or exploding stars acting to regulate galactic growth, may have changed relatively little over 12 billion years of cosmic history.<\/p>\n Galactic winds have long been considered a likely driver of rapid quenching, the process by which galaxies abruptly stop forming stars. But until now, direct evidence was lacking that early galaxies could generate winds powerful enough to matter. This new observation fills that gap, showing that even in the Universe\u2019s infancy, massive galaxies were capable of blowing themselves dry.<\/p>\n Scientists wanted to see if galaxy winds have changed over time. They examined 99 examples of star-formation-driven outflows spanning 12 billion years. These winds were studied in ionized gas, which is the easiest to detect both nearby and far away.<\/p>\n They compared how much energy from starbursts pushes gas out of galaxies<\/a>. The results show that the strength of these winds has remained roughly the same throughout cosmic history, even though galaxies themselves have changed significantly.<\/p>\n